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DIY Stompboxes => Building your own stompbox => Topic started by: frequencycentral on September 04, 2008, 03:22:05 PM

Title: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 04, 2008, 03:22:05 PM
I just started playing with these 5672 submini pentodes on the breadboard tonight, basically to check that they work. I bought four - they were manufactured in 1958! They are tiny, and are completely dwarfed by my 6111 submini dual triodes.

They require a 1.25 volt heater voltage (at only 50ma), I used a LM317 to provide that.

When I hooked up the heater voltage I expected to see a glowing tube..............but...........nothing.

So I rigged up a simple test circuit to check out if the tube was actually functioning - it was!

All of a sudden I was overdriving my VJ clone to saturation - basically what I usually use an LPB to do.

Here's the circuit, the clean boost is about 10db - and very tubey:

(http://i210.photobucket.com/albums/bb292/frequencycentral/PentaBoost.jpg)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on September 04, 2008, 03:30:33 PM
Weird, I was just about too search for something along these lines. Can't wait to see other responces. Very nice  :icon_mrgreen:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Renegadrian on September 04, 2008, 03:51:44 PM
Rick, I got a space charge 12bl6 tube - got to take out something from that tube...cheap and easy to find on the bay...
still I love to see how pentodes can be used!!!Gotta learn from your circuit!  :icon_wink:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 04, 2008, 03:54:25 PM
Quote from: Renegadrian on September 04, 2008, 03:51:44 PM
Rick, I got a space charge 12bl6 tube - got to take out something from that tube...cheap and easy to find on the bay...
still I love to see how pentodes can be used!!!Gotta learn from your circuit!  :icon_wink:

Didn't you buy a submini pentode a while back? I remember you mentioned it but I can't remember it's name (began with a 5 though) - maybe if you check the pinout against the 5672 you could use it in this circuit.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Renegadrian on September 04, 2008, 04:07:22 PM
Yes Sir, I got 5678 and 6205. :icon_wink:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 04, 2008, 04:59:23 PM
Quote from: Renegadrian on September 04, 2008, 04:07:22 PM
Yes Sir, I got 5678 and 6205. :icon_wink:

I don't think the 5678 is a pin for pin replacement for the 5672 (the specs are similar though). The heater pins are the opposite way round. In both tubes Grid #3 is connected to the filament pins. You should be able to work something close out though........ :icon_biggrin:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ambulancevoice on September 04, 2008, 05:11:07 PM
have you tried other pentodes???
just to see what they sound like
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 04, 2008, 05:13:44 PM
Quote from: ambulancevoice on September 04, 2008, 05:11:07 PM
have you tried other pentodes???
just to see what they sound like

5672 are the only ones I have right now........

..........and for sure I will be cascading them - for a "PentaDrive" !!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Steben on September 05, 2008, 04:21:41 AM
AFAIK,

pentodes have similar response curves to MOSfets (harmonic contents), more logarithmic, where triodes are square root.
Yet I think they still clip softer than any semiconductor.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ~arph on September 05, 2008, 04:42:27 AM
..the odds,

I just received 10 of these tuesday... I expected glowing too, none of that but they do work!
I'll try your heater supply, I was having troubles with it..

Regards,

a

EDIT:  btw, I allready figured out that these tubes do not have enough gain to do a PSO (for an all tube vibracaster)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 05, 2008, 06:42:30 AM
Quote from: ~arph on September 05, 2008, 04:42:27 AM
..the odds,

I just received 10 of these tuesday... I expected glowing too, none of that but they do work!
I'll try your heater supply, I was having troubles with it..


10 you say - maybe cascade the lot!!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ~arph on September 05, 2008, 06:57:25 AM
(read again)   :(
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 05, 2008, 05:14:54 PM
I realised that the 100k resistor from pin 3 of the pentode to earth is completely pointless - don't know how that got there! So i have removed it from the schematic.

Rick

(http://i210.photobucket.com/albums/bb292/frequencycentral/PentaBoost-1.jpg)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on September 10, 2008, 02:10:15 PM
1st attempt at a layout using Bancika's layout creator.  Apart from the LM317t needing a heatsink and the extra space that that will require does this look ok?

(http://i126.photobucket.com/albums/p94/williamthesweet/pentaboost1-1.gif)

  I'm working on a layout with both the 5672 and pot on board to cut wiring (thanks Rick!).
Title: Breadboard report
Post by: Renegadrian on September 13, 2008, 06:24:13 AM
Spent this saturday morning breadboarding, I tried the Pentaboost with the submini pentode I have, the 5678.
It works, and the 5678 is a good sub(mini)substitute.
I am powering the heaters with a AAA battery. It should be easy to wire the neg. to the input jack to cut it out when not connected, as all the other battery  powered pedals...
As for the valvy I am surprised to get a good sound out of a stupidly simple circuit...That's the beauty of DIY...
Rick, as I am looking for more gain, should I try the Pentadriver?
Title: Re: Breadboard report
Post by: frequencycentral on September 13, 2008, 06:38:35 AM
Quote from: Renegadrian on September 13, 2008, 06:24:13 AM
Spent this saturday morning breadboarding, I tried the Pentaboost with the submini pentode I have, the 5678.
It works, and the 5678 is a good sub(mini)substitute.
I am powering the heaters with a AAA battery. It should be easy to wire the neg. to the input jack to cut it out when not connected, as all the other battery  powered pedals...
As for the valvy I am surprised to get a good sound out of a stupidly simple circuit...That's the beauty of DIY...
Rick, as I am looking for more gain, should I try the Pentadriver?

Hi Adriano - pleased you have success with that. I thought it might work with a 5678 too.

More gain you say? Metal head!!   :icon_twisted:

I think you would be pleased with a PentaDriver. Maybe I should do some A/B/C soundclips of the Valvecaster, Pepper Shredder and PentaDriver.

You should maybe try your PentaBoost in front of your Valvecaster - or you Valvecaster in front of the Pentaboost. Could be interesting!

Adriano - you're a Veroboard man (I don't use Vero) - could you verify sweeywilly's layout - or suggest your own layout?

EDIT: I think if should be possible to mount both the tube and the pot on the Veroboard.

Title: Re: Breadboard report
Post by: Renegadrian on September 13, 2008, 07:05:02 AM
Quote from: frequencycentral
More gain you say? Metal head!!   :icon_twisted:
YEAH!!! (http://digilander.libero.it/le.faccine/faccinea/musica%20%26%20feste/0005034.gif)

Quote
Adriano - you're a Veroboard man (I don't use Vero) - could you verify sweeywilly's layout - or suggest your own layout?

Well, I breadboarded right from the vero layout posted by Willy...It seems correct all the way, so yep, I'd say

VERIFIED


Maybe he wired the VOL backwards? Usually is OUTPUT-->pin 3 and pin 1-->ground. Just flip the two wires.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on September 13, 2008, 08:59:09 AM
Yup, more than likely.  Seem to have a habit of reversing pot wiring.  Pin outs - fine, but pots?!??!?!

Thanks for the verification on the layout Adriano!

Rick, I'll incorporate at least the tube on the board in next version!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 13, 2008, 12:30:30 PM
Just a bump to publish the final schematic. I've been deleting and re-uploading the schematic in Photobucket when I have made changes - but it occurs to me that 'cookies' might prevent the viewing unless you click 'refresh'.

(http://i210.photobucket.com/albums/bb292/frequencycentral/PentaBoost-2.jpg)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on September 13, 2008, 01:54:26 PM
soundclips of this bad boy yet?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 13, 2008, 02:03:15 PM
Quote from: mth5044 on September 13, 2008, 01:54:26 PM
soundclips of this bad boy yet?

Believe it or not, I'm not planning to build this one. Designing the PentaBoost was just a stage on the way to designing the PentaDriver. I built the PentaDriver, which can also function as a clean boost. So I'll leave it to someone else (Adriano ?) to post soundclips.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Renegadrian on September 13, 2008, 09:24:35 PM
Why not, give me some days then... :icon_wink:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on September 13, 2008, 11:59:39 PM
While a sound clip isn't really necessary, it would sure help for me and other people to get a feeling as to what it sounds like. Is it a clean boost? I heard the pentadriver, and it was sick, but if that was only one extra tube, I'm imagining just half the gain from it.
Title: Pentaboost
Post by: Renegadrian on September 14, 2008, 05:36:16 AM
Yeah, I'd say clean booster with a little breakup if hit it harder...I'll try to post a sound clip anyway, but I'd say it reminds me those sounds - Still loving you intro - Knockin' on Heaven's Door intro - House of the Rising Sun intro (but cleaner than the Animals)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 14, 2008, 06:35:12 AM
Quote from: mth5044 on September 13, 2008, 11:59:39 PM
While a sound clip isn't really necessary, it would sure help for me and other people to get a feeling as to what it sounds like. Is it a clean boost? I heard the pentadriver, and it was sick, but if that was only one extra tube, I'm imagining just half the gain from it.

What's happening in the PentaDriver is that the first pentode is boosting the signal relatively cleanly, the boosted signal hitting the second pentode is too much for it's input to handle, so it clips. Not so different from how a FF works really.
Title: "PentaBoost"
Post by: Renegadrian on September 21, 2008, 04:44:26 PM
Here's my version...

(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=36696&g2_serialNumber=2)

After I successfully breadboarded it, decided to draw a vero layout by myself, now in my gallery (http://www.aronnelson.com/gallery/main.php/v/Renegadrian/Pentaboost.gif.html),
and decided to build and box it somehow...Found a little wooden box at Leroy Merlin while shopping
for spray cans, so I thought "WHY NOT?!"  :icon_lol:
So here it is...It uses a 5678 tube and it's powered by a 9V and a 1.5V AAA for the heaters.

(http://img220.imageshack.us/img220/6033/200902smiz4.th.jpg) (http://img220.imageshack.us/my.php?image=200902smiz4.jpg)(http://img220.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img291.imageshack.us/img291/402/200903smym1.th.jpg) (http://img291.imageshack.us/my.php?image=200903smym1.jpg)(http://img291.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img258.imageshack.us/img258/9229/200904smiy1.th.jpg) (http://img258.imageshack.us/my.php?image=200904smiy1.jpg)(http://img258.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img252.imageshack.us/img252/2954/200905smra0.th.jpg) (http://img252.imageshack.us/my.php?image=200905smra0.jpg)(http://img252.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)
(http://img401.imageshack.us/img401/692/200906smtz9.th.jpg) (http://img401.imageshack.us/my.php?image=200906smtz9.jpg)(http://img401.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img252.imageshack.us/img252/5687/200907smoa4.th.jpg) (http://img252.imageshack.us/my.php?image=200907smoa4.jpg)(http://img252.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img401.imageshack.us/img401/6921/200908smia7.th.jpg) (http://img401.imageshack.us/my.php?image=200908smia7.jpg)(http://img401.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img168.imageshack.us/img168/1553/200909smud7.th.jpg) (http://img168.imageshack.us/my.php?image=200909smud7.jpg)(http://img168.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on September 21, 2008, 05:01:43 PM
Very nice and unique build Adriano - such a thrill when someone builds my design too!! :icon_lol:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on September 21, 2008, 06:11:17 PM
Very cool, as usual.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 03, 2008, 01:50:33 PM
Was just warming the iron up to get my 1st effort finished when I saw Adriano's.  Mine's not anywhere near as pretty, but hopin it'll sound sweet just the same!

(http://i126.photobucket.com/albums/p94/williamthesweet/P011008_2236.jpg)

(http://i126.photobucket.com/albums/p94/williamthesweet/P011008_2238.jpg)

(http://i126.photobucket.com/albums/p94/williamthesweet/P011008_2239.jpg)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 03, 2008, 02:01:41 PM
Lookin good...radical in that Boss housing. Might be an idea to use a loop of wire to stop the tube moving about, soldered either side and bracing it. I like how you've mounted that tube on it's side though. Sweet. :icon_lol:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 03, 2008, 05:22:21 PM
cheers rick, got it working pretty much 1st go, but have a slight oscillation problem due to some poor lead dress!  will fix tomorrow and post sound clips.  not a huge boost on it's own - my wife said "all that effort for THAT?" - but when I stuck it in front of an EH English Muff'n with a 12AU7 in the gain stage it just pushes it's tubes beautifully.  can't wait to hear it in front of my amp!

nice work rick!

edit - dig the boss joke rick, outtasight...
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 03, 2008, 05:31:17 PM
Excellent - try a LPB in front of the Pentaboost, drive it hard and listen to it break up really nicely.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 03, 2008, 07:24:42 PM
Quote from: sweetwilly on October 03, 2008, 05:22:21 PM
cheers rick, got it working pretty much 1st go, but have a slight oscillation problem due to some poor lead dress!  will fix tomorrow and post sound clips.  not a huge boost on it's own - my wife said "all that effort for THAT?" - but when I stuck it in front of an EH English Muff'n with a 12AU7 in the gain stage it just pushes it's tubes beautifully.  can't wait to hear it in front of my amp!

nice work rick!

edit - dig the boss joke rick, outtasight...

This is all the motivation I need to actually get off my lazy ass and build the dual valvecaster with pentaboost in front of it. Thanks!

Oh and soundclips.  :icon_mrgreen:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 03, 2008, 08:24:03 PM
Quote from: mth5044 on October 03, 2008, 07:24:42 PM
Quote from: sweetwilly on October 03, 2008, 05:22:21 PM
cheers rick, got it working pretty much 1st go, but have a slight oscillation problem due to some poor lead dress!  will fix tomorrow and post sound clips.  not a huge boost on it's own - my wife said "all that effort for THAT?" - but when I stuck it in front of an EH English Muff'n with a 12AU7 in the gain stage it just pushes it's tubes beautifully.  can't wait to hear it in front of my amp!

nice work rick!

edit - dig the boss joke rick, outtasight...

This is all the motivation I need to actually get off my lazy ass and build the dual valvecaster with pentaboost in front of it. Thanks!

Oh and soundclips.  :icon_mrgreen:

i'm planning the exact same thing.  this build was a practice run and a b'day present rolled into one.  really simple design with great results. 

i was planning to use Renegadrian's Twincaster layout - you?

Rick - I ended up with LM317Ms not Ts.  with the 100R resistor I get 1.2v from Pin 2.  how much difference would 0.05v make here?  and my tube does get a nice amber glow going - simple things... ;D

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 03, 2008, 08:55:15 PM
Quote from: sweetwilly on October 03, 2008, 08:24:03 PM
i'm planning the exact same thing.  this build was a practice run and a b'day present rolled into one.  really simple design with great results. 

i was planning to use Renegadrian's Twincaster layout - you?

Rick - I ended up with LM317Ms not Ts.  with the 100R resistor I get 1.2v from Pin 2.  how much difference would 0.05v make here?  and my tube does get a nice amber glow going - simple things... ;D



I'm not making a 'twincaster' per se, but it will be two cascaded valvecasters with the pentaboost out infront. Although, the second valvecaster will not be avaliable unless the first one is on. It has a clever switching scheme with a clever name, but I will not reveal that until its done  :icon_mrgreen: Plus I like having lots of control and I'm pretty sure the twincaster had dual knobs for some of them.
Title: Pentaboost
Post by: Renegadrian on October 04, 2008, 02:20:49 AM
Nice board Willy!!! I like the way you placed things...And oh that ugly enclosure!!! Aahahah  :icon_eek:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 07:28:57 AM
Quote from: mth5044 on October 03, 2008, 08:55:15 PM
Quote from: sweetwilly on October 03, 2008, 08:24:03 PM

I'm not making a 'twincaster' per se, but it will be two cascaded valvecasters with the pentaboost out infront. Although, the second valvecaster will not be avaliable unless the first one is on. It has a clever switching scheme with a clever name, but I will not reveal that until its done  :icon_mrgreen: Plus I like having lots of control and I'm pretty sure the twincaster had dual knobs for some of them.

I eagerly await the revelation!!!
Quote from: Renegadrian on October 04, 2008, 02:20:49 AM
Nice board Willy!!! I like the way you placed things...And oh that ugly enclosure!!! Aahahah  :icon_eek:

Cheers Adriano, had to do something with the dead tremolo I had!  Waste not...
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 04, 2008, 07:36:20 AM
Quote from: sweetwilly on October 03, 2008, 08:24:03 PM
Rick - I ended up with LM317Ms not Ts.  with the 100R resistor I get 1.2v from Pin 2.  how much difference would 0.05v make here?  and my tube does get a nice amber glow going - simple things... ;D

The 5672 data sheet quotes 1.25 volts +/- 20%, so the minimum is 1 volt, the maximum is 1.5 volts. I don't think that 0.05 will make any difference. Adriano used a 1.5 volt battery for the heater in his build - and 9 volts for the plate. I'd be interested to know if there is any sonic difference there.

Damn - your tube glows?? Mine doesn't!! Damn!!

Yesterday I played about with asymettrical diode clipping at the Pentaboost's output, I tried loads of different diodes but only got reasonable results with a couple of germanium (I have no idea what they are). The sound was good, a very soft but pleasing overdrive, but failed to achieve unity with the bypassed signal. Now I'm trying to figure how to get more gain from a single 5672. Any ideas anyone?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 08:44:27 AM
Have been pulling hair out all morning trying to find the source of this high pitched squeal I get when I turn mine on.  It fades away within 10 seconds mostly, and oscillates sometimes so thought it might be wires running too close.  After a bit of poking about think it might be the tube itself.  A little tap increases the squeal significantly.  Out with it, and in with a new and we'll see how it goes!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 11:08:37 AM
Well, somehow turned a working Pentaboost into a brick and cannot figure out why!  Audio probed and racked mind but think that it's prob something to do with all the 2nd hand bits'n'pieces I used!

Figure I'll scratch this effort and try, try again!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 04, 2008, 11:28:42 AM
Quote from: sweetwilly on October 04, 2008, 11:08:37 AM
Well, somehow turned a working Pentaboost into a brick and cannot figure out why!  Audio probed and racked mind but think that it's prob something to do with all the 2nd hand bits'n'pieces I used!

Figure I'll scratch this effort and try, try again!


Yeah, similar has happened to me with other projects - persevere though.

If you want to post voltages at all 5 pins of the 5672 and the 3 pins of the 317 we can compare and maybe figure it out.

I've never had a 5672 squeal though.  ???
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 12:04:08 PM
Cheers Rick, really maessed this one up so making note of lessons learned and moving on!  Definitely worth the effort tho!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 04, 2008, 01:05:27 PM
Ah that sucks man, sorry to hear about the trouble.

I ordered five of the subminis incase some had trouble, plus they were just too cheap to not order more then one.

I hope you get your problems solved out before the big twincaster build!  :icon_mrgreen:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 04, 2008, 01:09:52 PM
sweetwilly, you really should debug though........don't waste your efforts so far, I bet it's something really simple. Post your voltages!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 04, 2008, 02:21:32 PM
Here's my 5672 voltages anyway, could be useful for someone sometime:

Pin 1: 4.24v
Pin 2: 7.72v
Pin 3: 1.25v
Pin 4: -0.18v
Pin 5: 0.004v
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 02:49:22 PM
Will do Rick.  Honestly, I rushed my first effort, poorly planned the wiring and re-used a lot of pieces.  Have rebuilt, much neater this time, but still no action.

My voltages are WAY out form yours and the fact that Pin 5 is 12v kind of tells me I made a slight mistake somewhere!

Will look into it tomorrow - definitely not giving up!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 04, 2008, 03:06:52 PM
Quote from: sweetwilly on October 04, 2008, 02:49:22 PM
Will do Rick.  Honestly, I rushed my first effort, poorly planned the wiring and re-used a lot of pieces.  Have rebuilt, much neater this time, but still no action.

My voltages are WAY out form yours and the fact that Pin 5 is 12v kind of tells me I made a slight mistake somewhere!

Will look into it tomorrow - definitely not giving up!

Yeah 12 volts to the heater won't be good for it!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 05:03:55 PM
Yup.  My jumper from Pin 5 to ground overstepped by a hole! 

Reckon the tube's dead Rick, or could it be something I'm missing? Voltages are

1 - 0.00
2 - 10.94
3 - 1.20
4 - -0.01
5 - 0.00

Thanks!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 04, 2008, 05:28:53 PM
Quote from: sweetwilly on October 04, 2008, 05:03:55 PM
Yup.  My jumper from Pin 5 to ground overstepped by a hole! 

Reckon the tube's dead Rick, or could it be something I'm missing? Voltages are

1 - 0.00
2 - 10.94
3 - 1.20
4 - -0.01
5 - 0.00

Thanks!

Don't give up on the tube yet - they're pretty tough. Have you got a short to ground at pin 1? Are you sure the resistor between pin 2 and +ve is the right value?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 05:47:40 PM
Just to check, I swapped ol' squealy in to see what it's voltages are like.

Think I must have a short to ground somewhere as still nowt on Pin 1.  Pin 2 is only 3.12 on this one though.  FWIW - squealy glows, the previous one didn't (well it did, very brightly, when I had 12v going to the heater!).  Don't think this is of any consequence, just interesting,
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 04, 2008, 05:54:34 PM
I accidentaly put 12 volts through a 6111's heater recently (6.3 volt heater that one) - it survived though. Do you have a breadboard? Worth having one just to use as a test rig to check things. The small ones are a couple of quid at Maplin.

Keep me posted!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 06:05:52 PM
 :icon_redface: :icon_redface: :icon_redface: I know, quite ashamed I don't have one really. 

Sorted the short out - found a tiny solder bridge under the magnifying glass. 

Just probing and found at least 1 dodgy solder.  Will keep at it as long as the wife allows!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 04, 2008, 06:58:16 PM
Perseverance has paid off - I'm as close to your voltages as I think I will get and it's sounding sweet!  Another red face needed here -  :icon_redface: as this tube is behaving like the 1st - even though it's a different brand.  Have you found them to be quite microphonic or have I just stumbled across a couple by coincidence?  Thinking the squeal could be my "clean" power supply not being as clean as it could be.  It's only noticeable when not playing and I can't think of anytime I'd have a boost on while not playing so don't see it as a huge problem!

Will try to figure out how to post sound clips tomorrow and will post some pics - my best effort at lead dress to date and I'm quite proud!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 04, 2008, 07:15:54 PM
Glad to hear its working. Maybe you should invest in a 1spot 12v adapter? I've never had the 12v, but I have 3 9v's and they are all clean and reliable. Especially if you are going to build the twincaster and use 12v's. Plus I think they give out 1200mA so thats plenty enough.

Just a suggestion  :icon_mrgreen: Keep up the goodwork!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 05, 2008, 06:52:14 AM
Here are my working (with a slight squeal!) voltages.

1 - 3.19
2 - 6.21
3 - 1.25
4 - -0.01
5 - 0.00

Just waiting on my battery to charge and will post some pics. 

Thanks for everyone's help and encouragement!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 05, 2008, 07:01:20 AM
Quote from: sweetwilly on October 04, 2008, 06:58:16 PM
Perseverance has paid off - I'm as close to your voltages as I think I will get and it's sounding sweet!  Another red face needed here -  :icon_redface: as this tube is behaving like the 1st - even though it's a different brand.  Have you found them to be quite microphonic or have I just stumbled across a couple by coincidence?  Thinking the squeal could be my "clean" power supply not being as clean as it could be.  It's only noticeable when not playing and I can't think of anytime I'd have a boost on while not playing so don't see it as a huge problem!

Will try to figure out how to post sound clips tomorrow and will post some pics - my best effort at lead dress to date and I'm quite proud!

I ve never had squealing with 5672, and I've breadboarded lots of ideas with them recently. The do go 'ding' if I tap them with my fingernail though. In my PentaDriver I put foam padding round them.

The squealing could be a power supply issue, or a solder bridge. Did you try running it from a 9 volt battery to see if the squeal goes away?

Glad you got it working though - I bet the wife is pleased too!

Watch out for my 'Red Star Drive' coming up soon - another 5672 clipping device................


EDIT: I use this power supply: http://www.maplin.co.uk/Module.aspx?ModuleNo=32746
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 05, 2008, 07:10:13 AM
OK, after clipping a battery snap in and hearing no squeal I figured it was either the power supply or the hole in the wall.  Turns out to be the hole in the wall!  Tried another outlet and get no hum, squeal or noise! 

SWEET!!!!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 05, 2008, 12:13:11 PM
Ah the sweet smell of success.

Congrats.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 05, 2008, 12:44:44 PM
The squeal never went away  >:(  just wasn't noticeable without the amplification it gets from the rest of the gang.  This thing drives tubes so well that I won't be giving up on it.  I was going to give this to a mate that makes pretty messed up experimental stuff, so the squeal may appeal!

Mark 2 might even get a prettier enclosure and all!

(http://i126.photobucket.com/albums/p94/williamthesweet/P051008_1345.jpg)

(http://i126.photobucket.com/albums/p94/williamthesweet/P051008_1346.jpg)

(http://i126.photobucket.com/albums/p94/williamthesweet/P051008_1347.jpg)
Title: Pentaboost
Post by: Renegadrian on October 05, 2008, 05:26:38 PM
YEAH, don't give up, I know it gets you in a bad mood but hey when you get it working correctly it's like heaven... :icon_wink:

Red Star Drive - what is that? Mate, you ain't tired of tubes yet?!  :icon_wink: (hope you never will!!!)
Title: Re: Pentaboost
Post by: frequencycentral on October 05, 2008, 05:39:19 PM
Quote from: Renegadrian on October 05, 2008, 05:26:38 PM
Red Star Drive - what is that? Mate, you ain't tired of tubes yet?!  :icon_wink: (hope you never will!!!)

Red Star Drive = You have to wait - not fully cooked yet!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 05, 2008, 05:54:48 PM
Theres going to be 5 mini tubes isnt there? I mean, it only makes sense... star has five points, five tubes, all glowing red. Oh man.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 06, 2008, 03:29:55 PM
A little bit of tinkering again today.  Clipped a battery in and put it in front of the English Muff'n with it's volume cranked and there is next to no noise whatsoever.  Actually sounds pretty sweet running of the 9v.  That pretty much leaves the PS as the culprit of my squealing.  I'll give that Maplin one a try Rick.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 06, 2008, 04:42:00 PM
Quick sound clip running off the battery is  on my Myspace.

http://www.myspace.com/therealsweetwilly (http://www.myspace.com/therealsweetwilly)

It's Gibson Firebird with minihumbuckers, bridge pu into Pentabeast (as mine is apltly named) then into EH English Muff'n - mixer - Cubase.  The Muff'n has a 12AT7 in gain stage and a 12AX7 output, the gain set about 9 o'clock and the level at 3 o'clock.  2 runs through the riff with just the Muff'n then kick the Pbeast into action.  Bearing in mind that this is at 9v instead of 12, it's pretty impressive.  With 12v the boost is more noticeable, but my PS issues meant a good sound clip was impossible.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 06, 2008, 07:27:32 PM
Here's the clip so you don't have to suffer my myspace!

http://www.aronnelson.com/DIYFiles/up/Pentaboost_Clip.mp3 (http://www.aronnelson.com/DIYFiles/up/Pentaboost_Clip.mp3)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 06, 2008, 11:38:28 PM
Sounds good man.

Can someone give me the measurements on the 5672 tube?

The diameter is really what I need the most, at the bottom, so I know what size hole to drill. Thanks!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ~arph on October 07, 2008, 03:03:31 AM
It is not cilindrical. but more box shaped.   I'd say like 5x14mm, but that is a rough guess.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 07, 2008, 03:44:07 AM
Quote from: mth5044 on October 06, 2008, 11:38:28 PM
Sounds good man.

Can someone give me the measurements on the 5672 tube?

The diameter is really what I need the most, at the bottom, so I know what size hole to drill. Thanks!

Datasheet:

http://frank.pocnet.net/sheets/127/5/5672.pdf

http://frank.pocnet.net/sheets/030/5/5672.pdf

http://frank.pocnet.net/sheets/138/5/5672.pdf
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 07, 2008, 02:31:31 PM
Quote from: sweetwilly on October 06, 2008, 07:27:32 PM
Here's the clip so you don't have to suffer my myspace!

http://www.aronnelson.com/DIYFiles/up/Pentaboost_Clip.mp3 (http://www.aronnelson.com/DIYFiles/up/Pentaboost_Clip.mp3)

Hey Willy just had a listen to your soundclip - nice one! Sounds great - you can really hear when the boost kicks in!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 07, 2008, 02:39:38 PM
Thanks Rick, mine seems to fatten the signal when feeding other pedals, but is a pretty cleanish boost (breaking up a little with volume maxed) when at the end of the chain.

A really simple design that does exactly what it says it does.

Also, 9v sounds pretty good to my ear, but that's only with my home recording setup - into a good tube amp at volume and 12v might be better?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: pqt_bach on October 07, 2008, 06:04:29 PM
Hi everyone,

Cool project, but I have one issue with it... these tubes are VERY micophonic in my pedal. Did any of you encounter such a problem?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 07, 2008, 06:31:03 PM
Yeah, led me to tear down my first build as I thought the tube was dead!  If you can reduce the vibration to the tube it pretty much eliminates any troubles.  My tube is board mounted and I've used double sided tape that overlaps the board and makes it fit snugly into the enclosure, but protects it from the mechanical clunk of the switch. 
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 07, 2008, 06:41:03 PM
Quote from: pqt_bach on October 07, 2008, 06:04:29 PM
Hi everyone,

Cool project, but I have one issue with it... these tubes are VERY micophonic in my pedal. Did any of you encounter such a problem?

Quote from: frequencycentral on October 05, 2008, 07:01:20 AM
They do go 'ding' if I tap them with my fingernail though. In my PentaDriver I put foam padding round them.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: pqt_bach on October 08, 2008, 04:02:23 AM
Cool.

And did those measures eliminate the all of the microphonics and "thouch sensitivity" ?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 08, 2008, 05:32:14 AM
Pretty much. 
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 09, 2008, 12:42:59 PM
All (a)board layout!

(http://i126.photobucket.com/albums/p94/williamthesweet/pentaboost3.gif)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 13, 2008, 04:24:00 AM
hi rick, spoke to you on myspace a couple of weeks ago, thanks for the help there! got my build finished ant thought it was all good, when i plugged in power the valve glowed intensly and then all power stopped. pretty sure my hook up is all good. when i checked the power supply it was set to centre pos not neg. would this have caused this kinda problem do you think? sorry, pretty new to this! if it is just that i'll try a new valve in there, if not i'll rewire the lot!

sweet willy, are you going to be posting up your 'all on the board' layout again? it seems to have run away!

cheers and hello to all! this looks like a great forum for newbs to find people that know their stuff!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 13, 2008, 05:04:07 AM
there were some, er, school boy errors - fixed em now so here it is again.

(http://i126.photobucket.com/albums/p94/williamthesweet/pentaboost4.gif)

Having looked at Rick's Red Star Drive pic, I'm sure there's a better way to lay it out! - http://www.diystompboxes.com/smfforum/index.php?topic=71350.0 (http://www.diystompboxes.com/smfforum/index.php?topic=71350.0)

I fried a tube (though salvaged it for a rather snazzy necklace for the missus!) with a short.  I had same as you - big time glow then nothing.  Check the voltages on the pins of the tube.  I was getting over 10v on pin 2 and (and possibly pin 1 from memory) with the fried tube. You might want to replace the electros as well. RG made a great post earlier this week on this very subject! - http://www.diystompboxes.com/smfforum/index.php?topic=55003.0 (http://www.diystompboxes.com/smfforum/index.php?topic=55003.0)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 13, 2008, 05:50:12 AM
Quote from: stereovoid on October 13, 2008, 04:24:00 AM
hi rick, spoke to you on myspace a couple of weeks ago, thanks for the help there! got my build finished ant thought it was all good, when i plugged in power the valve glowed intensly and then all power stopped. pretty sure my hook up is all good. when i checked the power supply it was set to centre pos not neg. would this have caused this kinda problem do you think? sorry, pretty new to this! if it is just that i'll try a new valve in there, if not i'll rewire the lot!

sweet willy, are you going to be posting up your 'all on the board' layout again? it seems to have run away!

cheers and hello to all! this looks like a great forum for newbs to find people that know their stuff!

Definately replace the electro caps. These tube heaters are pretty hardy - though quite how hardy I'm not too sure. The LM317 might not have survived either. Shame! Just check out each bit at a time! Good luck!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 13, 2008, 05:56:05 AM
thank you so much for the replies guys, it was my own fault. to eager to get it running...before walking! got some spare valves (and a whole load of spare time coming up!-thank the victorians for inventing holiday leave!) going to try your all on layout sweet willy. think the whole situation has just made me more determind to get it going! will keep you posted! thank you.



sorry about spelling and grammer.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 13, 2008, 06:04:38 AM
No worries.  As noted earlier in this thread, the tubes can be quite microphonic, so take that into account when planning the enclosure - you want something to dampen the stomp.  Most of the "mechanical" noise seems to transfer through the leads of the tube on mine, so not a great deal can be done there, but foam padding around and under the tube (you can glue a small piece onto the board under where the tube will lie) will make a big difference.

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 13, 2008, 06:15:35 AM
cool, i was holding my valve down with a plastic tie clip. used the holes of the vero board slightly enlarged to get it through. just to clarify, pin one of the lm317t goes in at h2 and pin one of the valve goes in at r1? not putting in a stomp as i'm looking at this being an 'always on' at the end of chain. could i incorparate an LED if it went from 12v pos on the wallwart to ground on the board? cheers.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 13, 2008, 07:57:33 AM
Yup, (although I had to look up the datasheet for the LM317 again to double check - you got me nervous!) pins 1 of the tube and LM317 go at R1 and H2 respectively.

If it's always on, any need for an LED at all?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 14, 2008, 11:11:18 AM
cool thanks for that, yeah the LED idea was more for an artistic paint job idea once its complete, not essential but was wondering if that would be how to do it if i did put one in! got to get it working first though!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 14, 2008, 11:27:57 AM
just wire the led up from the powersource to ground. You could just put it with a resistor right across the power jack I guess.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 15, 2008, 04:11:29 AM
cheers for that! if i get the circuit working i wanted to paint a lighthouse on the case...don't know why, just a bit of an art procect! was going to use an LED as the beacon! will be wiring up the jacks today, will let you know how i get on!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 15, 2008, 04:37:36 AM
procect = project...can never find that j on the keyboard!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 15, 2008, 04:50:51 AM
In that  case you definitely NEED that LED!!!  Think about the sailors!  You can get flashing LEDs (they flash around 1 - 3 times per second) which could be a cool visual effect.  Mucho mojo!

http://www.elexp.com/opt_6bid.htm (http://www.elexp.com/opt_6bid.htm)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 15, 2008, 05:21:09 AM
now that is a super sweet idea! they do them at maplin too, and under a pound...could be well worth it! by the way sweet willy, i added you as a a friend on myspace (im club27). really like your bands songs! you guys should hos up to norwich sometime!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 15, 2008, 05:42:02 AM
Post pics when it's done - won't get the full flashing effect, but I think we can imagine it!

And cheers - is just my bedroom recordings that have been really well produced and mastered.  I play pretty much everything except the drums which I either program or steal, sh!  ;)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 15, 2008, 01:26:50 PM
Quote from: sweetwilly on October 15, 2008, 04:50:51 AM
In that  case you definitely NEED that LED!!!  Think about the sailors!  You can get flashing LEDs (they flash around 1 - 3 times per second) which could be a cool visual effect.  Mucho mojo!

http://www.elexp.com/opt_6bid.htm (http://www.elexp.com/opt_6bid.htm)

My concern would be that LEDs draw a lot of current when you turn them on, which can cause 'LED popping' (http://www.muzique.com/lab/led.htm). I'm not sure, but I think the flashing LED might cause ticking in the audio path. Maybe not, I guess the only way to find out is to try it. If the pedal ticks, you have a culprit!

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 15, 2008, 03:09:25 PM
Learn something new every day around here!  Thanks Rick, I wasn't aware of that.

Just debugging my second Pentaboost now.  Is working OK until I close it.  There's a short somewhere me thinks.  This one's just a touch prettier!  Pics soon.

Voltages of the 5672

1 - 1.35
2 - 5.89
3 - 1.25
4 - -0.31
5 - 0.00

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 15, 2008, 03:18:21 PM
Good news!

Did you see my Red Star Drive stripboard layout yet? Pots and tube on the board too.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 15, 2008, 04:34:12 PM
Yes, yes I did, just after I finished the board for this Pentaboost   :-[  (slight exaggeration!)

Don't think there are any 1n67a's amongst the diodes I have either.  Another for the list!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 16, 2008, 12:54:32 PM
the LED doesn't matter at the mo...cant get the circuit working! i bet im doing something stupid wrong, like i said to fc, this is my first build. can someone maybe help me make sure i'm not wiring up wrong...

at the mo i have:
circuit out going to tip of output jack.
ground going to sleeve of out jack and across to sleeve of in jack.
sleeve of wallwart going to 12v in on circuit
tip of wallwart going to ring of input jack
circuit input going to tip of input jack

thats it, no switch, no LED. when i plug in it just makes white noise. as i turn the pot clockwise the white noise goes away to no sound at all. can't here any guitar sound. sure its something ive done wrong. any help would be most appreciated! steve.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 16, 2008, 01:09:32 PM
Quote from: stereovoid on October 16, 2008, 12:54:32 PM
the LED doesn't matter at the mo...cant get the circuit working! i bet im doing something stupid wrong, like i said to fc, this is my first build. can someone maybe help me make sure i'm not wiring up wrong...

at the mo i have:
circuit out going to tip of output jack.
ground going to sleeve of out jack and across to sleeve of in jack.
sleeve of wallwart going to 12v in on circuit
tip of wallwart going to ring of input jack
circuit input going to tip of input jack

thats it, no switch, no LED. when i plug in it just makes white noise. as i turn the pot clockwise the white noise goes away to no sound at all. can't here any guitar sound. sure its something ive done wrong. any help would be most appreciated! steve.

Steve, you need to post voltages from all five pins of the 5672. Also, check all your resistor values and the polarity of the two electrolytic caps. Also, maybe post a close up photo of your build, boths sides of the board.

You didn't mention a ground connection from the board to the in/out jack ground - do you have that?

Rick
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 16, 2008, 01:20:48 PM
sorry, yep ground is going from board to out jack sleeve and this is also connected across to in jack sleeve. is the best way to post pics using photo bucket? i'll sign up and get some up.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 16, 2008, 01:25:21 PM
Quote from: stereovoid on October 16, 2008, 01:20:48 PM
sorry, yep ground is going from board to out jack sleeve and this is also connected across to in jack sleeve. is the best way to post pics using photo bucket? i'll sign up and get some up.

Yup, Photobucket rocks!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 16, 2008, 03:29:31 PM
i'll try get those readings up before work tomorrow. think ive done something bad though as the heatsink isn't warming up now! doh, i'll get it in the end! :icon_frown:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 17, 2008, 03:59:45 AM
my girlfriend has taken the camara to work today so will post pictures this evening. as for multimeter readings...getting no life to any of the valve pins. im pretty sure ive populated the board as of sweet willy's 'all on' vero layout, can't see any solder bridges or wrong values. one thing, is a 47nf cap equal to a 0.047uf cap? that is the only component that could be wrong if not. anyway, know you need the readings to try and help so might just start populating a new piece of vero. sorry i'm being a pain with this but thanks for the help!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 17, 2008, 04:25:33 AM
 :icon_redface: :icon_redface: :icon_redface:

I think I may have made a slight error.  I can only apologise!  Pretty sure the jumper from Pin 4 to Row M should be to the right of C1 and R1. 

Really, really sorry if this turns out to be the only problem!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Jimmy-H on October 17, 2008, 04:28:58 AM
Quote from: stereovoid on October 17, 2008, 03:59:45 AM
as for multimeter readings...getting no life to any of the valve pins. im pretty sure ive populated the board as of sweet willy's 'all on' vero layout, can't see any solder bridges or wrong values. one thing, is a 47nf cap equal to a 0.047uf cap?

How about the voltage of your powersupply.
If there is no life, then no life on the rest.
The cap should be O.K.

Succes with your build! ;D
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 17, 2008, 04:38:02 AM
Stereovoid - have you got the 12v in at J1 on the board?  Should be feeding 12v to Pin 3 of the LM317.  Maybe check the heatsink isn't shorting against anything also.

Pretty sure about that jumper to Pin 4 being wrong, but can't see how that would stop all power from getting to the tube.  Or am I missing something forhead slappingly obvious?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 17, 2008, 04:43:38 AM
jimmy, tried a diff power supply, same thing. but think my multimeter might be bugging cause its old and tatty! sweet willy, will try moving the jumper. think what it really comes down to is i'm trying to 'paint by numbers' rather than understand how things work. hopefully with the help of people like yourselves and fc and can better my understanding. asking my girl if she'll get me an electronics book for that pagan festival day at the end of december...any recommendations? seriously, thank you guys, this is a great forum to be part of. steve
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 17, 2008, 04:48:53 AM
yep, in at j1. put my voltage regulator on the otherside of the board as i have a diff heatsink to you, but its still oriantated the same way round as yours, pin one, when looking at the written side of the chip, to h2...its like internet chess...bishop to f4!!  :icon_lol:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 17, 2008, 05:02:28 AM
I'm in much of the same boat.  Full time work + wife + band + recording + building = not a lot of time for theory.  Got a breadboard now so going to be spending some time figuring out why these things are so.

I've built a 2nd one now (the Pentabeast is being shipped to a mate in Australia).  Kept the prettier one for myself -

(http://i126.photobucket.com/albums/p94/williamthesweet/PentaboostMKII.jpg)

I got 1 dud tube, but found it makes an attractive pointer for the knob!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 17, 2008, 05:05:45 AM
yaahoo! with the jumper moved, life we have!! lots of interferance though, but its not in a box at the mo and i've been pulling things out and bending components so could well have a dodge solder or something now! one thing that seems strange...as i turn volume counterclock the signal goes up and viseversa signal goes down, so my pot is working backwards! no biggy though!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 17, 2008, 05:12:25 AM
me again!!!   :icon_redface: but then, I've left it that way on everything I do.  and besides, reverse wired pots sound SO much better! :icon_wink:

again, sorry about that!  it sucks when you're sure you've done everything exactly as instructed only to find out the instructions were wrong.  glad it's getting sorted now though. 

The power supply you get is probably the most important component of all with this.  I bought a supposedly clean, regulated PS for over £13 and it hissed and sputtered like a cornered snake.  The one I got for £8.99 from Maplin is dead silent (thanks to Rick for the tip!).
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 17, 2008, 05:12:39 AM
that build looks sweet man, could you maybe show its insides?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 17, 2008, 05:17:00 AM
might pop up to the old maplin now, with the smile of success ;D on my face! i have two more of these valves so might try another one of these and a redstardrive! thank you all. will still put up pics and take some readings!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 17, 2008, 05:18:44 AM
Gladly, just ran out of memory on my phone last night and couldn't be bothered emptying it!

This was from when I was planning the layout.  Was trying for a tiny build so was using a salvaged mini pot from a dead Boss pedal, but ended up getting a slightly larger one to allow for foam padding and such.

(http://i126.photobucket.com/albums/p94/williamthesweet/Planning.jpg)

It's a great booster when you get it running - just can't say that enough!

That box is only £3.49 at Maplin also.  Even has room for a 9v battery (this thing sounds good on either 9 or 12!)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 17, 2008, 05:30:13 AM
looks sweet man! i'll post pics of mine later tonight! think the multimeter is defo dead! still nothing! had the black to common ground. put pos on each pin of the tube and no readings! looks like its time to make some investments! so what is a bread board? you can lay out parts and make sure its working before soldering?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 17, 2008, 05:39:29 AM
yup

(http://i126.photobucket.com/albums/p94/williamthesweet/bb_002.jpg)

You can pick somethig like this up for less than a fiver.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 17, 2008, 05:49:33 AM
ah cool! will have a look in town! the feeling of getting something working is grand! think the two probs were the jumper and also a dodge solder on the wallwart. just wired it to a 9v battery and no interference, just lovely sound! new power supply it is! right, part 2...what is the smallest enclosure i can get this in! haha!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 17, 2008, 06:01:30 AM
With a bit of planning it would fit the MXR size box at Maplin.  That's the one I used.  It's 111x60x27 inside.  Also depends on what offboard components you've got.  Enclosed jacks tend to be a bit smaller than open ones, etc...  Lead dress (how you lay the wires in the box) is also pretty tricky, so having a bigger box 1st time might be a better idea.  When your skills improve you can always rehouse it.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 21, 2008, 07:13:34 PM
Jasper Oosthoek over at AX84 has come up with an interesting variation on the PentaBoost/Red Star Drive. He's used a low current bipolar PNP silicon transistor as a constant current source instead of an anode resistor. Technically, it's not in the signal path, from what I understand, using the transistor mean more voltage is available to the plate instead of being used up by the anode resistor. A very significant amount more gain is the result. I just breadboarded some of his ideas tonight. I've put a trimpot in the schematic, though on the breadboard I measured the ohmage of the voltage divider created by the trimpot and the 1M resistor, and was able to replace the trimpot with a 68K resistor, so the trimpot is there to take account of transistor variances. Here's the PentaBoost MkII schematic, I'll be updating the Red Star Drive shortly - the mod with that one is similar but slightly different.

(http://i210.photobucket.com/albums/bb292/frequencycentral/ee01f88b.jpg)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 22, 2008, 04:37:24 AM
http://i448.photobucket.com/albums/qq201/stereovoid/look010.jpg

http://i448.photobucket.com/albums/qq201/stereovoid/look009.jpg

http://i448.photobucket.com/albums/qq201/stereovoid/look011.jpg

http://i448.photobucket.com/albums/qq201/stereovoid/look012.jpg

here are some pics of my build...if i've used photobucket correctly!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 22, 2008, 10:18:06 AM
I'm really looking forward to trying out the new version - only wish I'd left room on my layout for mods!  Might have to make a up an add-on board for this. 

Bring on the Red Star MkII!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ~arph on October 22, 2008, 10:38:58 AM
A so also more gain when 9V is used ?  ;D
I'll try this when I get back home..
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ~arph on October 22, 2008, 12:16:12 PM
 ;D

Well, what can I say, that really makes a lot of difference! actually usable now at 9v.
Thanks, I had seen the same kind of arrangement too with a j201 somewhere (I believe on tim escobedo's site)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 22, 2008, 12:37:52 PM
Quote from: ~arph on October 22, 2008, 12:16:12 PM
;D

Well, what can I say, that really makes a lot of difference! actually usable now at 9v.
Thanks, I had seen the same kind of arrangement too with a j201 somewhere (I believe on tim escobedo's site)

Yeah, nice isnt it? I'm just not technical enough to have worked it out myself - so all thanks to Jasper Oosthoek for his great work. Jasper has done the math on this, and has come to the conclusion that the the transistor addition gives the circuit an output equivalent if the circuit had been run at 22 volts, here's a qoute from one of his posts on the AX84 (http://www.ax84.com/index.php/bbs/index.php?area=31) thread:

"If you're wondering how this system works:

In the old schematic the anode voltage I measured was about 3.5 volts and the (AC) load resistance was 50k. (The 100k load resistor parallel with the volume pot). The input signal modulates the current in the tube by a certain amount: Irms. This get's converted to a voltage by the AC load resistance to a voltage equal to Irms * Rac. So if the Rac increases, the output will increase too.

The transistor is a trick to raise the anode voltage and load resistance without changing the supply voltage. Raising the anode voltage will create more gain too because it raises the "Transconductance" which is the ratio between the input voltage and Irms.
The (AC) load resistance in your new schematic will be 100k (only the volume pot). The load resistance of the transistor is much higher and can therefore be neglected. Also the anode voltage can be raised to 9 volts (with 130uA). This limits the maximum voltage swing to about 2 volts before it becomes dangerous. Still that's MUCH higher than the old circuit.

This means the output is identical to the original circuit working on 22 volts (9 + 130uA*100k). And that's without a volume pot that steals 6dB (because the AC load resistance is 100k not 50k)."


Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: mth5044 on October 22, 2008, 02:36:27 PM
hey stereovoid thats pretty cool, but I got two questions

1) Did you just glue of those rocks down?
2) how does your chicken head knob rotate paste the top of the lighthouse? not the pointer, but the other end looks like it would get stuck. I guess if you have it up high enough..
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 22, 2008, 02:49:02 PM
Yeah, sorry Sterevoid, forgot to say that's a sweet looking pedal!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ~arph on October 22, 2008, 03:10:34 PM
The PNP power does seem to  have a slight drawback..

I tested it wtih a 1spot.. worked fine. Then I used a reasonably fresh battery

Here are the results:

1spot   9.4V @ 61mA
batt     8.8V  @ 72mA

Different voltages (or should that rather be currents) into the PNP's base means rebiasing the base current
So, do we need a regulated powersupply for this or is there a way around.

What struck me most though is that with the battery the gain was MUCH higher than with the 1spot..   ???

One other thing I noticed (this was not involved in the test above) is the 100k and 1uF on the grid plate.. (pin 2) If you remove both and just stick a 100R resistor from pin 2 to 9V you get a lot more headroom. (it breaks up a lot later)

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 22, 2008, 03:12:22 PM
I just tried all the different PNP transistors I have and I can report that they ALL work really well.

Here's what I tried:

Si: BC212, BC557C

Ge: 2n2000, 2n404, SFT353, GT403

A couple of the Ge I tried didn't work so well - leakage? But at least one of each type did work fine

The silicons both required the trimpot to be about 68/32, so a voltage divider ratio of 15:1 approx, so 68k / 1M should be close enough.

The germaniums all required the trimpot to be 30/70, a voltage divider ratio of 35:1 approx, so 27K / 1M should be close enough.

In terms of 'mojo' sonic difference between the Si and Ge, there was none. I guess because the transistor is not in the audio path.

In terms of 'mojo' visual difference I obviously be using the big fat black metal can 2n404!

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on October 22, 2008, 03:16:03 PM
and you'll be installing a teeny weeny plexi window and a backlighting LED and all I guess?   ;)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 22, 2008, 03:17:34 PM
Quote from: ~arph on October 22, 2008, 03:10:34 PM
The PNP power does seem to  have a slight drawback..

I tested it wtih a 1spot.. worked fine. Then I used a reasonably fresh battery

Here are the results:

1spot   9.4V @ 61mA
batt     8.8V  @ 72mA

Different voltages (or should that rather be currents) into the PNP's base means rebiasing the base current
So, do we need a regulated powersupply for this or is there a way around.

I guess it's a case of finding the 'sweet spot' for whatever power supply you are using, so it might be best to leave the trimmer in rather than replace it with fixed resistors.

From what you say, the downside of battery powering this circuits is that as the battery dies the sweet spot wil be lost. Hmm.

Quote from: ~arph on October 22, 2008, 03:10:34 PM

What struck me most though is that with the battery the gain was MUCH higher than with the 1spot..   ???


Weird - I have no idea why.....

Quote from: ~arph on October 22, 2008, 03:10:34 PM

One other thing I noticed (this was not involved in the test above) is the 100k and 1uF on the grid plate.. (pin 2) If you remove both and just stick a 100R resistor from pin 2 to 9V you get a lot more headroom. (it breaks up a lot later)


I just tried this but only got lower gain.  ???
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ~arph on October 23, 2008, 02:19:52 AM
I will continue my experiments.

But so far battery powering doesn't seem like a good idea, perhaps if you use a 7V zener as a regulator, but then you are lowering the voltage again..

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on October 23, 2008, 11:06:49 AM
"hey stereovoid thats pretty cool, but I got two questions

1) Did you just glue of those rocks down?
2) how does your chicken head knob rotate paste the top of the lighthouse? not the pointer, but the other end looks like it would get stuck. I guess if you have it up high enough.."

cheers, pretty chuffed with it! yep just glued them down with gel super glue and they all hold fine! might put a couple of coats of clear lacker over to give them shine! the knob just clears the stones, i left a 3mm gap and the highest stone is 2mm, so all cool! going to make a little battery box to go along the top as i screwed up measurements with the jacks and can't get one in!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on October 26, 2008, 03:11:42 PM
I've just doing been doing a bit of tweaking - change the volume control to a 470K for a tad more boost.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: forsakenrider on November 02, 2008, 04:11:51 PM
I have built two of these now using 6088's. One is stand alone running off two 9v in series (but im going to try the pnp mod to see how it sounds off a single 9v) and the other is in my valvecaster wired infront of it with a "boost" stomp switch.

for me the 6088's are CRAZY microphonic. like, yikes. if you tap it you get a DINGGGGGGGG for atleast a minute... and playing loud with a little floor rumbling it doesnt stop. do the tubes you use have the same issue? or have you found a way to minimize it?

also, for my valvecaster-pentaboost i have an extra hole to fill with a switch or a pot. ive tried the "squish", and noticed noting really, even with a few different caps. ive tried using it as a volume for the boost, but it seems pointless. right now its wired for cliping like the Red Star Drive, but im noticing minimal differences. The only thing i can think of putting in there would be another tone, but that seems boring. Any ideas?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on November 02, 2008, 05:45:55 PM
The 5672 are a little microphonic - they certainly don't DING for a minute though. I've put foam around mine which mostly cures it.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: stereovoid on November 03, 2008, 05:12:25 PM
same for me with the 5672's. slight chime if you flick them but nothing like when your amp goes microphonic! i raised mine off the vero board with some round cork stickers (you can get them from focus) and held the valve in place with a plastic tie clip. did the job for me!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: forsakenrider on November 03, 2008, 09:20:07 PM
Ugh, its really not working out at 9volts!!! i wish it would, as that the only easy way i can lend it out! but with the PNP mod it nneeds re-biasing as the voltage drops. hmmm

Im curious as to how the valvecaster works at 9v (so people have said) yet this little guy doesnt seem to handle it. or maybe its just me.

Has anyone had success with a 9v bat??
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on November 04, 2008, 02:35:47 AM
Quote from: forsakenrider on November 03, 2008, 09:20:07 PM
Ugh, its really not working out at 9volts!!! i wish it would, as that the only easy way i can lend it out! but with the PNP mod it nneeds re-biasing as the voltage drops. hmmm

Im curious as to how the valvecaster works at 9v (so people have said) yet this little guy doesnt seem to handle it. or maybe its just me.

Has anyone had success with a 9v bat??

I built my first Valvecaster as a 9 volt battery only device. I soon replaced it with a 12 volt wall wart only device. Much happier.

With tubes the simple answer is more volts = more gain/boost.

As you point out, the Pentaboost plus PNP turbo isnt going to work well with batteries due to the baising issue.

Other options to explore (without the PNP boost) would be deriving 18 volts from two 9 volt batteries in series, or using a 9 volt battery together with a voltage doubler circuit such as MAX1044/LT1054/LMC7660 - I would guess good things could result from that, you could get the plate voltage up quite high!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: forsakenrider on November 04, 2008, 08:54:28 AM
Yeah, Ive already done the 18v.... But after 18 with the PNP mod.... I dont think i can go back to the 100ohm resistor
I guess Its back to regulated 12v.


A voltage doubler or trippler is a good idea! too bad ill have to order a special IC for that. Maybe i will try that though.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: kurtlives on November 18, 2008, 08:16:08 PM
Thought it was in this thread....

Rick you posted a schem from an idea at AX84...something about this simple compression control. Don't remember much about it but the pot connected to the cathode haha.

Know what I am talking about?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on November 19, 2008, 03:50:06 AM
I think that might be the 'squish' idea which was discussed in the Red Star Drive thread. I haven't had the opportunity to experiment with that yet.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: kurtlives on November 19, 2008, 04:05:58 PM
edit

Guess that control would only work with pentodes and not triodes...
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on November 19, 2008, 07:24:56 PM
Quote from: kurtlives on November 19, 2008, 04:05:58 PM
edit

Guess that control would only work with pentodes and not triodes...

Yup - correct.

I seem to remember someone tried it and reported it to b 'very subtle'. Maybe it works better at high voltage.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: sweetwilly on November 19, 2008, 09:09:10 PM
I tried it, but as Rick said, very subtle if anything.  Haven't tried it on the turbo version or on the Cold War Drive yet, but don't know what if any effect that'll have on it.
Title: "PentaBoost" + Max1044 = "PentaMAX"
Post by: frequencycentral on February 03, 2009, 11:54:58 AM
Fresh from my "Murder One" (http://www.diystompboxes.com/smfforum/index.php?topic=73222.0) amp, experiments I still have the MAX1044 circuit on my breadboard, so I thought I'd see what happens to the PentaBoost with 70 volts running through its veins.

This is how to do it:

- Apply 70 volts from the MAX cap/diode array to pin 1 of the 5672 via the 100K resistor.

- Leave pin 2 just as it is, connected to 12 volts (or 9 volts).

The boost from 70 volts is MASSIVE. That's using twelve diodes and caps. The caps get pretty big physically when rated for 70 volts. And that's a lot more components too.

However:

The boost from just three doubling stages is excellent too, just not quite as massive. And that's only six caps/diodes - and the caps can be very physically small when dealing with these voltages.

Just thought I'd contribute this idea - not sure if it's any use to anyone, but well worth breadboarding if you have the parts about anyway.

For details of the MAX circuit, see my "Murder One" (http://www.diystompboxes.com/smfforum/index.php?topic=73222.0) thread, or go to 'Circuit Sweepings' at GEOFEX.


Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 03, 2009, 07:04:53 PM
Worked up a vero layout for this based on my experiences with using resistors in place of the lm317 on the most excellent Red Star Drive. runs best at 9v, you might have to play with R1's value a bit to use higher voltage.
Not verified, please let me know if there are any problems, And a big thanks to frequencycentral for all his work with subminis.
(http://i301.photobucket.com/albums/nn71/svsguitarhero/Pentaboost9v20.gif?t=1233705869)

Thanks!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on February 03, 2009, 07:26:02 PM
Quote from: svstee on February 03, 2009, 07:04:53 PM
Worked up a vero layout for this based on my experiences with using resistors in place of the lm317 on the most excellent Red Star Drive. runs best at 9v, you might have to play with R1's value a bit to use higher voltage.
Not verified, please let me know if there are any problems, And a big thanks to frequencycentral for all his work with subminis.

Hi, looks like it should work - but C1 should be 0.047 (47n) not 0.0047. Here's a cap conversion chart: http://www.justradios.com/uFnFpF.html

You are aware that C1 and C2 are polarised electrolytic? You would normally use the polarised cap symbol for them.

You could route R1 from d2 to a2, save yourself a jumper and a track cut.

Probably not good practice to have C3 over R3 - but I've done worse in the past! I assume you have a cut at b7.

You should get a bit moore boost by changing the pot for a higher value - 250K or 500K.

Good luck!

Rick

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 03, 2009, 07:27:58 PM
Thanks much. Revisions are on the way!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 03, 2009, 07:40:59 PM
Here it is:
(http://i301.photobucket.com/albums/nn71/svsguitarhero/Pentaboost9v21.gif?t=1233707752)
Thanks for all the help, man. And to clear up a few things:
C2 and C3 are multilayer film caps, I use them on everything from 0.1 uf to 2.2 uf. beter tolerances than electrolytic, smaller, not polarity sensitive, and cheaper.
Why is it not a good idea to have C3 over R3? I do have a trace cut under them.
Just to let everyone know, R1 does get warm, so giving it a bit of room is a good idea.

Edit: Just built it with this layout, works great, sounds awesome! Adds a bit of high end and shimmer and a lot of volume. Can be run off a 9v battery, but it sucks a lot of power. Thanks for the schematic, this is a great circuit.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on February 04, 2009, 12:56:54 PM
Quote from: svstee on February 03, 2009, 07:40:59 PM
Why is it not a good idea to have C3 over R3? I do have a trace cut under them.

Nothing actually wrong with doing that electronically, just not prefered practice to have one component on top of another on a board - I guess because it could make debugging or changing out a part more difficult. I would probably have run R3 from c3 to a3 to avoid having C3 on top of it. Like I said, I've done worse when struggling for space, and it works so don't lose sleep over it.

Quote from: svstee on February 03, 2009, 07:40:59 PM
Just built it with this layout, works great, sounds awesome! Adds a bit of high end and shimmer and a lot of volume. Can be run off a 9v battery, but it sucks a lot of power. Thanks for the schematic, this is a great circuit.

Hey glad it worked out and that you like it! Enjoy!  8)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 09, 2009, 12:29:50 AM
Hey, what is the best way to deal with microphonics? it wasn't an issue for me when the boost was just a circuit board with juice and jacks attached but when I boxed her up they became loud and nasty. Tried double sided tape, foam insulation, and a combination of the two with poor results.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on February 09, 2009, 12:30:46 PM
Quote from: svstee on February 09, 2009, 12:29:50 AM
Hey, what is the best way to deal with microphonics? it wasn't an issue for me when the boost was just a circuit board with juice and jacks attached but when I boxed her up they became loud and nasty. Tried double sided tape, foam insulation, and a combination of the two with poor results.

Yes they can be microphonic little buggers at times - some are worse than others. The filament in these tubes is long and spring-like, which doesn't help. There is some discussion of how to combat microphonics earlier in this thread. What I do is make sure the tubes are not touching anything and pack a little foam around them - it cuts the problem down to size.

Quote from: sweetwilly on October 13, 2008, 06:04:38 AM
As noted earlier in this thread, the tubes can be quite microphonic, so take that into account when planning the enclosure - you want something to dampen the stomp.  Most of the "mechanical" noise seems to transfer through the leads of the tube on mine, so not a great deal can be done there, but foam padding around and under the tube (you can glue a small piece onto the board under where the tube will lie) will make a big difference.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 09, 2009, 05:58:45 PM
If the foam touched the walls of the enclosure and the tube I had the same problems. What about using a foaming glue to hold the leads in place, cuuting of the microphonics from that end?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 09, 2009, 07:20:30 PM
The who enclosure is hypersensitive, just touching the top makes things get microphonic, and stomping the switch is out of the question. I think my problem is the direct mounting of the pot onto the stripboard, the whole thing is acting like a spring.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on February 09, 2009, 07:51:05 PM
Quote from: svstee on February 09, 2009, 07:20:30 PM
The who enclosure is hypersensitive, just touching the top makes things get microphonic, and stomping the switch is out of the question. I think my problem is the direct mounting of the pot onto the stripboard, the whole thing is acting like a spring.


Hmm, dont know what to suggest. My Red Star Drive isn't microphonic at all, and the pots and tube are mounted on the circuit board. My Pentadriver was a little microphonic - just the first tube, not the second - sorted with foam. My Murder One isn't at all either. Maybe the ultimate protection would be to shock mount the circuit board within foam (with wires between the board and pots) so that there is not direct contact between board and enclosure. seems a little extreme though. Out of interest, what brand are your 5672's? I have Valvo (German), Raytheon (USA) and CEI (French) - I prefer the Raytheon.

Did you get your Pentadriver working yet?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 09, 2009, 08:46:55 PM
Maybe a rubber washer on the knob might work. would glue on the underside of the circuit board cause problems?

And yeah, the pentadriver is mostly working, gain pot is backwards though, and doesn't give much volume boost. I think I had a bad battery. :icon_redface:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on February 10, 2009, 05:36:50 AM
Quote from: svstee on February 09, 2009, 08:46:55 PM
Maybe a rubber washer on the knob might work. would glue on the underside of the circuit board cause problems?

And yeah, the pentadriver is mostly working, gain pot is backwards though, and doesn't give much volume boost. I think I had a bad battery. :icon_redface:

Yeah the washer should help. Glue would be fine as long as its not conductive. I'm amazed that you even run the Pentadriver from battery. A low battery would cause the heater to be starved - all sorts of unpredictable behaiour could ensue! The circuit draws 100ma +, so usable battery life isnt going to be long either.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: petemoore on February 10, 2009, 10:54:29 AM
  Tubes are known for having various microphonic tendancies, one tube more than the other, so to swap.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 10, 2009, 11:49:27 PM
 
Quote from: petemoore on February 10, 2009, 10:54:29 AM
  Tubes are known for having various microphonic tendancies, one tube more than the other, so to swap.

I would, but this tube was fine before I boxed it up, so I don't think that's it. I built the circuit with just in/out jacks and it wasn't microphonic at al.
On another note, would longer leads make the problem better or worse?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: ~arph on February 11, 2009, 03:29:34 AM
Quote from: frequencycentral on February 09, 2009, 12:30:46 PM
The filament in these tubes is long and spring-like, which doesn't help.

Anyone tried running the guitarsignal through the filament?  :icon_surprised:
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: petemoore on February 11, 2009, 09:48:30 AM
The who enclosure is hypersensitive, just touching the top makes things get microphonic, and stomping the switch is out of the question. I think my problem is the direct mounting of the pot onto the stripboard, the whole thing is acting like a spring.
  Tubes always make a little noise, sometimes more.
  "For car use" tends to mean "may be subjected to intense or prolonged vibration"..to what degree shock endurance was designed into them of course is different than suggesting the design took into accout that vibration might occur...I guess these are intended to be used where vibrations may be present.
  Tankin' on the tube lightly with a chopstick, bumping it a touch, well...experienced tube bumpers know what to listen for...a sound, but with very little resonance or sustain, once you've heard an old rattley tube...remember that sound...it'll probably be different with the next tube you hear rattling.
  The tube noise of the
  How 'used' is the tube?
  Between shock damping the tube and shocking it with a little vibration [not that I haven't had some funky wire make funny noises when tube-tapping...and think it was the tube...] sorting out what type of noises the tube makes as a 'source', decide whether that tube is the one.
  Increasing and decreasing the vibrations a 'hot tube is subjected to...it isn't as easy as flipping a switch or turning a knob, but ~ has about the same range of effect sometimes.
  On a similar note my 'AT@38' ~valvecaster makes 'nosey' sounds and the olifactory of the tube absolutely can be heard if my foot even gets near the box it seems. Oh yea, microphonic...
  I have the tubes waistline in a 3x3'' ring/clamp dampener, and doesn't jump into whining until the guitar gets close...and that's when the gains up...and I keep the gain down for a less 'thunky' tone.
  And it sounds just great and I don't mess with much it other than exacting more deliberate, accurate stomponit moves than my Chip boxes, mostly it just stays on, and I play with that through a tube amp that is the smallest I've yet to complete [2w+]...very nice to have super sweet tones @ sweet volume...Otherwise the thing is quite stable and low noise floor-O.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: esdiezy28 on February 13, 2009, 02:48:39 PM
Hi All! I just got in some 6088 sub mini's yesterday, very similar to 5672 but lower power output, and I'd like to share that the Penta Boost is VERIFIED with a 6088 tube, run at 9V. Although I'm quite confident that it will work at 12V as well, but my test board's power supply is variable only up to 9V.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 13, 2009, 03:03:56 PM
Petemoore, I think you are onto something, because it got WAY worse with the amp distorted. I was running it through an Ampeg J-12T reissue, which breaks up pretty quick. I'll run it through the clean channel on my Randall and see if it is still there. Problem is, it sounds really good pushing existing amp distortion to the next level.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 16, 2009, 02:39:49 PM
OK, I used double sided foam tape on both sides of the pot and the switch. Huge improvment, but still not great. I'm gonna run short leads from the pot to the circuit and see if that helps. Another idea and a couple questions.
1: How hard would it be to run an AA battery to the heater and 18-24v from a wall wart to the rest?
2: How long would the battery last?
3: Would a C or D be better?
4: What would the best way to hook it up be?
5: Would it be worth it to run it to an spst as a "power on/heater on" switch?

Thanks!
Title: Re: "PentaBoost"
Post by: Renegadrian on February 16, 2009, 02:56:09 PM
svstee - here's my pentaboost - altough it works ok with a 9v battery, I have to report a really nice use of my voltage multilier, so I tried running it at 50V - that was a good one!!!


Quote from: Renegadrian on September 21, 2008, 04:44:26 PM
Here's my version...

(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=36696&g2_serialNumber=2)

After I successfully breadboarded it, decided to draw a vero layout by myself, now in my gallery (http://www.aronnelson.com/gallery/main.php/v/Renegadrian/Pentaboost.gif.html),
and decided to build and box it somehow...Found a little wooden box at Leroy Merlin while shopping
for spray cans, so I thought "WHY NOT?!"  :icon_lol:
So here it is...It uses a 5678 tube and it's powered by a 9V and a 1.5V AAA for the heaters.

(http://img220.imageshack.us/img220/6033/200902smiz4.th.jpg) (http://img220.imageshack.us/my.php?image=200902smiz4.jpg)(http://img220.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img291.imageshack.us/img291/402/200903smym1.th.jpg) (http://img291.imageshack.us/my.php?image=200903smym1.jpg)(http://img291.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img258.imageshack.us/img258/9229/200904smiy1.th.jpg) (http://img258.imageshack.us/my.php?image=200904smiy1.jpg)(http://img258.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img252.imageshack.us/img252/2954/200905smra0.th.jpg) (http://img252.imageshack.us/my.php?image=200905smra0.jpg)(http://img252.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)
(http://img401.imageshack.us/img401/692/200906smtz9.th.jpg) (http://img401.imageshack.us/my.php?image=200906smtz9.jpg)(http://img401.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img252.imageshack.us/img252/5687/200907smoa4.th.jpg) (http://img252.imageshack.us/my.php?image=200907smoa4.jpg)(http://img252.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img401.imageshack.us/img401/6921/200908smia7.th.jpg) (http://img401.imageshack.us/my.php?image=200908smia7.jpg)(http://img401.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)(http://img168.imageshack.us/img168/1553/200909smud7.th.jpg) (http://img168.imageshack.us/my.php?image=200909smud7.jpg)(http://img168.imageshack.us/images/thpix.gif) (http://g.imageshack.us/thpix.php)

Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on February 16, 2009, 03:04:06 PM
Nice, how did you wire to the cell? Did you just solder right on to it? I see what you did with the stereo jack, but I like to leave all my pedals plugged in, so I think I'll just run - through an spst toggle.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: svstee on March 22, 2009, 09:13:29 PM
Well, after getting sick of the microphonics I switched out the tube for another one, NOS, right out of the box. same problem, hardly any better. I'm using foam, rubber washers, and foam tape and am still not having much luck. It really sucks because this circuit sounds GOOD, especially in front of my FF and TS.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Berger on May 04, 2009, 04:42:47 PM
What are the requirements for the pentode. I picked up a couple submini 5639 pentodes, and all I've been able to get out of them is some ticking. I was wondering if this pentode is too different to work in this setup?

-Berger
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on May 04, 2009, 04:54:39 PM
Quote from: Berger on May 04, 2009, 04:42:47 PM
What are the requirements for the pentode. I picked up a couple submini 5639 pentodes, and all I've been able to get out of them is some ticking. I was wondering if this pentode is too different to work in this setup?

-Berger

It should be possible to make a similar circuit with the 5639. have a look at the data sheet:

http://frank.pocnet.net/sheets/087/5/5639.pdf

How have you got it set up specifically?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Berger on May 04, 2009, 04:58:22 PM
i used the penaboost schematic and just used the corresponding pins.

I used:
pin 1(Grid #1)
pin 5(Plate)
pin 7(Grid #2)
and the heater connections on pin 3 and 6.

Thanks for the quick response!
-Berger
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on May 04, 2009, 05:05:14 PM
Let me have a look at it and come back to you tomorrow.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on May 04, 2009, 07:16:26 PM
Quote from: Berger on May 04, 2009, 04:58:22 PM
i used the penaboost schematic and just used the corresponding pins.

I used:
pin 1(Grid #1)
pin 5(Plate)
pin 7(Grid #2)
and the heater connections on pin 3 and 6.

Thanks for the quick response!
-Berger

This tube has a seperate cathode which you need to connect. In the 5672 the cathode is internally connected to the heater +ve. So I think you'll need a connection to either of pins 2, 4 or 8, which are all the cathode. You could try referencing it to ground with a low value resistor paralleled with an electo cap, try 1K and 10uf for starters.

I'm assuming you're giving the heater 6.3v ?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Berger on May 05, 2009, 02:45:19 PM
That worked! Yup supplying it 6.3 volts. I really like the sound of this. i hopefully will have the 5672s coming in as well, I'm a big fan of the Trotsky drive and am looking to build the red-star drive that you made like it.

Thanks for the quick replies and the help!

-Berger
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on May 05, 2009, 04:22:31 PM
Quote from: Berger on May 05, 2009, 02:45:19 PM
That worked! Yup supplying it 6.3 volts. I really like the sound of this. i hopefully will have the 5672s coming in as well, I'm a big fan of the Trotsky drive and am looking to build the red-star drive that you made like it.

Thanks for the quick replies and the help!

-Berger

Hey that's cool! Excellent, well done! You should be able to just hang a couple of mixed Ge/Si diodes off the output of your 5639 to make it into a Red Star Drive. Also check out the Deliruim 5672 tremolo thread, you should be able to do that too with the 5639. Is the 5639 microphonic at all?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Berger on May 05, 2009, 04:27:45 PM
I have the leads at about 1.5-2" and its not monophonic. I really like this since it uses the 6.3v heaters, much like the other mini tubes I've been using.
I'll look at the Deliruim 5672 tremolo thread, should be fun. I can always use more tubes on my pedal board.

I'm also playing around with a 6U10 triple triode tube, it just sounds like fun.

-Berger
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Magnus on February 03, 2011, 01:26:09 PM
Hello together,
I am working on a layout to build the PentaBoost MkII,
but there are two points where I am not sure if everything is allright,
would be nice to know if the Voltage-Regulator LM317T is wired exactly
and the trim-potentiometer too (maybee I have to connect two pins of the trimpot?)

(http://img3.fotos-hochladen.net/uploads/pentaboostmkiim95sfjqrpy.gif)

I know the layout is not ready yet, the Volume-Potentiometer,
the jacks, the switch and the dc-jack are missing,
I will update everything after I know the things explained/asked above  ;)

Thank you!


Greetings from Germany
Magnus
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Magnus on February 08, 2011, 03:47:29 AM
Hello,
can anyone help me?

(post above)


Greetings
Magnus
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: blackcorvo on March 06, 2011, 04:46:55 PM
Quote from: frequencycentral on May 04, 2009, 04:54:39 PM
It should be possible to make a similar circuit with the 5639. have a look at the data sheet:

http://frank.pocnet.net/sheets/087/5/5639.pdf


That looks like a tube you could use for a small tube amp design.

I know, "yet 'nother submini amp idea"... but I think this one could make some serious noise from what I see in the datasheet. Maybe you could get something like 1/2w from it in SE at 150v, maybe 2w in PP, I'm just guessing.

It just really sucks that I can't get any of these little tiny tubes. There's only one place here that sells these, but they ask for more than 100 bucks for them, so... no deal. And I don't have a paypal or a credit card, so I can't really buy anything from e-bay.
Otherwise, I'd be making some crazy stuff with these babies. SRPP boosters (trying combinations with 2 pentodes, or "pentode-bottom/transistor-top" and stuff, to see what I can get), distortion boxes, wah wah... anything. Ideas are always flowing from my mind.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Ratbones on April 23, 2011, 03:10:39 AM
I've got this breadboarded and I've got no output at all...
I'm using an lm317 and 7812 for regulation and I'm getting 1.26 to the heater and ~ 11.8 - 11.9 volts from the 7812.

my pin voltage readout is as follows:
1 ~ 1.37v
2 ~ 4.16v
3 -  1.26v steady
4 ~ 0v
5 ~ 0v

I'm not sure why the voltage to pins one and two are so low... I've got 100k resistors between v+ and the pins as the schem suggests... Any ideas?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on April 23, 2011, 04:36:50 AM
0v at pin 4 - that's the input. Doesn't seem right. How is the input grounded?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Ratbones on April 23, 2011, 11:36:15 AM
Ah, I guess when I got readings I had the guitar unplugged... I'll check again with it plugged in.  Is there a reason that pins one and two would be seeing low voltage?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on April 23, 2011, 12:35:32 PM
Sure you've got the tube the right way round? The red dot is at pin 1. Have you followed the schematic exactly? 1uF cap from pin 2 to ground even?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Ratbones on April 23, 2011, 05:03:31 PM
I'm pretty sure everything is exact, but I may just pull everything and breadboard it over while highlighting the schematic just to be sure. I'll post back with my results
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Ratbones on April 23, 2011, 08:56:28 PM
Well, embarrassingly, I mistook a FIFTEEN ohm resistor for a 1 M resistor... So all my guitar signal was merrily diverting to ground. I've got the thing working now, but my power supply is buzzing nastily. What I can hear sounds cool though! I'm running my 12v ps into a little rc network ps filter that I built, but it doesn't seem to be helping a lot... anything else I can do to clean up the nasty hum?

EDIT: Goodness gracious, apparently I need to increase my caffeine consumption if I'm going to be attempting anything electronics related.  I forgot to ground the freakin ground bus that the guitar jacks were hooked to.

Everything is working optimally now, and this thing sounds beautiful!!! I'm totally sold on this circuit, and I plan on building a pentaboost --> valvecaster build very soon!!!
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: MetalUpYerEye on April 24, 2011, 12:56:52 AM
I've been looking at boosters to build to drive my Blackstar HT5 a little harder on the gain channel. It does 80's thrash sounds well but doesn't have quite enough gain for new style metal...

So I had it narrowed down to the Omega from Runoffgroove, but this is sounding a bit better. What do you guys think I should build: Omega or Pentaboost?
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Magnus on July 18, 2011, 02:51:38 PM
Hello together,
thank you very much for this great project Rick 8)

I made a small layout that I build as a mojo-version,
it is verified and works, here are the files and photos from my work:

PentaBoost MkII-Layout (http://forum.musikding.de/cpg/albums/userpics/17258/PentaBoost_MkII.jpg)
PCB-File for etching (http://forum.musikding.de/cpg/albums/userpics/17258/PentaBoost_MkII-PCB.pdf)

(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Platine%7E18.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Platine%7E18.jpg)

I will post the pictures when the pedal is finished  ;)


Greetings
Magnus
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: esdiezy28 on August 29, 2011, 10:24:55 AM
Penta Boost is verified using a 6088 pentode tube. Basically the same as a 5672, but smaller total power output.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: iccaros on April 28, 2012, 02:55:53 AM
My quick build...
Had a small box wanted to do something with it. \
Still needs painting, but it is cool as a lead boost. I changed the output cap to .022 so it gives a nice treble boost, not much gain.

(http://dl.dropbox.com/u/14312589/Pentaboost1.jpg)
(http://dl.dropbox.com/u/14312589/Pentaboost2.jpg)
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Magnus on April 29, 2012, 03:24:52 PM
Hello together,
I don't know if I have posted my PentaBoost MkII in the "Picture-Thread" yet (I will look for it when I have some more time),
but I said I will post the pictures here - so here it is  ;)

(finished in November 2011)

(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Submini_Valve_Boost_%282%29.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Submini_Valve_Boost_%282%29.jpg)(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Submini_Valve_Boost.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Submini_Valve_Boost.jpg)(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Submini_Valve_Boost%2C_aktiv.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Submini_Valve_Boost%2C_aktiv.jpg)(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Platine%7E18.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Platine%7E18.jpg)(http://forum.musikding.de/cpg/albums/userpics/17258/Platine_%282%29%7E3.jpg)(http://forum.musikding.de/cpg/albums/userpics/17258/normal_Elektronik%7E28.jpg) (http://forum.musikding.de/cpg/albums/userpics/17258/Elektronik%7E28.jpg)

Thank you for this great circuit Rick  8)


Greetings
Magnus
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: frequencycentral on April 29, 2012, 05:04:05 PM
Nice to see this project still alive!

Really nice vintage looking layout Magnus.
Title: Re: "PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube
Post by: Magnus on April 30, 2012, 06:44:47 PM
Hello Rick,
thank you  :)

It sounds really warm - from vintage to raw - a pleasure to play with  8)

...and it is very quiet, theres only a small bit of noise on full boost - great!


Greetings
Magnus