Author Topic: Tube boost + overdrive running off a 9 volt battery  (Read 1754626 times)

Zben3129

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #240 on: February 20, 2008, 06:28:04 PM »
Just built my 3rd valvecaster. My first one was for me, and the first time I brought it to a rehearsal, my buddy asked me for one. I made him one, and his brother wanted one  :P.His brother actually offered to pay for it!

Long story short, these things rock!


Quite a thread we got going here aswell. I looked back to my first posts on this thread way back, and I realized this thread is what prompted me into building tube amps. 2 amps and 3 Valvecasters later, I finally feel like I know a thing (maybe 2) about tubes.

Zach

Zben3129

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #241 on: February 20, 2008, 06:32:38 PM »
Oh, and by the way, I had my friend bring his to a rehearsal, and afterwards, we got it set up with a switch that cuts all the gain directly to clean boost. I brought my meter, and about 50 resistors valued 1ohm to about 15k. We figured out where the maximum clean headroom with his main axe on full volume was, I measured it, and ended up putting in a 12k resistor, and added a stomp switch for clean boost (did I mention I brought my drill aswell  ;D).

 Zach

andrew_k

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #242 on: February 20, 2008, 07:09:38 PM »
And for what I understood...higher resistance value = more gain?
It would seem that's the case. I'm a newbie too, so I just mess with things until I break it or it sounds cool  :D

I'm a little concerned about the affect an increased gain would have on tube life. Maybe one of the more experienced guys can chime in here...?

After experimenting with all sorts of boosts before and after, I'm going to box mine up without any extra gain stages (maybe a high impedance buffer at input to retain more sparkle, I'll be testing that on the weekend). If I want more gain I'll just use another boost or OD pedal before or after the tube drive.

Zben3129

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #243 on: February 20, 2008, 07:23:48 PM »
I'll give about 90% confidence on this one...so don't be mad if im wrong  ;D

I don't believe the added gain will do anything to tube life, at least on a measureable scale. Keep in mind, these things are designed to run more than 10-20 times as much voltage as you are running here. If theres anything that is going to reduce tube life here, it is the fact that you are running them on suck low voltage, which (I believe) causes stripping, and decreases life.

So, unless anyone corrects me otherwise, go ahead. Build a gain monster!

Zach

Aren

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #244 on: February 20, 2008, 07:47:36 PM »
I added a 7812 regulator, and it now works like a charm!
Makes my acoustic sound half decent when going direct!  ;)

kurtlives

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #245 on: February 20, 2008, 07:50:07 PM »
Oh, and by the way, I had my friend bring his to a rehearsal, and afterwards, we got it set up with a switch that cuts all the gain directly to clean boost. I brought my meter, and about 50 resistors valued 1ohm to about 15k. We figured out where the maximum clean headroom with his main axe on full volume was, I measured it, and ended up putting in a 12k resistor, and added a stomp switch for clean boost (did I mention I brought my drill aswell  ;D).

 Zach
How did you wire it?

snoof

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #246 on: February 21, 2008, 11:38:31 AM »
running the heaters at above or below the required voltage will do harm to the tube over time.  I wouldn't use any of your NOS super mojo tubes in this design unless you run the heaters at 12v.(or 6v if using pins 4+5 and 9).

Zben3129

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #247 on: February 21, 2008, 12:40:11 PM »
Oh, and by the way, I had my friend bring his to a rehearsal, and afterwards, we got it set up with a switch that cuts all the gain directly to clean boost. I brought my meter, and about 50 resistors valued 1ohm to about 15k. We figured out where the maximum clean headroom with his main axe on full volume was, I measured it, and ended up putting in a 12k resistor, and added a stomp switch for clean boost (did I mention I brought my drill aswell  ;D).

 Zach
How did you wire it?

Sorry if this is wrong, I'll go look at the schem in a minute...

but I just used a spdt, pin 3 of 12au7 going to middle lug of switch, one side of switch had pot, the other had the 12k

Zach

Caferacernoc

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #248 on: February 21, 2008, 02:25:36 PM »
Adding resistance to the plate resistors(R1 and R2) will increase gain. Adding resisitance to VR1, in series with the gain pot, will decrease gain.

Zben3129

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #249 on: February 21, 2008, 02:31:13 PM »
Hmmm...

I didn't have the schematic with me, all I know is I used a spdt somehow and a 12k resistor.

Maybe it was "after the pot" to the middle lug, one side going to ground and the other to a 12k to ground.



Zach


Krinor

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #250 on: February 21, 2008, 03:39:05 PM »
For the benefit of Mr. Chawk (and anyone else who wants to build this thing), here are some gut shots of the point to point version of the Valvecaster. Please note that this was done quickly and eagerly, so the soldering is rather crappy.  :icon_wink:








Renegadrian

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #251 on: February 21, 2008, 04:03:50 PM »
NICE SHOTZ!!!
Done an' workin'=Too many to mention - Tube addict!

Chawk

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #252 on: February 21, 2008, 04:17:15 PM »
Fantastic!!! Much thanks!   :D
"Why don't those stupid idiots let me in their crappy club for jerks!"--Homer Simpson

Boogdish

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #253 on: February 21, 2008, 05:33:58 PM »
so the soldering is rather crappy.  :icon_wink:

if that's what counts as crappy, then I got a LOTTA catching up to do.

DryRoasted

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #254 on: February 21, 2008, 05:37:52 PM »
I knocked this up today to have a play with the circuit.  Looking around the net I found a few tube circuits in the same vien and this board is enitirely plug and play to allow maximum tweekage.  Me and her are gonna get real aquanted over the next few weeks :)  (sorry, hill billy mode)



<edit> Yes I know it shpuld be a glass of JD and coke for the full rock n roll kudos but hey, i'm English :D
« Last Edit: February 21, 2008, 05:39:59 PM by DryRoasted »
Sticking a tube into a tube screamer to get good sound is about like rubbing yourself all over the weight stacks at the gym to get stronger - R.G.

Krinor

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #255 on: February 21, 2008, 06:05:00 PM »
Now that's nice and clean!
Be sure to post your findings here (once you get to know her).
And I thought englishmen only drank tea ?  ;)

Renegadrian

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #256 on: February 21, 2008, 06:38:55 PM »
Well, There's the Ruby Tuby, both preamp or full amp - and other sophtamps creations...Sad I suck at reading schematics...
If I only find vero/perf/pcb of any of these...
« Last Edit: February 21, 2008, 08:33:41 PM by Renegadrian »
Done an' workin'=Too many to mention - Tube addict!

Aren

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #257 on: February 21, 2008, 09:22:41 PM »
Hmmpf... I would just replace the opamp stage with a JFET buffer, stick the Valvecaster in front of it, and feed it to a 386 amp.
Seems easier...

Krinor

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #258 on: February 22, 2008, 02:24:08 AM »
Well, There's the Ruby Tuby, both preamp or full amp - and other sophtamps creations...Sad I suck at reading schematics...
If I only find vero/perf/pcb of any of these...

Surely you are aware of Dano's "Tube Cricket" ? That one seems like a logic progression from the Valvecaster.


DryRoasted

Re: Tube boost + overdrive running off a 9 volt battery
« Reply #259 on: February 22, 2008, 09:21:54 AM »
First observations from the valvecaster test rig:

Using a 12AX7 at 12V and no tone stack, everything else stock - a bit "wooly" for my liking not alot of note defination, a bit boomy (this is coming from a confirmed metal head).  Change the input cap (C1) to 22nF and its a whole new game.  Lots of ACDC-esque tone, lovely response and works well with humbuckers (no idea about single coil).

Next up, same as above but changed R3 from 100K to 240K and moved VR1 from the leg of tube pin 3 to pin 8 and jumpered pin three to ground - Not a masive change but enough to give a noticable comparison.  Most obvious thing is the response of the gain control VR1, before, most of the control was in the last 1/4 turn but now its more evenly spread.  Overall tone remains useable.

Sticking a tube into a tube screamer to get good sound is about like rubbing yourself all over the weight stacks at the gym to get stronger - R.G.