Tube boost + overdrive running off a 9 volt battery

[Papa_lazerous]

I know where there are more for cheap money.  PM me if you want to know more mate

[bancika]

you've got a PM

[Jered]

hehehe...I just meant they didn't sound good in this circuit as is. I'm sure with a little tweaking they can sound good too.
  Jered

[col]

This looks interesting. Can you use the standard 1/4 watt resistors or do you need higher rated ones due to the amount of current this is drawing? Has anyone measured how much current it draws in total? Also, would chaining two or more produce an overdrive?
I have an old Babani book that has a valve compressor schematic using 2 12AX7s but it needs at least 100v. I wonder if it would work using 2 12AU7s and 12v.

[Jered]

  1/4 watt resistors worked fine for me. This thing burns through batteries, use a power supply/wall wart if you have one.
  Jered

[Papa_lazerous]

This looks interesting. Can you use the standard 1/4 watt resistors or do you need higher rated ones due to the amount of current this is drawing? Has anyone measured how much current it draws in total? Also, would chaining two or more produce an overdrive?
I have an old Babani book that has a valve compressor schematic using 2 12AX7s but it needs at least 100v. I wonder if it would work using 2 12AU7s and 12v.

Hmmmm did you say valve compressor, feel free to e-mail me a copy of the schem   PM for my e-mail address I will ofcourse be forever greatful

[bancika]

[quote author=col link=topic=63479.msg504405#msg504405 date=1199031766
I have an old Babani book that has a valve compressor schematic using 2 12AX7s but it needs at least 100v. I wonder if it would work using 2 12AU7s and 12v.
[/quote]

I doubt it, doesn't seem reasonable to me that 12au7 which has much less gain will work even close to 12ax7 under 10 or more times less voltage.

[dano12]

  No, I didn't change anything except the pinout and voltage. I thought it sounded best at 7 volts, but the difference between 7 and 9 volts was marginal. I didn't have time to really mess around with components so you might be able to bring out the best with some tweaks. It sounded great as is, two of these together might give you a gain monster of a circuit.
  Please let me know if you find improvements for this, I still have it on the breadboard and plan on trying a few things when I have time.
  Thanks, Jered

I did a bit of searching and found some 6111's for 7 dollars at tubesandmore.com.

Have a few on order now, I can't wait to start tweaking with this new tube.



On a related note, I dug up the datasheet for the 6111, and as it was designed for missles and aircraft, the datasheet says "For Operation at Altitudes up to 60,000 Feet" . Never saw that spec before

6011 Datasheet found here for anyone who is interested: http://frank.pocnet.net/sheets/079/6/6111.pdf

<edit: also found a potentially great way to mount those flying lead wires: use an 8-pin DIP socket as seen here: http://www.geocities.com/koalavilla/images/audio/pencil_pre_10.jpg >

[bancika]

<edit: also found a potentially great way to mount those flying lead wires: use an 8-pin DIP socket as seen here: http://www.geocities.com/koalavilla/images/audio/pencil_pre_10.jpg >

cool

[andrew_k]

Wow, those 6111's are TINY! I might have to try that after I've built the 12AU7 version (tubes should be here any day )

Has anyone tried a two tube version yet? If so, would you mind providing wiring advice? I would like to try it, but my simple mind comes up with stupid ideas like making two entire circuits, running them in series and using dual gang pots to control both at once. Yeah.. I'm a newb.

[dano12]

Wow, those 6111's are TINY! I might have to try that after I've built the 12AU7 version (tubes should be here any day )

Has anyone tried a two tube version yet? If so, would you mind providing wiring advice? I would like to try it, but my simple mind comes up with stupid ideas like making two entire circuits, running them in series and using dual gang pots to control both at once. Yeah.. I'm a newb.

here's a rough, unverified splice of the schematic showing two tube stages:



The 6111's arrived today, smaller than I thought!

[kurtlives]

So with the added gain stage there is more gain?

Do you have full layout?

[Zben3129]

im assuming r3 goes to 9v?

Zach

[Papa_lazerous]

im assuming r3 goes to 9v?

Zach

Its a safe bet that R3 goes to +9V as the plate would get no DC otherwise as the connection to V1A is de-coupled with a cap (C3) so only AC gets through there.

Looking at it I'd probably loose the first gain control, also has anyone worked out the loads lines or where the bias is set on these?  I know its only at 9volts but it would be interesting to see where they are operating within there range

[Isaiah]

Surely C3 needs to connect to pin number 2 on the 2nd 12AU7, doesn't it?

[MetalGod]

Surely C3 needs to connect to pin number 2 on the 2nd 12AU7, doesn't it?

yep, looks like a drawing mistake.

I'm interested now, found some 6111s and gonna try to find some 6112s (I'm sure they can be made to sound good)

[Papa_lazerous]

I think that someone needs to re-draw it as the C an R numbers are repeating where its been copies and pasted.  I am not going to do it as I am not building it but someone with some time could

[dano12]

Regarding the schemo....That's just a rough splice showing the OP where to start. I wouldn't build off that

I tried two 6111's in a row last night on the breadboard, it drew too much current for my puny little 9vDC wall wart so I can't comment yet on how two in a row sound. I would hazard a guess that it would be quite noisy and may sound farty unless the gain is adjusted for each stage.

With a single 6111 it sounds pretty good, but I think the heater voltage is going to need to be kept to under 6.3v to avoid burning out the 6111. The little buggers get HOT by the way.

[andrew_k]

Thanks for the diagram Dano

I decided to put a SHO-like booster in front of the tube boost, hopefully to attain a little bit of that "hot signal into tube pre-amp" sound -- I have the circuit perfed, but I'm still waiting on damn slow valve delivery before I can test it out and attempt to tune for the sound I'm after.

This experimentation is FUN  ...though yesterday my girlfriend finally commented on the quickly growing pile of circuits in my home studio

[Krinor]

I've been following this thread for some days now. Very, very interesting. Thanks for sharing Dano! I'm just waiting for you guys to come up with a final multi-verified circuit here, and THEN I'll build one too.  My knowledge of tubes is too limited yet, but this looks like what might become a nice entry point into the valve-realm for many people.