Tube boost + overdrive running off a 9 volt battery

[Jimmy-H]

hi i just built the valvecaster
it seems the volume is a bit weak, it needs to be at around 3 o clock to maintain the bypass level.. is it all this way or just mine?
and i don't think the gain is enough, i used a 100k log pot besides the 50k, is it because of this?
and i feel its too bassy what mods can i apply to it?
i used a 12au7 tube running off 9v
no problem with noise
i used a booster pedal before it, and it sound great
but as a standalone.. i don't know..
can you guys pls suggest some modifications? thx!

Hi awitee,

You could try to run off 12 volt.(more headroom)
But you have to watch the heater voltage.
If you connect 12 volts to 4 and 5 of the tube, you will be alright.
With the bass thing....you can change the input cap.
I believe a smaller cap --> less bass.
Also, you can try to remove the tone-circuit or make it switchable(gives a little more gain).

success with your valvecaster!

[Stellan]

hi i just built the valvecaster
it seems the volume is a bit weak, it needs to be at around 3 o clock to maintain the bypass level.. is it all this way or just mine?
and i don't think the gain is enough, i used a 100k log pot besides the 50k, is it because of this?
and i feel its too bassy what mods can i apply to it?
i used a 12au7 tube running off 9v
no problem with noise
i used a booster pedal before it, and it sound great
but as a standalone.. i don't know..
can you guys pls suggest some modifications? thx!

Hi awitee,

You could try to run off 12 volt.(more headroom)
But you have to watch the heater voltage.
If you connect 12 volts to 4 and 5 of the tube, you will be alright.
With the bass thing....you can change the input cap.
I believe a smaller cap --> less bass.
Also, you can try to remove the tone-circuit or make it switchable(gives a little more gain).

success with your valvecaster!

+1 on the 12V. Mine was barely more than unity gain with 9V. The input cap needs to be higher to brighten the pedal. I doubled mine and that works great! It is still "warm" sounding, but now you go from smooth dark tone to somewhat transparent eq with the toneknob. Try it, I really like mine now! I dont get overdrive without hitting it with a booster, but i also have low signal pickups on the relic strat i used it with. Have yet to try it with humbuckers. I think I will end up putting a booster in there with it just because i get GREAT sounds with my Tubescreamer set to minimum gain into the Valvecaster.

[awitee]

hi i just built the valvecaster
it seems the volume is a bit weak, it needs to be at around 3 o clock to maintain the bypass level.. is it all this way or just mine?
and i don't think the gain is enough, i used a 100k log pot besides the 50k, is it because of this?
and i feel its too bassy what mods can i apply to it?
i used a 12au7 tube running off 9v
no problem with noise
i used a booster pedal before it, and it sound great
but as a standalone.. i don't know..
can you guys pls suggest some modifications? thx!

Hi awitee,

You could try to run off 12 volt.(more headroom)
But you have to watch the heater voltage.
If you connect 12 volts to 4 and 5 of the tube, you will be alright.
With the bass thing....you can change the input cap.
I believe a smaller cap --> less bass.
Also, you can try to remove the tone-circuit or make it switchable(gives a little more gain).

success with your valvecaster!

mods i made was, i paralleled the 1M resistor with 690k to get a lower resistance for more gain
i also changed the input cap to .022microfarads to lessen the bass
and then i changed the gain pot back to the 50k B from 1M A
and also i now run it at 12V
results... OH YEAH hahaha
so happy with the result, great overdriven sound!! i couldnt be more happier
sounds super great when i drive it with either my queen may booster or ts808 clone
super great tone
im not sure what to do with the "But you have to watch the heater voltage." coz im not really experienced with tubes hehe this is my first tym
but it's still working so i guess im fine hehe thx alot for the help and instructions on this thread!

[armstrom]

So, what is the expected gain of this circuit (at 12V) anyway? I'm planning to use this as a preamp for my power amp and I'm concerned that it may not provide enough gain to sufficiently drive the amp. I can adjust the gain of the power amp input stage but I'm not sure that will be enough if the gain from the preamp is too low. Keep in mind I'm not looking for crazy overdrive/distortion. This is going to be for blues so if the gain goes from clean to just starting to break up when cranked, it will be perfect. Of course, this assumes the distortion comes from the first stage overdriving the second, not both overdriving the power amp

Also, why would you reduce the input impedance if you're trying to get more gain? The lower the input impedance is the more input signal will be lost to ground. If anything, I would say to try 2M on the input resistor to increase the signal available to the first gain stage. Or am I missing something?
-Matt

[frequencycentral]

Subcaster working!

All I did was remove C2, the 47nf cap across the supply rails and replace it with a different kinda 47nf cap. Weird. Hmmm, been bugging me for weeks!

So - I fired my Valvecaster into my Subcaster - WOW!!

It seems to me that the hassle of creating a 6.3 volt supply for the 6111 heater is a pain in the butt compared to powering a 12au7 heater at 12 volts. There really is no saving on space when you consider the extra circuitry required for the voltage regulator - and a heatsink on the LM317 too! There is a whole lot of heat generated by a 6111 in comparison to a 12au7. add that to the heat the LM317 gives out and you can warm the living room up nicely with a Subcaster!

My rule of thumb now will be to only use 6111's in pairs and run the heaters in series of 12 volts.

So - go ahead and build a Valvecaster. Or a dual Subcaster. Or a Pepper Shredder using two 6111's, like I'm doing next.

(Shit, I would do it this weekend but I have to write some music for Volvo!)

Just don't build a single 6111 Subcaster!

[Pushtone]

I had weak fizzy, farty tone with pathetic amount of gain with a $8.00 Yugoslavian tube.
Switched it with an $18.00 EH 12AU7 and I had plenty of gain and a nice over drive distortion.

After that...
I switched out the decoupling cap between stages to 0.0022uF to tune the bass where I like it with humbuckers.
Then I replaced the 1uf electro with a film cap.

I think it sounds great and I have plenty of gain. Yes a booster in front makes it sing!

Pics:
Top - link
Insides - link

Posted these in the pictures thread a while back.

[gaussmarkov]

Pics:
Top - link
Insides - link

gorgeous dave! 

[DougH]

I had weak fizzy, farty tone with pathetic amount of gain with a $8.00 Yugoslavian tube.
Switched it with an $18.00 EH 12AU7 and I had plenty of gain and a nice over drive distortion.

These comments lead me to believe that you need a way of adjusting the bias for different make/models of tubes. Aron included a bias adjustment in his Shake Tube for this purpose. You might look at that for ideas or there may be suggestions earlier in this thread (I haven't read the whole thing). I suspect you could get this to work with a lot of different tubes (with correct pinout) if you had a way of adjusting the bias.

[eddieod]

Hi all,

I encounter similar problems in using different brands of tubes within the 12au7. When I put a JJ (former Tesla) 12au7 into this circuit (valvecaster) there's hardly any output at all! I have similar problems with other designs on low voltages also (like a pedal I developed called the "ts-tube"). Sometimes a tube really puts out a great amount of output and tone and sometimes it's just plain dead! EH's seems to be most consistent in working within such designs, but not always...I think it has something to do with the way the heater can generate sufficient electrons for the cathode to be able to work...Anyone with similar experiences? What can be done to have this solved? I personally don't believe you can get away with this just by changing the bias point for the reason in cause I mentioned earlier: if there's not enough dissipation from the cathode, there isn't anything to begin with...

What are your opinions on this?

Like to know.

Have fun,

Ed's Custom Shop
Edwin Thoen
Maarssen
The Netherlands
www.edscustomshop.com

[Renegadrian]

Well, I own so many 12au7s, so i tried them all, and while their tonal nuances are all slightly different, they all work great...
I got NOS GE, Raytheon, RCA ecc. and a new EH as well...

[DougH]

These comments lead me to believe that you need a way of adjusting the bias for different make/models of tubes.

http://www.diystompboxes.com/smfforum/index.php?topic=63479.msg538894#msg538894

[Jimmy-H]

Hi there,

Just finished a Subcaster with a 6111 of GE.
The amount of gain for overdrive isn't that much.
But that I don't mind, because I want to use it for Boosting Solo's.
Therefore the Subcaster works great.
I'll place some pictures, as soon as I have boxed it in.
But that can take a while

But I changed the input powersupply filter from Dano a littlebit.
Because when you use Dano's scheme, you loose at least 1.5 volt.
Just do the maths (current for heater is 300mA and R1= 47 oHm leads to roughly 1.5 volt loss)
So I moved/replaced R1 with a coil of 1mH.
I made a change in Dano's scheme, Hope you don't mind Dano!
Otherwise I remove your drawing!!

[frequencycentral]

But I changed the input powersupply filter from Dano a littlebit.
Because when you use Dano's scheme, you loose at least 1.5 volt.
Just do the maths (current for heater is 300mA and R1= 47 oHm leads to roughly 1.5 volt loss)
So I moved/replaced R1 with a coil of 1mH.

I removed both R1 and C2 From my Subcaster - it seems to work just fine.

Just finished a Subcaster with a 6111 of GE.
The amount of gain for overdrive isn't that much.

I found my Subcaster gives similar gain to my Valvecaster. My 6111 is a French CSF tube, I have a Penta 12au7 in my Valvecaster. I do have some dodgy unbranded 12au7's, which give less gain and a softer sound  - nice though. I have some Raytheon 6111's for my next build - so I'll see if they're different.

As someone said earlier in this thread - 'its all about the tubes!'

[puretube]

Hi there,

Just finished a Subcaster with a 6111 of GE.
The amount of gain for overdrive isn't that much.
But that I don't mind, because I want to use it for Boosting Solo's.
Therefore the Subcaster works great.
I'll place some pictures, as soon as I have boxed it in.
But that can take a while

But I changed the input powersupply filter from Dano a littlebit.
Because when you use Dano's scheme, you loose at least 1.5 volt.
Just do the maths (current for heater is 300mA and R1= 47 oHm leads to roughly 1.5 volt loss)
So I moved/replaced R1 with a coil of 1mH.
I made a change in Dano's scheme, Hope you don't mind Dano!
Otherwise I remove your drawing!!

One milly is better than no Henry at all,
but if this Dano "subcaster" schemo
is the one you compare yours with,
check out where in Dano`s the heater current is running through (R1, and causing a drop...), going where,

and which current is running through L1 in yours,
and will that ever effect the heater? 

[Jimmy-H]

One milly is better than no Henry at all,
but if this Dano "subcaster" schemo
is the one you compare yours with,
check out where in Dano`s the heater current is running through (R1, and causing a drop...), going where,

The voltage drop is on B+, wich you don't want.
The coil hardly gives a drop on B+.
But you can leave R1 (and L1) out when you use a good powersupply just what frequencycentral wrote.

And which current is running through L1 in yours,
and will that ever effect the heater? 

everything except for the heater current, causing hardly a voltage drop on B+
The heater current is going through the regulator so there will be hardly a Hum there.

[armstrom]

Has anyone tried this circuit with a 12U7? They're designed to run with a plate and heater voltage of +12V. I'm wondering if they will produce any better results than using the 12AU7 which wants +100V or so on the plate.

Oh, and they're cheap...

-Matt

[frequencycentral]

Has anyone tried this circuit with a 12U7? They're designed to run with a plate and heater voltage of +12V. I'm wondering if they will produce any better results than using the 12AU7 which wants +100V or so on the plate.

Oh, and they're cheap...

-Matt

This is a long thread.....but if you check back I'm pretty sure someone mentioned using a 12u7 and getting a softer sound with less gain.

[emx]

How well does this work on line-level stuff?  I'm looking to build something like this in stereo for synth use.

[Jimmy-H]

Hi there,

I finally had some time to box my pepper shredder in.
I called it the INDIAN TWIN TUBE DISTORTION>
Only the knobs are missing.
The box i used was an old printer switch (one printer more computers).
There were some holes in the lower part, that I had to close.
Put some tolex over it, and the holes were gone!

I also placed a 6-way switch for the input caps.

So here are some pictures :





I'm very pleased with the overall look.

[Renegadrian]

Nice work...Want to listen to some clips!!! And maybe some detailed info about your pedal, the circuit, the components used, the PCB, etc...