Tube boost + overdrive running off a 9 volt battery

[fatecasino]

I read lots of these pages, I am definitely wiser before I started this project,
I built valvecaster 2.0 with two tubes in the row JJ and electroharmonix golden pin.
Electroharmonix is just amazing, JJ is so-so.
Now I have a question,

Is there an alternation of the schematic so I can use valvecaster for an acoustic quitar(piezo)? Could it be as simple as trying other tubes, 12AT7/12AX7? or other makes Mullard, rca, etc?

[fatecasino]

Is there an valvecaster version for acoustic instruments? I tried valvecaster with electroharmonix golden pin and JJ, and my acoustic guitar sounded distorted 

Should I change some resistance values?
Should I try other tubes? 12AX7?12AT7? other makes?Mullard, rca, etc?
or can you suggest any other simple schematic for acoustic preamp/pedal?

[Rawdata]

Hi guys,
Thanks for all these posts. Would it be possible to use this as a "filter" for my acoustic instruments? I really like the warmth and compression of a tube, so a version/alteration which would not distort/overdrive the signal would be great.
Any ideas?
Many thanks in advance!
Marc

[vigilante397]

Welcome to the forum The best way to use this pedal in an overdrive-free situation would be to stick with the 12AU7, which are lower gain than the 12AX7, 12AT7, etc. You would probably also want to experiment with resistor values to substitute for the gain pot to give you a "stuck clean."

[Rawdata]

Thanks Vigilant, that would mean higher value resistors for the gain, right? In what range would you advice to experiment?
I have Philips 12AU7's that have a really "hifi" characteristics, also.

[vigilante397]

The gain pot for the original circuit is 50k, so I would guess something in 30k - 40k range. An additional option would be to replace the gain pot with a trimpot and adjust it until you have the maximum gain you will want in the circuit then just leave it there.

[Rawdata]

Thanks again!
I guess I'll make two versions for electric and for acoustic  (with the trimpot).
Cheers

[george79]

Just finished mine with 6111 tube.working like a dream.I have one problem only.i need more volume when the pedal engaged.power is 12vdc.what can i change?or a 6112 with mu70 will do the job?feed it with higer volts?adjust anode resistors?just need more volume.what do you suggest?

[suncrush]

Hi all!  I'm going to put one of these together as my first DIY stompbox project.  Super excited!

I've been reading through the thread, learning things, but I have a few questions I can't find answers to since this thread is huge.

I want to run it at 18V to get more headroom and get a cleaner boost.  I know I need to add a resistor to drop the heater input to 12.6 V.  Are any other modifications required?

I'm not really sure what most of the resistors and caps actually do. I'm happy to figure that out by experimenting, but are there any that would be a really bad idea to change?

Thanks heaps.  Glad to be here.

[lluis3.0]

Schematic with last mods:

Hi guys,

Can you verify if this vero is correct??



Thank you very much!!

[lluis3.0]

Schematic with last mods:

Hi guys,

Can you verify if this vero is correct??



Thank you very much!!

I forgot to mention that the SW is an SPDT on off on switch.

[funkyjunky]

Hi all!
valvecaster is my first diy stompbox project. I made a prototype on the breadboard and was happy with the sound and decided to build a real thing using a stripboard and altoids can box. I decided to make my own stripboard  design. Yesterday I finished soldering and powered it on and was not happy with the noise which is coming out when i turn off the gain pot. Also there is noise coming out of it when I touch any potentiometer. The distortion is not working, only tone pot affects the sound. On the breadboard all was fine. Here is my schematic:



I am not into electronics and cant understand what caused that. Any help much appreciated, Thank you.

[th!nk]

Okay, looking at building one of these, with a few mods. I'm thinking of putting a mosfet booster before it to get more gain out of it, but I'm curious what I should do with the valvecaster's gain pot in that case - obviously I don't want two gain pots. If it helps any, I'm looking for more of an overdrive than a boost.

[duck_arse]

what I should do with the valvecaster's gain pot in that case - obviously I don't want two gain pots.

well, th!nk, someone's going to come in and tell you to call it "drive" instead, so it may as well be me.

"call it 'master' instead."

[th!nk]

Heh, very good. I guess I'll find a value I like with it in there and then replace it with a resistor. Should probably have thought of that earlier to be honest.

[peterg]

Funkyjunky - the components look like they are laid out ok but your gain pot isn't connected properly. You need to switch the connections of 2 and 3. That way the gain will increase as the shaft is turned clockwise. This won't fix the noise problem though. Check your connections and look for solder bridges. Running a knife along the grooves will cut bridges if there are any. Also check your component values. If that doesn't help refer to this page for debugging:

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[suncrush]

I finished breadboarding my build, and I'm waiting for parts to box it.  I tried swapping out caps and resistors to try things, and turned out preferring the original values.  The only mods are losing the tone knob (superfluous, and ditching it brightened the sound), and running it at 18 V.  With the extra headroom, the boost sounds delicious, and the growl at high gain is still fantastic.  I tried a new-built JJ, and a 1960's-built Sylvania. The Sylvania is going in the final build.

[Sid-W]

Hello everyone - first post here

I'd like to build a version of the Valvecaster as a complete low watt practice amp. I'm thinking about putting the output of the VC into a TDA2003. I've scanned the thread ( well, parts of it  ) for clues and it seems the low input impedance of the TDA2003 is a problem. Could anyone suggest a buffer circuit to put between the two ?

Would the first one here do ? http://www.beavisaudio.com/techpages/Buffers/ - I have built this already as a guitar\soundcard interface and it works fine.

Thanks !

[duck_arse]

Sid! welcome to the madhouse.

the output impedance of the valvecaster should be adequate for the tda, which I think has op-amp inputs? in this case, the input impedance is determined largely by the resistor used with (chosen for) the tda.

have a look for the tube cricket at beavis.

[Sid-W]

Thanks ! - what is confusing me is that two guys mentioned that they tried to hook the VC up to a TDA2003 without success, while pages earlier another guy showed some pictures of his two builds into old radio chassis which were fine. No actual details of the circuits involved though.

I'm not sure what to think really  I see what you mean about the Tube Cricket schematic...could it be as simple as the value chosen for the volume pot ?