Tube boost + overdrive running off a 9 volt battery

[Renegadrian]

77 pages are quite hard to read, but yeah we wrote several times that a 12V supply is better suited for that kind of tube!

[zambo]

I have now built 2 of these that sound identical. Both on 9v power supply. When I hook up 12v it hums loud. I cant tell if its regulated. Also..when I changed to a 12ax7 I noticed a hesitation when I hit a note hard. Anyone else notice this?

PS. Thanks  Dano and Renegadrian for all the layouts. I have read most of the forum. Lots of mods and tips.

[tipetu]

yeah, mine has a lot more hum when using 12V. I use 9V and a 12AU7. My impression is that the 12AX7 needs alot more power than the 12AU7, therefore the AU7 is more apropriate for this build. I`ll post some shots of the inside if anyone wants?

[Renegadrian]

12AX7 needs higher voltages, I made some experiments at 50V but didn't get a decent sound out of it...
both the AU and the AT are good in the Valvy - dunno about the AY.

Pics are always appreciated!!!

[tipetu]

I`ll open it up tomorrow and upload some.. btw, it`s not the most pretty one I tell ya that! but it works!

[tipetu]

That black tape in the middle of the tube socket is just to isolate the yellow led

[tipetu]

Today I tried the pedal on my transistor marshall for the first time and there were actually NO HUM! I`ve been using this pedal on three other amps in which 2 of them are tube amps and the last one is a Crate transistor. All of them gave hum, but not the marshall. Strange... What amps do you guys run this pedal through?

[REGNAD]

i have mine in a chain feading an epi valve jr stack and the wet output of my mistress into a SS amp. all very quiet!
guitar>cs-3>fuzz>valvecaster>bk tube driver>big muff>carbon copy>mistress>SS amp
                                                                                                                 >boss eg>valve jr

[earthtonesaudio]

I remember when this thread was under 10 pages... who knew it would become such an epic!

I just pulled a 12AU7 from a cheap old multimeter that was headed for the trash heap, so I decided to try this.  I guess I'm a little late to the party.  Sounds pretty good though!

[Renegadrian]

You are never late to join the tube club...I am sure yours is going to be a great pedal!!!

[earthtonesaudio]

I wired up a tube socket-to-breadboard adapter and have been going mod crazy and swapping tubes to see what all the fuss is about.  A couple interesting notes:
I tried a couple RCA 5963 tubes and was very surprised to see them working with a plate voltage of less than 5V.  I think I dropped the plate voltage all the way down to 3.8V and was getting some dirty boost and gain.  I had no idea tubes could work at such low voltages.
Also, I made each section into a SRPP stage with first MOSFETs and later BJTs as the "upper" section.  I also replaced the cathode resistance with JFET constant current sources.  None of this made a huge effect on the sound.   

[pudelko]

I just finished my valvecaster today. I ran into some problems with it not working and spent a few hours searching for what could be wrong.

I used an old input jack from a strat copy I had and didnt look carefully enough and wired the input connections backward  . I also used caps that were not 47nF but much smaller, after fixing these two problems it finally works! But if I turn the volume up past a quarter or so there is a loud constant humming sound, so some more work needs to be done, Im only on page 20 of this 80 page thread. I want to read through the whole thing before I decide what to do next, maybe Ill find a few mods to do  .

It sounds Amazing! Especially with the Valve Junior tube amp that I also picked up today. Really fat sounds coming from my Epiphone Les Paul Standard.  Its a bit late tonight, but tomorrow I will make a demo video/mp3 file.

Here is  pic of it:


I will end up painting it once Ive read everything and make it work properly.

[silentmike]

It's been a while since I managed to finish my valvecaster/sparkle boost pedal and it's really nice, gives a really smooth overdrive. I'm using it on bass and recently I've upgraded to a Markbass amp. It's a lovely amp, but it's very trebly and while I've managed to reign it in for my clean tone, when I step on my valvecaster I can hear a noticeable loss in the low end. Does anyone know how I could make it a bit more bass responsive? I've heard something about changing the input and output caps, but I'm not sure what sort of values I should be looking at.

Cheers!

[charbot]

Sorry if this has already been covered, but has anyone tried making a stereo preamp like for an ipod or something, with two 12au7's? One for each channel.   maybe something like thepedal-sized  zvex stereo tube amp. Any suggestion for keeping the signal ultra clean and is Hi-FI quality possible when opperating at this low of a voltage? if this is an old idea please direct me to where it was discussed, ...I cant find it?
thanks

[Ripthorn]

In general, you won't get anywhere near hi-fi with this kind of a setup.  The higher the voltage, the higher the clean headroom for a given circuit topology.  There may be exceptions, but I am not aware of any off the top of my head.  If you want something hi-fi, you should go the the musicelectronics forum and look at the tube hi-fi systems in the hi-fi section.  Something like the valvecaster was not designed for pristine reproduction of the input signal.

[earthtonesaudio]

A mod:



Besides the output buffer and changes to part values, this basically shows an different way of doing a gain control on the Valvecaster.  By moving a few connections around (not adding or subtracting any parts) you get a totally different gain control.  To the left of the wiper it's essentially the stock gain control.  To the right, it also acts as a variable load on V1 and a variable input impedance control for V2. 

I encourage you to try this mod while you're building your next Valvecaster.  If you don't like it, simply short the rightmost lug (in my schematic) to ground to restore the stock Valvecaster configuration.  With stock Valvecaster values, this mod should provide more bass at high gain settings, as well as slightly more maximum gain.

[kurtlives]

Looks good your input grid on the second triode looks a bit small though.

[earthtonesaudio]

Looks good your input grid on the second triode looks a bit small though.

That's correct.  It was mostly intentional.  Such a low value makes a low impedance load on the plate of the first triode, so the first triode is attenuated more as the gain is turned down.  Basically it makes the gain control have a better "feel" at the cost of lower maximum gain.

I tweaked a little more and stopped here:

[sbm]

Wow, what a post....I think I quit at 15 pages though and skipped to the last 3 lol.

I think it's time to play with this, first with the original circuit....whew!

[jrmcgrath13]

Hi all,

I just started looking at this thread a couple days ago, and I found this diagram.  Is this an proper/accurate diagram for the standard valvemaster with a stomp switch, etc?  (You know, without any mods?)  Thanks so much!

this is what i used...