Tube boost + overdrive running off a 9 volt battery

[forsakenrider]

Dear Renegadrian, Check out this link: http://www.dxing.info/equipment/wall_warts_bryant.dx . Build it with a LM317 with a heatsink and you adjust your power output via trim pot and its got enough filtration for most applications. (It was literally night and day when I added it) Cheap and simple.
also, Have you tried changing any resistor values for higher gain? It sounds awesome when I crank the volume and gain to 10, but id like to be able to go past that and turn it down a bit as well...

[soulsonic]

I traced another low-voltage tube circuit recently.
http://www.diystompboxes.com/smfforum/index.php?topic=66061.0

[Renegadrian]

quote forsakenrider
Dear Renegadrian, Check out this link: http://www.dxing.info/equipment/wall_warts_bryant.dx . Build it with a LM317 with a heatsink and you adjust your power output via trim pot and its got enough filtration for most applications. (It was literally night and day when I added it) Cheap and simple.
THANKS MY FRIEND, IT SEEMS A VERY USEFUL LINK!!!

also, Have you tried changing any resistor values for higher gain? It sounds awesome when I crank the volume and gain to 10, but id like to be able to go past that and turn it down a bit as well...
NOT FOR NOW, I JUST MADE THE VERO VERSION I LAYED OUT THAT YOU CAN FIND SOME PAGES AGO, I PUT SOCKETS FOR R1 AND R2 - I NEED THE OTHER PARTS. (I'LL GO BANZAI IN A COUPLE OF DAYS...)



Also, I was messing around with my Valvecaster, my "Stratoblastered" guitar and an AMZ mosfet booster - for now using the two boosters with the Valvecaster leads to horrible sound and too much distortion...I'll try again as soon as I will have a quiet V. per se...

[forsakenrider]

Changing R1 and R2? Raising R1 above 1meg? Ive always seen it at 1meg in all the tube amp circuits. and raising R2, wont that lower the plate voltage? how does that increase the gain?

Another question i have is about the pots. Gain and Tone are not connected to ground in the layout but in the schematic they are, why is this?

[guitarx]

Hi All!

I have viewed this topic some days, this schema is very cool, but I never find with change this schema for one clean sound, it is possible? how?
The clean sound would like a "preamp tube clean". Because, when "Gain" control is decrement in original schema, still have a little overdrive.

Thanks for all, sorry for my beginner question.

[andrew_k]

guitarx: replace the 100k resistor with 47k. Replace the 220k resistor with 100k.
Beautiful cleans 

To fellow Valvecaster experimenters -- I've currently got this circuit on a breadboard, switching out everything and I have some items of interest to report, especially for those looking for more gain.

The nicest clean sound I've found so far, is with the following mods:
R2 = 100k
R3 = 47k
C1 = 0.1uf
Remove C4 and VR2

These changes gave a more honest clean sound than the original -- less distortion, better bass response and still adding the tube's character without too much change to the original clean tone. Increasing the gain brings in a light breakup that I really dig.

The nicest high gain sound I've found is from adding clipping diodes to the above mods. Two 1N34a Ge diodes with two 1N4148 Si diodes. I'm too much of a n00b to know the naming for clipping setups, so I'll just draw it in ASCii art

Code Select Expand


OUT        Ground
  |          |
  |---->|----|      Ge
  |----|<----|      Ge
  |          |
  |---->|----|      Si
  |----|<----|      Si



I tried a heap of different combos of those two diodes in symmetrical and asymmetrical configurations, the above setup sounded the best so far. I still have some other Si types, schotkies(spl?) and MOSFET clipping arrangements I want to try.

Introducing the Ge diodes caused a big drop in output volume, so I've added a JFET gain stage before the output, which bought the volume up to being even with the clean version.

Tonight I will be experimenting with tone stacks -- a SWTC for the clean side and a big muff-based tone with switchable mid cut for the high gain version.

My plan for all of this is a pedal to put between my OD/dist/fuzz pedals and my modulation/delay pedals. The valvecaster responds really well to too much signal from pedals before it, so I've been using it as a dirty limiter of sorts. There will be two stomp switches -- an A/B for clean/high gain and a bypass switch. Each channel has it's own gain, tone and volume controls, with different tone stacks. All sharing the one tube, and all fitting in a BB enclosure. I've already laid it out and it'll fit nicely, I just have to decide on component values to get the sound I'm looking for. I envisage this staying on all the time in clean mode, then being switched to dirty mode to provide a second channel for single channel amps. Currently I use a catalinbread hyperpak for this, but this pedal is well on it's way to achieving a better sound.

All just my uneducated opinion, based on my gear, of course

EDIT: all of the above is with a 12v power supply

[Renegadrian]

Andrew, you are great!!! I  want to experiment more on the Valvy, I already made the vero version I developed with sockets for R1 and R2, and ordered the other bits I was missing...With some different values GAIN pot...
I'll report my results...Please tell me more about the high gain channel, or how to obtain its highest gain...
It would be great to develop a kind of table with different uses (low gain, clean boost, high gain, ecc) and with sound samples...

[andrew_k]

Adriano - thanks, it was for you that I posted about high gain; I know we've both been chasing that since seeing this circuit 
I'll report back when I've played with other clipping options some more, but to my ears the distortion is much more usable when generated by diode clipping and a gain recorvery stage rather than swapping resistors in the circuit.

Swapping out C1 for something larger helps add some more of that "chug chug" high gain -- but this circuit doesn't do the modern metal sound. I'm currently using 0.1uF, but tried up to 1.5uF film cap. It got too mushy with the 1.5uF.

[Renegadrian]

I'd like to thank Jared for the gift...I received several tubes for free...That leaves me speechless...

Needless to say I tried them all...

Here's my thoughts on using them on Valvy running  at 12V

* 12AU7 = the main choice, good. The one I liked the most was a RCA.
* 12AT7 = not bad, try one and see if you like the result...They sound good stock and I believe they could be even better with minor tweakings...
* 12BH7 = Didn't know that kind of tube...They are great to use on this project!!! They give a little more gain too, to my ears...

More on that later, my friends...

[cyberk007]

man i built one of these and i just cant seem to get it to work, anybody think they have an idea of whats wrong? 
http://www.diystompboxes.com/smfforum/index.php?topic=66252.0

[Papa_lazerous]

man i built one of these and i just cant seem to get it to work, anybody think they have an idea of whats wrong? 
http://www.diystompboxes.com/smfforum/index.php?topic=66252.0

confused as to why you would post in this thread about another thread about an unrelated post, that has already been answered 

[culturejam]

I built one recently as well, and I really dig it.

It has a ton of hum, however, no matter the gain or volume setting.

Also, it seems to generate a noticeable octave effect, kinda like an octave-fuzz. More prominent on the higher frets and with the neck pickup.

Could this be a funky tube? I used a new JJ 12au7.

It's probably something I did wrong, but when working with tubes there is always a chance that it's the tube. 

[andrew_k]

It has a ton of hum, however, no matter the gain or volume setting.

It's definitely your build/tube, not the circuit.

Here's a sample of mine, same passage played twice -- first time bypassed, second time with gain on zero and volume at unity. There's almost no noticeable difference in sound (just as I wanted )

clean valvecaster sample signal path is carvin fatboy > valvecaster > roland microcube > mbox 2 (line in)

[brett]

Mostly, hum = grounding issues.  Check that the signal isn't "floating", with no reference to ground, at some point.

[culturejam]

It's definitely your build/tube, not the circuit.

Since nobody else mentioned hum, I figured it wasn't the circuit.

Check that the signal isn't "floating", with no reference to ground, at some point.

Will do. Thanks.

[tranceracer]

It's definitely your build/tube, not the circuit.

Since nobody else mentioned hum, I figured it wasn't the circuit.

Check that the signal isn't "floating", with no reference to ground, at some point.

Will do. Thanks.

It could be your power supply.  I used a small Boss 9V and got a lot of hum then changed to the bigger Boss PS (red one) and hum was gone.  I'm trying to build a filter ckt but the cheaper / smaller transformer still produces hum.  The bigger (red) Boss supply still runs this pedal clean.

[Renegadrian]

I definitely agree with you, my Valvy has this horrible hiss, I only have unreguated PS. I gave it to my GF brother to try it, he had no hiss at all, using REGULATED PS. So I am waiting to receive those 7812s to filter the power...It seems a must, try it, after all it's just a little mod that seems to be so useful, reading others experiences in the ast pages...

[forsakenrider]

LM317's and this circuit will remove your hiss http://www.dxing.info/equipment/wall_warts_bryant.dx . Thats what i use and mine is dead quiet.

[Renegadrian]

Finally received that 7812 - mounted with the 100uF filter cap on the dc jack - hiss is just a memory...
Now I really enjoy my Valvy!!!

[tranceracer]

Glad you got the problems resolved!   
Did you place the 100uF across the +/- of the power leads?

I used the C1, C2, D2 from this power filter and still get the 60 Hz hum from my small wall wart.



Maybe there's a better filter out there.  Any other recommendations?