Tube boost + overdrive running off a 9 volt battery

[cranedewd]

Disregard that last question. It is most definitely the wall wart. I hooked a battery to it and it was gone. I guess I need a better power supply.


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[ghostsauce]

For these, it's best to order a special supply. I snagged one off amazon for $20 or so, a 12v filtered supply. Works great.

I'd suggest changing the gain knob for a real gain knob though.. where it controls the volume between the sides of the tube. Sounds much better than the bias knob it currently is.

[cranedewd]

So many question, so little time. Could I run this on 12v?  How would I hook up that gain pot?  I'm a total noob bro!  Thanks


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[duck_arse]

crane - look very carefully at the nameplate on your buzy supply. give us the ratings, please, it may be you are overloading it some. or is it an AC output? nah, couldn't be, surely.

and if you are using 12A*7 valve/s, they are meant for 12V (or 6V) heater supply.

[cranedewd]

Yes I'm using a 12au7 valve. The power supply is just one I had laying around from something else. I don't even know what it was for!  I powered another pedal with it and it hummed too.



I ordered a filtered supply this morning.


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[duck_arse]

well, it says DC, so probably it just needs some extra filtering. but not for this valve project. if you have a 12V DC supply, also laying around, try that.

[ghostsauce]

More voltage sounds more better for this... Definitely worth the hassle. Theres a vid on youtube somewhere where you can hear the difference.

About the gain pot, I posted it a few pages back. Sounds so much better.

[cranedewd]

If I run 12v, I can keep the same caps and resisters?


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[ghostsauce]

Yep, you're good.

[cranedewd]

Rookie mistake. I found a 12v supply, plugged it in and Pop!  Didn't check polarity. Dang. Did I just ruin this valve or just one of the caps?


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[vigilante397]

Rookie mistake. I found a 12v supply, plugged it in and Pop!  Didn't check polarity. Dang. Did I just ruin this valve or just one of the caps?


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Probably just a cap. Valves tend to be pretty resilient and forgiving of (most) mistakes.

[Jamdog]

You should add reverse polarity protection...  Just in case.

[cranedewd]

Guys, I'm at a loss. I greatly appreciate all your help, but I just cannot figure this out. I bought these sockets for my power supply to the box.



When I mount the socket to the box and plug in the power supply, nothing happens. If I remove the socket from the box and plug it back in, it works!  I don't get it. Thanks for any suggestions.


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[vigilante397]

Guys, I'm at a loss. I greatly appreciate all your help, but I just cannot figure this out. I bought these sockets for my power supply to the box.



When I mount the socket to the box and plug in the power supply, nothing happens. If I remove the socket from the box and plug it back in, it works!  I don't get it. Thanks for any suggestions.


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That will be your problem. Metal jacks mounted on a metal box is going to create problems. We use center negative sleeve positive on our power supplies for pedals, but by convention audio jacks are opposite. So you're connecting the ground to the metal box through the input/output jacks, then you're connecting 9V DC to the metal box through the power jack. This is a problem

[bluebunny]

...in other words, you're shorting out your power supply. You can try to insulate the jack, or else get a plastic one.

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[Jdansti]

What they said-like this.
http://www.taydaelectronics.com/dc-power-jack-2-1mm-enclosed-frame-with-switch.html

[suncrush]

So many question, so little time. Could I run this on 12v?  How would I hook up that gain pot?  I'm a total noob bro!  Thanks


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The circuit will run without modification on a 12V supply.  I run mine on an 18V supply, and the only mod for that is adding a resistor in the heating circuit. (You can run these valves with 18V through the heater, but their lifespan will stink.)

Actually, truth be told, if I were running the circuit on 9V, I'd modify it to run the heaters in parallel, and put a resistor in to drop the voltage to 6V.

[cranedewd]

Could I use a 12ax7 in this pedal?  How would it sound?


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[stallik]

I think the general concensus is that 12ax7's don't work as well but my experience is that old ones do. Brimar, Mullard etc sound pretty good but newer valves really need higher voltages.

[vigilante397]

I think the general concensus is that 12ax7's don't work as well but my experience is that old ones do. Brimar, Mullard etc sound pretty good but newer valves really need higher voltages.

Agreed. I've tried older Mullards that still sound good, but I've tried brand new Sovteks and JJ's that sound awful.