Tube boost + overdrive running off a 9 volt battery

[Jdansti]

^ +1

In additon to a low battery, if your 9V power supply is unregulated, you might be getting 10V to 11V output when connected to he Valvecaster, which would help. If you have a meter, it would be a good idea to check the voltage of the power supply disconnected and connected to the VC. Same for your battery. BTW, due to the current draw of the heaters in the tube, you're going to go through batteries pretty quickly.

If possible, try to find a regulated 12V supply. The 12A_ tubes are designed for 12V across both heaters in series (6V in parallel).  The glow is barely noticeable even at 12V, so don't expect much there.

[Ark Angel HFB]

I have a charge pump regulator combo I think I posted a while back in this thread that will give you 32vDC to the plates... and a regulated 6vDC to be connected to pin 9 then just ground pin 4&5.

[jonasramen]

       my thingy didn't work very good, first the tube turned on but without any sound, after that i realized i was wiring th 1M ohm resistor in a bad way , then i modified it and the tube didn't turn on again i dont know if the tube is damaged its an old one that i picked up from an old radio y bought all the parte in steren except the valve and the socket maybe thats the problem can you help me please? im from mexico and here the valves are very expensive

[Ark Angel HFB]

The valve should still be ok... but without picture and voltage reading it is hard to tell...

as far as the valve being bad... idk...

[Burdin]

Hi,
I finally finished my valvecaster and it it's great pedal, my previous problem was given by old wires, they get easily broken during manipulation, so I  bought new ones and now it works ok.
But I still have one problem, for switching valvecaster off/on, I used simple truebypass foot switch, with 3 connectors, at middle one is going input signal, then in first position it goes through valvecaster circuit and in the second it goes directly to output. Here comes the problem, when it's in the second position, the signal reacts with volume pot, so I can't adjust volume correcly, when it's off, signal is weak and when it's on signal is too strong etc. I'm not sure, but I think it shouldn't be a problem, wires from circuit and from switch going on the same place at output connector. here's the picture of finished stompbox, there's big mess so I'm uploading it just to show connectors and switch. Thanks for the answers.

[iq01221]

Posted by: Burdin
Hi,
I finally finished my valvecaster and it it's great pedal, my previous problem was given by old wires, they get easily broken during manipulation, so I  bought new ones and now it works ok.
But I still have one problem, for switching valvecaster off/on, I used simple truebypass foot switch, with 3 connectors, at middle one is going input signal, then in first position it goes through valvecaster circuit and in the second it goes directly to output. Here comes the problem, when it's in the second position, the signal reacts with volume pot, so I can't adjust volume correcly, when it's off, signal is weak and when it's on signal is too strong etc. I'm not sure, but I think it shouldn't be a problem, wires from circuit and from switch going on the same place at output connector. here's the picture of finished stompbox, there's big mess so I'm uploading it just to show connectors and switch. Thanks for the answers.

That's 'cause you don't make it true bypass. The out signal is going to the volume pot, actually.
True bypass happends when U use a two position-two throws switch: meanning dpdt. Than, connect the IN side yust as U made it in one side, aaand, the out in the other.
That way, U avoid the out signal goes to the circuit from the back side.
Best regards!!

[Jdansti]

^^ Take a look at this:

http://www.muzique.com/schem/dpdt.gif

[Burdin]

Thank you guys for your help

[Willverine]

I finally built a working version of this circuit into a Hammond enclosure.  I've also tried some various clipping diodes on the output that make it sound even better.

[Willverine]

http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/IMG_20130721_173842_569.jpg.html http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/IMG_20130730_213457_289.jpg.html http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/IMG_20130730_213510_266.jpg.html http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/IMG_20130303_082344_522.jpg.html
I had originally hoped to build the circuit into a cigar box, but I couldn't get it to even barely work...

[Willverine]

So the pedal doesn't "crunch" anymore, it only boosts and the gain pot works but is very scratchy.  Connecting the box of clippers should cause the signal to get distorted, but there is no change.  Anyone have any thoughts of what is wrong?  I've tried to locate and solve any physical shorts, but I'm not finding any.

[Ark Angel HFB]

So the pedal doesn't "crunch" anymore, it only boosts and the gain pot works but is very scratchy.  Connecting the box of clippers should cause the signal to get distorted, but there is no change.  Anyone have any thoughts of what is wrong?  I've tried to locate and solve any physical shorts, but I'm not finding any.

both problems could be caused by lack of gain in one section... ether the tube has gone bad or the pot... or a resistor solder joint is bad... or the law of physicist have change only inside the box...

we won't know till we get some voltages...

[rutabaga bob]

Not trying to derail any troubleshooting discussion, but has anyone built a Valvy using a 6J6 tube?  It's a dual triode, 7-pin tube...uses about half an amp, has an amplification factor of 38, and the typical plate voltage is running 100V...did I mention they're cheap?   
- Larry

[puretube]

Not trying to derail any troubleshooting discussion, but has anyone built a Valvy using a 6J6 tube?  It's a dual triode, 7-pin tube...uses about half an amp, has an amplification factor of 38, and the typical plate voltage is running 100V...did I mention they're cheap?   
- Larry

Whaddaya pay for the socket,
and where do ya get the 2nd cathode from???

[psychedelicfish]

and where do ya get the 2nd cathode from???

Two cathodes aren't necessary if the cathode is grounded

[rutabaga bob]

I usually scavenge sockets from old tube radios, tape recorders, etc., but you can get them from TubeDepot.com or Antique Electronics Supply.  The 6J6 only has one cathode.  Larry

EDIT: Read today that the 6J6 tends to be noisy and microphonic, but I haven't personally used one yet...maybe use 2 6AT6's or 6AV6's instead?  Sorry for interrupting the flow.

[mistahead]

For Aussies David Crittle (AKA Critter) from Retrovox is an amazing hand and has some (david@retrovox.com.au) amazingly obscure stuff from time to time, good prices and express post from Wagga Wagga where he's located.

I can't recall if I asked about matching tubes as a service, but at the time of my last order (a while ago now) he was getting over a back injury so was barely able to walk over to his warehouse for me, got great NOS/AnOS 12AU7's.

[Willverine]

So the pedal doesn't "crunch" anymore, it only boosts and the gain pot works but is very scratchy.  Connecting the box of clippers should cause the signal to get distorted, but there is no change.  Anyone have any thoughts of what is wrong?  I've tried to locate and solve any physical shorts, but I'm not finding any.

both problems could be caused by lack of gain in one section... ether the tube has gone bad or the pot... or a resistor solder joint is bad... or the law of physicist have change only inside the box...

we won't know till we get some voltages...

Thanks, I haven't taken the meter to it yet, but I tried both 12AU7 tubes I have and they both didn't produce.  I found the same issue with the J&J ECC82 I bought when the 12AU7s worked.  I've since turned that tube into a necklace.

Also, love the quote at the bottom of your posts, I had a multi-effect system that picked up a hispanic radio station whenever I used it.

[Willverine]

It looks like the wire carrying the filament voltage was shorting out onto the plate of the second stage triode due to poor build quality on my part.  Could that damage tubes?  I'm still getting the same boosted sound and all the controls behave as they should.

[psychedelicfish]

It looks like the wire carrying the filament voltage was shorting out onto the plate of the second stage triode due to poor build quality on my part.  Could that damage tubes?  I'm still getting the same boosted sound and all the controls behave as they should.

Tubes are actually quite hardy things, except for the heaters, and those are normally OK as long as you don't burn them out with too much voltage, or damage them with too high of a voltage between the heater and the cathode, which is incredibly unlikely at low voltages like those found in a valvecaster (the 12a*7 series can take 100V or so across the cathode and the heater). So no, you probably haven't damaged the tube.