Twin Valve Caster and ECC83 tube

[served]

Hello!
I just got 2 ECC83 tubes (should be like 12AX7) and i cant find any 12AU7 tubes but i still would like to build that Valve Caster. Could some one tell me what should i do to get it working with ECC83?
Is there any schematics or could you tell me what should i change in the Valve Caster schematic.

Served.

[Renegadrian]

I tried a jj 12ax7 in my Valvies, but with no good results...Maybe some components change and it could work ok, but...dunno...

[served]

I reed some datasheets from this site http://www.drtube.com/tubedata.htm
the 12AU7A and the 12AX7 datasheets, if you could take a look, there are some caps value differences, may be it helps you to help me

[frequencycentral]

The ECC83 (12ax7) has higher gain than the ECC82 (12au7). Maybe try increasing the value of the cathode resistor on the second triode, and putting a resistor in series with with gain control on the first triode. That should lower the gain on both stages.

And have a look at the Pepper Shredder for a dual Valvecaster workalike, uses 12u7s though, which are apparently just 12au7s handpicked for even lower gain: http://www.tube-town.net/diy/lov/lov02-peppershredder.html

[Pushtone]

I noticed the Marsha Valve circuit uses a 12AX7.

Check out the two tube versions in Erik's gallery for suggested values.
http://www.aronnelson.com/gallery/main.php/v/vanhansen/


If a pure 12AX7 fails to satisfy you could built the one with the J201 output stage.


Also look at the Tone Gods Bullitt.
It uses 12AX7 and you could remove the LFO and tone stack from the circuit for a stripped down the overdrive.

Good luck, Dave

[frequencycentral]

Hey Pushtone - building a 'Bipolar Disorder' yet??

[Pushtone]

Hey Pushtone - building a 'Bipolar Disorder' yet??

Right, the speed ramping tube tremolo.
I was going to do a layout. thanks for the reminder.

Dave

[served]

Well, now I'm actually interested in this  Pepper Shredder. Its heavy metal distortion pedal. I'll try to build it as it is shown on the scheme and ill change some values later, with your help.

[snap]

The ECC83 (12ax7) has higher gain than the ECC82 (12au7). Maybe try increasing the value of the cathode resistor on the second triode, and putting a resistor in series with with gain control on the first triode. That should lower the gain on both stages.

And have a look at the Pepper Shredder for a dual Valvecaster workalike, uses 12u7s though, which are apparently just 12au7s handpicked for even lower gain: http://www.tube-town.net/diy/lov/lov02-peppershredder.html

Who said that?

http://www.mif.pg.gda.pl/homepages/frank/sheets/127/1/12U7.pdf
http://www.mif.pg.gda.pl/homepages/frank/sheets/137/1/12U7.pdf

[served]

The ECC83 (12ax7) has higher gain than the ECC82 (12au7). Maybe try increasing the value of the cathode resistor on the second triode, and putting a resistor in series with with gain control on the first triode. That should lower the gain on both stages.

And have a look at the Pepper Shredder for a dual Valvecaster workalike, uses 12u7s though, which are apparently just 12au7s handpicked for even lower gain: http://www.tube-town.net/diy/lov/lov02-peppershredder.html

Who said that?

http://www.mif.pg.gda.pl/homepages/frank/sheets/127/1/12U7.pdf
http://www.mif.pg.gda.pl/homepages/frank/sheets/137/1/12U7.pdf

So 12AX7 is not a bossibility? I think ill order two 12u7 tubes to be sure.

[frequencycentral]

So 12AX7 is not a bossibility? I think ill order two 12u7 tubes to be sure.

Probably for the best, as Renegadrian said, 12AX7 are not reported to sound so good in this circuit. You could got ahead and build it anyway with the 12AX7, just sub in the 12AU7 when they arrive.

[served]

But why snap said his lines? What it means?

No pepper shredder with 12AU7?

[frequencycentral]

But why snap said his lines? What it means?

No pepper shredder with 12AU7?

I think he was making the point that 12U7 are not handpicked 12AU7.

Renegadrian says in his Pepper Shredder thread: http://www.diystompboxes.com/smfforum/index.php?topic=69514.0

I am using a couple of 12AU7 and not the 12U7 per the schem. I read that you can use both in that same site (Tube-Town)

....so you can use either. I'm just now building one using 6111 submini tubes.

[puretube]

Don`t put a 12U7 into circuits working off >30V that were designed for 12AT7, 12AU7, 12AX7, 12AY7, or the like...
(no danger the other way `round).

[served]

Don`t put a 12U7 into circuits working off >30V that were designed for 12AT7, 12AU7, 12AX7, 12AY7, or the like...
(no danger the other way `round).

OK! Thanks!
Ill go for 12AU7 and ill let you know!

[served]

Hey!
I got my tubes and bought all the other stuff for the pepper shredder. But now i have got a question. Does computes powersupply works for it? Or i need something special?

[Jimmy-H]

Hey!
I got my tubes and bought all the other stuff for the pepper shredder. But now i have got a question. Does computes powersupply works for it? Or i need something special?

Hi Served,

I know a build from Holland, and he used a Computer powersupply.
It worked very well
Only when there is a cooler on the powersupply, you can get some noise from it.
So he made the cooler switchable

[served]

Hey! Thats awsome!  I think ill look for some old ATX powersupply without the fan. There sitll are some moving around.

[Franky]

Actually you need a heatsink or a fan when you draw a lot of current from the PSU, but for one or two tubes, that might not be necessary.. If you have to power more tubes or draw more current, give a try to watercooling 

[Steben]

To make things clear:

there are "normal" tubes and "low voltage" tubes.
12AU7, 12AT7, 12AX7: are all "normal" voltage.
12U7: low voltage (max 30V), made for early car radio's.

Although some 12A*7 tubes work in low voltage ("starve"... usually no cathode resistor), 12U7 will not work on high.