Tube pedal 901

[Arno van der Heijden]

I just found the schematic for this tube overdrive pedal. It looks like the Tube Driver from Generalguitargadgets, with some different component values and Fet-switching. The pedal is called "Tube pedal 901" and here's the best part: People in Holland and Germany can buy it for only ~70 euro from Conrad (mail-order company for electronics).  :mrgreen:

I wonder if it's a clone of the Tube Works Tube Overdrive 901. The 901 thing can't be a coincidence...

Picture:
http://www1.nl.conrad.com/IMS_Docs/AF/AF5E953E3482078EE10000000A010251.JPG

Schematic:
http://www.produktinfo.conrad.com/datenblaetter/300000-324999/300299-sp-01-en-pedal_901.pdf

[Arno van der Heijden]

So, does anybody know if this is a clone of the Tube Works Real Tube Overdrive 901?

[puretube]

it is a low-plate-voltage-thing in any case
:wink:

[Arno van der Heijden]

it is a low-plate-voltage-thing in any case

Yeah, I know, but for 68 euro...  :lol:

[amz-fx]

That does appear to be the RT-901.  The output of T1 is 12v AC.

regards, Jack

http://www.muzique.com/

[Marek]

I just found the schematic for this tube overdrive pedal. It looks like the Tube Driver from Generalguitargadgets, with some different component values and Fet-switching. The pedal is called "Tube pedal 901" and here's the best part: People in Holland and Germany can buy it for only ~70 euro from Conrad (mail-order company for electronics).  

Schematic:
http://www.produktinfo.conrad.com/datenblaetter/300000-324999/300299-sp-01-en-pedal_901.pdf

Folks, could somebody please explain what U2B, U2A, D5, D6, Q1 & Q2 are there for?

And... in the tone stack, which is Trebble pot, which is Bass and which Mid?

And, If those OPAMPS are some kind of switching, then this is not a 'true bypass' pedal, right? In that case, which parts could one simply throw out of the circuit?

Thanks, M

[Nasse]

I just took a quick look and believe following:

U2A&B may be some kind of bistable flip flop circuit that changes state when (stomp)switch is actuated, D5&6 must then be for some protecting or timing cap shunting purpose.

If that is true, Q1 shunts signal going to tube circuit ground so that it mosly can not heard, while Q2 switches signal direct to output.

when flipflop is in another state, Q1 does not attenuate anything and Q2 is looks as high resistor and attenuates "direct" signal to output.

[Arno van der Heijden]

Isn't this just fet-switching just like in Boss pedals?

I guess U2A and B are there for the led-indicator to work, which is two-colour btw.