Hey guys I just built up the following project and can not totally figure out how to wire it up.
How would you apply the following wiring guide
http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf (http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf)
to this project? Everything is pretty self explanatory except for the volume pot and blend pot.
http://www.sabrotone.com/wp-content/uploads/2011/06/TubeScreamerDerivative.gif (http://www.sabrotone.com/wp-content/uploads/2011/06/TubeScreamerDerivative.gif)
I have it wired up and am getting bypass signal and effect signal, however, there is no overdrive on the effected signal. The tone pot seems to be having minimal impact. The drive pot is having no impact. The volume pot seems to be working properly. Can't really tell if the blend pot is working or not since there is no overdrive. Any help would be appreciated.
You did something right if your getting signal bypassed and effected. From what your describing I'm concluding that you wired up the blend pot or maybe the fat switch incorrectly since your not getting any distorted signal.
To wire up those two pots you really just follow the instructions. It might help to draw it out if your having trouble visualizing it.
Volume 3 - Comes from bottom left corner of board.
Volume 2 - Connects to Blend 3.
Volume 1 - Goes to GND.
Blend 3 - Connects to Volume 2.
Blend 2 - Fat switch Lug 2 (first pole middle lug)
Blend 1 - Fat switch Lug 4 (second pole middle lug)
Fat switch lugs 1 and 6 are connected together, lug 1 is effect out and lug 3 is GND.
Is that how you connected them all together? If you want I can draw it out for you, maybe that will be easier? :)
Also if you have an audio probe you can test to see if your distorted signal is working up to the point where they are blended or anywhere else. This would let you know that it is something to do with the wiring/post circuit board connections.
Hey thanks. This is still not making total sense to me. When I look at the schematic I don't see a connection between the blend pot and the Fat switch.
Yes your right. I pulled up a similiar schem (http://www.sabrotone.com/wp-content/uploads/2011/06/2in1_od_boost_schematic.png) the fat switch is a SPST so that's only the two strips labeled on the vero and its not connected to the blend pot.
It took a few times looking at it to understand what was going on. The input comes straight from input jack and the bypass is done within the circuit. If you wanted use true bypass like the Madbean wiring (now I see what your looking for) first your gonna discard the whole on/off switch. You would connect the volume pot normally into the blend pot lug 3, blend lug 2 would become the fx out to your 3PDT, and blend one would connect to where the vero layout says on/off lug 5. Then you can wire the input how you are used to. :)
Ok thx that is how I did it. Good to get confirmation. I think one issue is related to IC1. I didn't have a TL071 so I used a TL072 and just realized the pinouts are different. Could that be part of the reason I am getting no overdrive?
They are different chips w/ different pin-outs so there's no way it would work. The required chip (TL071) is a single op-amp while the one you put in is a dual op-amp. Also the Vcc on the TL071 is on pin 7, the TL072 Vcc is on pin 8. Tayda has them super cheap :-\
What I thought. Well hopefully it will be rocking with the correct chip. Thanks for your help.