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Hi guys. I'm trying to modify the circuit of a  Marshall Lead 12 preamp to use it with a single +15V power supply, so I need to bias the opamps to Vdd/2.

The first attachment is the original circuit, and the second is my attempt at biasing those opamps. I'm not too sure about the second one, does it look about right?


Hi guys & gals, a n00b here with some questions about my first amp build.
The amp is essentially the application example in the TDA7267A datasheet:

I'm also in the process of building a Bazz Fuss V3 pedal so I thought I could put that little circuit in the amp to have an overdrive "channel"

The idea is to put the Bazz Fuss in front of the TDA7267A and use a switch to bypass it for the  clean channel.
So I have a few noob question for you:

1. The initial plan is using a 12V power supply and a 7809 to get the Bazz Fuss the required 9V. I could use 9V for everything and leave the 7809 out, but would I be losing a significant amount of output by feeding the amp 9V instead of 12V? ETA: I should have RTFM before asking. The answer to this is right there in the chip's datasheet.

2. Do I need all the coupling capacitors from both circuits? Can just use an input cap & an output cap and connect the output of the Bazz Fuss directly to the input of the amp so that when I bypass the Fuzz I leave the input cap there to do it's job? or do I need another coupling cap in between the Fuzz and the amp?

3. For what I could gather, the input impedance of the Fuzz is 1K Ohms while the amp's is 100K. Mentioning just in case there could be an issue there

4. I want to have tone, gain and volume controls. The volume with a logarithmic 50K pot at the output of the amp, the gain with a 1K or 5K pot between the Fuzz's transistor emitter and ground. But I'm not sure what to do about the tone pot. Can I just put a, let's say, 4.7uF and a 68nF cap with a pot in between to implement the tone pot? Or would I be better off trying some of the tone stacks found here?

I think that's all for now, any suggestions/corrections appreciated. Thanks in advance