Blackstar Artisan Negative Feedback Loop

Misterg

ICBM said:

A better way to do it would be to bypass (shunt) the 470K resistor between the NFB connection and ground (while keeping the 470K in series with the loop, or it will kill the signal).

That would work - lift the end of the 1M resistor where it joins the 470k resistor and link it to the grounded end of the 470k resistor instead.

Along with everyone else, I really would recommend leaving it alone, though. The effect will be *nothing* like disabling the 'output to PI' (global) NFB often talked about by tinkerers (more like a fuzzy mess).

jpfamps

ICBM said:

Misterg said:

You can't disable it by removing components ('lifting' them or cutting their leads) - you would need to find and break the connection marked 'X' below:

A better way to do it would be to bypass (shunt) the 470K resistor between the NFB connection and ground (while keeping the 470K in series with the loop, or it will kill the signal). Best of all, make it variable - ie connect the 1M resistor to the rotor of a 470K pot - that way you could control the amount of NFB.

I don't know exactly what that would do to the sound or necessarily be desirable though - other than definitely giving a lot more gain. So I would try to hook it up temporarily and not do anything destructive until you find out. Don't mess up such a well-made amp if you don't have to.

Isn't more gain always better?

ICBM

jpfamps said:

Isn't more gain always better?

Yes, always. Too much is always just short of enough .

Back in the 80s and early 90s a lot of people would ask me whether I could mod their old Marshalls for more gain, and how much it would cost. I always said "yes - £29". Mostly they were surprised that it was so cheap and asked why, so I would then pull out my Boss DS-1 and show them  .

jpfamps

ICBM said:

jpfamps said:

Isn't more gain always better?

Yes, always. Too much is always just short of enough .

Back in the 80s and early 90s a lot of people would ask me whether I could mod their old Marshalls for more gain, and how much it would cost. I always said "yes - £29". Mostly they were surprised that it was so cheap and asked why, so I would then pull out my Boss DS-1 and show them  .

Any only £39 today! Bargain.