Resonance controls in Fender like amps?

[Mark]

Hi

I have put a resonance control in my Mesa Boogie SOB. I’m using the Limit control position for the control and it’s perfectly located for the task.

I initially found out the Marshall values are rubbish in the Fender circuit. The 1M pot is useless as most of the travel of the pot Is disengaging the negative feedback. I found that the pot should be about ten times the negative feedback resistors. Thus a 10K audio pot did the trick.
The Marshall circuit used a 0.001uF cap and was way too small, through experimenting I found 0.01uF sounded good.

However, I still not entirely happy with it as I find it lifts the volume of all notes. The bass notes are louder which is good, but I easily hear a volume increase on the high E at the twelfth fret. I thought it might have been an ESR thing with the 0.01uF Mallory 150 cap in the resonance circuit. I thought I would see what happened when I put a 0.001uF silver mica cap across the 0.01uF cap. There was no difference.

What are your findings on resonance controls?
Does your circuit perform like my circuit?
Can I limit the gain to the desired frequencies?

Thanks for your time and assistance.

[LOUDthud]

Try a bigger cap. Double the value of the cap and keep going larger doubling the cap every time until you find the value that works.

[Stevem]

What’s your reason for wanting feedback in the amp in the first place?

[Mark]

What’s your reason for wanting feedback in the amp in the first place?

Thanks for your reply.
The amp sounds tight. I want get more bass response if I can.

[Mark]

Try a bigger cap. Double the value of the cap and keep going larger doubling the cap every time until you find the value that works.

Thanks for your reply.

I can give that a go. I don’t know if that will stop the overall increase in gain though. I like where the bass boost is occurring (largely around low E.)

[Stevem]

To me feedback makes for tighter bottom end more then it does more low end really.

Is this Fender amp one of the 70 or 135 watt silver face models with a UL output stage?



Just keep in mind that if you play the amp loud enough to run out of feedback voltage that all the things you might like about applying feedback to a circuit go away in a big hurry!