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DIY Project - preamp-gain causes noise
DIY Project - preamp-gain causes noise
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Old 10th June 2012, 09:11 PM   #41
Cypheron is offline Cypheron
diyAudio Member
Join Date: May 2012
Problem solved! The amp sounds PERFECT now, it's mindblowing!

Thank you Loudthud. After reading your post I googled for parasitic feedback and read a bunch of stuff of how "Presence" control works: The output signal is fed back into the circuit. By turning down Presence, more negative feedback signal is fed back into the control loop. The output signal mixes with the input signal, leading to frequency resolution / damping (opposite frequencies annihilate eachother).

After that I was SURE that the phase of my output signal had to be shifted, so that instead of resolving frequencies, they overlapped. I changed OT primary wires and voila!

So somehow I didn't get a squeel but just a rattle, having my phase switched on the output. Interesting.

Im working on the faceplate at the moment, when it's done, Im gonna post the final result here. Probably gonna make a youtube presentation .

Even though I didnt find the error right away, Im very glad with this. My lead dress got really clean, and I finally have just one star ground point. There is virtually NO hum or unpleasant distortion / noise / side-effects, even when playing on single coils.

It's great. Thanks thanks thanks to everyone.

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Old 15th June 2012, 04:54 PM   #42
Cypheron is offline Cypheron
diyAudio Member
Join Date: May 2012
Even though no one is probably reading this anymore, here are some final pics.

My rig:
Jetmaster800 014.jpg
Amp faceplate, closeup:
Jetmaster800 009.jpg
Jetmaster800 002.jpg
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