How to install a DEPTH mod?

[888guitars]

Is this just a pot in between the output jack and the feedback resistor? Any schematics out there?

[defaced]

What amp and all that jazz? Got a schematic? Depth controls are in the NFB loop. Looking at at Peavey 5150 schematic would give you an idea of how they're implemented.

[888guitars]

well its a home build with no tone stack. I am using .02uf for the coupling caps. but It still seems to be lacking in the low end department. Thought this might be the way to go. I have had a few attempts with using a neg fdbk resistor, but it made the amp even thinner or would couse it to oscillate too much. Wondered if the pot would get me closer?

[888guitars]

I did look at the 5150 and whew! there is alot of stuff going on there! I am not quite sure I understand where that is getting back into the audio path? I thought it (neg fdbk)would go into the cathode of the last stage?

[Jazz P Bass]

The 5150 negative feedback goes into the phase inverter.
Kinda standard stuff.
The fact that your feedback made your amp oscillate sounds weird.
It is after all "negative feedback".
It should attempt to make the amp more stable.
Maybe your output transformer primary is wired backwards.
(Not that this has anything to do with the tone)
A good check of the OPT wiring is to lift the feedback resistor while monitoring the output (ie: speaker leads)
If the signal amplitude increases then the wiring is correct (negative fedback is working correctly)
If the signal amplitude drops, then you have a positive feedback condition.
OPT primary wiring needs to be reversed.

[Jazz P Bass]

You can achieve bass increase in the feedback path.
See the attached file (from Tubeswell)
Here is the complete file.http://music-electronics-forum.com/a...9258-darr2.pdf

[888guitars]

Well your article talks about the use and theory of the NFBK but I need some more examples of how to install. I know its either a fixed resistor or a pot from the pos. output jack feeding back into the last stage or phase inverter.

[Jazz P Bass]

If what you rquire is the theory behind negative feedback, that is beyond this site.
Did you look at the Peavey 5150 schematic.
Admittedly it is called "Resonance".
Speaker output is fed back through a 39K resistor into a .0047uf capacitor.
The cap is then paralleled by a pot.
Then the whole circuit is bypassed by a 180pf cap.
Hook it up & try it.