Chandler tone control 'feedback' what is it?

[mylesgm]

As the title says what is the feedback control on the germanium tone control actually controlling in the circuit?  Is it simply feeding some of the processed audio back to the front of the signal chain of the unit (positive or negative or perhaps altered specifically) or is it something more complex?  Thoughts?

 

[AK79]

you can control the negative feedback path of the amplifier with this. low settings give more distortion. afaik a unique feature

 

[emrr]

Not unique.  That's how the Manley tube preamps work, and it's how pretty much every op amp based preamp works. 

 

[mylesgm]

So its not a global negative feedback but around a particular amplifier altering the gain of that amplifier then?  If so I would have thought increased negative feedback would have reduced output/distortion as thats how open loop gain is reduced correct?

 

[mylesgm]

Anybody else with info or insight?

 

[emrr]

Would assume it's a range control on either overall NFB, or possibly a shorter loop section.  It would be unique in audio if it was positive FB, but I doubt it is. 

 

[saint gillis]

I made a partial schematic to repair one unit.. if some are in need (please don't ask if you're just curious, there's nothing particularly crazy in this, I'm mean, it's a good piece of gear anyway..but classic design)