a study of DF control

[digi01]

there are lots of way to adjust a standard chip amp's performance such as snubber psu,regulated psu,zobel network,T network.
My project is adjust a chipamp's DF.So I can listening tube sound without tube?

Depiction below.

An externally hosted image should be here but it was not working when we last tested it.

Its a standard no-inverted amp.C2 is dc block cap that can be bypassed.K1 for set the amp's DF.there are three K1 switch positions:
K1 switch to 1,DF approach to 1.the amp just like a no feedback vacuum amp.
K1 switch to 2,DF approach to 10.the amp like a vacuum amp with feedback.
K1 switch to 3,the amp perform as standard chipamp.

just a rough idea,
Zang

 

[Gcollier]

Interesting idea Digi....I wonder how well this would work for a guitar amp.

 

[BWRX]

Another option could be to put a N-channel power mosfet between the speaker and ground and use a pot to adjust the gate voltage bias and thus the resistance of the mosfet. That would give you infinite variability.

 

[Samuel Jayaraj]

Any chance of showing the N-channel mosfet idea in a diagram? Thanks.

 

[SY]

Pete Millett demonstrated an amp like this at ETF06 in December- a very neat idea. His was continuously variable, with a pot setting the ratio of voltage to current feedback.

 

[digi01]

sch file attached.

Zang