Adding nfb to an se amp

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cressy
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#1 Adding nfb to an se amp

Post by cressy »

Ok. Quite frankly the demented smash robot el34 se amp wot I built however long ago sounds abit crap compared to the f5.

Buuuuut, it has plenty of gain, much more than the f5, so I can actually use the turntable with the shure m97xe and the benedict audio phono stage. The f5 is fine when using the atf7 moving coil into the denon head amp, but the f7 cart has had it.

So i was wondering wether wrapping some feedback around the amp would help clean up the sound and possibly remove some of the colouration that it has.

I havent a clue about feedback tbh, some people here do, so is it an avenue worth looking at?
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#2 Re: Adding nfb to an se amp

Post by Neal »

Maybe, if the amp has sufficient gain and is linear to start with
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cressy
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#3 Re: Adding nfb to an se amp

Post by cressy »

The front end is a paralleled ecc83 so has plenty of gain to play with, it looks fairly linear, or it did on the graphs when i selected the op points, but that doesnt mean very much
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Nick
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#4 Re: Adding nfb to an se amp

Post by Nick »

The problem may be that phase shift in the transformers stops you using large amounts. You could try feedback from the secondary to the output stage cathode.
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#5 Re: Adding nfb to an se amp

Post by pre65 »

Nick wrote: Sat Jun 24, 2017 8:34 pm You could try feedback from the secondary to the output stage cathode.
Ant, had you had any more thoughts on this matter ?

I seem to remember Mike H going over this some time ago, but I can't remember where.
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#6 Re: Adding nfb to an se amp

Post by cressy »

I cant be arsed at the moment to be honest phil, it was more an idle musing, thinking about methods of cleaning up the distortion in the amp. Its crap compared to the f5, perhaps ive been spoiled by the f5 having so little quoted distortion
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