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Unity gain NFB speaker-buffer
Unity gain NFB speaker-buffer
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Old 27th October 2005, 01:17 PM   #1
Skorpio is offline Skorpio  Denmark
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Default Unity gain NFB speaker-buffer

I want to try with a special buffer between my poweramp and the speaker, to isolate the feedback loop from the speaker load.

I have a trafo 18-0-18V/800VA and 2x47.000uF, + heavy heatsinking...

Now I need a circuit to use...do some of you have some experiences?

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Old 27th October 2005, 05:31 PM   #2
PMA is offline PMA  Europe
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Yes.
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Old 27th October 2005, 05:50 PM   #3
darkfenriz is offline darkfenriz  Poland
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these circuit are called "power followers"
You'll find one in PMA'a webside, nice one.
I guess he meant this saying "yes".
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Old 27th October 2005, 05:59 PM   #4
PMA is offline PMA  Europe
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Darkfenriz,

you are right. I prefer a little bit of self-confidence and creativity, for example to perform a search. I belive that it leads to better results than just following recommendations.
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Old 28th October 2005, 09:22 AM   #5
djk is offline djk
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This looks interesting, two versions, 'hot' and 'cool'.

http://www.audiodesignguide.com/my/Hot_Follower1.GIF

Full text:

http://www.audiodesignguide.com/my/index.html#MY_A
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Old 28th October 2005, 01:06 PM   #6
Skorpio is offline Skorpio  Denmark
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Nice design PMA

But I don't like the output configuration, I prefer a standard darlington type.

Do you have any remarks to the termal stability this type in your circuit?
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Old 28th October 2005, 01:11 PM   #7
Ultima Thule is offline Ultima Thule  Europe
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Hi,

I guess you have 2 ch stereo amplifier... take the output of one channel and feed the other channels input through a resistor divider corresponding to the gain of your amplifier, done!

Cheers Michael
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Old 28th October 2005, 01:13 PM   #8
richie00boy is online now richie00boy  United Kingdom
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Unity gain NFB speaker-buffer
I assume that you are wishing to use a non-global feedback power follower and some favourite main amp then? Or the exercise is pointless as the follower will be affected by the back EMF etc even worse (due to massive feedback) so the problem remains. In fact, instead of such a power follower, why don't you just make the main amp non-global feedback? This would be cheaper, easier, smaller, use less parts, less heat...
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Old 28th October 2005, 07:21 PM   #9
AndrewT is offline AndrewT  Scotland
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Hi,
try http://www.altmann.haan.de/splif_page/ just up your street.
Global feedback to get the best out of your classAB power amp and a follower stage to drive the speakers. Even a guide on multiple followers if you want to have separate outputs for individual speakers. A cheap way to bi-amp your speakers, but not suitable for active speakers
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Old 30th October 2005, 08:31 AM   #10
mtlin12 is offline mtlin12  Taiwan
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Hi,

Try this NFB Power Diamond Buffer ,

and some pictures are in http://www.diyaudio.com/forums/showt...=&pagenumber=2.
It has been tested with tube-pre & speakers and worked quite good for several months.
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