Unity gain NFB speaker-buffer

Skorpio · 27th October 2005, 12:17 PM

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?

PMA · 27th October 2005, 04:31 PM

Yes.

darkfenriz · 27th October 2005, 04:50 PM

these circuit are called "power followers"
You'll find one in PMA'a webside, nice one.
I guess he meant this saying "yes".

PMA · 27th October 2005, 04:59 PM

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.

djk · 28th October 2005, 08:22 AM

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

Skorpio · 28th October 2005, 12:06 PM

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?

Ultima Thule · 28th October 2005, 12:11 PM

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

richie00boy · 28th October 2005, 12:13 PM

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...

AndrewT · 28th October 2005, 06:21 PM

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

mtlin12 · 30th October 2005, 07:31 AM

Hi,

Try this NFB Power Diamond Buffer ,

and some pictures are in DC adjustable double-Sziklai Power Diamond Buffer.
It has been tested with tube-pre & speakers and worked quite good for several months.

27th October 2005, 12:17 PM	#1
Skorpio diyAudio Member Join Date: Mar 2004 Location: Denmark	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?

28th October 2005, 12:11 PM	#7
Ultima Thule diyAudio Member Join Date: Jan 2004 Location: Koskenkorva Land	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 __________________ "If transistors are blueberries and FETs are strawberries, then tubes must be.. pears" Michael 29th January 2010

28th October 2005, 12:13 PM	#8
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	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... __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

30th October 2005, 07:31 AM	#10
mtlin12 diyAudio Member Join Date: Nov 2003 Location: Taipei	Hi, Try this NFB Power Diamond Buffer , and some pictures are in DC adjustable double-Sziklai Power Diamond Buffer. It has been tested with tube-pre & speakers and worked quite good for several months. __________________ EuLeit Audio Studio one of the best hi-end Amp design house in Taiwan http://www.euleitaudio.com

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27th October 2005, 04:31 PM	#2
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Yes.

27th October 2005, 04:50 PM	#3
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	these circuit are called "power followers" You'll find one in PMA'a webside, nice one. I guess he meant this saying "yes".

27th October 2005, 04:59 PM	#4
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	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.

28th October 2005, 08:22 AM	#5
djk diyAudio Member Join Date: Feb 2001 Location: USA	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

28th October 2005, 12:06 PM	#6
Skorpio diyAudio Member Join Date: Mar 2004 Location: Denmark	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?

28th October 2005, 06:21 PM	#9
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	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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