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-   -   No - feedback amplifier (http://www.diyaudio.com/forums/solid-state/197276-no-feedback-amplifier.html)

Gudmund 25th September 2011 04:15 PM

No - feedback amplifier
 
1 Attachment(s)
Search for a no-feedback amplifier showed the attached circuit from

TUBEAMP

What about the design? Want's to built a new amplifier.

jan.didden 25th September 2011 04:32 PM

Well I'm sure it will sound good.
Technically, it isn't a no-feedback design - there's lots of local feedback / degeneration; has to be to get good sound.
But it certainly is a non-GLOBAL-feedback amp.

jan didden

Gudmund 25th September 2011 04:47 PM

Local feedback
 
Quote:

Originally Posted by janneman (Post 2723573)
Well I'm sure it will sound good.
Technically, it isn't a no-feedback design - there's lots of local feedback / degeneration; has to be to get good sound.
But it certainly is a non-GLOBAL-feedback amp.

jan didden

Ok, thanks.

I was told that amplifiers without FB sounds well. So - local FB can not be avoided concluded out from your statement.

Gudmund

Gudmund 25th September 2011 05:03 PM

Symmetrical
 
Quote:

Originally Posted by janneman (Post 2723573)
Well I'm sure it will sound good.
Technically, it isn't a no-feedback design - there's lots of local feedback / degeneration; has to be to get good sound.
But it certainly is a non-GLOBAL-feedback amp.

jan didden

Forgot to ask.....do you prefer a symmetrical solid state design?

Just short....symmetrical or ?

jan.didden 25th September 2011 05:25 PM

Quote:

Originally Posted by Gudmund (Post 2723606)
Forgot to ask.....do you prefer a symmetrical solid state design?

Just short....symmetrical or ?

Well, I find it difficult to say that a particular topology is better or not. You can make great symmetrical amps and great non-symmetrical as well.
So much depends on the circuit details and the implementation.
Things like the grounding layout, (remember, not all grounds are created equal!) or power supply decoupling, and supply routing probably have at least the same impact as the topology.
If you are not experienced in those issues, your best bet for a successfull implementation is to selct a design that you like and where the designer gives info about how to put it together, and follow those.
With a circuit like the one you showed, and good implementation practise, your amp will certainly sound very well.

Gudmund 25th September 2011 06:23 PM

Quote:

Originally Posted by janneman (Post 2723621)
Well, I find it difficult to say that a particular topology is better or not. You can make great symmetrical amps and great non-symmetrical as well.
So much depends on the circuit details and the implementation.
Things like the grounding layout, (remember, not all grounds are created equal!) or power supply decoupling, and supply routing probably have at least the same impact as the topology.
If you are not experienced in those issues, your best bet for a successfull implementation is to selct a design that you like and where the designer gives info about how to put it together, and follow those.
With a circuit like the one you showed, and good implementation practise, your amp will certainly sound very well.

Understand....well , I have made some amplifiers, and know that the wire connection from PSU to the PCB might affect the stability of the outputstage...also depending on the ground layout as you mentioned.

I shall stay with the symmetrical design...it looks good... from my point of view.

Thanks
Gudmund

digits 25th September 2011 06:42 PM

Just a shame the parts are not physicaly as symetric as the schematic would imply....

Gudmund 25th September 2011 06:45 PM

Quote:

Originally Posted by digits (Post 2723690)
Just a shame the parts are not physicaly as symetric as the schematic would imply....

Which parts do you refer to?

SemperFi 25th September 2011 07:21 PM

That amp was sold as a kit and it sounds fantastic in class-A. It was offered in a low power (40watt) class-A amp, or as a >100W class-AB amp. I havent heard the high power AB version, but the 40watter was plenty loud and sweet sounding.
My two Ýre.

jaycee 25th September 2011 07:44 PM

Plenty of feedback, just not the usual type. Looks like current rather than voltage feedback. Why on earth would you choose to use crap like the TIP41/42 as drivers to 2SC3281/2SA1302's...


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