ASR Shafer Emitter 1 and 2

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#2
in their papers ASR is telling us that they use volume control that is not in the signal path....
my opinion is that it is probably in the feedback (becuase at the input ASR is using AD843 opamps)....

any opinions how to control gain in order not to have that control directly on the signal path..?....
 
#3
sparkle said:
in their papers ASR is telling us that they use volume control that is not in the signal path....
Click to expand...
A total volume control using the feedback loop would make an amp that sounds a lot different at low, mid, and high volume. It would very difficult to impliment without sonic penalties worse than the sound of a pot in the signal path.
Are you sure they are not decribing a shunt volume control?
I copied the ASR Emitter II chassis scheme in an amp. Four chassis, one for circuitry, one battery supply for opamp input stages, and seperate ac suppplies for the output stages.
I liked the results. Batteries with lots of decoupling are great for opamp input stages. Did sound better than a regulated supply powered from the rails.


George
 
#5
Well...they are so pretty that i could have it only to decorate my home

The clear blue and this one are extremelly pretty.

Do not need to sound good...those one are to be watched only.

If sound good too...well..in this case we found something to dream.

regards,

Carlos
 

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#8
The Schäfer & Rumpf has relay switched shunt volume adjustment since the 1999 update.

German school amp, along with AVM and SAC, which also started manufacturing opamp imput power amps in the 1980s.
Just like Sphinx overhere and Greggy Ball in Ozland with his Eidetics.
I've seen the Emiiter-I go through so many stages that i've lost count
Interesting project for DIYs, with regard to the powersupply philosophy and chassis building.
Biggest effort will be designing the board layout (if you own a pro package for that size)
 
#10
The output stage of the Emitter I/II is not spectacular.

German school generally means driving the output stage from the rails of the opamp, Scylla is another example from overhere that manufactured power amps like that.
Lots of example schematics to be found here and on the web. ASR even tells you which opamp and mosfet brand/type to use, such as
here
here

The big job is combining all the different operations, and the hardware part. That's the challenge for a diy person.
Ever heard a Schäfer & Rumpf Emitter amp, btw ?
 
#16
Holger,
i believe the term was used by one of your collegues.
(Stereo, iirc)
I can't think of any other country where the concept(opamp output driven or from the rails) has become so popular and/or close to a tradition.
(I nagged Günther Mania's head off during his 1987(?) power amp article in SP.

PS:
Sparkie, i can hand you the schematic for the opamp input mosfet power amp from the article above.
I'm not posting it here and not giving schematics of the other brands, because i know/met the guys of those companies in one way or another. Wouldn't be very respectfull.
 
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