I've heard of an op-amps being used as the input stage to an otherwise discrete design, (replacing the constant current source and differential amp) but I don't know how it is done. Can anyone direct be to examples, either hobbiest or commericil. I would especially like to see a schematic rather than just a statement of general principls.
sam9 said:
You have an example,here:
http://web.tiscali.it/audiofanatic3/Tipo/Stato_solido/pic_finaliSS/300W_MJ15003_15004.jpg
Cheers
Re: Forbidden link
Try:
http://web.tiscali.it/audiofanatic3/Schemi/Tipo/Stato_solido/finali/Schemi_finaliSS.html
Is the 16 on the list
sam9 said:
Try:
http://web.tiscali.it/audiofanatic3/Schemi/Tipo/Stato_solido/finali/Schemi_finaliSS.html
Is the 16 on the list
With ±24V and an OPA2604 opamp, this circuit will do 50W/4R
http://www.delphion.com/fcgi-bin/an...+TARGET=_top%3EOrderPatent%3C/A%3E&SCALE=0.35
If you change the feedback loop to this scheme up to 1KW may be had with suitable outputs, drivers, and supply.
http://www.delphion.com/cgi-bin/viewpat.cmd/US04467288__
http://www.delphion.com/fcgi-bin/an...+TARGET=_top%3EOrderPatent%3C/A%3E&SCALE=0.35
If you change the feedback loop to this scheme up to 1KW may be had with suitable outputs, drivers, and supply.
http://www.delphion.com/cgi-bin/viewpat.cmd/US04467288__
Audio Analogue products, the "Puccini" and Puccini S.E.", use opamps as input stage.
These product were reviewed as particularly well sounding, so having a look at this page might be useful... you can find the complete schematics as well as some tips to improve the commercial products...
http://www.pi.infn.it/~federico/unofficial.htm
Cheers
Andrea
These product were reviewed as particularly well sounding, so having a look at this page might be useful... you can find the complete schematics as well as some tips to improve the commercial products...
http://www.pi.infn.it/~federico/unofficial.htm
Cheers
Andrea
"That´s even simpler."
Surely you jest!
ESP 76 not only has more parts and complexity than the RCA patent, it is totally inferior.
I suggest that you don't understand how the RCA circuit works.
Perhaps you should look at this:
http://www.audiodesignguide.com/my/Cool_Follower1.GIF
Surely you jest!
ESP 76 not only has more parts and complexity than the RCA patent, it is totally inferior.
I suggest that you don't understand how the RCA circuit works.
Perhaps you should look at this:
http://www.audiodesignguide.com/my/Cool_Follower1.GIF
"djk, i was referring to the 300W-beast (first link in the thread) so...
the patent you´ve linked to looks real simple.
did you try it?
i always get tempted so easily with simple circuits...."
I understand now, but your link was to the ESP 76 design. No matter. The 300W design is an old one, the first time I saw this was in the early 70s from BGW. They used the 70V/µS LM318 for the opamp and a dozen 2N6259 in a tunnel for their BGW1000, 1KW bridged.
If you make the RCA circuit with MJE15030/31 as drivers, and six pairs of MJ21193/94 as outputs with the Transnova feedback scheme and ±95V you can get 1KW/2R, 650W/4R, 450W/8R from this circuit. The drivers and the bias resistors are to be fed from the ±15V opamp supplies.
For use below 1Khz we can simplify the Transnova circuit to an LM1875 for the opamp driving a 10 ohm resistor connected to ground. The MJ21193/94 pairs are connected straight to the output of the opamp.
http://www.diyvideo.com/forums/attachment.php?postid=182299
What we have here is a 1KW gainclone!
the patent you´ve linked to looks real simple.
did you try it?
i always get tempted so easily with simple circuits...."
I understand now, but your link was to the ESP 76 design. No matter. The 300W design is an old one, the first time I saw this was in the early 70s from BGW. They used the 70V/µS LM318 for the opamp and a dozen 2N6259 in a tunnel for their BGW1000, 1KW bridged.
If you make the RCA circuit with MJE15030/31 as drivers, and six pairs of MJ21193/94 as outputs with the Transnova feedback scheme and ±95V you can get 1KW/2R, 650W/4R, 450W/8R from this circuit. The drivers and the bias resistors are to be fed from the ±15V opamp supplies.
For use below 1Khz we can simplify the Transnova circuit to an LM1875 for the opamp driving a 10 ohm resistor connected to ground. The MJ21193/94 pairs are connected straight to the output of the opamp.
http://www.diyvideo.com/forums/attachment.php?postid=182299
What we have here is a 1KW gainclone!
sam9
As the originator of the thread, what I was thinking og\f was something where an opamp feeds a more or less conventional VAS which feeds a more or less conventional OPS and where the global NFB connects back to the inverting input of the opamp (or the non-nerting if ones sets it uo other way'round).
I haven't had time assimilate all this info except for running a quick Spice model of the Schroeder patent which get the peculiar result of a spectrogram full of odd order spikes all of the same magnitude marching off to right as far as I cared to look. Maybe it would do for a PA system.
Someone (offline) showed me a schematic of a Carver M-400, but there was so much other stuff going on that it's a bit hard to digest. Noted, however, that he seemed to clase a local feedback loop around the opamp and then close the global loop around that.
As the originator of the thread, what I was thinking og\f was something where an opamp feeds a more or less conventional VAS which feeds a more or less conventional OPS and where the global NFB connects back to the inverting input of the opamp (or the non-nerting if ones sets it uo other way'round).
I haven't had time assimilate all this info except for running a quick Spice model of the Schroeder patent which get the peculiar result of a spectrogram full of odd order spikes all of the same magnitude marching off to right as far as I cared to look. Maybe it would do for a PA system.
Someone (offline) showed me a schematic of a Carver M-400, but there was so much other stuff going on that it's a bit hard to digest. Noted, however, that he seemed to clase a local feedback loop around the opamp and then close the global loop around that.
"Someone (offline) showed me a schematic of a Carver M-400, but there was so much other stuff going on that it's a bit hard to digest. Noted, however, that he seemed to clase a local feedback loop around the opamp and then close the global loop around that."
The early M400 had one inverting channel and one non-inverting channel.
The non-inverting channel is probably the best opamp input stage of all time, used in virtually all the Carver equipment from 1980 on.
The first amplifer that I saw that used this design was the Crown M600, around 1975.
In my mind this would be an ideal 'universal front end card', needing only a couple of resistor changes to run on any ± rails.
I would be willing to participate in a 'group buy' for something like this.
The early M400 had one inverting channel and one non-inverting channel.
The non-inverting channel is probably the best opamp input stage of all time, used in virtually all the Carver equipment from 1980 on.
The first amplifer that I saw that used this design was the Crown M600, around 1975.
In my mind this would be an ideal 'universal front end card', needing only a couple of resistor changes to run on any ± rails.
I would be willing to participate in a 'group buy' for something like this.
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