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__
Certainly a wide variety of approaches here. I find the description "Distortion-Free" a little amussing. I wonder if the patent office should treat claim for distortion-free amplifiers the same way as perpetual motion machines.
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....
Regards
Jens
"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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