another amp schematic

[Jan Dupont]

It surely needs a predriver/driver configuration

[Jan Dupont]

It surely needs a predriver/driver configuration

[jan.didden]

Huh? It HAS a driver-predriver config doesn't it?

Huh? It HAS a driver-predriver config doesn't it?


Jan Didden

[Jan Dupont]

Yep!
Then it just need a driver-driver

[kevin gilmore]

quote
Didn't Bose use this design in their first (high) power amp?

Something damm close for sure. In 1975 i was in college
working part time for midwest hifi. We sold the bose
monstrocity. It sounded absolutely horrible. One weekend
i borrowed one, took it to the lab and tested it. High
frequencys were already down by about 4db at 10khz.
Way down at 20khz. Low frequencys were miserable
too. Distortion at rated spec was over 1%. What a piece
of marketing diatribe. Typical bose then. Typical bose now.

To be fair back then the crown dc300 and the phase linear
400 and 700 were all quasi-comp designs. And all of
these amps sounded much much better than the bose.
At less money too. (not a lot less money, but can't remember)

The fully complementary dynaco 400 and sae amps were
better still.

[Tony]

the output transistors used had a 7amp IC rating, Pd of 150watts and Vceo 0f 250, so it can easily be replaced with mj21193/94 in a full complimentary circuit...the drivers can be mjw1302A/mjw3281A, the ic can be any of the latest variety of singles or duals.....the output stage itself has gain of 18x....

[mozikluv]

just for laughs guys ok? if you lack heaters in your home, this thing will do. he, he, he

[Tony]

input is complimentary common-base with a gain of about 6, the second stage vas, is common emitter...the input buffer ic can be left out of the feedback loop.if it has a gain of 1...

[Elso Kwak]

Originally posted by C3PO
hi guys, anyone have an idea for these amp? does anyone here tried to build it?

Hi C3PO,
It looks a little bit like a Bose 1801 but is is not. The Bose had a differential stage after the opamp.

[millwood]

Originally posted by kevin gilmore
quote
Didn't Bose use this design in their first (high) power amp?

the amp posted here has a bootstraped opamp as input. You can easily find better parts to build one like it. but why?

I have played with quite a few bootstraped opamp-based amps. They usually don't sound good.

One way to go may be using a high-voltage opamp, or even a power opamp (like lM3875) and use it to drive an output stage without the bootstrap. However, the only thing you gain there is higher current capabilities.