check this out..higher the voltage of this amp

[clovi_kate]

i have this design and my power supply is higher than the supply of this design..so i will be going to change output transistors into 2SC5200 and 2SA1943, and add more to make 4pnp and 4npn..
i need your comment guyss

thanks a lot..

Ryan Jan

[MOER]

Not a very good design.

The differential pairs are simply driven by resistors from the rails. Poor CMRR and if you change the power supply voltage then the currents up the differential pairs will change which will then change the current up the VAS which will then change your idling current which if it is too high will blow up your amplifier.

The trimmer in the bias circuit is dangerous. If the trimmer wiper lifts, you output stage will blow instantly since all bias control will be lost.

There are many good designs on the web. This circuit which you have posted is a classic full complementary design which has been done for over thirty years now.

[MOER]

Dending on your rails, the VAS transistors will not be Ok as far as dissipation is concerned. The pre-drivers (TIP41C/42C) are a very poor choice and are only rated at 100v Vceo so be careull

There are many TO220 driver pairs which are vastly superior to the antiqauted TIP series.

based on your post that you intend to replace the outputs with Tosh 5200/1943, I presume your rail voltages will be in the order of +/- 60 to +/-80v, am I correct?

[clovi_kate]

do u have any good design with exactly or higher than 200rms at 8ohms?..but not Fet trnasistors..thanl you

Ryan Jan..

[edl]

Originally posted by clovi_kate
do u have any good design with exactly or higher than 200rms at 8ohms?..but not Fet trnasistors..thanl you

Ryan Jan..

my power supply is higher than the supply of this design

What kind of psu have you got?

For 200W/8ohm-RMS you'll need about +/-75V...

Best regards,

[MikeB]

Originally posted by edl

What kind of psu have you got?

For 200W/8ohm-RMS you'll need about +/-75V...

Best regards,

Hmm, i calculate 62v, including 5v rail losses ?

Mike

[edl]

Sorry, I mistyped, it's +/-70V.
For true RMS 200W on 8ohm at such low as 20Hz and in every condition, using 2*10.000uF per channel I need: sqrt(200*16)+[(200/8)*sqrt2]+6 idle voltage. That means about 70V. My other formula gives the same 70V. So you need a 2*50V trafo.
Let's refer to Phase Linear 400, that produces 2*200W RMS on 8ohm, with +/-75V, with 5600uF caps in the psu.
Regards,
edl

[MikeB]

I obviously forgot the voltagedrop in the caps...

Mike

[BlackMTX]

Originally posted by clovi_kate
do u have any good design with exactly or higher than 200rms at 8ohms?..but not Fet trnasistors..thanl you

Ryan Jan..

try this one:
http://users.otenet.gr/~athsam/power_amp_300w.htm

[clem_o]

Originally posted by BlackMTX


try this one:
http://users.otenet.gr/~athsam/power_amp_300w.htm

Hmm, that doesn't look like a very stable design - there are improvements over the 1st schematic, in terms of power-supply decoupling of the input stages and constant-current source for their emitters; output SOA limiting - yet the input pair isn't balanced, the VAS is running wide open (save for an RC to one supply rail), rather lowish FB corner (330pF || 10K).

Cheers!