Studio Reference Amplifier

Apex,
How have you managed to get high power reliably from the 2sa1943/c5200 when used with +-95Vdc supply rails?

The datasheet shows the 25degC SOA as 40W (421mAdc) and this must be de-rated for Tc > 25degC.

The same datasheet shows 1A for 100ms @ 84Vce.
A 5pair output stage will have a 100ms maximum current capability of 5Apk when @ 85Vce.

This transistor is very low power at high voltages.
To me, it seems to be the wrong transistor to select for the +-95Vdc supply rails, that you specify.
 
Apex,
How have you managed to get high power reliably from the 2sa1943/c5200 when used with +-95Vdc supply rails?

The datasheet shows the 25degC SOA as 40W (421mAdc) and this must be de-rated for Tc > 25degC.

The same datasheet shows 1A for 100ms @ 84Vce.
A 5pair output stage will have a 100ms maximum current capability of 5Apk when @ 85Vce.

This transistor is very low power at high voltages.
To me, it seems to be the wrong transistor to select for the +-95Vdc supply rails, that you specify.

Andrew, what transistors you suggest for output stage?
 
small mods to accomodate 10uF cap... very nice sounding little beast :D
 

Attachments

  • SR50old.GIF
    SR50old.GIF
    64.3 KB · Views: 1,900
  • sr50new.JPG
    sr50new.JPG
    558.9 KB · Views: 1,890
  • SR50 Track.pdf
    41.5 KB · Views: 585
  • SR50 Parts.pdf
    78.2 KB · Views: 566
good question

MJW have a very different SOA.

Any of the >=150W Onsemi or Sanken would do the SOA job far better.

But that does not answer my question.

How did you make the amplifier reliable with 1943/5200?

+1


Does the same thing applies to a SR200,MJL/W21193/94 instead 2SA1943/2SC5200? SOA for those two (pair of) transistors are very different at most critical points,that really should be said and underlined when amplifiers of that power are being represented to a public that beleives in you and does your designes with great enthusiasm and strong beleife in you and your work up till now.
 
I don't use 2SA1943/2SC5200 for SR800, I use MJW21195/MJW21196. I just notice 2SA1943/2SC5200 on schematic as most popular outputs useing in diy amplifiers.

MJW have a very different SOA.
the MJW has an SOA of ~2.1A @ 85Vce cf 1943 of ~ 0.421A @ 85Vce.

You would need 5pairs of 1943/5200 to equal the SOA of 1 (one) pair of MJW21193/4

1943/5200 are not suited to high voltage operation.
 
5 pairs of MJW21193/4 will be OK for SR800.

The same for driver or something with higher hfe? What does 2X47Ohm/5W from base to output?

BTW, SR200 is half ready...

How about sch for those who are not that lazy? :rolleyes:

P.S.
Tomorrow it's going to look a bit different... ;)
 

Attachments

  • SR800.pdf
    52.8 KB · Views: 614
  • SR800 to3.JPG
    SR800 to3.JPG
    470 KB · Views: 1,534
Last edited:
The same for driver or something with higher hfe? What does 2X47Ohm/5W from base to output?

BTW, SR200 is half ready...

How about sch for those who are not that lazy? :rolleyes:

P.S.
Tomorrow it's going to look a bit different... ;)

SR800 output stage circuit is triple emiter folower with MJE340/350 as predriver and drivers can be MJE15032/15033 (driver emiter resistor is 4R7/5W not 47R/5W).
For SR800 schematic use reverse engenering :)
Regards
 
SR800 output stage circuit is triple emiter folower with MJE340/350 as predriver and drivers can be MJE15032/15033 (driver emiter resistor is 4R7/5W not 47R/5W).
For SR800 schematic use reverse engenering :)
Regards

Yes, 4R7, my mistake.

Plan is to spend some time in forward "engenering" en look what's going to happend. For a hoby it is a quite and enough efort i belive...

With more power standard PSU become impractical and more costly... Did you ever try this modul or B500 with something like this or similar? Eny prognose or segestion whit this type of PSU?
http://www.hypex.nl/docs/SMPS1200_datasheet.pdf