Studio Reference Amplifier

[mathez]

thanks to Apex&Alex for this SR200

 

[saw audio]

very nice amp

 

[dentarthur]

Cooling needed?

I have built one SR200 and have it running on +/- 70V.
I can set bias for it to be at 100mA (10Ohm resistors do not go up in flames).
However, the MJE 340/350 all get very hot. During short up-times I did some measuring and it seems that each of these MJE's has approx 67V between E-C and runs some 10mA. Should these T's get warm with these numbers? Should I heatsink them (I see heatsinks on them in some builds.
Or does this mean that there is an error in my build?

 

[drowranger]

This buffer can be use instead preamp.

sir apex i want to make a pcb for your buffer but it seems that 2n5462 symbol is not meant for transistor and also symbol for fet i dont know which one is source and which one is drain.symbol for fet is not clear.please can you give us the correct schematic.thank you..

 

[alex mm]

.....schematic for preamplifier with fet , terminal identified ... Sir Mile can tel us if I'm correct .
Alex.

 

[eesbiboi]

For more outputs you must use triple darlington topology. Maximum power can be 750W/4R, and +/-110V rail voltage.

sir mile

can you please show to us how to implement triple darlington topology...so we can try to feed the amp with +/-110v for 750w max output...

thanks


regards
ees...

 

[amptech]

I have built one SR200 and have it running on +/- 70V.
I can set bias for it to be at 100mA (10Ohm resistors do not go up in flames).
However, the MJE 340/350 all get very hot. During short up-times I did some measuring and it seems that each of these MJE's has approx 67V between E-C and runs some 10mA. Should these T's get warm with these numbers? Should I heatsink them (I see heatsinks on them in some builds.
Or does this mean that there is an error in my build?

it would be best if you fitted heat sink tab's for the mje340/50's to aid there cooling...

 

[sasek]

apex regulator

apex i make car smps and connect to your regulator.i want to use+-65v,what suitable voltage should i produce from smps and than regulate using your regulator?or have calculation.because i confuse which better input 90v regulate to 65v or input 75v regulate to 65v.

 

[dentarthur]

Cooling needed?

Anyone else done this too?
I run SR200 on +/- 70V and found that 5 transistors get pretty hot. It all works just fine, however, I made some cooling on the MJE transistors and the 2 BC550's that connect to the + via the 100ohm resistors (see picture).

Isn't it strange that the 2 BC550's on the '-' side do not get as hot as the ones on the + side?

 

[Luke]

Regulated PSU for Amps with 4 pairs of outputs, output voltage can be set from +/-55V to +/-90V.

Hi Apex, did you ever make a pcb for the regulator in post 14 with 4 output transistors?

 

[apexaudio]

Anyone else done this too?
I run SR200 on +/- 70V and found that 5 transistors get pretty hot. It all works just fine, however, I made some cooling on the MJE transistors and the 2 BC550's that connect to the + via the 100ohm resistors (see picture).

Isn't it strange that the 2 BC550's on the '-' side do not get as hot as the ones on the + side?

It's strange that the 2 BC550 get hot. MJEs must be hot and BCs must be cold in cascode VAS...

 

[drowranger]

why is resistor r9 and r10 is before the r11.how can you get the ideal 4ma when your voltage is only 15volts?

 

[Luke]

anyone made a pcb for the higher power reg as in post 14?

 

[drowranger]

anyone?can you please help me on r9 and r10.is it before r11 or after?check me if im wrong r9, r10,d2, and c5 are used to regulate the supply of ic1. im making new foil pattern for this one. thank you for your time.

 

[apexaudio]

thanks to Apex&Alex for this SR200

Nice work, be welcome,
Regards

 

[apexaudio]

I have built one SR200 and have it running on +/- 70V.
I can set bias for it to be at 100mA (10Ohm resistors do not go up in flames).
However, the MJE 340/350 all get very hot. During short up-times I did some measuring and it seems that each of these MJE's has approx 67V between E-C and runs some 10mA. Should these T's get warm with these numbers? Should I heatsink them (I see heatsinks on them in some builds.
Or does this mean that there is an error in my build?

Yes, MJE's need cooling, there is no error,
Regards

 

[drowranger]

sr 50

APEX SR100 Studio Ref Amp

Hope this may help(based on the original schematics of SR50).

ENJOY!!!

 

[drowranger]

correct parts placement guide.(previous is in mirror image).sorry.

 

[drowranger]

sr50 incolored top view

correct parts placement guide.(previous is in mirror image).sorry.

 

[yassud]

You can use Coolets pcb design for SR50 and add another pair of outputs,
Regards

Sir Apex, can you give examples of schemes SR100 (VAS cascode)? Thank You