Studio Reference Amplifier

[apexaudio]

SR200

 

[panggih]

Mr.Mile
my sr200 can't set bias,why????would you like to help me??

 

[panggih]

i used this pcb design but can't set bias, 000.0mV on the display multitester. i turn vr for bias but no movement.

 

[Vostro]

I can't remember the offset on my SR200, its posted somewhere, I used LF411 for servo and got about 0mV dc on my Fluke 79

 

[panggih]

I can't remember the offset on my SR200, its posted somewhere, I used LF411 for servo and got about 0mV dc on my Fluke 79

Hi vostro,
i used LF411 too,my sr200 working with deep bass,very clear and it's good,the trouble i can't set bias only.i meassure bias across resistor 0R33/5watt..
if there is another way to measure the bias please Tell me how..

 

[amptech]

Hello to all,regarding bais setting there are a few ways to do this..1 via mv setting across emitter resistors,2 reading the volts over the tracking transistor,3 current idle draw with no signal or load..remove one of the supply fuses and place your meter
in current mode and adjust the bais pre-set to 100ma..

 

[panggih]

Hello to all,regarding bais setting there are a few ways to do this..1 via mv setting across emitter resistors,2 reading the volts over the tracking transistor,3 current idle draw with no signal or load..remove one of the supply fuses and place your meter
in current mode and adjust the bais pre-set to 100ma..

Amptech,
thanks ,i will try 2 & 3 way of measurement.because I've done the first way but have not been successful

thanks a lot

 

[apexaudio]

Mr.Mile
my sr200 can't set bias,why????would you like to help me??

Use 1k5 instead 1k resistor in bias circuit (Vbe multiplayer around BD139)

 

[panggih]

Use 1k5 instead 1k resistor in bias circuit (Vbe multiplayer around BD139)

Mr.Mile

thanks,i will try to change 1k with 1k5 resistor around BD139

 

[apexaudio]

Mr.Mile

thanks,i will try to change 1k with 1k5 resistor around BD139

Vce on BD139 must be about 2V...

 

[olafk]

A super layout by John Bali

Here is my version with only a few small changes to Johns layout. For the second channel, I will adjust the position of the MJE yet, then it will be perfect.

Sound is good at bass and very clear in the middle and treble. But I have checked only at old car speakers for test. Amp comes immediately after the AX14 in the favorites list.

regards Olaf

 

[apexaudio]

Here is my version with only a few small changes to Johns layout. For the second channel, I will adjust the position of the MJE yet, then it will be perfect.

Sound is good at bass and very clear in the middle and treble. But I have checked only at old car speakers for test. Amp comes immediately after the AX14 in the favorites list.

regards Olaf

Nice work,
Regards

 

[panggih]

Vce on BD139 must be about 2V...

Hi,Mr.Mile
thanks alot,,now i can set bias at 12mV after changed 1k with 1k5 around BD139..but the 5200 & 1943 geting hot,,is this normal,or how??

 

[apexaudio]

Hi,Mr.Mile
thanks alot,,now i can set bias at 12mV after changed 1k with 1k5 around BD139..but the 5200 & 1943 geting hot,,is this normal,or how??

Outputs must be on heatsink

 

[panggih]

Outputs must be on heatsink

i used tihis HS sir,,20x9cm for TR outputs ,DCoffset 16,4mV.BIAS 11,9mV. VCC 32VAC WITH PSU REGULATOR

 

[AndrewT]

the heatsink can only achieve specified cooling when standing up with clear air gap all around.

 

[panggih]

the heatsink can only achieve specified cooling when standing up with clear air gap all around.

thank Andrew T,

ok,i'll put 2 fan to aid cooling

 

[olafk]

Second channel ready

Just a few photos. Sound is excellent.

regards Olaf

 

[alex mm]

Thank you ,very nice,well done

 

[apexaudio]

Just a few photos. Sound is excellent.

regards Olaf

Nice work,
Regards