Studio Reference Amplifier

Hi Sunny, that's the point - bias is zero but the heatsink is very hot most likely means either oscillation or some mistakes in assembling the boards (like TO-126 transistors soldered backward for example, etc.). SR200 is a mature design, built many times, so being built with no mistakes it is expected to work no problem.
Anyway, an oscilloscope is the best friend of a DIY builder, even some simple one. It makes sense to have it always connected to the output until you are sure everything works perfectly - you can catch an oscillation early and react accordingly, you can also see the oscillation parameters, giving you ideas on its nature.
Testing amplifiers with no scope is like doing it with your eyes closed. Not enough information for troubleshooting.
 
Greetings sir...
Regarding SR300 will you recommend it in Class H version i have 10 pairs of MJ21193/4 i am thinking to make 5pairs per channel what stepper can you recommend?
i have 4x43VAC traffo... thank you...

regards
sam

Use stepper from HX11 or from BA2000. or use class G from B2000.
 

Attachments

  • Apex HX11.jpg
    Apex HX11.jpg
    54.8 KB · Views: 901
  • BA2000.JPG
    BA2000.JPG
    573.9 KB · Views: 961
  • B2000.JPG
    B2000.JPG
    551 KB · Views: 934
  • APEX AX11 H-KLASA.JPG
    APEX AX11 H-KLASA.JPG
    73 KB · Views: 879
Last edited:
i have assembled two boards of SR300 and tested them today. output voltage is about 10Vrms,bias per cold pair is 30mA 10mV across 0,335Ohm and it is stabile. with heatsink about 60 degrees Celsius it reaches 12mV or 35mA per pair. i think i have made a mistake at Signal LD circuite because it is lighting with no input-output signal,i mist check that. power and clip LED work just fine. also,i have not yet tested protection that is on an amplifier pcb.

i have tested it with 10r in paralell with 470nF and it does not showing any oscilations. it "rings" a little bit but i have some troubles with my tone generator,so osciloscope shows same ringing at amp input and output. when i solve that tone generator trouble i will show some more pictures here. anyway,amp worked with 10Vrms and square signal at output ,on 10r paraleled with 470n for about hour and a half,and survived with no troubles.

next is test with no security-light bulbs in series with positive and negative power supply,and than if everything is all right there will be first audio testing.
 

Attachments

  • DSC_0040.JPG
    DSC_0040.JPG
    369.5 KB · Views: 563
  • DSC_0039.JPG
    DSC_0039.JPG
    513.6 KB · Views: 660
  • DSC_0038.JPG
    DSC_0038.JPG
    509.9 KB · Views: 657
  • DSC_0036.JPG
    DSC_0036.JPG
    534.6 KB · Views: 794
  • DSC_0041.JPG
    DSC_0041.JPG
    789.6 KB · Views: 224
i have assembled two boards of SR300 and tested them today. output voltage is about 10Vrms,bias per cold pair is 30mA 10mV across 0,335Ohm and it is stabile. with heatsink about 60 degrees Celsius it reaches 12mV or 35mA per pair. i think i have made a mistake at Signal LD circuite because it is lighting with no input-output signal,i mist check that. power and clip LED work just fine. also,i have not yet tested protection that is on an amplifier pcb.

i have tested it with 10r in paralell with 470nF and it does not showing any oscilations. it "rings" a little bit but i have some troubles with my tone generator,so osciloscope shows same ringing at amp input and output. when i solve that tone generator trouble i will show some more pictures here. anyway,amp worked with 10Vrms and square signal at output ,on 10r paraleled with 470n for about hour and a half,and survived with no troubles.

next is test with no security-light bulbs in series with positive and negative power supply,and than if everything is all right there will be first audio testing.

Nice work,
Regards