Studio Reference Amplifier

[Dragan100]

If we plans to make output stage with multi pairs of STD03 to achieve more output power (150, 200WRMS...),
they must be closely matched (pairs) and then we go with step-by-step adjusting pair per pair idle/bias currents
in little alternating steps to obtain bias current 65mADC per output pair,
also drivers needs more current (+30mADC per additional output pair) , bigger heatsink, we need then higher PS...
There will be some interactions in this adjust steps and also we need to check "in-between" to re-adjust the driver+Trak bias to 26-27mADC and 4mADC respectively!

I forgot to mention that each of multiple output pairs need an own multiturn bias trimmer,
so we can precisely adjust even output bias current distribution per output pair (... slightly different darlingtons parameters, Beta, V_formard Trak diodes, R_e...)

 

[apexaudio]

I forgot to mention that each of multiple output pairs need an own multiturn bias trimmer,
so we can precisely adjust even output bias current distribution per output pair (... slightly different darlingtons parameters, Beta, V_formard Trak diodes, R_e...)

Nice work,
Regards

 

[lenraminam]

Sir good day, may i ask about sr 800, what about its power supply how many volts do it needs for operation? thank you.

 

[vandk]

Hi Apex! I want to pcb SR200 which you finished the better, can you share for me? Thanks.

 

[thanhsubasa]

Hi Mr Apex,

I've finished the SR200 with 50Vac input and DC offset is 1mv for both board, I am not test the sound yet, because I want to integrate PSU board to the amp

- I use the 2 x 15000uf/100V for this amp, is that ok?
- The trafo is 50x2vac, 250W, that's enough for this amp?
- That capacitor is screw type, so can you please to help me design the PSU board have terminal with the rail of screw, so that make me easy to connect the wires!
- does this amp need pre.amp? If not what is the value of potention volume?

Thanks in advance.

Regards,

 

[conrongco]

SR250H

 

[44250]

SR250H

have you tested it,and if you did - how it sounds?

i started smaller version today:

 

[apexaudio]

Hi Mr Apex,

I've finished the SR200 with 50Vac input and DC offset is 1mv for both board, I am not test the sound yet, because I want to integrate PSU board to the amp

- I use the 2 x 15000uf/100V for this amp, is that ok?
- The trafo is 50x2vac, 250W, that's enough for this amp?
- That capacitor is screw type, so can you please to help me design the PSU board have terminal with the rail of screw, so that make me easy to connect the wires!
- does this amp need pre.amp? If not what is the value of potention volume?

Thanks in advance.

Regards,

Nice work.
Regards

 

[thanhsubasa]

Here is my SR200 amp

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

Thanks apex

 

[apexaudio]

Here is my SR200 amp

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

Thanks apex

There is no pictures...

 

[AndrewT]

Please attach your pics.

 

[thanhsubasa]

Sorry for the links

Back

Front

Regards,

 

[apexaudio]

Sorry for the links

Back

Front

Regards,

 

[DenVeR777]

Hello to all!
I want to build 4 chanels SR200 for my custom studio monitors based on 15' tannoys DC drivers (8ohm).
I started my project with regulated psu based on Mr. Mile's scheme.
Here first question: can i use 3 pairs of output transistors to supply two SR200 with relevant transformer about 600-800VA@50vac?
Thank you in advance for reply!

 

[DenVeR777]

I've got preaty big caps and decide to put em outboard either transistors.
This is a not an issue?
Here is PCB.

An externally hosted image should be here but it was not working when we last tested it.

Is there any bug on it?

 

[DenVeR777]

Sorry, trouble with hosting.

An externally hosted image should be here but it was not working when we last tested it.

 

[AndrewT]

Then don't host.
Attach to DIYaudio.

 

[DenVeR777]

I've made it. It work well. Thanks for help.

 

[DenVeR777]

Hello, again! When i connect 35vac traffo, on output i get 80v AC on pos and neg.
And when i disconnect power it stil 80vac present.
what could be the reason?

 

[DenVeR777]

I've made wires to 5200 and 1943 shorter(about 3cm), and VAC on negative rail is dissapear, but on positiv still 80vac
I trying to check it with osciloscope, but found nothing - line is straight as arrow(
Please help me!