Studio Reference Amplifier

[thimios]

...... to layout this rev.3.1 I spend days and hours from my free time , all the time I need Q.C and this is your contribution to find mistakes , errors and let me know and corect my PCB . I'm glad to help DiyAudio comunity with my skil ......
All the best ,Alex.

Or this
Has anyone test this pcb .
I want try to rebuilt sr 200 in a diferent version pcb.
Thanks to all.
regards.

 

[alex mm]

....you can try this one , was built and it's OK ......

 

[TonyTecson]

hey alex, do you files in pdf?

 

[alex mm]

..... here it's the files you wish to have.....
Regards ,
Alex

 

[TonyTecson]

thank you...

 

[thimios]

sr200 studio refer.

....you can try this one , was built and it's OK ......

Oh dear Alex, welcome pcb specialist!
I try it anyway
Thank you
Υours forever.

 

[thimios]

sr 200

Replace R18 with 2k2 instead 1k, I have no expirience with this pcb but you must add zobel network.
Regards

Hi My Apex .
i has replace R18 WITH 2K2 .
the problem became smaller but it's still here.
please take a look at these photos.
I has made some modifications but.....
I replace 2sc5200/a1943 with 2sc3264/a1295 two pairs upgrade rail voltage to +/-45v .
When this problem is present the R=10R (PART OF RC IN OUT) OVERHEATED.
I have a video from testing process Where the problem is clearly visible .Maybe tomorrow i can upload it.
Strangely when overdriving the unit seems to disappear.

 

[Junie]

Hi Thimios,

I encountered oscillation when I build mine, check my post in #770. Also MJ777 found two missing caps, read his post in #810. Though it's a different PCB layout but I hope it will help you.

BR,
Junie

 

[thimios]

sr200 studio refer.

hi friend i see this about 100pf decapling at the input.
This included to alex mm for Sanken pcb witch i use
Strange is that unit is funcion and i test today hard and is still function......
junie have you ever checked your own amplifier with oscilloscope?

 

[presbel]

Hi alex you forget one of the zener diode.

 

[thimios]

sr200 studio refer.

The omission of the RF attenuation capacitor will have an effect on the way the input transistor sees the outside world.
But I would not expect the amplifier to oscillate (output Zobel overheating) just because the RF cap was missing.

There must be some other problem that is hiding just under the surface.

Hi Mr Adrew

what's your opinion about this problem?
Please see my post 1167 either
best regards.

 

[SERGIODS]

..... here it's the files you wish to have.....
Regards ,
Alex

Thank you for this new version, leave the link to the previous version. for they are not lost looking for it.

version 3.1

 

[alex mm]

Hi alex you forget one of the zener diode.

.....I don't think so , where ?

 

[presbel]

.....I don't think so , where ?

See Attachment

 

[presbel]

Sorry Alex you move it near theLF411.

 

[apexaudio]

Hi My Apex .
i has replace R18 WITH 2K2 .
the problem became smaller but it's still here.
please take a look at these photos.
I has made some modifications but.....
I replace 2sc5200/a1943 with 2sc3264/a1295 two pairs upgrade rail voltage to +/-45v .
When this problem is present the R=10R (PART OF RC IN OUT) OVERHEATED.
I have a video from testing process Where the problem is clearly visible .Maybe tomorrow i can upload it.
Strangely when overdriving the unit seems to disappear.

Replace 2k2 with 1k8 or 1k5, this test is on 20kHz, can you post with 1kHz and 10kHz?

 

[thimios]

Replace 2k2 with 1k8 or 1k5, this test is on 20kHz, can you post with 1kHz and 10kHz?

Of cource i can.
I have a full test ,results i post soon.
thanks Mr. Apex.
best regards.

 

[apexaudio]

Of cource i can.
I have a full test ,results i post soon.
thanks Mr. Apex.
best regards.

Replace R11 with 8k2 instead 15k.
Regards

 

[thimios]

sr200 studio refer.

This time i have this
Take a look
I connected the oscilloscope on R=5R6 (R/C OUTPUT)
I have connect in the same point a frequency meter. i put at the input of the amlifier a squerwave 5.84khz AT THIS MOMENT THE RESISTANCE overheated and the frecuency meter shows the DOUBLE FREQUENCY.
This never happens with sinusoidal.
The second photo sqerwave at 1Khz you order
And in photo 3, 20khz/1volt RMS inp. 32.55 v RMS OUT in this cace problem not visible .If try to minimaze signale input a little it is visitable again.

 

[apexaudio]

This time i have this
Take a look
I connected the oscilloscope on R=5R6 (R/C OUTPUT)
I have connect in the same point a frequency meter. i put at the input of the amlifier a squerwave 5.84khz AT THIS MOMENT THE RESISTANCE overheated and the frecuency meter shows the DOUBLE FREQUENCY.
This never happens with sinusoidal.
The second photo sqerwave at 1Khz you order
And in photo 3, 20khz/1volt RMS inp. 32.55 v RMS OUT in this cace problem not visible .If try to minimaze signale input a little it is visitable again.

Add 10pF for compensation.