VSSA PMI version vs Peeceebee Shaan version

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It is usefull if we have opinions about those measurements.
Keep in mind that two amplifiers have the same Power Supply ,linear +/-32v ,36000uf/rail when inputs is in parallel.Outputs are under scope control at 6,9v RMS on a dummy load=6R
Each unit tested alone.
These measurements was repeated 4 times for each module
 

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Last edited:
It is usefull if we have opinions about those measurements.
Keep in mind that two amplifiers have the same Power Supply ,linear +/-32v ,36000uf/rail when inputs is in parallel.Outputs are under scope control at 6,9v RMS on a dummy load=6R
Each unit tested alone.

Hi thimios, I made VSSA with CCS too. CSS will make the PSRR higher.
I see PMI version have higher noise. THD should be same. I think Shaan version have better PCB layout.
 
Hi thimios, the thread title is interesting, I have attached my pcb lay-out of Shaans PeeCeeBee but employing PMIs component. If you wish to go deeper into the comparison test I guess the PCB might unlock some mystery :D ;)

..just a thought though..:)

Regards!

BTW The assigned component on the PCB was my own mod, provided also was PMIs original schematic and can also be followed "as is" using my PCB lay-out. The PCB lay-out is tested and is fully functional, this is my VSSA unit at home.
 

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Hi thimios, the thread title is interesting, I have attached my pcb lay-out of Shaans PeeCeeBee but employing PMIs component. If you wish to go deeper into the comparison test I guess the PCB might unlock some mystery :D ;)

..just a thought though..:)

Regards!

BTW The assigned component on the PCB was my own mod, provided also was PMIs original schematic and can also be followed "as is" using my PCB lay-out. The PCB lay-out is tested and is fully functional, this is my VSSA unit at home.

Hi Abetir,

I am etching your layout as I type. I don't see a place for the trimmers on your layout. Did you do something different there?

Thanks, Terry
 
Terry,

Man that was fast! I assume you are referring to the dc offset trimmer (PMIs original), this was replaced by 2 resistor in parallel (for better regulation- LCs recommendation) placed just below the fet ccs. Try to work with the resistor from values of 750k to 920k depending on your PSU rail. I find lower values to be near zero dc offset but sonic distortion may arise and higher value, higher dc offset.

Regards!
 
BTW which component have you installed? my mod or PMIs original. I wanted to replace the 2sk246gr with 2sk117 but I still can't locate these type in my area. In my build I removed the VAS heatsink I find it to be non-necessary at 27vdc rail voltage. Also just in case work with the cdom values from 22pf-47pf.

:cheers:
 
I basically followed your silk. I changed a few things based on what I had in my parts bin. I used 220uf for the 100uf. I used 2SK246. I have 2SK117 if they are necessary but I figured for use in the CCS it wouldn't matter. I'll try using some pots to find the best value and then pull them and install resistors. I used BC546C/556C because I have a lot of them and I wanted to be able to try higher rails. I'll let you know how they work out.

Blessings, Terry
 
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