Swordfishy/ASPEN FETZILLA power amp

[klewis]

Hugh,

Parts list C2 says 220nF, Schematic says 220pF.

Ken

[JKC]

Hugh,

I have found that C7 and C8 designators on schematics should be swapped. They are OK on PCB however. Could you please tell me how big are the fuses and what is external diameter of L1 inductor. Thanks.

Regards,
George

[AKSA]

Thanks Ken, George,

Changes made, now correct, please inform any other errors.

Inductor is 25 turns of 0.9mm DTE wire tight wound on a 5mm former. This gives just shy of 7mm OD and 23mm length.

Fuses are standard 3AG, old style, with pcb holders, commonly available.


Hugh

[JKC]

Hugh,

There is one more, designators of C15, C16, C17, C18 should be corrected on schematics to match PCB.

George

[JKC]

Hugh,

There are double C10 designators on schematics.

George

[AKSA]

George,

Both corrected, many thanks,

Hugh

[JKC]

Hugh,

It will be useful if you can post bigger version of just top overlay layer so all designators will be easy readable. This way it will be much faster to check for any mistakes.

George

[AKSA]

George, I'm limited by my screen capture, so will do LEFT side and RIGHT side for clarity, but some visual gymnastics may be required. That OK?

Hugh

[JKC]

Hugh,

Thank you, now it is much better readable. There is one more correction needed, optional caps C5 and C6 have different values on schematics comparing to parts list.

George

[AKSA]

Ah, that's an interesting one....

The values on the schematic, 0.1pF for both phase lead and shunt fb, are in fact minimal values set for the simulator to figure the stability.

For difficult loads (read electrostatics!) the parts list is correct; these should 47pF for C5 (phase lead) and 22pF for C6 (shunt fb).

In almost every application where the load is NOT an ESL, these caps can be usefully omitted.

That saves a bit of angst, silver micas, essential for good sound in these crucial positions, are hard to source, but you guys in North America have a great source at HOSFELT ELECTRONICS, INC..

Cheers,

Hugh