PCB for Gary Pimm's CCS & SS Pentode

[Rescue Toaster]

I designed a somewhat updated PCB for Gary Pimm's CCS & Solid State Pentode circuits. I wanted to make the changes for a couple reasons:

1) Move both transistors to the same side and put them on a standard (1") center.
2) Provide for creating both the CCS & SS pentode circuit with no modifications
3) Provide for screw terminals

And most importantly, recreate it in Eagle and at a standard size for Seeedstudio and Itead's PCB service, which gives you 2" x 2" PCB's with silk & mask both sides for all of a buck a board.

I started building out a set for a headphone amp:


I need to make a few tweaks, and before I could post the Eagle and/or Gerbers, I have to get permission from Gary, whose email no longer works. So if anyone has a contact for him please let me know or point him to this post. Thanks!

[kevinh]

You might a PM to Lynn Olson.

This would be real nice.

[EvilMose]

Excellent work! Hope you can connect with Gary to make this happen.

[Rescue Toaster]

I did get his email from Lynn, so I'm just waiting to hear back.

[kevinh]

Good Hopefully Gary P will be onboard with this.

The boards look real nice!

[dgta]

How do you mount that? I see mounting holes at 2 corners, but none and no room for any at the other 2 corners.

[Rescue Toaster]

The board is rather light. It's designed for the main two TO-220 transistors to be mounted to a case or otherwise secured heatsink, not for small unsupported or pcb-mounted heatsinks. Because of this you can really mount it with only one or two screws (on the left side) or honestly with none, as long as the heatsink is secure.

Generally the PCB will stick out at a 90 degree angle from the heatsink surface, or the transistors can be mounted on the bottom and bent out sideways, and the mounting holes can be used with small standoffs and screwed into the heatsink surface as well.

There are some examples of this on Gary's page: Here is the newest member of the CCS family You can see down below that assuming the heat load isn't too great, you can often just use the case itself as a heatsink.

[jkeny]

Interested in these boards. I have some other CCS boards which I have modified for use as SS Pentode & have populated the boards but haven't had the time or large enough heatsinks to try them.

Has anybody actually built a SS Pentode amplifier? I need some motivation to finish this, so let's hear some reports about this amp.

[Rescue Toaster]

I built a single channel differential test amp that is basically the driver stage of the SS Tabor, for use with headphones. The measurements even with a really budget Edcor transformer were very good. 2nd Harmonic - 75db, 3rd -67db, 4th -86db, 5th+ -100db or lower. This was at ear-destroying power levels. Total THD in rightmark was 0.074, IMD&N was 0.100. Dynamic range was 88db, the limiting factor mainly being 60 & 120hz hum from my choke-input supply. And all this was on a rather budget USB 'sort of' pro audio card, which probably contributes about 10-20% of the distortion and only has about 92db dynamic range on its own anyway.

And this was on a breadboard with very, very long wires and the circuit built as the nastiest perfboard monstrosity ever. My biggest issue so far is the monstrous magnetic field produced by the choke-input supply coupling into the output transformers. Moving the transformers around with a scope on the output helped me find some 'dead spots' that I might be able to take advantage of in the final build, or just use a separate supply.

[kevinh]

Originally Posted by jkeny

Interested in these boards. I have some other CCS boards which I have modified for use as SS Pentode & have populated the boards but haven't had the time or large enough heatsinks to try them.

Has anybody actually built a SS Pentode amplifier? I need some motivation to finish this, so let's hear some reports about this amp.

Lynn Olson wrote about it, he said it sounded like a very good Pentode amp but dead quiet.