xrk971 Pocket Class A Headamp GB

[silasmellor]

I built a setup based on X's advice on veroboard using euroblock connectors that allows me to use different load resistors (10K should work for BA-3) and also includes a 10:1 voltage divider for protecting the interface. With 10K load on the BA-3 you probably don't need the voltage divider so you could just connect the 10K load with a jack in parallel to go into the focusrite (for 1 channel at a time).

 

[DontHertzMe]

I am waiting for Gerbers from BDHM...

Whoops! So is everyone happy with the last layout? If so, I'll send the gerbs.

 

[JPS64]

Lastest Eagle PCB view?

JP

 

[DontHertzMe]

Lastest Eagle PCB view?

JP

Post #1604 . Only change was the addition of a JST header for a power switch.

 

[xrk971]

So this one then?

Looking good.

 

[JPS64]

If wanted, I´ll do some cosmetic modifications and 3D model before ordering?

I´m using EAGLE 7.5.0.

JP

 

[DontHertzMe]

If wanted, I´ll do some cosmetic modifications and 3D model before ordering?

I´m using EAGLE 7.5.0.

JP

Cool. I'll send X the Eagle files (version 7.6, should be compatible). If not, let me know.

Edit: files sent

 

[yestro]

Is there BOM\schematics for power supply part of the desktop version? Having a hard time reading this image, being new to this doesnt help.

 

[xrk971]

This is the schematic as of now, JPS64 will fine tune the layout some more, so the BOM may be subject to change.

 

[yourownbuzz]

can't wait

 

[JPS64]

Hello Baby,

RK097 symbol is wrong! I need the schematic binary also.

JP

 

[prasi]

pin connection should be "GND-OUT-IN" when looked from shaft end.

 

[DontHertzMe]

Hello Baby,

RK097 symbol is wrong! I need the schematic binary also.

JP

How odd ! IIRC it's the symbol and package that came with Eagle. Will send it to you.

 

[xrk971]

The first amp was built with that symbol wasn’t it?

 

[prasi]

first amp meaning , your pocket HP amp? No it had a different pot with switch, i believe.

 

[xrk971]

My mistake. Yes Pocket amp had RK09 but with power switch built in so 8 pins.

 

[JPS64]

no problem, I‘ll work on it.

Patience!

JP

 

[DontHertzMe]

The pocket amp used part ALPS_RK0971221Z0N from library audio-pots, the problematic one is RK097-DUAL-ELEMENT from library alps_japan_potentiometers.

Good catch, JP

 

[JPS64]

Progress: left, Babys, right, corrections.

I´m thinking changing CAPx and CRCR placement.

JP

 

[xrk971]

Looks very nice, JP and BDHM. Thank you both. I was thinking if we should have a local smoothing cap near the Drain to each MOSFET to help de-couple rail perturbations from one channel to the other? Or make a very low impedance two--layer via plane for the main power node from the last CRCRC cap to each MOSFET Drain.

I recall from testing the PCA that when I ran it with little 47uF rail caps, the stereo separation was like -30dB, and with 2200uF caps it was -72dB, a substantial improvement. We still have room for a 4700uF 25v cap at each MOSFET don't we?

The last time I recall someone named "Baby" was in this popular movie from 1987 featuring Jennifer Grey: