I'll have the working unit at the MD/DC/VA meet tomorrow. Amp sounds great!

http://www.head-fi.org/t/754656/dc-area-head-fi-meet-george-mason-regional-library-sunday-april-12-2015-noon-5-pm

George Mason Regional Library

George Mason Meeting Room (on your left right after the entrance).

Date: SUNDAY. APRIL 12, 2015

Time: 12:00 Noon to 5:00 PM

Location: 7001 Little River Turnpike, Annandale, VA 22003

That meet is in my neighborhood, I might have to drop by.

by the way fully balanced version coming.

 

lots of parts!

 

100% differential

100% complementary

 

http://gilmore.chem.northwestern.edu/cfa3production.pdf

 

not sure why it took me years to come up with this

 

NO FEEDBACK of any kind

thd <.005%  and absolutely flat over the 10hz to 200khz

 

frequency response +0, -3db   .017hz to 4.43 MHz

Edited April 12, 201511 yr by kevin gilmore

Omfg, I'm going to need a bigger case.

Can you do the phase splitter as a separate board so I can add to what I've got?

Edited April 12, 201511 yr by GrindingThud

well the phase splitter is just the ubal to bal board.  and then there are pieces missing.

plus you would have to build 2 more boards anyway.

 

http://gilmore.chem.northwestern.edu/cfa3.jpg

 

for your thing, you could just adjust the gain to 1 and then use the ubal to bal board.

 

the stax mafia moves at light speed

 

someone really needs to check this one over hard.

 

the miracle of cut and paste is not necessarily foolproof.

 

this is probably as close as I can get to the ayre stuff without actually having the schematics.

 

I could go all krell on this and stuff it full of power supply caps...

Edited April 12, 201511 yr by kevin gilmore

so what you're telling me is I need to donate a kxr to the Gilmore group

preamp plus power amp please.

 

I will send it back.

 

actually more interested in the amp, because I know I'm extremely close on the preamp part.

 

this really should be the end all dynamic amp, with 80 volts peak to peak output and up to

2.5 amps (more with a bigger heatsink) it should drive both hd800 and he6.

 

you could actually put the volume control in the middle for even more reduced noise, although

the noise is about 95db down.

Are you going to add a place for a pot between the splitter and amp sections? Might be useful, and you can always bypass it 

I'm sure I will add that.

 

found a bunch of errors which hopefully I fixed.

 

and I took out the surface mount transistors because they are only 200mw  and there are a few places where its 270mw

 

picture updated

Edited April 13, 201511 yr by kevin gilmore

Ah, looks a little different than what I thought. I'll get the single ended version cased up before I move to the balanced one, which I think I will. Whats a few more boards.

Got a lot of puzzled faces at the meet today.... people somehow expect less when all the guts are hanging out. Once jacked in, it was all smiles and amazement. Most people preferred it to the Krell clone.

well the phase splitter is just the ubal to bal board. and then there are pieces missing.

plus you would have to build 2 more boards anyway.

http://gilmore.chem.northwestern.edu/cfa3.jpg

for your thing, you could just adjust the gain to 1 and then use the ubal to bal board.

the stax mafia moves at light speed

someone really needs to check this one over hard.

the miracle of cut and paste is not necessarily foolproof.

this is probably as close as I can get to the ayre stuff without actually having the schematics.

I could go all krell on this and stuff it full of power supply caps...

Edited April 13, 201511 yr by GrindingThud

speaking of krell klones

 

 

http://www.ebay.com/itm/Assembled-Krell-KSA-05-Class-A-preamplifier-board-with-headphone-amp-CL-232-/191538328292?pt=LH_DefaultDomain_0&hash=item2c9892f2e4

 

and

 

http://www.ebay.com/itm/YJ-Assembled-KSA-5-headphone-board-with-C1237-horn-delay-protection-circuit-/221740126195?pt=LH_DefaultDomain_0&hash=item33a0bdcff3

Edited April 13, 201511 yr by kevin gilmore

could it plossible just simply using 4 boards instead cfa3 design to complete balanced build? seems possible

thinking 4 board would be more flexible for me

sure you can do that, but you need a phase splitter, or have to run balanced input only

if you want balanced output.

doesn't the original design have feedback?

short detour to the post office today:

dual k170s and j74s from someone on diyaudio. should have a good home in the phase splitter

the cfa2 has gain, so it has feedback

the cfa3 has no gain, so the phase splitter has the gain

speaking of krell klones

 

 

.........

and

 

http://www.ebay.com/itm/YJ-Assembled-KSA-5-headphone-board-with-C1237-horn-delay-protection-circuit-/221740126195?pt=LH_DefaultDomain_0&hash=item33a0bdcff3

A cheap CANADIAN clone?  Who woulda guessed?

Back bacon is extra.

For CFA2 is it possible to up the gain to 7? I've not figured out how to do it with this circuit.

raise the value of R1, say 1k will give you 3db more

Thanks!

raise the value of R1, say 1k will give you 3db more

started to look at the layout for the phase splitter + cfa output

 

does your legend apply to the output only, or both sections? your schematic has 2s* parts in the phase splitter, and I seem to remember there being a version of the ubalbal board that accepts mps* parts.

the new verskon uses the bc parts

Is it published here? I mean balanced differential cfa3

http://gilmore.chem....ern.edu/boards/

I think not. Any progress please?

http://gilmore.chem.northwestern.edu/boards/cfp3rs.zip

 

someone really needs to check this hard to make sure when I changed

the transistors everything still goes to the right place.

Hmm you switched to SMD? Pity. Any chance to design them simultaneously please - SMD and all TH?

I've got plenty of MPSW.