GrindingThud Posted April 11, 2015 Report Posted April 11, 2015 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
VPI Posted April 11, 2015 Report Posted April 11, 2015 That meet is in my neighborhood, I might have to drop by. 1
kevin gilmore Posted April 12, 2015 Author Report Posted April 12, 2015 (edited) 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, 2015 by kevin gilmore
GrindingThud Posted April 12, 2015 Report Posted April 12, 2015 (edited) 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, 2015 by GrindingThud
kevin gilmore Posted April 12, 2015 Author Report Posted April 12, 2015 (edited) 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, 2015 by kevin gilmore
nopants Posted April 12, 2015 Report Posted April 12, 2015 so what you're telling me is I need to donate a kxr to the Gilmore group
kevin gilmore Posted April 12, 2015 Author Report Posted April 12, 2015 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.
nopants Posted April 12, 2015 Report Posted April 12, 2015 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
kevin gilmore Posted April 13, 2015 Author Report Posted April 13, 2015 (edited) 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, 2015 by kevin gilmore
GrindingThud Posted April 13, 2015 Report Posted April 13, 2015 (edited) 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, 2015 by GrindingThud
kevin gilmore Posted April 13, 2015 Author Report Posted April 13, 2015 (edited) 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, 2015 by kevin gilmore
ang728 Posted April 13, 2015 Report Posted April 13, 2015 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
kevin gilmore Posted April 13, 2015 Author Report Posted April 13, 2015 sure you can do that, but you need a phase splitter, or have to run balanced input only if you want balanced output.
nopants Posted April 13, 2015 Report Posted April 13, 2015 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
kevin gilmore Posted April 13, 2015 Author Report Posted April 13, 2015 the cfa2 has gain, so it has feedback the cfa3 has no gain, so the phase splitter has the gain
JimL Posted April 14, 2015 Report Posted April 14, 2015 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?
GrindingThud Posted April 15, 2015 Report Posted April 15, 2015 For CFA2 is it possible to up the gain to 7? I've not figured out how to do it with this circuit.
kevin gilmore Posted April 15, 2015 Author Report Posted April 15, 2015 raise the value of R1, say 1k will give you 3db more
GrindingThud Posted April 15, 2015 Report Posted April 15, 2015 Thanks!raise the value of R1, say 1k will give you 3db more
nopants Posted April 21, 2015 Report Posted April 21, 2015 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.
kevin gilmore Posted April 21, 2015 Author Report Posted April 21, 2015 the new verskon uses the bc parts
Helium Posted May 29, 2015 Report Posted May 29, 2015 Is it published here? I mean balanced differential cfa3 http://gilmore.chem....ern.edu/boards/ I think not. Any progress please?
kevin gilmore Posted May 29, 2015 Author Report Posted May 29, 2015 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.
Helium Posted June 5, 2015 Report Posted June 5, 2015 Hmm you switched to SMD? Pity. Any chance to design them simultaneously please - SMD and all TH? I've got plenty of MPSW.
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