kevin gilmore

I would carefully check all the solder joints on the pzta parts I have been known to miss a couple

This is typical of all power amps with unregulated power rails. There is a solution (see uberamp2) which requires a lot more of a lot of stuff. You can mess with the filter settings in audio precision to make much of that appear to dissapear. Still 100db down is better than .01% thd, 3rd harmonic invisible, typical of bipolar outputs done that way. About the best you can do without feedback or lots and lots of current mirrors reducing distortions in circuits is not an easy thing, best to start with something decent to begin with.

You know that there IS a solution for that problem. But it's a slippery slope looking at the board now, its an astounding job. and its only 2 layers. infinitely better than the "professional" crap

There are other gerber viewers that work with the latest files. soon I will upgrade to the newest version that does the X2 version of Gerbers with full polygonal and contour support and that will probably make a mess with many of the viewers

want a pair of them real bad. (office/home)

Oh no the singlepower filament circuit very bad

for the high voltage 16 kohm 20 watt, you need a pair of them. for the low voltage 500 ohm 2 watt

yep that board and that power supply. what you want for the transformer is a real good torroid, or even better a R-core transformer although I used a Hammond transformer for my build because it was easy to source.

always check the power supply first. Into a set of resistors if possible.

The ksa5 is voltage limited, so for things like the he6, not enough oomph. And its single ended, although nothing prevents you from stacking 2 of them for balanced in which case its going to have serious amounts of power. ss dynahi is for all practical purposes way overkill for all modern in production headphones. Very nice on vintage electrovoice and jbl horn speakers. I did just pick up a pair of original "voice of the theater" set, if I bring them home i'm dead for sure. ss dynalo is what I listen to when I listen to dynamic headphones. as I only use the he6 now for testing. any of the audio-gd headphone amplifiers are better than that eddie current piece of crap in every single way, sound quality, build quality etc. And less than half the price. I hope the black widow is reliable because its stuffed with obsolete parts (although the layout for the thatcorp/Motorola front end is obviously there), repairing the thing is almost as bad as trying to repair a cavalli piece of trash. compare the picture above with this for $520 http://www.audio-gd.com/Pro/Headphoneamp/NFB1AMP/NFB1AMP9.JPG

would one more gain stage, and some output stage stability have killed them? Maybe $499 of course then it would be similar to a srxplus or half a megatron birgir can post the inside pictures, even with the crap case its still built better than any cavalli or ec I know of. and once you play with nagra gear including the stuff that is 30+ years old, nothing looks like nagra, nothing feels like nagra, nothing is built like nagra, even the rotary switches are different from everything else.

here you go its better than a lot of other eddie current stuff I have seen people that think that shunt regulated power supplies are better than really good linear supplies are wrong the input stage is very familiar really weak output stage with virtually no heatsinking painted really cheap steel chassis there are a number of ksa5 clone boards on ebay, some are mine and are obvious, but no one putting my board inside a chassis at the moment. if you have to buy one now on ebay, this one is complete, the power supply is not as strong as the original, but its cheap http://www.ebay.com/itm/Headphone-amplifier-Imitation-KRELL-ksa5-line-CPI-full-DC-amp-machine-ClassA-amp-/112050882595?hash=item1a16c0c823:g:61kAAOSwu4BVkJvH this one has my board but a different power supply http://www.ebay.com/itm/Finished-Kevin-Gilmore-KG-version-KSA5-headphone-amp-preamp-amplifier-HL-230-/142031703076?hash=item2111bfcc24:g:6GMAAOSwM4xXaLnE this one is my power supply with a different heatsink http://www.ebay.com/itm/Assembeled-Power-supply-board-for-KG-version-KSA5-headphone-amp-PSU-/322047929078?hash=item4afb8d6af6:g:-~UAAOSwoudW8MxP so you could buy the right board, and the right power supply, put it in your own chassis with a transformer for about $300 total...

capacitors floating in air filament transformers also floating in air with chipamp drive circuits not really a headphone amp is it.

singlepower made a sds xlr gold plated that was over $30k. inside it looked like all the other ones. craig published one picture of a obviously hand built electra that looked decent except for the el-crapo connectors. I have been told production models are the same garbage as always. companies that refuse to show whats inside are obviously not proud of their work. buy a Chinese made ksa5 klone.

get me one for a couple of days, then everyone will know. lately things getting high praise by many over there turn into massive pieces of poorly build crap.

with 2 x p-channel fets as the inputs, yes

updated board, one of the fets was labeled wrong

ether e not shown with ll2 or ll2t? these would not be the first stats to require 2500vppss

maybe they need 800v bias. otherwise the efficiency, or lack of it is going to require a cheap chip amp feeding transformers. Not exactly high end.

How d'agostino ish i would do the whole thing in copper, but that is stupid expensive. make the holes in the copper a bit big to take care of the thermal expansion differences

how thick is the mounting bracket?

The black color is supposed to make it harder to reverse engineer. Turns out it makes it easier with the appropriate lighting and photoshop. definitely the black color makes repairs harder, but its really the size of the circuit lands, the 1 oz copper and the diameter of the pads that makes it worse.

http://www.us.tdk-lambda.com/ftp/Specs/km.pdf medical grade, switches at 132 kHz. definitely can fit everything inside the box. This would be the most expensive part at $80 even cheaper if you go for the 15 watt version. definitely everything fits in the box, and no phase splitter or other crap because its a true differential balanced amplifier. the quad alpha pot would be the 2nd most expensive part at $30 so say $200 in parts plus about $25 for the box. and it won't blow up even into a 4 ohm load. or a dead short.

My point was not that made in china was crappy, it was that made in china is priced such that made in usa cannot compete. Audio-GD for example makes ultra high caliber equipment, and at a price that i cannot even buy the parts for. Ksa5 boards now on ebay that are my layout stuffed with parts and assembled and sell for a fair bit less than i can buy the parts for.

Headroom designs were ahead of their time and infinitely better quality i still think I can build something much better and still get it all inside the same size box