kevin gilmore

From the cavalli web page and stuff cavalli has said maximum power 9 watts into 50 ohms absolutely every solid state otl amplifier I know of with a reasonable power supply increases its output power as the load impedance decreases. which means that it should deliver more power into 32 ohms than it does at 50 ohms. yet this amplifier and the liquid fire both deliver less power into 32 ohms than they do at 50 ohms because of the power supply. furthermore alex has said that the liquid gold uses standard + and - 15 volt power supply rails and that the amplifier has mosfet output transistors. This would imply that the amplifier has a rail to rail output voltage. No mosfet that i'm aware of except for highly non-linear low voltage mosfets for power switching applications are capable of this. So the 9 watts is highly optimistic. One of the highest power headphones amps. Really?? Even a single ended dynahi has more power and more class A power, a balanced dynahi has 4 times the output power, the GSX mk2 with the 20 volt power supply rails has more power, rays piece of shit darkstar has 80 volt rails and stupid amounts of power etc. Fully balanced and differential ?? If that is the case, why is there a drv134 in there to convert single ended to balanced? super symmetry dynahi does that all by itself. Schiit mjolnir also does that all by itself. No single ended to balanced converter needed. Pure class A output for the first 550mw... Seriously... The first dynahi's were 18 watts of pure class A. The current GSX are 4 watts of class A (or something like that) The krell ksa5 klone is 5 watts of pure class A The new singlepower squarewave clone is adjustable from 2 watts of pure class A to 3 watts of pure class A (single ended) THD of .0015% @ 3 watts into 32 ohms. how about 9 watts into 50 ohms. And how much feedback is there, what is the intermodulation distortion, because with a thd that low, there has to be oodles of feedback. From the looks of it, its definitely a nice chassis. So I ask... http://www.youtube.com/watch?v=AwbyH9THoQo

original power supply version of the krell ksa5 power supply also suitable with lower voltages for the singlepower squarewave the later version coming shortly http://gilmore.chem.northwestern.edu/ksa5psorig.jpg http://gilmore.chem.northwestern.edu/ksa5psorig.zip and here is the alternate version of the krell ksa5 power supply http://gilmore.chem.northwestern.edu/ksa5psg.jpg http://gilmore.chem.northwestern.edu/ksa5psg.zip

All are current production mouser parts. mje210 863-mje210g 1 0.49 0.49 mje200 863-mj3200g 1 0.54 0.54 2n5210 512-2n5210ta 3 0.21 0.63 2n5087 863-2n5087g 2 0.13 0.26 2n4393 610-2n4393 2 2.69 5.38 opa134 595-opa134pa 1 2.94 2.94 1n914 512-1n914 2 0.1 0.2 heatsink 513202B02500G (newark) 2 1.67 3.34 dip8 socket 571-2-1571552-2 1 0.81 0.81 2 pin terminal 651-1729128 2 0.82 1.64 3 pin terminal 651-1729131 1 1.21 1.21 .1uf 100v ls=5mm 80-R82EC3100DQ70J 4 0.32 1.28 4.7uf 63v wima 505-MKS24.7/63/5 2 4.33 8.66 22pf ls 3mm 598-CD5EC220JO3F 1 1.79 1.79 10 ohm 71-rn60d-f-10 2 0.11 0.22 49.9 ohm 71-rn60d-f-49.9 1 0.11 0.11 100 ohm 71-rn60d-f-100 2 0.11 0.22 200 ohm 71-rn60d-f-200 1 0.11 0.11 221 ohm 71-rn60d-f-221 1 0.11 0.11 332 ohm 71-rn60d-f-332 2 0.11 0.22 10k 71-rn60d-f-1.0k 4 0.11 0.44 34.8k 71-rn60d-f-34.8k 1 0.11 0.11 75k 71-rn60d-f-75k 1 0.11 0.11 1M 71-rn60d-f-1M 2 0.11 0.22 50k pot 652-3299w-1-503lf 1 3.25 3.25 34.29 per channel not including the circuit board (should be about $5 each if we make 100) plus power supply, chassis, pot... cheapest thing the stax mafia have done to date.

if you are building the older version with a lower voltage opamp and the regulators for it, there are weird lock up issues with the regulators that cause the opamp to do whacky things.

and since the krell ksa5 klone is wrapping up... this should be final version http://gilmore.chem.northwestern.edu/squarewave.jpg as usual with all singlepower stuff, the sound was very right, and the implementation was very wrong. well this fixes all of that, adjustable bias, heatsinks for the transistors, and a dc servo, and otherwise just about as simple as possible. Just kickass for hd800 3.1 x 3.1 inches Arizona desert ironwood knobs coming out absolutely gorgeous. harder than ebony. and a lot less trouble.

Make sure that is really a 10k resistor feeding the led

I've built a couple of those, they are known to work.

don't do that. go to radio shack if you have to. white led's are 3.8 volts

pull the opamp make sure that both 10k pots in parallel with the 500 ohm resistors are set at max resistance. just noticed that one of them is going to be full ccw and the other is going to be full cw. make sure the other 2 10k pots are set in the exact middle. or start by not populating any of the 4 pots.

Shorted 1815 or open led or led in backwards.

if the outputs are at +VCC then probably Q20 is shorted. or the led is toast. Need to know the voltages at the top of D11 and D12

gerbers were posted on page 5

those look real in every way. And kerry, that's a great job.

http://gilmore.chem.northwestern.edu/ksa5klone.jpg the fat version of the pot fits perfectly. I figure about 5 hours of build time total if I had all the parts ready to go without having to start and stop waiting for multiple orders.

Inu, nice use of Teflon tubing to get all the small transistors exactly the same height.

my guess is that the output transistors and the 2 ohm resistors are toast.

yep that is going to cause smoke.

ok, so the krell documentation is a little questionable, but when they measure the bias they do it from emitter to emitter. so the number is twice as big as the two test points I put on the board. specifically its 250 millivolts emitter to emitter cold, and 180 to 200mv hot. so at the two test points provided its 125 millivolts emitter to output no load cold a,d 90 to 100 millivolts hot. which sounds about right.

1) I think so, but I don't remember at this point. 2) just make sure the bolt does not touch the top and the bottom of the chassis at the same time. otherwise you get a shorted turn and that is real bad. if you use the Teflon wire and pre-tin, makes it much easier to do the amphenol connectors. at least 1 hour each.

That would work out to 2 watts per transistor, 8 watts, per channel. A bit too much, should be about 5 watts, about 1.25 watts per transistor. so about 125 mv.

its less than that, but I have that info at home. will look later. specific voltage across the emitter resistors.

The one board is clearly working, adjust the offset pot to get the outputs close to zero. On the other one, make sure the differential pot is set to the middle first and the offset pot set for the higher end of the resistance range.

so what we really want is avid part number 513202b02500g which is 2.0 inches high or 513302b02500g which is 2.5 inches high which is the to220 only version neither of which are stocked by digikey or mouser instock at Newark

I have the bigger heatsinks but one of the holes seems to limit The thermal efficiency. Will test... Would be nice if there was a taller heatsink with only one hole

this is the original krell heatsink mouser 532-513102B25