kevin gilmore

depends on which end the pot is at. 1.8k or 2.2k the 500k resistors are really a safety thing. best to simulate the pot for real, but they are ok, just a bit noisy.

although absolutely nothing can compare with Mikhail's build quality (well trevornetwork and hennyo).... The squarewave done right would have been a kickass amplifier. And the klone definitely is. extended use of stock LLmk1 and probably LLmk2 due to heat and other issues is going to definitely cause reliability issues, and out of warranty repairs are going to be nasty. LF are already known to be very hard to repair. Not allowing pictures to be shown elsewhere just makes it worse because the manufacturer has no reason to make better or more repairable products in the future.

1) with both boards connected the temps will drop a bit 2) you should change the 2k resistor to get the voltage to zero before you add the servo

With pot at minimum bias is 120 ma with pot at max it's 200 ma Probably should cut 75k resistor to 50k And 1 meg resistor to 100k. Servo takes 2 minutes to go from 200 mv to .2 mv with 1meg resistor. Thd and noise below baseline of my meter. Slew rate which is already Limited by input filter is very fast. Just great with hd800. Going to add pads to measure bias on next board rev

what I had to do is add an extra inverter on top of the servo to get it to work right, shades of sijosae with that inverter http://gilmore.chem.northwestern.edu/sqwave1-1.jpg http://gilmore.chem.northwestern.edu/sqwave1-2.jpg http://gilmore.chem.northwestern.edu/sqwave1-3.jpg updated schematic http://gilmore.chem.northwestern.edu/squarewaveproduction.pdf

If you are using the central semiconductor metal can fets on the square wave boards They have to be flipped from the plastic parts so put them in backwards. And the servo does not work and will need to be rewired so pull the opamp and you Should get about 200 to 300 mv of offset. Fix coming.

you could be right that one of the hunks of iron on top is a choke. and I do see 4 large power diodes and a CRC in the middle so that would be the DC filament. Just like mikahil. Except done right. 5u4 filament would be AC anyway. In any case, its still really nicely done.

I finished my singlepower squarewaves last night. pictures when I get home. really sounds nice with hd800.

two transformers topside one transformer on the bottom (blue thing) 2 chokes (E/I core black things) 2 large poly caps (white/silver things) 2 power resistors (gold things)

Its just not worth the labor to do what birgir did to that board. And its a HUGE improvement. much more awsum New replacement board about $42 (quantity 10, 3 oz copper, alex's board was 1 oz copper) (about 7 x 9 inches) the parts a bit cheaper than a pair of kgsshv amp boards (16 large heatsinks total) using the new lsj74 input fets, 2sa1968 or ixys current source, 4686 or new Fairchild parts ... so about $500 fully stuffed. boards will NOT be black, and WILL be twice as thick

I was making a joke about the weight distribution

I know for a fact that the liquid fire was built every bit this bad, and also not repairable, and i'm guessing that the liquid gold is also not repairable given the way its assembled. Another pretty chassis with crap inside. by the way, very few of you will ever see this, so have a good laugh, the cavalli packaging http://gilmore.chem.northwestern.edu/wca.jpg

unlike some other product we have been discussing recently, sure looks built really nice with premium grade parts. especially the output caps. and since this is basically a singlepower extreme done to the extreme, its going to kick ass for high impedance headphones. cathode resistors are visible and are bolted to the heatsinks. betcha no ground loops inside this thing. sure looks to be leaning a bit to the left however. I wonder why that is.

by the way, the newer krell power supply was cloned from this one and only picture http://gilmore.chem.northwestern.edu/newkrellps.jpg no schematics were available, and no one I know actually had one, boozebuttons had the older one

both supplies now fully tested and i'm really happy with each of them. the bigger one easily does 1 amp, so enough to run a pair of boards for balanced. http://gilmore.chem.northwestern.edu/krellsupplies.jpg

yep. the thing gets stinkin hot. because the bias has to be turned way up to compensate for all the extra capacitance it has to drive. even so, its not enough.

that really is the way it arrived. and in a few places on the top, hennyo like balls of solder on the parts. seriously the solder job on this is miserable. also notice NO CONNECTORS. the whole mess is soldered together board to board from the top. Also notice that getting any of the power transistors off the heatsinks is virtually impossible. especially the ones on the triple of small heatsinks. This thing is virtually unrepairable if a part blows. updated schematic with more stuff.

http://gilmore.chem.northwestern.edu/m10.pdf http://gilmore.chem.northwestern.edu/m20.pdf I think its safe to say that even an exstata is better than the kingsound amps.

2sa1486 moar better anyway

definitely. Alex should go into the custom chassis business. I have 3 chassis I need right now, and don't have the time to do myself.

Ksa1156 from mouser Current part

Do a quick calculation noticing that the j176 is 10 times as noisy as the j74 With an amplifier with a voltage gain of 500 and see if you can get the Signal to noise ratio shown in that picture.

Well its a bright and sunny sunday morning and the don of the stax mafia says its ok for me to publish the schematic, so here it is. http://gilmore.chem.northwestern.edu/llmk1.pdf that triple current source at the top of the gain stage with the feedback from the output stage is what alex (knowingly or not) traded 1db of 2nd harmonic for 7db of 3rd harmonic. all the spice models are available, stuff them into ltspice and see for yourself. output transistor pics http://gilmore.chem.northwestern.edu/ll-2.jpg the tough one to take a picture of http://gilmore.chem.northwestern.edu/ll-3.jpg how about that quality way to jumper out a zener http://gilmore.chem.northwestern.edu/ll-4.jpg and a cold solder joint or 3 http://gilmore.chem.northwestern.edu/ll-5.jpg and here are some simple fixes that make the thing sound bunches better with just removing parts and only 2 jumpers http://gilmore.chem.northwestern.edu/llmk1fix.pdf at least alex did learn something from the exstata disaster. The power supply is no longer a shunt regulator. Its actually fairly quiet, and has a temperature stability of about 2% strictly due to the zener reference.

You have seen the singlepower esx rebuilds we have done right? remember this? http://gilmore.chem.northwestern.edu/liquidlightning.pdf well we built it just for fun and it sounded fucking awful. remember what alex said about it... it was a SLOW amplifier well the real thing is virtually identical to this. and its still fucking awful. but we have ways to fix it. at least we think we do. It is kind of a shame, the chassis is actually very nicely done and the power supply is pretty decent. The stax jacks are still way to tight and for no reason. Transformers are very nice. Now all alex needs is a decent amplifier to go inside the box.

there is a grounding error on the zener power supply on the final output cap on the minus power supply. the wrong side of this cap is grounded causing the minus supply to be grounded. simple fix, use a drill bit on the top to un-ground the grounded hole, then add a jumper on the bottom to the other side of the cap to the other cap to ground. http://gilmore.chem.northwestern.edu/dsc_0469.jpg http://gilmore.chem.northwestern.edu/dsc_0470.jpg