kevin gilmore

you need better eyes... http://gilmore.chem....u/ksa5orig2.jpg the relays are output relays driven by a simple delay circuit. no real protection. there evidently was an issue with 24v relays used on 21v. Q14 is the Vbe multiplier thermally tied to Q23 for output stage bias.

Board files available to all

The people at diy audio where i just posted this seem to think that Todd Eichenbaum actually designed it. I don't know, none of the people i knew at krell are still there so i have no way to verify. As a speaker amp, you probably want the most efficient horns you can get. Not a good idea.

Both Birgir and I have wanted one of these for quite a while, and they never seem to show up. So with a little help from one of the members here we were able to reverse engineer this one. http://gilmore.chem....rn.edu/ksa5.pdf http://gilmore.chem....rn.edu/ksa5.jpg still have work to do on the power supply. All the parts are still available, but identical and compatible parts also available. mpsw06 and mpsw56 and lsk389 I think this one is fairly cheap to do. And easy to assemble. Single channel is 10 x 3.65 inches. Single ended not really a HE6 killer, but balanced, a HE6 heavyweight for sure. If you replace the servo opamp with opa445, then you can go up to +/-35v rails. Then its definitely a HE6 killer single ended. picture of the original http://gilmore.chem....du/ksa5orig.jpg single ended with +/-21 power supplies, it does 10 vrms into 4 ohms or more. balanced 20 vrms into 8 ohms or more. single ended with +/-35 power supplies, it does 16 vrms into 4 ohms or more. balanced 32 vrms into 8 ohms or more.

8g3 also fake date code. There is one other fake date code that will take me a bit to find.

yep, those are the identical date code (0e4) that were the fakes that birgir and I shoved up dalbani's ass. Darlington, and good for no more than 30 volts.

output dc on the tubes should be close to 0. 150v is not right

You need to measure the high voltage rails to know more. If they are 20% high, then what you really have is the transformer wired for 200v running on 240v. And then the transformer gets very hot.

see if you can buy 2sk389/2sj109 or the singles versions... i'll bet you get a few hundred quotes.

This sucks bigtime.

done

No time for a while but I do want this done

patents are a hunting licence. In this case a very poor hunting license. i can think of at least 3 different and easy ways around this patent. actually with logitech vs jha, this could turn into another dishnetwork vs tivo. speaking of alo, their latest http://www.studiosixamplifier.com/ looks a little bit like the old marantz 8b but seriously gas tube power supply ??

change the 15 ohm resistors to 5 ohms. But really that is a lot of extra heat in the power supply. or remove the current limit entirely by removing Q9,Q10,Q13,Q14

about 90ma

And birgir's favorite topic too

in the third stage, if you are using the 2sa1968's, to increase the current decrease R8 and R9. Probably the lowest you can go and still get it to balance is 400 ohms. if you are using the ixys parts decrease the values of R12,R19 for the output stage, to increase current decrease the values of R6 and R5 probably not lower than 125 ohms.

http://gilmore.chem.northwestern.edu/kgsshvpsu.asc

please post the ltspice model for all to see. i can host it if necessary.

everything is on the table. in fact there is so much stuff on the table, the table is going to break.

no change in performance. no changes to the amp. strictly for much higher power tube stuff.

For next board production, there is a slight change in the power supply board. Now works with es1/es2 rebuilds, which are much higher current and +/-400v. Same thing with the universal power board.

spice models on tubes are notorious for incorrect output voltage swings. With a B+ of 300v, a plate resistor of 2.5k, the maximum voltage the tube can possibly do is 225VPP. And that maximum is theoretical because the tube is going to be hard saturated at the bottom, and the linearity is going to be crap. with a plate resistor of 1.5k its even worse, under 200VPP. Voltage gain this way will be under 2. Its all about the Rp of the tube, in this case spec is 800 ohms, but will quickly rise to 1k+ as soon as you start putting signal thru it.

The lowest plate resistance of all electrostatic amps out there is the hev90 which has a plate resistor (actually 3 in series) with a total resistance of 18.3K and runs on +550 volts. This is the maximum rating for an ecl86. Most of the stax amps have plate resistors in the range of 47k to 60k. birgir pointed me to this http://www.bartola.co.uk/valves/category/valves/dht-valves/ 6P21S would handle at least 600 volts. The emission lab tubes would fit the bill, but with good sockets are over $250 each and you need 4

2.5K for the plate resistors, what is the B++ No way that is going to work. The B++ has to be a minimum of 600v to be able to get enough linear voltage swing out of the output section. 800v or 1kv much better. I think that the 2a3 is not going to like 600v. But you will have to try it. A plate resistor that is a minimum of 25k is reasonable. 211's or 845's would be much more fun.