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.

Edited November 16, 201213 yr by kevin gilmore

Cool

This topic definitely interests me. Subscribed!

Curious did Dan D'agastino design this or someone else at Krell?

I'd definitely be interested in building a balanced version. Higher voltage of course.

Hmm... How suitable actually would this be for speaker duties? Most likely it would require a considerable bump in heat-sinking. Maybe even some meatier resistors.

I could build one for computer speaker duties. Maybe get me a pair of those Hsu's.

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.

Hmm... Maybe I had some mistakes converting vrms into power. In any case I still love my Dynalo and have a feeling that utility wise it would overlap with the KSA 5 (both being current happy).

Still too lazy (and afraid what you'll say about the wiring) to do a proper post at the DIY build thread.

The Dynalo and KSA-5 are similar is many ways but that is a very good thing in my book. I wouldn't try to use this for speakers though as the amp was never intended to do that. The PSU will not like it one bit too.

Huge thanks to Tom for his help on this and the reasons for me buying a HD-800 should be clear now. It should be quite cheap to build as all parts or subs are available but the electrolytic caps should add up quickly. This run balanced at +/-35V will be a beast to reckon with...

Why, oh Why do you guys keep coming up with these great clone builds. I have subscribed and will be looking forward to this one. Especially since parts are actually available for a reasonable price.

Because we can?

Another very interesting thread. I'm just hoping a few of these projects actually make it to the board fab shop...

Board files available to all

Edited November 17, 201213 yr by kevin gilmore

The Q14 - Q23 thing has me confused

Looking at the pic of the board, dont see Q23.

Also what is the function of the relays and other components in the middle of the board, between the two channels?

Startup delay?

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.

Edited November 17, 201213 yr by kevin gilmore

Zettler relays are very nice.

I see it now. I should a payed more attention to your overlay jpeg.

If anyone does a board run count me in. This looks like a pretty straight forward build compared to some of the others I am working on.

Subscribed.

nice, I probably dont need the higher voltage balanced version, but maybe I should build it just in case =) saw it over at DIYA, should be fun, will make my own boards if need be, thanks for that Kevin!

Interested as well

Edited November 20, 201213 yr by robm321

power supply board should be done by the end of this weekend.

I would be interested if boards are made

http://gilmore.chem....du/dsc_0177.jpg

The blackgate caps and the dact are mikhail's handiwork.

here are the schematics for the 2 power supplies.

The first one is the original supply that tom owns.

http://gilmore.chem.northwestern.edu/ksa5psschemold.pdf

this is the newer version

http://gilmore.chem.northwestern.edu/ksa5psschem.pdf

I think we will be doing the new version.

I'm sure they sound different.

Edited November 22, 201213 yr by kevin gilmore

mikhail's just awful hack job removed and correctly replaced

http://gilmore.chem.northwestern.edu/dsc_0234.jpg