Excellent!
I have reviewed it and will start compiling the info this weekend.
Remeber all, this IS a Wiki and anyone can add to or correct the info!
I should have some good stuff in it next week.
I have reviewed it and will start compiling the info this weekend.
Remeber all, this IS a Wiki and anyone can add to or correct the info!
I should have some good stuff in it next week.
Hey K-Amps,
You ought to post your spread sheet! That was a ton of help to me when I was trying to arrive at the correct bias point with using 6 outputs. I woulda probably burned down my house by now.......
without it . Can we add photos to the WIKI page? If we can I plan on doing actual P.O. and distortion measurements this weekend on my KSA-50. It would be nice to be able to post them there for others to compare to........ If we can't where would you guys like the photos posted so they don't get burried here?
Thanks,
Mark
You ought to post your spread sheet! That was a ton of help to me when I was trying to arrive at the correct bias point with using 6 outputs. I woulda probably burned down my house by now.......
without it . Can we add photos to the WIKI page? If we can I plan on doing actual P.O. and distortion measurements this weekend on my KSA-50. It would be nice to be able to post them there for others to compare to........ If we can't where would you guys like the photos posted so they don't get burried here?Thanks,
Mark
Class-A calcs
Fill in the yellow cells only or you will mess up the calcs..... wait, let me protect it for people like me.
enjoy Mark!😀
Fill in the yellow cells only or you will mess up the calcs..... wait, let me protect it for people like me.
enjoy Mark!😀
I think having the original KSA-50 specs, or even the entire review right at the beginning of the WIKI is probably the most appropriate thing that could be posted there.....
Mark
Mark
"Well then Mark, stick it in - we can all contribute! "
Tis not I that has it, apparently tis Jacco that has it..... I was just asking if I should post the test result photos here or on the Mike W thread?
K-Amps, Thanks for that spread sheet!
Mark
Tis not I that has it, apparently tis Jacco that has it..... I was just asking if I should post the test result photos here or on the Mike W thread?
K-Amps, Thanks for that spread sheet!
Mark
I am sorry, but I "forgot" this weekend was Easter..
Needless to say I did NOT start the wiki info page... I will this week/weekend..
On a side note.
Anybody try the KSA-50 mainboard with a regulated supply?
I am thinking of going regulated on the front end and unregulated on the output boards.
I am also building one of those Pass/Grey Mini-A amps to compare with this one..
And one last item..
I still have 3 pairs of boards left if anyone wants/needs them. That includes the pair I "bought back" from Stuart because of the flood of inquiries.
Needless to say I did NOT start the wiki info page... I will this week/weekend..
On a side note.
Anybody try the KSA-50 mainboard with a regulated supply?
I am thinking of going regulated on the front end and unregulated on the output boards.
I am also building one of those Pass/Grey Mini-A amps to compare with this one..
And one last item..
I still have 3 pairs of boards left if anyone wants/needs them. That includes the pair I "bought back" from Stuart because of the flood of inquiries.
Don't waste your time. Not that the Mini isn't a good amp. Its actually very good but it is a Mini with Mini results too. Good though for driving the tweeters in a bi or tri system. The Alsph 5 would be a better comparison to the KSA-50. The 50 in reality behaves more like a 100 watt amp... you might want to consider the Aleph 2 actually. I have not as of yet compared the 50 to my 2's but off hand the 50 has alot more resolution and sound stage than my 2's do. I think though that its just the difference between listening to an amp with 3rd harmopnic(Krell) and the Aleph with its 2nd harminic content. Both are very good, just different.
I would be curious to know what regulation scheme you come up with for the front end..... The Zeners although noisy do a pretty good job. Perhaps the addition of them biasing a pass transistir would clean it up a tad bit more. My KSA-50 is dead silent,more so than any of the Alephs I've built. A much more fair comparison would be to compare it to an Aleph-X.
Mark
Hey Mark-
Well when I say Mini-A, I mean Mini-A front end with the output boards and generous current capabilities. ~ 30 wpc Class-A.
As for the voltage regulation of the main-board I will prolly use Zang's boards..
http://www.diyaudio.com/forums/showthread.php?s=&threadid=39816
I'm just surprised no one else has gone the regulated route..
Well when I say Mini-A, I mean Mini-A front end with the output boards and generous current capabilities. ~ 30 wpc Class-A.
As for the voltage regulation of the main-board I will prolly use Zang's boards..
http://www.diyaudio.com/forums/showthread.php?s=&threadid=39816
I'm just surprised no one else has gone the regulated route..
I seem to remember suggesting regulation for the driver stage several pages ago, and getting panned for it...😉
Not surprising, the original ksa50 was tested at 180 uV.
Power of the ksa50 was measured at over 70 watts in 8, 1 KHz, 1 % distortion.
Frequency response up to 125 KHz.
From a German magazine test in the 80s.
The same magazine did a test of the KSA100 in '86 , the KSA100 was measured at 160 watts in 8 Ohm, 280 in 4, about the same numbers as the Threshold S300II in the same article.
I made a xerox of both tests, unfortunately those are in the order of 20 years old by now, and very difficult to scan.
I'll try if i can get a decent scan of the harmonic distribution graph and the distortion curve and post it here.
Power of the ksa50 was measured at over 70 watts in 8, 1 KHz, 1 % distortion.
Frequency response up to 125 KHz.
From a German magazine test in the 80s.
The same magazine did a test of the KSA100 in '86 , the KSA100 was measured at 160 watts in 8 Ohm, 280 in 4, about the same numbers as the Threshold S300II in the same article.
I made a xerox of both tests, unfortunately those are in the order of 20 years old by now, and very difficult to scan.
I'll try if i can get a decent scan of the harmonic distribution graph and the distortion curve and post it here.
Parts question
Looking at the parts list, got a few questions-
what xformer secondary should you use? I believe one of the earlier posts indicated 27VAC was the original, if we make this a little higher, will any of the other values change?
What should the output board use for base resistor values? At what wattage ratting?
What should the wattage for the emitter resistors be?
What should the wattage of the RVI protection resistors be?
If you have made one already, what did you use for these?
Looking at the parts list, got a few questions-
what xformer secondary should you use? I believe one of the earlier posts indicated 27VAC was the original, if we make this a little higher, will any of the other values change?
What should the output board use for base resistor values? At what wattage ratting?
What should the wattage for the emitter resistors be?
What should the wattage of the RVI protection resistors be?
If you have made one already, what did you use for these?
I didn't use any base resistors. The original Krell didn't either.
At least 5 watts. I believe that the original Krell used 5 watters.
I can't believe that anyone would build a Krell with any form of current limiting. That was wasted real estate on the PCB. Its not needed!
I always say build it like it was or why build it at all.......
Mark
Oh, Just say Aleph 30 then. hats a tad bit diferent. I recently built a 3 for a friend of mine and its a fantastic sounding amp. Much better than my 2's.
Jacco-
If you can scan it and send it to me I can run it through Photoshop for you and clean it up. Should look acceptable them. Try scans both in Grey cale and RGB or what ever full color mode you have on the scanner.
I donno why anyone would shoot that down. Thats exactly what Krell did in their next generation amps! Actually the 50 front end is Zener regulated now and the amp is pretty darn quiet. But fuurther regulation would still be an interetsting thing to try. Take a look at page 5 of the KSA-80 schematics on Lloyd McLean's site for some ideas.
http://home.ca.inter.net/~lloyd.maclean/Krell/TECHINF.pdf
Hey, Anyone intrested in doing up a set of KSA-80 boards?
Mark
Mark A. Gulbrandsen said:
Well, that's a much more complex beast, though I do like the balanced JFet input stage. Not something I could take on with the demo version of Eagle though. 😉
I have a sort of system plan coming together, Krell on the bottom driving Kef B220s in a TL, possibly an AX in the middle driving some Fostex 4" mids, and the Mini As on the top driving a yet unspecified tweeter...
I don't think the 80 would be as difficult as you think it would be. With a well laid out set of pcbs it should be no more difficult than the 50 just a larger project. Actually, I never think of things being more difficult, just larger in a sense. The biggest thing about building an 80 would be what fets to use..... I believe that some of the originals may now be now obsolete.
Mark
Mark