I was thinking the same. Why krell ksa 100 mkII ? then decided to look for some other kits and none of those had this CRD diode.Its called Active Bias.Found some patents from other big names online where they try to avoid the Krell way of biasing the amp.
Im not really and engineer but got some parts of it and i think this is the reason why is better -simplicity that cant go wrong and sounds good without needing properly matched components.
Also the amplification is very well stepped so you wont loose some frequencies in the incredible quantum bandwith of a single transistor.
I dont know about Aleph-X but the A680 or some other chinese kits( L28,L150 Fet) with Balanced inputs have much more potential.
Me listening right now to a well built Lm3886 300w and quite simply amazed by how it camed out (still not assembled the Krell amp-have the complete high grade kit).
Im not really and engineer but got some parts of it and i think this is the reason why is better -simplicity that cant go wrong and sounds good without needing properly matched components.
Also the amplification is very well stepped so you wont loose some frequencies in the incredible quantum bandwith of a single transistor.
I dont know about Aleph-X but the A680 or some other chinese kits( L28,L150 Fet) with Balanced inputs have much more potential.
Me listening right now to a well built Lm3886 300w and quite simply amazed by how it camed out (still not assembled the Krell amp-have the complete high grade kit).
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My own experiences echo those of Mark and John; driving my Apogee Duettas (2-3ohms), the Krell clone has a much more dynamic sound compared to the similarly built Aleph (both set for 60W / 4ohm class A). The Aleph was good, very good, but the Krell was great...with different speakers I think I could easily have preferred the Aleph for it's smooth demeanor.
FWIW the Aleph was much simpler to get working perfectly.
I have not built an Aleph-X so cannot comment on that comparison.
Stuart
FWIW the Aleph was much simpler to get working perfectly.
I have not built an Aleph-X so cannot comment on that comparison.
Stuart
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I built the Aleph-X and two KSA50 clones. I was very disappointed in the A-X. Bass was lacking and it was the hottest running of all my amps. I was so disappointed that a few months ago I disassembled it and sent to boards to a friend who had indicated he would like an opportunity to try and get it working better. I did discover later that the off board input caps I used were only .1uf rather that 1uf. That may have attributed to the poor bass response. I will have to wait until Bob has had a chance to set it up again to find if that was the culprit. The Aleph-X does take a fair amount effort to get everything adjusted. The offset is a bit tricky. The KSA50 on the other hand, is straight forward. Simple to build and not too picky to parts selection. The biggest thing with both of these amps is power supply and heatsinks. My KSA50 sound very good but the produce quite a bit of heat and of course, there is the fan noise. I sit only three feet away from my amps so it can become annoying after a while. Probably the reason I don't listen to them very often. If I had to recommend one to build it would be the KSA over the A-X, hands down. I sold my KSA100 boards to a fellow member here so hopefully he will be offering some opinions here soon. 
Blessings, Terry
Blessings, Terry
Aleph-X krell KSA 100
Hello,
I think the Krell is simple to build too.
I would like to build the KSA 100 later with a friend.
I have only heard the Aleph 0s.
It was very lively and very cleary of the Sound.
The Aleph 0s has 30 Watt in Class a.
I think the Krell KSA 50S is similar to the Aleph's. (only from Sound)
I would prefer the Aleph with 100 Watt in the right System
but the Diy Krell is sure very good.
Best regards
Alex
Hello,
I think the Krell is simple to build too.
I would like to build the KSA 100 later with a friend.
I have only heard the Aleph 0s.
It was very lively and very cleary of the Sound.
The Aleph 0s has 30 Watt in Class a.
I think the Krell KSA 50S is similar to the Aleph's. (only from Sound)
I would prefer the Aleph with 100 Watt in the right System
but the Diy Krell is sure very good.
Best regards
Alex
Hay Mark,
I hope I am not bothering you with this issue!
It's been a while since this post was active.
Anyway, is there any chance that you still have the Krell KSA100MK2 schematics?
If so, may I request you to send me schematics to my mail: branko@supermikro.rs
Regards
Branko Djurdjevic
I hope I am not bothering you with this issue!
It's been a while since this post was active.
Anyway, is there any chance that you still have the Krell KSA100MK2 schematics?
If so, may I request you to send me schematics to my mail: branko@supermikro.rs
Regards
Branko Djurdjevic
I prefer the sound of the KSA-50 clone over the Aleph amp type amps, I had the Aleph 3 commercial version. I Also built and had the Aleph X working for about 5 minutes so cannot comment on that! Sold the boards to someone here and used the case for my ExtremA.
The Krell is up there in terms of the best available amps that I've heard (has heat issues of course!) I've been out of DIY for some time but last I recall the KSA100 had not been perfected here, hope that has changed.
Maybe I was lucky, but with the help by other members on this thread, you know who you are, I have the best amp I have ever owned and when I added a tone control preamp, this amp took me back to the '60s when I listened and felt the robust bass shake the building. I have the KSA-100 with no heat problems. Yes I run 12V fans beneath heatsinks blowing the hot air up and out.
I built the very first KSA-100 Klone prototype way back when this thread started from quick turn boards made by advanced circuits. The first group buy boards were made in Canada because it was quite a bit cheaper at the time. The KSA-100 has always worked just fine, just as fine as the KSA-50 has. It generates a whole lot more heat than a ksa-50 and it has to utilize fans for cooling. Water cooling might be another option and I always wanted to try that. I am still amazed this thread is going and that many of these amplifiers have been built.
Here is the very first driver board that I built. I still have it and the prototype amp although it is in sections now in storage. Some day to be finished...
Mark A. Gulbrandsen
Here is the very first driver board that I built. I still have it and the prototype amp although it is in sections now in storage. Some day to be finished...
Mark A. Gulbrandsen
Attachments
Nice to see that there are still Krells being made! Fantastic amp farl, really love your design! But beware, putting that Krell logo in front of your amp could be dangerous... it resulted into a lot of negative feedback back in the day when I did something similar ;-). Actually mine is in full working order too, lgreen. Still using the Jims Audio boards which, I believe, are most close to the original design. However, after several accusations and renaming the original threat by someone, I have stopped with posting updates. I have made quite some improvements, especially with more efficient use of the heatsinks. It now does not exceed 50 degrees C. Indeed it is one of the best amps around. I am still enjoying it, although not on a daily basis; it consumes A LOT of power haha.
An externally hosted image should be here but it was not working when we last tested it.
I also was disappointed in my Aleph 5, and was very impressed with my KSA-50. The Aleph 5 sat unused for years, while the Krell got used on a daily basis.
One day, I decided to build a try a transformer based Single Ended to Balanced converter I built on it, and put it after my SE Aikido 6CG7/6DJ8 preamp. I was very impressed with it's performance. The Aleph 5 sounded so much better than single ended. It has since displaced the KSA-50, and now building an Aleph X. Also have matching JFETS on front end to try too.
I am sold on Balanced connections to these Pass amps. The balanced connections to the other amps I have (Icepower 1000ASP, Crown XLS2000, Carver Load Invariant) had a much lesser effect vs single ended.
Run these Alephs / Aleph X Balanced...
There for sure is a lot of advantage being balanced with the Alephs. I have a pair of Aleph 2's that I built back in 2002 and I couldn't believe the difference. Thing is, as good as the Aleph 2's are my KSA-50 still sounds better, has more authority, the KSA-100 is far better yet. My Recent White Oak Modified Phase Linear 700 is also better sounding than the Aleph 2's.
I've been considering scrapping the Aleph 2's out and building them into KMA-100's as I have a lot of static heat sinking available and wouldn't need a fan. Or perhaps Mono Phase Linear 700's with the White Oak Circuit.... Should do over 700 watts mono!
Mark
I've been considering scrapping the Aleph 2's out and building them into KMA-100's as I have a lot of static heat sinking available and wouldn't need a fan. Or perhaps Mono Phase Linear 700's with the White Oak Circuit.... Should do over 700 watts mono!
Mark
1N5309
Having just finished a fan cooled KSA50, I'm looking to finish the KSA100MkII...water-cooled.
I just don't want to spend 15 each on these 1N5309 diodes, I think I found replacements. I've managed to get my hands on original 2SJ313/2SK2013, will either of these diodes play nicely with those mosfets? The original schematic is looking for 3mA in this part of the circuit, will slightly under/over cause any issues?
http://www.mouser.com/ProductDetail/Semitec/E-352/?qs=sGAEpiMZZMtQ8nqTKtFS/G7SPLwmKeGy7MokZFFD704=
http://www.mouser.com/ProductDetail/Semitec/E-272/?qs=sGAEpiMZZMtQ8nqTKtFS/G7SPLwmKeGyBuajhQL/tgA=
Having just finished a fan cooled KSA50, I'm looking to finish the KSA100MkII...water-cooled.
I just don't want to spend 15 each on these 1N5309 diodes, I think I found replacements. I've managed to get my hands on original 2SJ313/2SK2013, will either of these diodes play nicely with those mosfets? The original schematic is looking for 3mA in this part of the circuit, will slightly under/over cause any issues?
http://www.mouser.com/ProductDetail/Semitec/E-352/?qs=sGAEpiMZZMtQ8nqTKtFS/G7SPLwmKeGy7MokZFFD704=
http://www.mouser.com/ProductDetail/Semitec/E-272/?qs=sGAEpiMZZMtQ8nqTKtFS/G7SPLwmKeGyBuajhQL/tgA=
Attachments
You can run, but you can't hide.
Welcome back. Please tell us your other improvements.Nice to see that there are still Krells being made! Fantastic amp farl, really love your design! But beware, putting that Krell logo in front of your amp could be dangerous... it resulted into a lot of negative feedback back in the day when I did something similar ;-). Actually mine is in full working order too, lgreen. Still using the Jims Audio boards which, I believe, are most close to the original design. However, after several accusations and renaming the original threat by someone, I have stopped with posting updates. I have made quite some improvements, especially with more efficient use of the heatsinks. It now does not exceed 50 degrees C. Indeed it is one of the best amps around. I am still enjoying it, although not on a daily basis; it consumes A LOT of power haha.
