Krell KSA 100 type amplifier

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#61
Krell KSA 100

Hello,

Has anyone been able to figure out the right transistor types on the KSA 100 schematic posted earlier?
It concerns Q1/Q2, Q3/Q4, Q5 and Q6.

Is there a schematic available of the KSA 100-S with the sustained plateau bias or any info on such method?

I have scanned the ML 20 files have been able to mail them partly to Freddie. Due to the size of the files (6 files of 2.5MB each) his mailbox being full rejects my e-mails.
I hope to get them all to him tomorrow and he will put them on a site where they can be downloaded.

That's it for now.

Thanks,
 
#64
"Has anyone been able to figure out the right transistor types on the KSA 100 schematic posted earlier? It concerns Q1/Q2, Q3/Q4, Q5 and Q6." Who cares? Q1, Q2 = 2N6431 Q3, Q4 = 2N6433 but these are not the best for diff pairs anyway. Q5,6 were TO202 case style parts, good luck finding them. The current version of the Leach amp is much better, just run the bias to what you want and as many outputs as you need. If you want to get fancy build the Super Leach with the Nelson Pass patent 5,343,166 Copy and paste this number into the search here http://164.195.100.11/netahtml/srchnum.htm Then go to the patent and click on 'images'.You will need a TIFF viewer AlternaTIFF: http://www.alternatiff.com/
 
#65
Hi djk,

Thanks for additional info. Primarily I wanted to know
the correct transistor types to simulate the behaviour
of this Krell KSA 100. I do this with Micro Cap V
which is very pleasing to work with. Unfortunately
it is a registered version with a dongle, so I cannot provide anyone with a copy. I mention this just in case the question would pop up sooner or later. However
for those interested there is a free student version
which can be downloaded at: http://www.spectrum-soft.com.

Of course if there are better topologies with even better
results than the current Krell, it is interesting to study them. I'll take a look at the links you mention.

Thanks for the info.
 
#66
In my opinion the KSA 100 is the best DIY

Hi,

If you have to build a power amp I think that the Krell still is the best, sound versus cost, its sound is just great much power in the low and a relaxed sound from mid and up.

Just clone it ! I think that will be a easy thing to do with all references we have from all kind of crap power amps kit or ready built from all kind of people who earned a lot of money showing the next best constructions the past 25 years.
 
#67
Hi Leffe,

The reason I'm specifically interested in the Krell KSA-100
and even more in the KSA-100S (Sustained Plateau Bias, schematics anyone??) is that my set of speakers the legendary Infinity RS-1B which consists of two mid/high screens and two bass columns (6 x 8" each) which can best be driven by a Krell amp with lots of power.

I have downloaded the Krell patent (5,331,291) and try to figure out how this bias thing works. Some have already metioned here that the KSA-100S sounds better. Some will definitely disagree on this method of biasing an output stage.

However if anyone has more detailed info on the Krell
KSA-100S or the Sustained Plateau Bias system or suggestions on how to achieve the same or better result in modyfiying the KSA-100 let him, so to say, speak.
 
#69
Consider figure 26 page 14.
http://www.onsemi.com/pub/Collateral/AN1308-D.PDF
If we delete Q5,6 we have basically the Krell, with better semiconductors. Consider figure 35 page 17. Same front end with a cascode, and series connected outputs. Replace R36,43 with 6.3V zener diodes and bring in +/- 40V with an ORing diode at the collectors of Q19,20,21,22 and Q23,24,25,26 .This is of course a variation of the Pass patent. It runs just like the Krell up to 40V, then it becomes a cascode for the rest of the way.
 
#72
Webbercarbman, Krell ksa100 power supply

Hi, I couldn't email you so here goes.
You state that you built the Ksa100 with 1200va transformers,
Was that the rating that Krell used?
I ask because I have some large Avel Lindberg transformers that
I bought years ago,but I don't know the VA rating, the seller claimed that they were the same spec as the Ksa100 transformers.
The secondary o/p is 40-0-40 the only numbers on them are
40/5629 and the date of manufacture is 1986. They weigh about 20lb each.
If you can shed any light it would be of help
Jules
 
#78
For those trying to download ML & Luxman schematics

The ML20.5 schematics and Luxman schematics seem to have been removed from, snow.prohosting.com/frty, for some reason..
And due to a computer virus, some things got lost including the schematics🙁
I may have a backup somewhere though.

/Freddie
 
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