Krell KSA 100mkII Clone

I finished these back on 12-2007


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Jacco, The whole diode issue was thought to be fully resolved months ago. Read back through the thread, efforts were made to deliver to all who had ordered. If for some reason you missed it, I'm sorry. A large number of diodes were sent to Jacco, perhaps he has some left? Mine are all gone.

Bob G.
 
Uncle Bob,

the ones i had have been sent out to KSA builders, fortunately they all arrived, there's just 1 left without a new owner.
Patrik made jokey, he received the CRDs i sent him, he was referring to Mark Gulbrandsen.

Exterminating KSA50-Sliders should be a mission from G-awdio.
The beautiful front plate with the big love handles of the S would be awesome to use for a KSA100.
Only problem for rebirthing a KSA50S chassis is the modest room/volume of the case interior, too small for a serious Class A critter.
 
jacco vermeulen said:
Uncle Bob,

the ones i had have been sent out to KSA builders, fortunately they all arrived, there's just 1 left without a new owner.
Patrik made jokey, he received the CRDs i sent him, he was referring to Mark Gulbrandsen.

Exterminating KSA50-Sliders should be a mission from G-awdio.
The beautiful front plate with the big love handles of the S would be awesome to use for a KSA100.
Only problem for rebirthing a KSA50S chassis is the modest room/volume of the case interior, too small for a serious Class A critter.

Yes, I would have to lower the bias and use it more like a 50W amp! Edit: Actually, since it's no plateau bias design, I'll have to settle for less in class A..

Problem is that the 50S almost works (it gets extremely hot, bias is at max all the time, but it sounds really good), so it may almost be criminal to gut it.

I don't think I ever got the diodes, but perhaps my memory plays tricks on me. I'll have to check my component trays.. What do these puppies look like? (Anything that makes them stand out from "a diode" look?)
 
hi.i didnt read all of the topics about krell..its too long:).my friend built krell ksa100 with 2pairs of mjl21193/21194.he says its 50watts now.he says it sounds very well..and he says its not necessary to give high bias..he says it is almost playing as same as AB mode..nelson says that its good to give highest bias to mosfets to get lowest distortion..but is it same for BJT's?what do you think about this subject?is there anyone builds ksa100 in semi class a mode?i want to build one Krell..thanks
 
umut1001 said:
hi.i didnt read all of the topics about krell..its too long:).my friend built krell ksa100 with 2pairs of mjl21193/21194.he says its 50watts now.he says it sounds very well..and he says its not necessary to give high bias..he says it is almost playing as same as AB mode..nelson says that its good to give highest bias to mosfets to get lowest distortion..but is it same for BJT's?what do you think about this subject?is there anyone builds ksa100 in semi class a mode?i want to build one Krell..thanks


Depends if you like luscious sound or good numbers ;)
 
You cannot generalize a number because of many variables like heatsink used, temp deration & SOAR etc. You cannot just crank up the bias mid-way and expect it to work...

Having said that, in my humble experience, Heavy biased B (i.e. Class AB) sounded better than optimally biased B even though it had higher distortion numbers. I do not know for sure if the temperature of the devices affects the sound or the odd/even nature of the increased harmonics...

You need to test it on your own. I can tell you that without the full class-A bias flowing, you will not get the bass slam that these amps are known for...

Give it a shot if you have no better alternative.. and keep an eye on the temp rise of the devices.... crank up the bias very slowly and gradually....over a period of hours perhaps to allow it to stabilize.