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Krell KSA 50

mandryka said:
I’d be very interested to know what you think of the Krell with no preamp, using digital or passive volume control.

Is the fan on yours original? They have a reputation for clicking, mine did till I got it replaced.
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I have a Bluesound Node 2 that I could try that with. However, the bulk of my listening is LP, so it’s academic, really as I’ll never use it that way in practice. As far as I’m aware the fan is original. It’s almost inaudible which is a pleasant surprise as I thought it might be noisier.
 
Yes, the fans are not a problem to me either, where I have a slight problem is with mains hum, but it’s not a big deal.

Someone I know said to me that he thought that Krells were brute muscle amps, and that I could only be so pleased with mine because the ESL 63s I use them with compensate somehow - but this guy hadn’t heard the KSA 50! I think Krell suffer from a bad rep, maybe deserved, from their larger amps, but this little one, baby one as Jez used to say, is sweet and refined, very good at at truthfully amplifying the nuances of acoustic timbre.
 
Nope, big toroids hum, no way around it really. A dc blocker may help a little, a compliant mount might help a little. But ultimately get used to it.
 
mandryka said:
I’d be very interested to know what you think of the Krell with no preamp, using digital or passive volume control
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Very good on acoustic stuff with a battery powered light speed attenuator, but much better all-round with a Concordant Exhilarant or Excelsior
 
I’d concur with the comments about it being good on acoustic stuff, which I didn’t expect really. I was worried it would just be all muscle and no subtlety but it’s every bit as good on brushed snare and solo voice as it is belting out Slayer. Having worked for Linn/Naim dealers back in the day I’d rather swallowed all the stuff about Krell being crap all those years ago but over the intervening years I’ve had plenty of direct experience in different dealers and heard them sounding good. Shows were the opposite, I’ve always found the Absolute Sounds rooms using Krell at those absolutely awful. I’m pleased I took the plunge with this.
 
mandryka said:
I’d be very interested to know what you think of the Krell with no preamp, using digital or passive volume control.

Is the fan on yours original? They have a reputation for clicking, mine did till I got it replaced.
Click to expand...


Though mine is only a KSA50 clone, I found this step up to be particularly wonderful...

IMG_20200430_211448 by Garf Arf, on Flickr

The Klone..

IMG_20201108_093817 by Garf Arf, on Flickr
 
mandryka said:
Tell me something. How reliable is the KSA 50? My heart sank slightly when I came across this discussion, but I don’t entirely understand it

https://www.vintage-radio.net/forum/showthread.php?t=167853
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It isn't exactly a large selection of KSA owners to be fair in that thread. Certainly there are plenty more happy owners out there, even us poor ones who have to make do with a KSA clone.

The moral of the story, with any DIY amp, is make sure you add speaker protection.
 
mandryka said:
Tell me something. How reliable is the KSA 50? My heart sank slightly when I came across this discussion, but I don’t entirely understand it

https://www.vintage-radio.net/forum/showthread.php?t=167853
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I use NTC resistors after the rectifier and before the smoothing caps and I can use fast fuses before the rectifier. For example I use 4A fast fuses with a 300VA transformer feeding a 33K uF cap, provides a lot better protection than a timed fuse which to all intents and purposes as far a semiconductors and speakers are concerned is a busbar.

https://docs.rs-online.com/e95e/0900766b814e822e.pdf
 
mandryka said:
Tell me something. How reliable is the KSA 50? My heart sank slightly when I came across this discussion, but I don’t entirely understand it

https://www.vintage-radio.net/forum/showthread.php?t=167853
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I’ve just checked back on this thread and the answer about reliability in my case is not very. One channel gave up the ghost. End result was all o/p transistors were replaced. Sounds great again but if you’re going to buy an amp from 1983, then best factor in service costs and related hassle. For the quality of sound it’s well worth what I paid plus the repair cost.
 
pocketkitchen said:
I’ve just checked back on this thread and the answer about reliability in my case is not very. One channel gave up the ghost. End result was all o/p transistors were replaced. Sounds great again but if you’re going to buy an amp from 1983, then best factor in service costs and related hassle. For the quality of sound it’s well worth what I paid plus the repair cost.
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Yes, I’m sorry to hear that. The fundamental question is, how long before it happens again? That’s to say, is the unreliability from normal wear and tear or is there something basically unreliable about the design?
 
I have to admit it is a key reason I went for an old Pass Aleph to scratch a long-standing solid state class A itch recently. They are just so well documented and supported in comparison. Everything is in the public domain, nothing proprietary, and NP himself will happily share advice if you get stuck. Very simple to work on once one figures out how to disassemble it. Nothing to adjust. It may well be a challenge to find the FETs if they ever fail, but I get the impression they run well their temp spec so should last well now the amp is back performing as it should.
 
Tony L said:
I have to admit it is a key reason I went for an old Pass Aleph to scratch a long-standing solid state class A itch recently. They are just so well documented and supported in comparison. Everything is in the public domain, nothing proprietary, and NP himself will happily share advice if you get stuck. Very simple to work on once one figures out how to disassemble it. Nothing to adjust. It may well be a challenge to find the FETs if they ever fail, but I get the impression they run well their temp spec so should last well now the amp is back performing as it should.
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I was told that the KSA series are well built and easy to work on.
 
mandryka said:
I was told that the KSA series are well built and easy to work on.
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The engineer that did the work (same guy that Doug Brady’s use) didn’t have any trouble. It’s an old design with everything about it we need to know and the fact it was nearly 40 years old before anything gave way speaks volumes about the design, I’d say. Although a previous owner had fitted posh phono sockets to it, everything else was original so, I’m expecting it to last longer than I need it to. If it lasts another 38 years it may well outlast me!
 
Speaker protection is advised with these as there is no built in protection whatsoever and it WILL destroy a speaker if it fails.
 
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