"Old" KRELL Help

puroagave said:
I say go for it. You'll get a lot of 'opinions' but from who and how far back to they go with Krell? My first 'super amp' was a Krell KSA-50 mkII I bought new in '87. from there it progressed up the line to the fin-cooled era culminating with MDA-500s (ca 1992 or so). if it were me, Id look for a KSA-80b (balanced input) Its a sweet amp id put up against anything made today. I would have kept it but it was shy on power running my then, Apogee Duetta Sigs. The 50S was a nice amp, I never owned one but heard it in dealer demos. I also think it was the first of the plateau biased series of amps (High Bias A/B).
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Thanks Rob. I think I may have seen, a KSA-80B. I'll have a Google...and on the KST series too.

But I figured I'd go straight to the horse as well. KST-100?
 
CDLehner said:
Thanks Rob. I think I may have seen, a KSA-80B. I'll have a Google...and on the KST series too.

But I figured I'd go straight to the horse as well. KST-100?
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the KST 100 was part of their 'budget' line, built to the same standard but did not operate in Class A up to its rated power. The other amp I liked a lot was the KSA-150 from that era, it was a lower powered version of tke KSA-250/MDA-500 and, IMHO the sonics were a high water mark for Krell.

I heard the D'Agostino momentum monos last week driving the YG Sonjas and wondered out loud how much better these were from Dan's Krells of the early 90s. me thinks not much, if at all.

Didn't you already have a Pass XA30 in the house?? dont take this the wrong way, but you gotta get off the box-swap[ping merry go round :)
 
puroagave said:
the KST 100 was part of their 'budget' line, built to the same standard but did not operate in Class A up to its rated power. The other amp I liked a lot was the KSA-150 from that era, it was a lower powered version of tke KSA-250/MDA-500 and, IMHO the sonics were a high water mark for Krell.

I heard the D'Agostino momentum monos last week driving the YG Sonjas and wondered out loud how much better these were from Dan's Krells of the early 90s. me thinks not much, if at all.

Didn't you already have a Pass XA30 in the house?? dont take this the wrong way, but you gotta get off the box-swap[ping merry go round :)
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I don't take it the wrong way Rob; you're damn right...and I'm trying.

Trying to simplify too. That's why I tried the PSA DsJ; 3 boxes, down to one. Sure...I've been having discussions, over in the PSA forums; about how the DsJ, just isn't going to live up to say, an ARC Ref 3, as pre-amp. But I'm hoping with the right amp; I can live with the results, and have just a 2-box system.

Yes; I had a 30.8, at a once-in-a-lifetime price. I regret letting it go, immensely :blush: I'd look, at the XA-25; but I really do think, I need the extra attenuation of Balanced in, with this DsJ.
 
Rob, any idea where the KMA came in?

puroagave said:
the KST 100 was part of their 'budget' line, built to the same standard but did not operate in Class A up to its rated power. The other amp I liked a lot was the KSA-150 from that era, it was a lower powered version of tke KSA-250/MDA-500 and, IMHO the sonics were a high water mark for Krell.

I heard the D'Agostino momentum monos last week driving the YG Sonjas and wondered out loud how much better these were from Dan's Krells of the early 90s. me thinks not much, if at all.

Didn't you already have a Pass XA30 in the house?? dont take this the wrong way, but you gotta get off the box-swap[ping merry go round :)
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KMAs were concurrent with the original KSA series. The KMA 100 shared the same chassis with the stereo 50 and the KMA-200 shared the same chassis with stereo 100. Those amps go back to the early '80s up to around '88, this was before Krell abandoned fan-cooled internal heatsinks. If you're looking to acquire one of these hold out for the Mk II vers. they were better built and sound better.
 
Looking at the FR and impedance of your PMCs I think they would work better with a tube amp; they are easy to drive with a 5.6 Ohm minimum impedance and have a scooped presence region coupled with an impedance rise; a tube amp will compensate the PMCs scooped FR as its FR will follow more the impedance of the speaker giving you a boost in that region.

It will also compensate that midbass notch.

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Anatta said:
Looking at the FR and impedance of your PMCs I think they would work better with a tube amp; they are easy to drive with a 5.6 Ohm minimum impedance and have a scooped presence region coupled with an impedance rise; a tube amp will compensate the PMCs scooped FR as its FR will follow more the impedance of the speaker giving you a boost in that region.

It will also compensate that midbass notch.

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Sounds like an EQ with power ..... :)
 
puroagave said:
KMAs were concurrent with the original KSA series. The KMA 100 shared the same chassis with the stereo 50 and the KMA-200 shared the same chassis with stereo 100. Those amps go back to the early '80s up to around '88, this was before Krell abandoned fan-cooled internal heatsinks. If you're looking to acquire one of these hold out for the Mk II vers. they were better built and sound better.
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What about KAS, First time i saw one of those was in 94 , his first 4 box attempt ...
 
^^ Yeah; again...I've always had great joy, with my class-A excursions. Cayin A-265ai, FW M2, Pass XA-30.8.

A 'phile friend and I were talking...about how class-A, is hardly the circuit-du-jour. If it hasn't changed...and in fact, may have had its heyday 20 years ago; why not try and get some old muscle, on the cheap.

But...probably too many variables; not understanding the line, and "Vintage" gear period.

The Rogue ST-100, was kinda the end-game anyway; and now...with this graph. How can I not? ;)
 
CDLehner said:
The Rogue ST-100, was kinda the end-game anyway; and now...with this graph. How can I not? ;)
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Anatta is correct that a tube amp might correct the FR because the impedance peaks line up with the FR dips...but there is a caveat, the amp must have high output impedance. This is not true for all tube amps, especially those with some form of feedback.

cheers,

AJ
 
AJ Soundfield said:
Anatta is correct that a tube amp might correct the FR because the impedance peaks line up with the FR dips...but there is a caveat, the amp must have high output impedance. This is not true for all tube amps, especially those with some form of feedback.

cheers,

AJ
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I cannot find, an output impedance...for the Rogue ST-100.
 
No tube amp can match the low output impedance of SS amps, even if they use some feedback.

The Rogue ST-100 seems like a fine amplifier and very good value, I'd go with it over other SS options.
 
Hi

If you can find a KSA 50 mk2 or KSA100 mk2, I suggest you buy it !

It will require a pcb (two 1000 uf at 25V caps per pcb) and four PSU cap and most likely new fans.

I have done a full recap on a KSA100 and replaced the cheap internal speaker wire with Van Den Hul The Wind. The results are more than satisfying.

Regards

Jozua
 
AJ Soundfield said:
You would have to ask Rogue. Maybe email them?
Unless the output impedance is high, you won't get much, if any, modification of the FR. The FR could end up being the same as with a typical SS (with feedback).
The Atlas output impedance was relatively low and thus had only a very slight mod to the FR https://www.stereophile.com/content/rogue-audio-atlas-power-amplifier-measurements
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OK; not sure if this makes sense...and certainly doesn't seem "high". But Rogue says the output impedance os the ST-100; is < 1 ohm.
 
CDLehner said:
OK; not sure if this makes sense...and certainly doesn't seem "high". But Rogue says the output impedance os the ST-100; is < 1 ohm.
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Relative to your speakers impedance its low enough, probably similar to Atlas in that there will be only a slight deviation, <1db. You'd be better off with a real EQ :).
Of course there are other aspects of tubes like the ST-100 that might have some allure also. These are all very personal preferences. I have speakers with similar sensitivity/impedance and my 35 watt Triode Labs drives them quite loud with good dynamics (the largely benign soft clipping of tubes helps here). They also respond well to 400 rms class D. ;) YMMV.

cheers,

AJ
 
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