Old Krell vs new Krell amps...

I think it's more a matter of taste. I've been told by Krell employees the FPB series is better than the KAS amps. I haven't listened to the Evos.

IMO, the older Krell KAS-2 mono amps are not Krell's best sounding amps, not by a long shot. Krell made a major step forward with the FPB series of amps. Therefore, if the newer Evo amps are at least as good as the FPB amps, then I would definitely opt for the Evo series.

I've upgraded to a pair of Krell Evo 600 from a Krell 700cx, and I love the new Evo series. The Evo series is more of everything: transparency, imaging, dynamic but the thing I've noticed the most was that the Evo series is very smooth which makes the older cx series grainy sounding. However, if you haven't heard the Evo line then the cx series would sound perfectly fine too.
So go for the latest series if you could is my opinion.

First of all, I have never heard the KAS amps. I have owned the KSA (150 and 200S) series, the FPB300c, then the FPB300cx and currently the EVO302. The 300c was good but the 300cx was far better, i.e., difference was very large between the "c" and the "cx" version. The older KSA (not to be confused with the KAS)were extremely grainy and not very reliable in my opinion. Finally, the EVO302 is significantly smoother (less listener fatigue) and has very, very impressive bass (perhaps since it is mated the the EVO222 preamp) making it sound much better than the cx version. Among the EVO, I recommend the 302 over the 402, since the 2-channels appear separated better in the layout of the 302 and this is reflected in the performance (maybe I am biased). Bottom line- if you can afford it, go get the EVO302 or economise and find a 300cx or the 400cx. Regards

Thanks for all those answers : they are very interesting !
I think that the best choice would be a new EVO 302.
The KAS and KAS-2 are old amps and reliability problems could occur fast...
I noticed too that the EVO 302 construction (layout) seems to be more "clean and symetric" than the 402.
In the 402, the two output stages with their dissipators are parallel and very close.
In the 302, the output stages are on each side, like in classical stereo amps.
Upgrade1394 : could you confirm me that they are actually 2 transformers in the 302 : a smaller one upside the big one (that is shielded) ? Another question : do you have compared your EVO amp with some Pass amps, like the X350.5 or the XA100.5 ?
Best Regards,

Upgrade1394 : thanks in advance for all new answer to my last post...
But all other advice is welcome too !
Regards,

I have to disagree with upgrade 1394, the KSA 250, KSA 200, and The KMA amps 160/400s are not at all grainy--they are very very refined and open. These all run pure class A. They have the big fins, run hot, and are very desireable on the collector market. When you think "macho" amps these are what come to mind. The KSA 150 and KSA 200s were later amps and perhaps were not 100% class A. I'm not 100% sure but I've heard others say the KSA S-series amps were the "whitest" of the Krells. BTW-- I've never heard a grainy Krell amp. I don't think that's a term "I" would ever use for Krell, that's just me though.

Peter

Hello Nico_g,
in my recollection, the Tannoys and the JBLs are really easy to drive, thus, some buddies here in Manila drive them with low-powered SETs with finesse.

IMHO, the Krells are the epitome of solidstate amps that are really "SOLID STATE". i am currently using my FPB 200c to drive my Sonus Fabers becaue my SF Power 2 just can't seem to cut it :-(

I think, too, that the FPBs are more desireable than the KAS or the newer EVOs but this is a matter of taste and personal biases.

If you can, please give them a listen in your own venue and then decide.

Best wishes in your quest!
.e.

Thanks again for all the answers.
I will try to compare the KAS to my actual amp : GamuT D2 mkIII.
Then I will go to the other store and compare the D200 with the EVO 302...

I agree with Breuninger - the old Krells were not at all grainy. It is true that they can sound grainy in two situations: either when they are cold - they need more than one hour heating before sounding "liquid" - and when the electrolytic capacitors have to be replaced. You can expect that a 15 years old amplifier that runs very hot needs new capacitors. They are not expensive and you can have them replaced with better 105ºC ones - you will have an excellent amplifier for the next 10 years!

I owned and enjoyed the Krell KSA 250 Amp for several years. I finally replaced it with the Pass Labs X350.5.
The Pass is much better in all things that matter.
The Krell was very good for its time.
Both run very hot, the Krell is the winner in this regard.

I agree with Breuninger. These amps were very revealing though, they would pass on anything rough that preceded them.

Ozzy : do you have compared the Pass with some actual Krell amps like FPB or EVO series ?
Thanks for your help !

I did try the FPB 600 when they first came out, I thought the KSA 250 sounded better.
The Evo, is that the present Krell ? If it is I heard it connected to Wilson Watt Puppy 8's .
I didnt like the sound, the bass seemed dis-jointed to the rest of the music. Perhaps it was the Watt Puppys.

If the Krell KAS are the huge two piece mono's connected by solid copper (or brass?) bus bars that went for around $35K back in the mid 90's, then I have heard them extensively in various setups along with the KAS-2's, various KSA amps and all the FPB series. I have not heard many of the latest amps, and certainly not the Krell Evo series, but the KAS mono's were easily better than any of the FPB amps and remain perhaps the finest amps I have ever heard...amazing.

I did not care for the KAS-2 as they were very much like the FPB-600's - flat and lifeless (the FPB-300 too). Just my opinion, of course. For reasons others have mentioned, unless the price were too good to pass up, I do not believe I would purchase the KAS mono's due to complexity, age, and likely astonomical cost associated with repairs. I really do not know, however, and am just speculating: for all I know the amps might last another 100 years...they sure looked like they could.

Yes, the KAS are in 4 blocks : eahc channel has its separate power supply.
They were built around 1990 and I don't have precise information about their reliability...
I have to test them seriously and if the shop offers a warranty, it could be interesting.

If I try to summarize all the answers, I get mixed results :
- 2 first posts : FPB are better than KAS,
- then 2 posts : EVO are the best,
- 2 posts : KSA and KAS are better than FPB.

So, there is no clear winner, I think !
Last result : Pass X350.5 is another very good solution...

I would be surprised if you picked any Krell over your amp,YMMV,good luck,Bob

And we are forgetting the Krell Reference krs 200 monoblocks (a pair just showed-up at Audiogon today) - some people consider it one of the best amplifiers ever manufactured.
SME founder Alastair Robertson-Aikman used a pair in in famous listening room, and as far as I know they are still being used to drive his modified ESL63.

Hello,
I've seen the KRS-200 on audiogon : very tempting too...
But I don't understand why the seller has to change the XLR inputs...

Usblues : you think that my actual GamuT amp is better than Krell amps ?

The KRS-200 are 20 years old...
Should I be concerned with reliability problems with those kind of amps ?

Well,its a fine amp and in the right place[synergy] could easily equal/surpasse the Krell offerings which are also fine depending.....Krell amps and Tannoy speakers?I don't quite get the reason for change.That speaker doesn't require lots of current.It seems on paper a single Mosfet/channel would be ideal.Am I missing something?Thats ALWAYS possible....Bob

Early Krell balanced amps used a pair of RCAs for the balanced inputs thus the XLR input change I suppose. The KRS amps are impressive but do use a lot of power and will probably require some service in the near future. Also, they are very heavy and shipping will be expensive when service is needed.

This is an old thread but I'd like to add a few comments here. ONE, the quality of the Krell amps sound is very VERY dependent on the supply power, 220 Volts and lots of it is ideal. The amps, any Krells, can sound flat, restricted and edgy on weak power. You have not heard how sweet they can be until you have heard on a good power supply. SECOND, I do not consider any of these unreliable, these are extreme performance amps that use a ton of power and create an enormous amount of heat, they are supposed to be serviced every 10 years! Look, Ferrari engines never last very long, they rev much higher and work much harder than a Honda civic so yes they do wear accordingly. Want low maintenance get a Adcom amp, and why are tube guys even discussing reliability?

I have heard Krell amps sound poor many times usually from poor installation or system matching. My 2250 will sound more dynamic than my FPB750MCX amps on a weak 15 amp 117 volt line; on a 220V 40 amp line the FPB Rocks! I also have a 100 amp isolation transformer with individual windings feeding the amps, they don't sound flat.

I think to properly compare the amps they must be under proper conditions and within the nominal service expectancy. If you compare a new EVO amp to a 15yo KSA 250 on a 110V 15 amp circuit of course the KSA will be at a huge disadvantage.

I have had the KAS's since they were released. They have been magnificent performers and only a month ago did one of the mono amps go up in smoke. Thus ~20years of conitnuous enjoyment. The amp is at the factory now for repair. I sent the other back about 2 years ago for repair. Otherwise they have been extrememly reliable for such high perfomance.

Fjmcsu, just wondering what speakers you drive with your KAS.
I am considering buying a pair of them and would need some guidance:
They are meant to be really good at driving very low efficiency and/or very low impedance speakers.
At the same time, many people consider the KAS to be fundamentally more musical than many other (and more recent) Krell designs.
The question is whether it's worth going for KAS if you don't have such load issues. I have a pair of JM Lab Utopias. They are not as hard to drive as the famous Apogee speakers (which made the KAS very famous as they were hard to drive with anything else), and they have decent sensitivity. They just need top quality amplification because they are very transparent, to be thightly controlled and some current.
The KAS will most likely drive them across the first 2-3 steps of the 5 stage bias system (ie I will never need more than 125W I think, most of the time even below 50W (Level 2).
Does it make sense to go for the KAS with a pure musicality objective in mind if you don't need all that power?
Moreover, does the KAS perform as well at low power than at higher power? You could argue that on the first couple of bias levels it is so cold that you'd wonder if the various components operate at their nominal temperature...
I currently have a KSA-150 (for ages). It has way enough power for my system and it took me a looong time to consider switching. Do you think I am going to experience a significant sonic improvement by switching to KAS?

Thanks,

I own 2 of the Kas-2 (purchased used 5 years ago). One of them went up in smoke, and I am reluctant to send them back to Krell. They told me (judging from the picture: top of circuit board burned badly), they do not have the replacement circuit board anymore, they can't fix it. I live in California, shipping would be very costly. Now that I hear about yours going up in smoke, I am scared to spend money on them. I love the sound, but Krell is not accommodating me at the least. Can you give me an idea? Attila

Did you ever get your amp fixed and if so by whom? Did Krell ever offer any support? Do you like the amps?

Hi Gentleman!, I am going to be your rescue!, I am a avid krell user, and have been for many years like your selfs, There is a gentleman named steven, He was the service manager at krell for numerous years untill Dan D Agistno departed, Steven trained Ray Muchler, the current service manager there at krell, the name of steven's company is called, The service Department Home,, steven is a specialist of all krell, also all vintage Krell equipment!, go to his web site, read the reviews of customers, Tell him Keith Henry-Audiolabyrinth of Mobile, AL sent you, Steven gurantees all His work, Let me know here if you gentleman talk to Steven, I will be checking back on this thread, I want to know what he tells all of you, I have a totally brand new inside and out Krell 700cx, steven did not do the job, Krell did, I have mods inside that krell claims that my amp is the only one out there like it, part of the mods is caps that were not available in 2005 that are 2014 caps, I talked to Steven before I did this very exspensive job to my amp, I did a three way conversation, my amp was sent to krell for the job to get in stock new cosmetics, steven would had to have ordered them, Steven is Honest!, He told me Ray Muchler that he trained could do the particular job I wanted, and I all my cosmetic new parts would be there, I could get my amp back a little faster, so at the end of the day, Steven is first class!, If I ever need anything else, The Service Department Home and Krell are my only choices, if Krell can't do the job, Steven can!, Cheers.

That circuit board rebuild will cost a fortune....

can't find Steven's site, could you pls indicate?
need some info for KBX B&W800, Krell actually can't any more. tia

@ Cciano, Hi, Just bing, The sevice Department, scroll around, then you will see, The service Department home, Steven is the name on the site, He is in the state of connecticut like Krell is, Let me know here if you find the site and if you talk to steven. cheers.

Thanks Keith, already found the site, looking for the service dpt + krell. Steven gave a quick response and I will call him tomorrow. Good to know a competent alternative to Krell itself. Thank you for posting about Steven. Cheers.

your welcome Cciano, Steven is a very,very good technician, like I said, He trained Ray muchler, the current service manager at krell, LOL!, He owns a kps-25sc I joked about wanting to buy from him, He will never sale it, I was not serious, He was about keeping it, The man loves vintage krell equipment, I believe you are in good hands, please keep me posted here, or you can E-mail me through audiogon mail, thankyou for your reply, also, If you can help me, post a post about anything on the cable thread I started, called, Tara labs cables, I want to keep the thread going, there is no specific topic criteria, I call it the peoples thread, Talk about any thing, I want to learn from you, If I see you make the thread, I can ask you questions that are not related to one topic there, cheers.

Cciano, Have you decided to use the service department home?, what has happened since we last spoke here.

Check out this guys system.
He's using Krell KAS amps on TAD Reference one speakers.
https://www.youtube.com/watch?v=biNGwFwortw