Latest krell saga

[mep]

When is a recap job not really a recap job?

As I have stated numerous times, I have been plagued by low level hum which does change in level by inducement from other electrical fields being too close to the power cord to the KSA-250. I paid Krell $1299 to repair my KSA-250 and for a "recap" job which I assumed meant all capacitors and especially the main filter capacitors as they see the most stress from the power supply.

I had a nagging suspicion that Krell didn't change out the main filter caps during the recap job. I called Krell yesterday and spoke to Ray and Ray said they weren't changed out as they only change them out "if needed." Again Ray told me how quiet my KSA-250 was after the repair job. I told Ray I wasn't happy as I thought the main filter caps should have replaced and the hum I have is common to both channels and they are a likely suspect. As filter caps get old and before they fail catastrophically with a big bang, they start losing their value. And by that I mean that a 1000 mfd cap might only measure 200 mfd for example.

I told Ray my worst nightmare was that I would pack the amp up, make the 3 hour round trip drive to the freight forwarder, send the amp back to Krell only to be told there is nothing wrong with it. Ray said he was going to call me back yesterday, but he never did.

I removed the Krell from my system earlier in the week and hooked up my pair of PL-400 Series 2 amps and they are perfectly quiet. Zero background noise which makes my noise floor whatever the source material's noise floor is. The problem is that PL amps are not close to being the same sonic league as the KSA-250. Nothing sounds *right* with PL amps compared to the Krell. The bottom end isn't as deep and extended, mid-bass is nonexistent, and voices aren't as fully fleshed out. In other words, it's almost threadbare by comparison.

I couldn't stand it anymore and put the KSA-250 back in the system last night. I hate to say it's night and day, but it's night and day. The KSA-250 passes through so much more information it's just incredible. Now if I could only make it not pass through the low-level hum I would have it made.

 

[RBFC]

Mark,

Stay after them about the issue. You now know how good the amp is. All my Krell amps have been dead quiet, so there's still something wrong.

Lee

 

[FrantzM]

mep

Talk to Krell. There is nothing that cant be solved with communications. Send the darn amp back to Krell and wait. Hum shouldn't part of High End Audio reproduction. Any low-fi receiver one can get at Brest Buy is hum-free why should a Krell? Yes it is a bother but I think it is well worth it... As for the darkness I would try another preamp just to have an idea... While some may laugh at this I would try a Spectral preamp if you can put your hands on one. It is an unusual pairing but I have heard it myself and was agreeably surprised. Else do have a listen on some of the newer ARC preamp ... I have heard the LS 27 in a all ARC system and if I were t go tube, this would be one of the first preamp I would audition..Pure in a way few tubes are but still a tube unit in its overall presentation ... Audition it if you can a few pream p in your system .. I hate to just go with some audiophiles myths .. I never remember the krell preamps to be that great ... Back when I paid attention to these, Krell was often paired with a different preamp often a Rowland ... I would listen and make up my mind after audition of different preamps in your system.

 

[LL21]

Not to sound too controversial...but i have been told by people when i had my Gryphon Antileon (now sold)...to try different fuses for the darkness.

As for the hum, unfortunately, i have to agree with those who say PERSIST...it will be worth it. Sometimes, it does not take the most experienced or the most knowledgeble audio tech to find the problem...it takes the most methodical and most persistent audio tech. i had a buzz in the Antileon that lasted on/off for nearly a year...eventually, one audiotech let it run straight for 6 weeks...it finally started buzzing in his system with the top off...and he found the problem. Super subtle, but he found it and dead quiet ever since, and again now sold.

Can you find a local audiotech who can come over and hear it? Can you record it and play it back for them? Or try having Krell on skype while your system is running so they can 'hear it'?

 

[MylesBAstor]

mep

Talk to Krell. There is nothing that cant be solved with communications. Send the darn amp back to Krell and wait. Hum shouldn't part of High End Audio reproduction. Any low-fi receiver one can get at Brest Buy is hum-free why should a Krell? Yes it is a bother but I think it is well worth it... As for the darkness I would try another preamp just to have an idea... While some may laugh at this I would try a Spectral preamp if you can put your hands on one. It is an unusual pairing but I have heard it myself and was agreeably surprised. Else do have a listen on some of the newer ARC preamp ... I have heard the LS 27 in a all ARC system and if I were t go tube, this would be one of the first preamp I would audition..Pure in a way few tubes are but still a tube unit in its overall presentation ... Audition it if you can a few pream p in your system .. I hate to just go with some audiophiles myths .. I never remember the krell preamps to be that great ... Back when I paid attention to these, Krell was often paired with a different preamp often a Rowland ... I would listen and make up my mind after audition of different preamps in your system.

+1

Krell has always prided itself on customer service and you should be getting it! I know when Dan ran the company, they made good on even the KSA-50s and 100s for a decade later

 

[mep]

Guys-I am talking to Krell. I talked to them yesterday and Ray owes me a phone call back. Since the hum is common to both channels, it may well be the big filter caps are going bad and I do think they should have automatically been replaced as part of the cap job I paid for. You also need to keep in mind that shipping this amp back to Krell will cost me over $600 for the round trip plus six hours of my time for making two round trips to the freight forwarder in Indianapolis. Not to mention bothering one of my neighbors to help me get the amp from downstairs into my vehicle and then back downstairs when it comes back. There is nothing cheap or easy about this if I have to send it back to Krell.

I think I’m going to pull the main filter caps and take them over to a friend’s house who has a nice Sencore cap tester and see if the caps have issues. It would be a simple and easy fix if it is the main filter caps. If I have to lug this monster out of my basement again, I would really want that to be the time it was getting sent to a new owner.

As for the KBL/KSA-250 combo, I think they sound great together. The KBL is super quiet and I happen to like the way it sounds. I would really have to hear another really good high-end preamp to pass judgment on the true top end extension vice the famed Krell darkness label. I’m pretty sure that because the Yamaha C2a/Phase Linear combo is so light sounding by comparison that it causes the highs to stick out like a sore…thumb. When the bottom end is weak by comparison and the mid-bass is practically non-existent, it tends to emphasize the highs and makes the Krell combo sound dark by comparison. So the question remains; is the Krell gear really dark sounding, or is everything else light, white, and bright in comparison? It’s not like you don’t hear plenty of air with wind instruments and cymbals because you do. Taken on its own, it’s a mighty fine sound.

 

[microstrip]

Mep,

If the the filter capacitors are the problem it is easy to diagnose locally. Get a voltmeter in AC position and measure the ripple across the capacitors. If one capacitor looses capacity it will give an higher reading.

Just one detail - do you have hum if you disconnect the cable coming from the preamplifier cable, insert all the shorting plugs in the input and switch on?

 

[MarinJim]

I agree with those who say get it fixed locally. If Krell can not even give you th respect of a return call back, it seems they want to wash their hands of this amp.

 

[mep]

Micro-Yes, I have shorted both sets of inputs with the amp hooked to my speakers and the hum is still there. I tried lifting the ground on the AC cord from the amp with a cheater plug and the hum is still there. The amp is plugged into a new dedicated 20A circuit I had installed just for the KSA-250. I will have to take the top off of the amp to have a look-see, but I don't think you can get to the caps to measure them with the amp up and running because I believe there is a CCA over the tops of the caps.

 

[treitz3]

Hello, mep. I'll start off by being honest. I have not read through this entire thread but I do hate what it is you are going through. It's frustrating, to say the least. Especially when the sonics without this issue are as they say you are. That said, I did happen to run across this article by Stereophile and what was written on page two might be of interest to you...

http://www.stereophile.com/content/krell-ksa-250-power-amplifier-page-2

Shortcomings
The KSA-250 is not perfect. It is harmonically bettered by the Jadis tube electronics, and does not resolve leading edges of instrumental and vocal attacks as well as the Mark Levinson No.23. It produces a constant low-level hum through the speakers, which could probably drive some people nuts. It runs extremely hot, and sucks juice out of the wall like a sponge. So what? Audiophiles are supposed to suffer a little, aren't they?

Has this low level hum always been there or is it something that just recently reared it's ugly head? Is it constant or does it seem to follow the volume? <<<Important

Have you checked to insure that all ground wires from the plug, all of the way to the CB have not worked them self loose or were perhaps incorrectly installed?

Additionally, here's something I'm sure that you have covered but I'll go ahead and ask anyways.

The wiring to and from the amplifier, and all components in general, should be arranged in a neat, organized manner. Specifically, AC wires should be separated from audio wire. This insures the avoidance of hum or the introduction of other unwanted noise into the system.

This came straight from the owner's manual. I take it that the basics have been covered at this point but it doesn't hurt to ask. Sometimes it's the simple things that are overlooked.

 

[LL21]

Wow...good stuff, Treitz.

 

[mep]

Hello, mep. I'll start off by being honest. I have not read through this entire thread but I do hate what it is you are going through. It's frustrating, to say the least. Especially when the sonics without this issue are as they say you are. That said, I did happen to run across this article by Stereophile and what was written on page two might be of interest to you...

http://www.stereophile.com/content/krell-ksa-250-power-amplifier-page-2





Has this low level hum always been there or is it something that just recently reared it's ugly head? Is it constant or does it seem to follow the volume? <<<Important

Have you checked to insure that all ground wires from the plug, all of the way to the CB have not worked them self loose or were perhaps incorrectly installed?

Additionally, here's something I'm sure that you have covered but I'll go ahead and ask anyways.
This came straight from the owner's manual. I take it that the basics have been covered at this point but it doesn't hurt to ask. Sometimes it's the simple things that are overlooked.

Very interesting to say the least. I never saw that quote from Stereophile where they mentioned the low level hum coming from both speakers and the fact that it will drive some people nuts. It drives me nuts because I know it shouldn’t be there.
The hum stays the same regardless of volume level. You can make it worse by letting the power cord come to close to other cables, but that’s another issue.

I know my 20A circuit is wired correctly. I have one of those circuit pecker checkers that you plug into an outlet and it tells you if something is miswired or not grounded. I tested it and it is correct.

 

[treitz3]

Mep, why did you originally send the amp in for service? Was it because of the same issue or something different?

 

[mep]

I bought the amp and it was supposedly working. When it arrived, it wouldn't turn on and that is why I sent it back to Krell. There are two relays involved in the turn on process and they were both bad.

 

[mep]

From the Stereophile review:

"Shortcomings
The KSA-250 is not perfect. It is harmonically bettered by the Jadis tube electronics, and does not resolve leading edges of instrumental and vocal attacks as well as the Mark Levinson No.23. It produces a constant low-level hum through the speakers, which could probably drive some people nuts. It runs extremely hot, and sucks juice out of the wall like a sponge. So what? Audiophiles are supposed to suffer a little, aren't they? "

I guess the damn thing is working perfectly.

 

[treitz3]

Oh boy. Making you mad was not the intention of my post. In fact it was the furthest from what I was trying to accomplish for you, I was trying to troubleshoot. I do hope you realize this.

I think I'll go stick my head in the sand or something at least move on to something more productive. My apologies, mep. That said, if all of the bases have been covered, perhaps it's time for another amplifier to sooth your musical soul. If you are dead set on this amplifier, maybe give them a link to the article and ask what upgrades or modifications they have done since then to alleviate the issue?

 

[mep]

Tom-I'm not mad at you silly. I'm mad that somehow I missed that sentence in the original Stereophile review and that people back in the day thought it was normal and acceptable. Hell, maybe I have the exact Krell that Lewis Lipstick had when he wrote the orignal review. Maybe that was what Ray from Krell meant when he said my KSA-250 was real quiet after repair at Krell. Maybe it was real quiet for a KSA-250.

 

[DaveyF]

I have a similar issue with my Rowland 8, hums all the time. I knew this problem going in, as it was mentioned by listeners in the Far East as a problem. The issue was traced to the choke power supply that Jeff used in the amp. Unfortunately, when Jeff caved into the pressure and changed the power supply to accommodate the Far East market, he succeeded in removing the hum, but also threw away a lot of the inner resolution that the amp is capable of. Now why amp designers cannot get this hum issue resolved in this day and age is a real question to me? Seems that any amp designer worth his salt should be able to get these basics right from the get go. The integrated amps from Japan from the seventies never illicit this problem! Couldn't Jeff Rowland or Dan D'Agastino get this seemingly MAJOR issue under control.
Okay, that's it for the rant, I still love the amp, but come on guys!!!

 

[microstrip]

From the Stereophile review:

"Shortcomings
The KSA-250 is not perfect. It is harmonically bettered by the Jadis tube electronics, and does not resolve leading edges of instrumental and vocal attacks as well as the Mark Levinson No.23. It produces a constant low-level hum through the speakers, which could probably drive some people nuts. It runs extremely hot, and sucks juice out of the wall like a sponge. So what? Audiophiles are supposed to suffer a little, aren't they? "

I guess the damn thing is working perfectly.

Mep.

I would not be so sure about it .

I looked for the review and found there is something strange about this comment. THD + noise is said to be less than .1% at moderate and high levels. Krell specifies S/N ratio: 120dB, "A" weighted.

If there was any hum it would show as a peak at 60 or 120Hz in Fig.2 THD+N (%) vs frequency at (from top to bottom) at 100Hz): 100W into 8 ohms, 4W into 2 ohms, 2W into 4 ohms, 1W into 8 ohms

Although the review was carried with 94 dB/W speakers, nothing in the measurements indicates such an audible hum. (I hope I am not bringing the objectie/subjective debate here ) .

 

[mep]

I have talked with other people who claimed they have owned the KSA-250 and all of them said they didn't have this problem which surprises me. I know my listening room has a very low noise level which makes issues like this worse than someone who has a noiser background than I do. But if this really was a problem that affected all KSA-250 amps, that tells you there was a design flaw in the power supply. I'm sure it is low levels of 60 Hz hum coming through.

Also, I just read the measurements that were taken as part of the review and they never mentioned any hum which I find quite curious given that Lewis Lipstick mentioned it in his review.