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Urgent help!!! Please help me decide Krell solo 575 vs Classe Omega
- Thread starter Ashl777
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Svend P
Addicted to Fun and Learning
It is 0.5 dB at 20 KHz. No way anyone can hear that.
One of the best measuring amplifiers, the Benchmark AH82, has the same behavior. Please read Amirns description of how it sounds. (I tease, he never describes how amplifiers sound, since they all sound the same)
Review and Measurements of Benchmark AHB2 Amp
This is a review and detailed measurements of the Benchmark AHB2 Amplifier using THX technology to reduce distortion. I was going to request one for testing due to membership demand but to my pleasant surprise, the company volunteered to contact me and send not one, but two units! I requested...
www.audiosciencereview.com
MAB
Major Contributor
The measurements look fine, very representative of a Krell amp. And very good for an amp in general. The Sonos amp is good too.
The metric referenced by Ray is actually SINAD, Signal over Noise and Distortion. Frequency response, Distortion and Noise, and Power output pretty much sum up an amp. And reliability, since many amps are not reliable.
The xrt2k is an easy speaker to drive. Impedance is very easy, and with moderately high sensitivity it doesn't need much power.
I have to agree with Svend P, no way the Benchmark's frequency response variations are audible. The Classé and Krell amps are both excellent amps. Since frequency response is often the most obvious flaw in amps, let's compare the Stereophile data on these monsters. I will include Bryston 28 as well, since I am a bit of a Bryston fan, and they come with a 20 year warranty, and it is a monstrously powerful monoblock. I am also a reliability fan.
Here are the three compared across 2, 4, and 8 Ohm loads:
This is really great performance out of all three amps. It's so hard to pick a winner. If there is a flaw, the Classé starts to sag at upper frequencies in 2 Ohms, the Bryston less so, the Krell is almost unflinching at that low impedance. None of this is audible, none of your speakers are low enough impedance for this to become a problem that you could hear.
Into Stereophile's simulated load:
Good grief these are all awesome low output impedance amps with negligible FR variations!
Even if I obsess, the Classé is perhaps the flattest at high frequency, the Bryston the flattest at low frequency. But there is really nothing between these amps' frequency response.How about THD+N (SINAD)?
Stereophile didn't provide 2 Ohm THD+N measurements on the Krell. The Classé and Bryston are both great performers into 2 Ohms, the Bryston being a bit better.
At 4 Ohms, all are great. The Krell is slightly higher THD+N of the three, but still excellent performance. Very consistent with Ray's measurement, the amp stays below 0.01% THD+N until several hundred Watts. Perhaps the Bryston and Classé are in a neck and neck battle with the Krell competently performing just a bit behind.
From the THD+N graphs you can see they are all incredibly powerful amps. The Bryston being the most powerful unless you are driving a 2 Ohm load, which you are not.
I will not be able to hear the differences using most commercially available speakers. These three amps are all incredible. Switching between the three is side-grading. They might be distinguishable is if you had a pair of Apogee Acoustics Scintilla speakers or some other crazy load, in that case I expect there are some differences that may be audible. The other is with a high efficiency driver, like a horn, in that case the amp with the lowest noise is going to have the least audible hiss. These are corner cases, and shouldn't form the basis of your decision.
At this level of performance, the choice comes down to other factors for me. Reliability and warranty support being a main consideration. If I was in the market and had unlimited funds, I would likely get the Bryston. But if I closed my eyes, I wouldn't be able to tell which one of these is playing.
OP
Ashl777
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Thanks for the evaluation. Im trying to wrap my head around the comment about the xrt2k. 64 midrange drivers, 40 tweeters and 6 x12inch woofers per speaker will have a low impedance? So you telling me a 50w amplifier and a 2000w monoblock will give the same results on the speaker? I tried 6 different amps until n felt enough control over the woofers. So if i volume match all these amps let say from a trinnov mic and record the rew….analyze the measurement it will be the same? Small amp wont introduce much more noise to reach the same spl?The measurements look fine, very representative of a Krell amp. And very good for an amp in general. The Sonos amp is good too.
The metric referenced by Ray is actually SINAD, Signal over Noise and Distortion. Frequency response, Distortion and Noise, and Power output pretty much sum up an amp. And reliability, since many amps are not reliable.
The xrt2k is an easy speaker to drive. Impedance is very easy, and with moderately high sensitivity it doesn't need much power.
I have to agree with Svend P, no way the Benchmark's frequency response variations are audible. The Classé and Krell amps are both excellent amps. Since frequency response is often the most obvious flaw in amps, let's compare the Stereophile data on these monsters. I will include Bryston 28 as well, since I am a bit of a Bryston fan, and they come with a 20 year warranty, and it is a monstrously powerful monoblock. I am also a reliability fan.
Here are the three compared across 2, 4, and 8 Ohm loads:
View attachment 452600
This is really great performance out of all three amps. It's so hard to pick a winner. If there is a flaw, the Classé starts to sag at upper frequencies in 2 Ohms, the Bryston less so, the Krell is almost unflinching at that low impedance. None of this is audible, none of your speakers are low enough impedance for this to become a problem that you could hear.
Into Stereophile's simulated load:
View attachment 452602
Good grief these are all awesome low output impedance amps with negligible FR variations!
How about THD+N (SINAD)?
View attachment 452603
Stereophile didn't provide 2 Ohm THD+N measurements on the Krell. The Classé and Bryston are both great performers into 2 Ohms, the Bryston being a bit better.
At 4 Ohms, all are great. The Krell is slightly higher THD+N of the three, but still excellent performance. Very consistent with Ray's measurement, the amp stays below 0.01% THD+N until several hundred Watts. Perhaps the Bryston and Classé are in a neck and neck battle with the Krell competently performing just a bit behind.
From the THD+N graphs you can see they are all incredibly powerful amps. The Bryston being the most powerful unless you are driving a 2 Ohm load, which you are not.
I will not be able to hear the differences using most commercially available speakers. These three amps are all incredible. Switching between the three is side-grading. They might be distinguishable is if you had a pair of Apogee Acoustics Scintilla speakers or some other crazy load, in that case I expect there are some differences that may be audible. The other is with a high efficiency driver, like a horn, in that case the amp with the lowest noise is going to have the least audible hiss. These are corner cases, and shouldn't form the basis of your decision.
At this level of performance, the choice comes down to other factors for me. Reliability and warranty support being a main consideration. If I was in the market and had unlimited funds, I would likely get the Bryston. But if I closed my eyes, I wouldn't be able to tell which one of these is playing.
... followed by 3 bangs.
Interesting lingo graph. Is there a version of this graph, which provides the lingo for positive attributes of what most adult humans actually hear?
MAB
Major Contributor
The sheer number of drivers doesn't reduce the impedance, it's their individual impedances, and how they are wired. Also, the drivers are not the only part of the speaker that determines the impedance, the crossover plays a large role, often much more important than the impedance of the array of drivers. McIntosh states explicitly that the speakers are an easy 8 Ohm load, are '8 Ohm for compatibility', etc. They seem to go out of their way to emphasize this. I would love to see an actual impedance trace. I doubt it is a difficult load given what McIntosh states. I tend to believe McIntosh at their word, they were pioneers of honest specs and seem to still stick to that. They also state that the speakers can be drive with as little as 75W, which is consistent with the 90dB at 1 meter with 2.8V applied (1 Watt).
Yes. 2k Watts will play louder than 50 Watts, that's about the only difference unless the small amplifier is driven to clipping.
Actually, into 8 Ohms, the Krell is 'only' 575 Watts (625 as tested at Stereophile.)
The Sonos will get your speakers to about 108 dB, quite loud. The Krell to about 117 or 118, ear splitting. 2k Watts to a terrifying 123 dB. I have a pair of speakers that will do about 125 dB, it is indeed terrifying.
Also, I think you can appreciate that the difference between 'only 575 Watts' and 2 kW is not that much in terms of SPL.Once level-matched any of these three amps I have been going on about are indistinguishable unless overdriven to clipping. When compared to a low power amplifier that also has flat frequency response, also indistinguishable. I tend to use a Voltmeter and test signal since it is more precise and also quicker/easier for me. But yes, level matched is critical as was stated in the David Clark study I linked earlier. Additionally, David Clark and many others have pointed out the importance of matched frequency response. Amps with wonky frequency response anomalies are audibly different from flat FR amps... Your Krell, and the Classé and Bryston examples in my previous post all have exemplary FR performance. The Sonos does not have good FR performance:
It would not sound horrible, but it is rolled off in the bass, and the rolloff on the right channel compared to the boosted treble on the left is likely to be audible. The treble L vs. R FR and overall differences is less dramatic than most room's asymmetries, but for goodness sake not what we are wanting in our reproduction systems. Already enough going on, plus you paid some money for your gear and likely won't appreciate the Sonos' performance.
It's not as bad as these Wavac amps:
Wavac SH-833 monoblock power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements "Perhaps I should just measure one of the amplifiers," I said, eyeing the eight chassis that comprise a pair of the Wavac SH-833 monoblocks, all of them sitting at the business end of Mikey's room. Even so, as neighbor Wes Phillips and I manhandled the 550 lbs of...
You have some awesome amps. The Classé is kind of a side trade. But if you have the money and really want it, go for it. If it was me, I might go another direction, like a pair of self-powered studio monitors from Neumann or Genelec or even JBL.
I hope this helps.
A speaker with high impedance is actually an easier load for the amp. Number of drivers has nothing to do with this in any case.
Plenty of vintage 1970s speakers with multiple drivers (I have some with six drivers per side) but they still have high impedance (over 8 ohm average) and usually high (over 90dB) sensitivity.
Any amp will drive those speakers optimally, they are intended for the amplifiers of the early 1970s - usually a receiver with about 20 watts a side and a tiny little frame transformer.
Put that same receiver into a modern speaker with average 4 ohm impedance, big phase swings and 2 ohm impedance down in the bass, sound quality will be terrible.
That was the whole point of Krell et al - they were required to get the best out of speakers with very low impedance when such speakers started appearing at the end of the 1970s.
Plenty of vintage 1970s speakers with multiple drivers (I have some with six drivers per side) but they still have high impedance (over 8 ohm average) and usually high (over 90dB) sensitivity.
Any amp will drive those speakers optimally, they are intended for the amplifiers of the early 1970s - usually a receiver with about 20 watts a side and a tiny little frame transformer.
Put that same receiver into a modern speaker with average 4 ohm impedance, big phase swings and 2 ohm impedance down in the bass, sound quality will be terrible.
That was the whole point of Krell et al - they were required to get the best out of speakers with very low impedance when such speakers started appearing at the end of the 1970s.
Good decision in my opinion.
Bulldogger
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I have experience with everything except the Classe amp. In my travels, I've never seen that model. I have owned Mcintosh MC501 and MC252 amplifiers. I sold the Krell Duo 300 and upgraded to the new amp, the KSA-i400. I also have the Mcintosh XR200s in my system. It's been a very long time since a dealer demoed the B&W Matrix speaker to me when he was trying to convince me to buy them instead of Focal Electra 936. He'd just taken the B&Ws in on trade.
Krell is using a pseudo-class A approach with the i-bias. I"m not sure you gain anything with the Classe if that's what you are seeking. The Krells ibias amps are the most dynamic amps I have used.
I know you aren't asking this but if you ever get a chance to try the new KSA-i400 or i800 on those XRT2k, it's going to be a new experience for you, unless you've had something like the $100k Boulder monoblocks or something. I don't have nearly as many drivers as you on the XRT2k but I have a lot compared to most speakers. The Krell is offering a level of precision in the sound that I have not experienced at home. That's mostly in the highs. I have had nearly all the regular amps, Bryton,Parasound,Pass Labs,Aragon,Classe and of course Mcintosh. I"ve had the MC 2301s at home for demo as well. Krell improved the i400 and i800's ability to drive the highs. That's a profound understatement.
Krell is using a pseudo-class A approach with the i-bias. I"m not sure you gain anything with the Classe if that's what you are seeking. The Krells ibias amps are the most dynamic amps I have used.
I know you aren't asking this but if you ever get a chance to try the new KSA-i400 or i800 on those XRT2k, it's going to be a new experience for you, unless you've had something like the $100k Boulder monoblocks or something. I don't have nearly as many drivers as you on the XRT2k but I have a lot compared to most speakers. The Krell is offering a level of precision in the sound that I have not experienced at home. That's mostly in the highs. I have had nearly all the regular amps, Bryton,Parasound,Pass Labs,Aragon,Classe and of course Mcintosh. I"ve had the MC 2301s at home for demo as well. Krell improved the i400 and i800's ability to drive the highs. That's a profound understatement.
