Krell KRS-200.
When biased as intended you will be looking at approx. 400 Watts Class A before it reverts to Class AB.
When biased as intended you will be looking at approx. 400 Watts Class A before it reverts to Class AB.
Pure Class A amps above 100 Watts?
What are the best options in Pure Class A amps above at least 100 watts in 8 ohms? The ones I know of are:
1) Pass Labs XA100.5
2) Pass Labs XA100.8 (and above)
3) Accuphase A-200
4) Soulution 530
Any others? Im trying to keep it under $10K, which the first two options can be had for used.
1) Pass Labs XA100.5
2) Pass Labs XA100.8 (and above)
3) Accuphase A-200
4) Soulution 530
Any others? Im trying to keep it under $10K, which the first two options can be had for used.
43 responses Add your response
Wilson Shen asserts Clayton M300 are full class A amplifiers but they are fixed internally bridged designs with each channel composed of two balanced bridged 75 watt full class A amplifiers. I believe all Constellation Audio amps and Naim Reference Amps are also balanced bridged designs. Not sure about their class of operation. |
Been Solid State boy close to 15 Years, before that it was tubes. Now I'm back to Tubes but using OTL Atma-Sphere Amplifiers. It does what the Solid States can but also all the goodness of Tubes. So my Recommendation at min the M60 but you should aim for the Atma-Sphere MA1, Plenty of Power, Purity, Smoothness, Musical Presentation, Fatigue Free Listening, Emotional Impact, Speed, Dynamics, Clarity and above all Satisfaction. The Solid State put me on the merry go round, the Atma-Sphere took me off it. Iv had a bunch of SET amplifiers & Push and Pull. Over time I always go back to my OTL Amps. |
Hello George, Thanks for putting my rather modest efforts in perspective, haha! We need the audio equivalent of Jay Leno’s Garage, where we could all wander around a big warehouse space and look at sound systems from various eras. As for sound, my proudest moment was when I tricked an electrician into thinking I was playing the cello. The electrician was working in my kitchen and I put on Pablo Casals playing the Bach Cello Suites, in the living room. I went off into the bedroom to work on the computer. Later, the electrician told me he went out into the living room expecting to see me there playing the cello, lol. I had my classical guitar teacher sit down and listen to the stereo. He kept pointing at the big Gryphon and asking if that was the third speaker. Haha. |
larrykell OK you asked for it, believe it or not time. Sorry no pics, young and stupid back then, all I wanted was was biggest Class-A I could make using water as cooling, after I built and heard Nelson Pass A20 http://www.firstwatt.com/pdf/art_classa_20.pdf also they were film cameras back then and no internet so pics were a hassle. It weighed a lot, and was a two man lift in the order of 100kg, that power supply fed some for memory 36x Hirel EB and ED 204 bjt transistors 20amp 200w 200mhz each, one of the best transistors eve made, no longer available. The amp was on a naked platform 1mt X 1/2mt, which had a machined water cooling jacket which all those hirel’s bolted to the outlet hose went to the top of a small car radiator, the bottom hose of the radiator went to a very quiet pump which then went to the inlet of the water cooling jacket. I had a Garard turntable motor with a Davis Craig plastic fan on it turning at 33 rpm to blow air through the radiator. The whole thing after 10 years started to corroded, I very rich businessman offered me a fortune for it as a resto project and I sold it to him, he may still have it, but I doubt it, even the 1/2 farad of caps were on the way out. I was a trip making it a showing it off, one of the times it powered Otto Majors system (rip) Quad 57 restorer extraordinaire even better than original. He had double stacked quad 57’s with Decca Kelly ribbons from 10khz up, and from 100hz down two 24" Hartly woofers in the wall where the room behind it was the speaker box. Front end was a Linn of course with an Infinity Black Widow arm and a Stax Electrostatic!!!! best ever sounding cartridge, going into it’s own power supply and riaa, which then went into my Lightspeed Attenuator MkI passive and into the water cooled beast! What a sound, remember the Dire Straits album "Love Over Gold" very well it was holographic!!. http://mniec.files.wordpress.com/2012/11/hqdusa_resize.jpg?w=594&h=413 https://i.pinimg.com/originals/ff/28/0e/ff280e10ff8268ed43348aa59b805d2a.jpg https://farm8.staticflickr.com/7479/16018366265_aeda7012db_b.jpg https://www.vinylengine.com/turntable_forum/viewtopic.php?t=23803 Cheers George |
Haha, George, what a trip! Thanks for sharing that information. Do you have any pictures of that water cooled amp? Nothing succeeds like excess. I owned a Mac computer that was water/liquid cooled. It weighed a ton. How much did your amp weigh? I guess you wouldn’t want your water cooling system to spring a leak, would you? I’m terrified of anybody approaching my Colosseum with a drink in their hand, a fear shared by my friend who runs the Mephisto Solo mono blocks. |
My Gryphon Colosseum draws 500w while idlingMy water cooled one I built, drew over 2500w at idle, with 230v mains, and had a special h/d power point, as the normal 10amp ones use to get hot and give connection problems over time. When this beast was switched on with the 5kva transformer, 45A bridges, 1/2 farad of supply caps, the mains wire from house barge board to the street pole used to flex up and down 6" for a second. This amp ran my Acoustat 1+1 https://i.ebayimg.com/00/s/MTYwMFg5MDA=/z/bkAAAOSwlddc1IW9/$_1.JPG crossed over passive 18db at 80hz to two very rare Kef B1814’s in 11cu ft vented sub enclosures that Neville Thiel (rip) designed for me after measuring the B1814’s, the system ended up flat to 18hz. http://i66.tinypic.com/nnr1fr.jpg Cheers George |
My Gryphon Colosseum draws 500w while idling. I don’t idle, meaning, letting it run without signal, so that is no worry to me, lol. I can’t see how any Class A amp can draw only a few watts when the point of Class A is that the transistors are on all the time. Once ConEd installs smart meters, I’ll get to see how much my monster draws. I know it’s not going to be pretty. |
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Nobody but you George has ever questioned that these operate in Class AIt's a play on words. " 300 Watts continuous rms into 8 ohms in Class A 600 Watts continuous rms into 4 ohms in Class A" If this above is to be believed as your are believing, it would be worded like this instead. "300w pure Class-A into 8ohms but will say the amps do sound good, and particularly for the cost.I'm not saying they sound anything but good. I'm disputing how they advertise the Class-A ability of them, especially with no fans and top mounted flat heatsinks like that, there is no convection cooling at all, they'd be lucky to be 50w Class-A Cheers George |
I find the 800 watt power consumption and 300 wpc Class A a bit inconsistent unless the design is similar to the Krell so called sliding bias or something along those lines. Otherwise, something more like ~2500+ watts is more realistic which I believe is the point George is trying to make.I hear you (and George) on that point and cannot really speak to the designer's choices and specs except to say, they are what they are. I do understand the amp is a dual differential design where the MLs and Krells may not have been, if that makes a difference. I am not going to disagree with or argue the technical points but will say the amps do sound good, and particularly for the cost. |
As good as those ML2s were in their day, a new Pass XA25 has a similar performance without the need to use that much iron. But that aside, I find the 800 watt power consumption and 300 wpc Class A a bit inconsistent unless the design is similar to the Krell so called sliding bias or something along those lines. Otherwise, something more like ~2500+ watts is more realistic which I believe is the point George is trying to make. |
Indeed, since the low bias setting still provides class A operation up to 200 watts, you should hear little difference between the settings most of the time. For the absolute highest quality reproduction of dynamic material and the most critical listening, the amplifiers should be set to the high bias level for full class A operation.Nobody but you George has ever questioned that these operate in Class A - as indicated in the mfg’s statement above. However, your unsolicited challenge doesn’t really matter after all the positive reports/reviews of these amplifiers. Have you ever heard a pair? BTW, the Lamm M1.2 Reference amps (also Class A) I owned at the same time as my M300s had similar heat sinking to the ML amps in your picture and although the Lamms were quite good, my musical preference was for the Clayton’s, so I sold the Lamms. |
Sorry Mitch you been had, this is A/B what you think is Class-A. "Class A Operation / Fully Balanced / XLR Inputs Only"This is not an indication of 300w Class-A. "300 Watts continuous rms into 8 ohms"This is an indication of rms watts Class-A/B "Power Consumption: Low Bias Mode - 300 Watts"This is the "power consumption", not the Class-A bias "Power Consumption: High Bias Mode - 800 Watts"This again is the "power consumption", not the Class-A bias If this amp had the Class-A bias you think it has it would be the size of a house!! Here is an example of what heat sinks are needed to have just a 25w Class-A mono block amps with nothing over 25w (no Class-B at all) if it were say 50w of A/B the "heatsink area" for the same 25w of Class-A would more than double. They are the famous 25w Class-A Mark Levinson ML2 monoblocks, but that’s all they had 25w!!!! https://ibb.co/d6zvmMR Cheers George |
They actually do say 300wpc in Class A George. The amps also have a bias switch and the manufacturer states they provide 200 wpc in Class A when the switch is in the low bias position. The Clayton Audio M-300’s are high current differential True BalancedTM amplifiers using class A design in both the driver and output stage. All gain transistors are operated in their linear region for the smoothest, purest sound reproduction.They run very hot. |
Not with the way those heatsinks are arranged, and they don’t say 300w Class-A. They say 300w into 8ohms which will be a/b with a few watts of Class-A bias. Again power consumption is rated at 300w, big difference to how much Class-A bias is on them. M300 - 300 watt monoblocks Cheers George |
This was a sales marketing error!! The 125wpc is draw when at idle. So true as I explained above, MF have a habit of doing this, so do many others it needs to be shut down,claims of large amount of Class-A bias on A/B amps with heatsinks too small for what they claim. Also there's a practice of wattage doubling for each halving of load impedance (EG: 8ohms100w, 4ohms 200w ect ect) many do this by first understating the 8ohm wattage so the 4ohm looks like it's doubling. Cheers George |
Hands down that would be the Krell Duo 300 iBias. Delivers 300 watts Class A power but without the heat typically associated such beasts. And only draws like 2 or 3 watts in standby! It’s a wonderfully sounding amp that at last Look was $9,500. But there are dealers out there who will work magic in trades to net it down. It would be my top choice for the money. I have two of them. |
mikethehunterguy Sorry Mike impossible, a 400w Class-A/B amp with 125w of Class-A bias would have to have heatsinking 10 x more of what they have on this. At a guess that heatsink with the rail volts needed for 400w a/b, could accommodate at most around 20-30watt of Class-A, without any serious fan forced cooling. As the rail volts go up for more A/B wattage, the Class-A heat factor to be dissipated goes up exponentially for each watt of class-A I built a 200w A/B amp that had 150w of Class-A bias, the only way was to water cool it. It was the size of a coffee table, and a 2 man lift. Cheers George |
These might be hard to find used, but great amps! Power for days! 125wpc Class A. 400wpc AB. A great value that disappeared all too soon. http://www.aragonav.com/palladium-1k-klipsch |
Sure, If you really want to rock find a pair of Parasound JC-1s. First 25 to 50 watts are class A then there is another 300 watts in reserve just in case you want to get Gary Clark Jr's volume right. These amps spent 15 years on Stereophile's recommended list. Longer than any single component in history. There are very few amps that can match the effortless power these amps provide and yet still have the airy lightness of a tube amp. And as a bonus they can drive anything. Only amps costing 3-4 times as much can compete. |
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Gryphon Antileon Evo monoblocks 175w Class-A, I believe will trump all others https://gryphon-audio.dk/shop/power-amplifiers/antileon-evo-mono/ Then if you don't have the funds for them you get the Antileon Evo stereo, with 150w Class-A https://gryphon-audio.dk/shop/power-amplifiers/antileon-evo-stereo/ And then Mephisto and Colosseum and so on https://gryphon-audio.dk/wp-content/uploads/2018/10/Technical_Specifications-4.pdf Cheers George |
