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In Reply to: RE: N core posted by cawson@onetel.com on January 21, 2018 at 04:53:12
It's described very inaccurately as digital! It's plain ol' Class AB with a Class H rail. Its main difference with conventional amps is that it uses feedforward (distortion cancellation) in addition to feedback:
"The AHB2 is a linear amplifier that surpasses the sonic purity of all class-A amplifiers. No amplifier delivers lower noise or lower distortion. The small, passively cooled chassis, cleanly delivers 480 Watts bridged mono into 6 Ohms, with additional reserves for driving difficult speaker loads. Unlike power-hungry class-A amplifiers, the AHB2 achieves a power efficiency that rivals that of a Class D (switching) power amplifier."
https://benchmarkmedia.com/products/benchmark-ahb2-power-amplifier
In practice, it doesn't sound like the Class D amps I've heard.
Anyway, to me the question is does it really suck the life out of music? Because the absence of distortion doesn't do that for me. As someone said, live acoustical music has plenty of life into it, and no distortion whatsoever.
When I first got it, I level matched it and tried ABing it with my A-21. It seemed better in almost all respects. I've never heard such pure sound. And this was compared to a low distortion, high bias AB design that's mostly operating Class A.
So I guess the question Davey and others had (and I do too) was whether you were complaining about the absence of euphonic distortion or something else.
When I listened to piano through it, the transients and envelope of the AHB2 seemed off. The A-21 was far better (in all fairness, it's been reported to outdo even Pass in that one respect). It sounded like an actual piano, something most amps I've listened to don't do.
I asked John Siau about that at AES and he attributed the difference in sound to lower harmonic distortion, to which he says piano is very susceptible.
Anyway, the AHB was then out of my system for a while while I worked on other things and when I plugged it back in I got a rude shock because it seemed to be doing exactly what you said it did -- suck the life out of the music. What was missing were the transients. As with the piano, they seemed to be rounded off. That's why I was interested in what you wrote because you had apparently observed independently the same thing that I had.
I still have to do more listening, though. The Benchmark isn't supposed to require burn in but I hadn't used it for a while so I'd want to rule that out, and I'm using a more revealing DAC and did some major repairs on my speakers. Also the amps weren't level matched. So I want to do more long-term listening to make sure that I wasn't fooling myself.
I'm not really interested in the technology of amps, nor much their specs regarding matters beyond my low interest level! I just want the things to provide music that really excites - the nearest SENSATION to live music, whether there's a bit of distortion or not. SETs have high harmonic distortion, but they are the ones that make the sound so good.
I had my Benchmark for about 8 weeks although I was away for a couple of weeks. It was used quite a lot during that time and I listened to it exclusively before doing any comparison tests. I wrote my one and only equipment view here - http://db.audioasylum.com/mhtml/m.html?forum=amp&n=205426&highlight=benchmark+ahb&search_url=%2Fcgi%2Fsearch.mpl%3Fforum%3Dgeneral%26searchtext%3DEmotiva
I presume your A-21 is a Sugden. After I returned the Benchmark, I tried many power amps including Sugden FPA-4, Accuphase A-36, GamuT D200, Quad Platinum, NAD M32, Micromega M100.
I would have loved to find the Accuphase in particular provided the sound I wanted. It is Class A and so beautifully built, with very good controls and facilities. It was certainly a step up compared with the Class A Sugden, but not such that I'd keep it in favour of my old 845-based SET monoblocs.
The Quad was a big disappointment, but the Gamut was wonderful. For a while I was using this D200 fed by NAD M12 digital preamp and was very happy. When I home demo'd a NAD M50.2 CD player / CD ripper / hard drive music store / streamer I was offered the loan of a NAD M32 integrated amp. To my surprise this equals the much more costly M12 + D200 combo. Now this arguably a digital amp, although not so according to NAD's white paper attached - the M32 uses an updated version of the M2's processor. It's effectively a "DAC that can power speakers". Whatever its technology, it really is an excellent amp and FAR more enjoyable than the Benchmark. It's considerably better than the Quad and Sugden (and Red Wine) and marginally better than the Accuphase. It's advantage over the M12 + D200 combination is solely cost and reduction of cables.
I love it and the M50.2 that I bought recently. That's all I need. I now need no CD player as the M50.2 plays CDs, no PC to rip CDs, no NAS to store files, no radio and no streamer, as the M50.2 does all of these things. I have one digital AES/EBU cable and one pair of speakers - that's it! Peter
A-21 is a Parasound. Nice amp overall, high bias class A smoothness and free of most bipolar grain, but it has some flaws, namely flabby midbass (which actually sounds quite nice), less definition and soundstage precision than some of the very best, and highs that aren't the last word in cleanliness.
I confess I'm not personally fond of amps that add harmonic distortion. They sound syrupy or grainy to me, and I find both effects fatiguing (the latter far more than the former). What I love about the old tube stuff is that it was usually so free of unpleasant distortion. Yes, it rounded off the sound, but it lacked the harsh distortion one so often hears from solid state and for me that meant a much better listening experience.
So really, I prefer the absence of unpleasant distortion to the presence of pleasant distortion, and that for me accounts for a lot of the difference, not the presence of the euphonic coloration which is a drawback. I was listening to a 1950's mono recording of Duke Ellington mentioned in TAS the other day and it was wonderful. So much closer, despite the limitations of the technology, to what one actually hears at a live performance than the typical commercial release. Not I think because of the euphonic colorations, but because of the absence of non-euphonic ones!
For me, the Benchmark does that beautifully. For example, high notes like triangles are pure and bell like, while the same notes listened to through the A-21 sound more like a chuff of noise. And it does it without any syrupy coloration. It's the purest amp I've ever heard.
It's the dynamics that bother me, and I'm still not entirely sure about that -- as I said, I have to do more listening. But that for me is what robs the music of life.
Add in no to very little jump and mine would shut off on high dynamic passages ....
Really? Protection circuits? I haven't had that happen yet, thankfully.
I was operating them on a low-z load. never had it happen on 4 ohm maggies, they did on the 2/3 ohm Diva's.
Regards
Edits: 01/24/18
Heh, yes, I can see that happening. At AES, John Siau told me how delighted he is with how reliable the AHB has been in the field. It seems they've got a microprocessor in there monitoring everything from output current to what you ate for lunch. But I guess that rules out of seat-of-the-pants scenarios . . . good to know, since it means I can't drive my 2 ohm ribbon without the resistor in series . . . I have a feeling that when I triamp, the AHB2 is going to live on the ribbon, since its highs are so stunningly pure.
I think we're on the same wavelength on this. I possibly dwell less on the technology and just get on with listening to the sound I hear. To me (as you'll notice if you read my review), I was inclined to turn down the volume and maybe forward to the next track with the Benchmark, but to turn up the volume with the valve amps. To me that's a pretty useful pointer as to one's enjoyment of what one's hearing! At that time I had no other SS amps apart from the unsatisfying Red Wine.Since Sugden have been selling various versions of their well regarded A21 23 watt Class A amp, I rather assumed you were using Sugden. The Parasound is a much more powerful AB amp (first 7.5 walls Class A?) and I know nothing of it apart from what I see on their website.
My speakers are 102dB so I really only need a handful of watts, but I've found that more powerful high quality amps add significantly to the depth and control of bass. I noticed this most with the Gamut D200 - an old design with single MOSFET per channel. The NAD offers as good performance and I'd recommend you try to get a home demo of the M32.
Since your profile has no system details (I wish everyone would include these details) I don't know what speakers you use or what you feed your amp. The M32 has a DAC built in and has the option of a streamer card allowing access to NAS, PC, Tidal, Qobuz, radio, etc as well as being an integrated amp.
Edits: 01/21/18
You'll have to forgive me, as an old engineer, from being interested in the technical aspects. :-)
The Parasound is IIRC 10 watts of Class A. Which really covers most listening. A well-regarded John Curl design that many consider the beginning of high end amplification and a very popular amp because its economical. I know that I could happily listen to it forever, but it falls short of the very best and more expensive and often less practical (higher power Class A). I think if I could experiment with any amp now it would be a John Curl Class A design but I'm triamping so limited in what I can spend and how much heat and power usage I can tolerate! (Not to mention that my back isn't what it used to be . . . )
I've always been curious about the NAD amps. Would be fun to try. My problem is that there's no dealer here, so I usually hear things only at shows where everything sounds subpar or I have to buy them used or new and try them here, a slow and frustrating process. I bought the A-21 used and the AHB2 new. Most of the used amps I'm interested in checking out now seem to be in short supply, I've been watching the listings.
Apologies for the lack of a profile! My system has been in flux as I rebuilt it after a period with nothing and then a temporary system while we were renovating the house. I really should get around to it.
But basically, it consists of a pair of Tympani IVA's that I bought used and have been fixing up (delamination now repaired, I still have to do some work on the connector panels). I also have 16 Neo-8 planar drivers that I'm going to use to replace the Magnepan midrange, Satie here came up with that mod and by all accounts it's a dramatic upgrade to the old Maggies.
So anyway my plan is to tri-amp but I have to at least bi amp because as you can see in the photo my small listening room and the projection screen require me to move the two mid-tweeter panels in front of the four bass panels, so I have to delay them so everything will be in time:
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To do the delay, I got a MiniDSP OpenDRC DA-8, which has SPDIF in and eight channels out. That will also let me experiment with FIR filters and phase and frequency compensation and room EQ. But I'm not sure I'm happy with the sound of the MiniDSP, I have to do more comparisons but in the brief ones I did it didn't equal my other converters.
For my source, I built an HTPC that's both silent and powerful -- fanless power supply and graphics card, SSD's, sound damping case, humongous and therefore quiet fan on the processor:
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:-) I've been delighted with the results, you can't even tell it's on from more than a foot away and yet it uses a fast processor that will do any processing I want (I have a projector and my room does double duty for home theater so I couldn't go with a minimal configuration). Running JRiver for audio and video and Tidal's app for streaming. I have a Dragonfly Red that I've been using to experiment with MQA since I don't have a real MQA DAC.
Anyway, I needed a solid source of SPDIF for the MiniDSP and everything I read put the Lynx E22 at the top of the heap so I got one on Ebay. Since then, though, I've been experimenting with the analog outputs of the Lynx and they sound better than the Mini DSP. So if the MiniDSP doesn't prove out sonically, I think I'll have to get a multichannel converter. I was thinking either of the ExaSound e28, which has been replaced by the e38, or a pro rack like the Lynx Aurora 8 (which has also been replaced), but as usual have no way to compare.
In the meantime, I've been using the converter on the Lynx card for analog out to the power amp, and I'm finding that as its reputation suggests it's a very capable converter, if not quite the equal of what's available today.
Also have to do some work on acoustics, I have a couple of GIK QRD diffusers but need some absorption and deal with a cavity resonance (which will probably mean building a cabinet in the cavity).
So as you can see, a work in progress! But really sounding quite excellent even as is, with the Lynx feeding the A-21 and driving the Tympanis full range.
So basically I need a couple of small sweet amps for the mid-tweeter panels (the Neo 8's are more efficient than the woofer panels and of course the tweeter doesn't require a huge amount of power) and I can leave the larger A-21 doing bass duty.
Nice .....
Thanks.
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Thanks for the background information.
My present attempts at system upgrade were prompted by my move from a London flat with an acoustically excellent 5-sided room with 10 ft ceilings to my present room of 975 sq ft and 7'7 ceilings. It's less the size than the shape and materials that present problems. It's parabolic in shape (pointed end of an egg-shaped building) with floor-to-ceiling glass on most of the curved wall. Not ideal! The speakers are either side of a central support column facing across the room.
The photo is rather cluttered with test amps and a pair of demo Quadral speakers
My initial thoughts were to look for a better amp and I've described my quest.
Now I'm also looking at possible alternative speakers. I posted something on the Planar section and was contacted by a Quad 2905 owner who lives a few miles away. We exchanged home visits and I was impressed enough to buy a used pair of Quads. They were doomed to be re-sold as these "barn doors" are aesthetically unacceptable in the middle of the room. Maggies would be even worse! So my likely choice is Martin Logan 13A, despite the ridiculous trans-Atlantic mark-up. They are £18.000 here - about $23,500 including taxes.
I'd really like to hear these too - http://blanko.nu/?lang=en - another see-through design but active with tube amps! I'll visit them when in Holland later this year.
Don't Crutchfield offer a free home trial on NAD? If they or someone else did, you may end up buying them - or looking for a used M32 as I did! Peter
Beautiful room! I an see that the acoustics would be a challenge, though.
I wouldn't be surprised if those Blankos sound better than the Logans, assuming of course that they did a good job with the design. The Logans look cool, but they suffer from the hybrid woofers with a high crossover.
Have you considered the Scaenas? I'm thinking that narrow line sources might work aesthetically.
As intriguing as it is, the M32 is more than I want to spend on an amplifier at this point. I may well have to spend $2k on a new DAC before this is done and have dental expenses next month so I was thinking of something in the $1500 range. If my budget were $3K, I'd probably try a Pass XA30.5 next. I've never heard anything less than love expressed towards those amplifiers and it isn't so big that heat, weight, and power consumption become an issue. I think I could get away with the Pass on the midrange because the Neodynium magnet BG line source is a good deal more efficient than the Maggie woofers, and because the Pass is really an AB amp with a super high bias (Class A to 30 watts, which would be 60 watts into 4 ohms, then about 160 watts Class B, and single-ended at low levels).
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