JSmith
Master Contributor
Is it?
Benchmark AHB2 Power Amplifier
Benchmark's new AHB2 Power Amplifier - "The Quietest, Cleanest Audio Amplifier on the Planet"
JSmith
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Class A/AB vs D -- Is it Audible in 2021?
- Thread starter watchnerd
- Start date
JSmith
I was talking about the Devialet ...Is it?
Benchmark AHB2 Power Amplifier
Benchmark's new AHB2 Power Amplifier - "The Quietest, Cleanest Audio Amplifier on the Planet"benchmarkmedia.com
JSmith
The AHB2 is an AB/H ... and a very good one...
Would be interesting to get some lab test measurements on the Devialet to compare to the AHB2 - two different takes on the FeedForward principles.... and then add a Quad Artera to the mix
JSmith
Master Contributor
Well my 3 way Gallo Reference 3.2... are an example of the difficult genre...
Nominally 6ohm with a difficult tweeter and woofer load.
Some have run them with low powered valves and had great results (6moons) - on the other hand, those valve designs often have high current capabilities.
My own experience with them started out with a high powered Onkyo AVR (140W@8ohm for 7 chn, 170W@8ohm stereo) - it sounded good! - but for the hell of it, I decided to try out my spare power amp - a Quad 606.... unconditionally stable into any load... not huge on currrent though, rated at 140W@8ohm... swapped it in, swapped it out, listened for a few weeks to the AVR, then a few weeks on the Quad - yep the Quad sounded better... not by much... it just felt like the high end was a little smoother, the midrange a touch more detail - the preference was consistent over some months of periodic swapping.
I experimented with BiAmping the speakers using the AVR's internal amps.... didn't seem to make a difference - experimented with BiAmping using 2x Quad 606 - again, no substantive improvement.
Anthony Gallo used to demo these speakers using a 500W@8ohm Class D amp... I had nothing like that available and the Spectron Musician that Gallo had used was outside my budget.... but then word started spreading about the Crown XLS pro Class D amps.... some swore by them, others claimed they made no difference (or worse... issues with hiss, fan noise etc...) - on the other hand at $300 for an XLS2500.... I got two of them to try out with BiAmping - worst case I could flip them without much loss.
These didn't quite match the Spectron... but manufacturer ratings of 440W@8ohm and 1200W@2ohm seemed indicative of an amp that would not break a sweat with difficult loads...
First attempt just using a single XLS in stereo mode driving my speakers, was an immediate success - the same improvements I heard moving from the AVR internal amps to the Quad amps, were magnified - taken a notch upwards. Was it a huge, paradigm shift change... no... but it was audible, and repeatable - I then swapped amps over a period of over a year, giving myself at least a month between changes to see what was what.
The Class D Crowns were my preference every time, consistently. My ranking was consistently Crown XLS>Quad 606>Onkyo 876.
Could I live with my lowest ranked option - yes, easily, and when we moved and had disarray, and a newborn - the additional cabling, complexity, racking, space etc... made me stick with the 876 on its own for a couple of years.... But the Crowns are back in the system now... they do sound better (and even better with BiAmping and Dirac!) .
The flaws that some people found with the Crowns I have never heard - No audible hiss (I wonder whether some peoples pre's and the Crowns gain were mismatched... - I keep the gain on the crowns at around 75%, no higher) - I've never heard the fans turn on either.... not surprising, as in my use, they barely idle - the first led on the meter lights up, the 2nd barely flickers when things get very loud and dramatic... I've never seen the third LED light up at all... let alone the fourth "clip" LED. (First LED is "Signal" 2nd is -20db, 3rd is -10db -which I have never seen, 4th is the clip indicator)
So to finish my war & peace novel here - yes audible differences - in this case a Class D design gave me the best results, I feel sure that if I had a Class AB amp of similar current/low impedance capability, I would get similar results.
Just for the hell of it I calculated the 8 ohm equivalent power of the LED's on my Crowns:
Red LED / Clipping 440W SPL with 86db/wm = 112 db
-10db LED 50 W 102 db
-20db LED 4W 92 db
Signal LED ?
So under normal circumstances I seldom use more than 4W (92db) - and never use 50W (102db) - although given I am not focusing on the meters during dramatic moments... it is possible that I missed the occasional peak !
Red LED / Clipping 440W SPL with 86db/wm = 112 db
-10db LED 50 W 102 db
-20db LED 4W 92 db
Signal LED ?
So under normal circumstances I seldom use more than 4W (92db) - and never use 50W (102db) - although given I am not focusing on the meters during dramatic moments... it is possible that I missed the occasional peak !
JSmith
Master Contributor
Probably these meters may not in all circumstances be fast enough .
Thanks for pointing that out!
Scanning through the associated thread, it seems a very contentious brand... however these are very good test results.... but the AHB2 is still an order of magnitude better....
I wander where the Quads sit in this hierarchy...
Another thought - the Quads are a relatively simple design, the Devialet and Benchmark are much much more complex designs... seems the old 80/20 rule may apply here too.... you get 80% of the performance for 20% of the effort.... then that last 20% takes 80% of the effort... diminishing returns!
There is this one:
Devialet Expert 200 Amplifier, DAC and Streamer Review
This is a review and detailed measurements of the Devialet Expert 200 Amplifier, DAC, Phono premaplifier and wired streamer. It seems to be a generation behind the current products offered by Devialet. The Expert 200 cost US $9,650. The Devialet line of amplifiers made quite a buzz when...
www.audiosciencereview.com
- Rich
It is also an integrated amp, so that may involve some tradeoffs as well, or maybe they figured that was good enough for the purpose.
I'm just glad Devialet fixed it after the initial testing disaster!
I find the whole Class D vs AB debate interesting. On the one hand there are those that are absolutely adamant Class D is the new all conquering tech that will pummel “ old school “ Classes into oblivion and those that equally are adamant Class D sounds too clinical ( lets not even mention those that think all amps sound the same, yeah, right, and all cars must drive the same given they all have 4 wheels right?)
I don't subscribe to either view, I simply think they go about what they do in very different ways and therefore appeal to very different people.
I bought a very well regarded Purifi amplifier earlier in the year from March. Specs of course unbelievable. Build great. Couldn’t “ technically” fault this amplifier. Only one problem, it didn't engage me and instead had me critiquing everything not listening.
I sold it within weeks. I recently bought an outdated, massive, heavy, inefficient obscure brand ( April Music Stello Ai-500) that I am sure would not stack up technically in any way vs the March ( bar current output) and despite it being the big block V8 to the March’s more powerful and efficient EV (a mere 300wrms 4ohm vs 420wrms) just like the EV can’t beat the emotion of said V8, I found the Stello more involving, and it makes me just want to listen and stop critiquing.
So, just like the demise of the V8 is inevitable to make way for more efficiency, better specs and lower production costs (when our choices cease to be our own) I’ll just enjoy whatever Class makes me listen more till the end of my days.
I don't subscribe to either view, I simply think they go about what they do in very different ways and therefore appeal to very different people.
I bought a very well regarded Purifi amplifier earlier in the year from March. Specs of course unbelievable. Build great. Couldn’t “ technically” fault this amplifier. Only one problem, it didn't engage me and instead had me critiquing everything not listening.
I sold it within weeks. I recently bought an outdated, massive, heavy, inefficient obscure brand ( April Music Stello Ai-500) that I am sure would not stack up technically in any way vs the March ( bar current output) and despite it being the big block V8 to the March’s more powerful and efficient EV (a mere 300wrms 4ohm vs 420wrms) just like the EV can’t beat the emotion of said V8, I found the Stello more involving, and it makes me just want to listen and stop critiquing.
So, just like the demise of the V8 is inevitable to make way for more efficiency, better specs and lower production costs (when our choices cease to be our own) I’ll just enjoy whatever Class makes me listen more till the end of my days.
Yes, LISTENING is the main point, hence I don't do much comparison test. I'd amend your statement to "enjoy whatever AMP makes me listen more" as I don't believe amplification class automatically means anything. Nor that a V8 is always better than another engine (though I loved my 5.0s! And an AMG E63 wagon I was test driving for a while, wheeee AND 23mpg). Or that direct drive is better than belt drive and on and on and on and on...
True. Wording could be better. I didn't actually say a V8 was always better than another engine however, yes I prefer my V8 over other engines but this analogy was more in relation to emotion and that efficient and highly specced isn't always a better thing ( my old school Audi V8 sounds dramatically better than the wheezy v6 twin turbo they replaced it with for example and the "no sound at all" Ev's, the later two leave me cold no matter their efficiency, the former makes me wind the window down ). I guess my point was not to get too hung up on amplification Class this and that and the next but whatever makes you kick back and enjoy is the best for you.
Cheers
When comparing class AB and in general I think output headroom should not be forgotten.
Typical budget/value class D like the popular offerings from aiyima/fosi typically have equal sustained and peak output (Watts)
My old AB HK receiver also outputs 80W sustained but delivers far more (like 1200w?) during short peaks.
Since music is dynamic my logic tells me higher unclipped peaks is better (when listening loud)
Dynamic headroom probably depends more on the power supply than amp typology but weak powerbricks are far more common with class D amps.
Typical budget/value class D like the popular offerings from aiyima/fosi typically have equal sustained and peak output (Watts)
My old AB HK receiver also outputs 80W sustained but delivers far more (like 1200w?) during short peaks.
Since music is dynamic my logic tells me higher unclipped peaks is better (when listening loud)
Dynamic headroom probably depends more on the power supply than amp typology but weak powerbricks are far more common with class D amps.
A bit late to this thread.
Can I just say (with usual qualifiers - competently designed - yada yada yada):
"no"
or at least:
"not in 2023"
Can I just say (with usual qualifiers - competently designed - yada yada yada):
"no"
or at least:
"not in 2023"
Required headroom for your system should always be a consideration. Determining your maximum power needs should help drive your choice of amplifier.
Class D amplifiers typically have regulated supplies. Modulating the power rail can cause distortion, but historically regulation has been very expensive, so few A or AB amplifiers had (have) regulated power rails. Thus equal sustained and peak power ratings can be a pro and not a con.
I doubt the 1200 W number but one could as readily argue that the HK's power supply and/or output stage (current and cooling capacity) are woefully inadequate for the continuous and peak ratings to be so far apart. Class D has enabled fairly inexpensive high-power amplifiers, unlike decades ago when 10~20 W/ch receivers were common and 200 W amps almost unheard of. The ability to buy an amplifier rated for continuous power at the loudest level you listen means dynamic headroom (a term rarely defined adequately) is irrelevant. Even back in the day, dynamic power was mostly a marketing ploy to cover a marginal design.
So you can buy an 100 W/channel receiver with perhaps 2-3 dB of headroom yielding perhaps 200 W peaks for transient bursts. Or a 200 W amplifier (of any class) capable of deliver that much power sustained over long periods of music and movie scenes.
High dynamic headroom implies the voltage rails sag when higher power is drawn, so they can only sustain high output for a very brief period. Or thermal management is inadequate for sustained higher output, leading to output (etc.) device failure. Those are the main factors in limiting long-term power output that I have seen, no matter the amplifier class. I have not seen evidence of "weak powerbricks" being a common problem with class D amplifiers, but I have not spent a lot of time researching the issue.
The FTC cracked down on power ratings many years ago to prevent unsupportable dynamic power ratings. Guidelines have relaxed somewhat, but even so choosing an amplifier with high dynamic headroom is simply one choice and trade among many. And is unrelated to amplifier class of operation. There is a fairly wide range of power specs even for class D amplifiers, often related to thermal management rather than power supply regulation, some class A/AB amplifiers with tightly regulated supplies and low dynamic headroom, and all sorts in between.
Roland68
Major Contributor
You mean more like 120 watts of short term pulse power.
With its top amplifiers, HK often specified a 50% higher pulse power at 4 ohms (80W -> 120W), but this was not achieved in the various laboratory tests either.
1200W pulse power (at nominal 80-100W) belong in the fable area of the audio world and were used by dubious companies for marketing. I haven't seen such dishonest statements from HK in the last 40 years.
I recently replaced a 25 years old onkyo integra stereo amp with a fosi BT20A pro.
At low volume the difference I can detect is a faint hum with the old onkyo. But it's so low that I can only hear it with my ear near the tweeters.
But at high volume the old onkyo sounds better. I would describe the sound as less compressed and with better bass control.
The fosi outputs 2x40W @8ohm (36V powerbrick). The onkyo is rated at 2x80W @8ohm, but one channel is dead so I only used 1 channel.
So I assume the rms power is fairly equal.
Someone in my neighborhood had a 15 year old hk amp for sale. It was cheap and in fine condition. So I bought it and use it to power my subwoofer.
Relieved from the sub duties the fosi sings a lot better with mid and high frequencies.
So I have been wondering why the 1x80 from the old onkyo seemed more powerful than the 2x40 (with identical loads). And dynamic headroom seems the only logical explanation.
I know it could all happen in my head. But after amirms test I had high expectations for the fosi amp and really wanted to love it. And together with the HK amp I actually do like it a lot.
Maybe I'm missing some other explanation as to why the fosi seemed lackluster compared to the old onkyo?
At low volume the difference I can detect is a faint hum with the old onkyo. But it's so low that I can only hear it with my ear near the tweeters.
But at high volume the old onkyo sounds better. I would describe the sound as less compressed and with better bass control.
The fosi outputs 2x40W @8ohm (36V powerbrick). The onkyo is rated at 2x80W @8ohm, but one channel is dead so I only used 1 channel.
So I assume the rms power is fairly equal.
Someone in my neighborhood had a 15 year old hk amp for sale. It was cheap and in fine condition. So I bought it and use it to power my subwoofer.
Relieved from the sub duties the fosi sings a lot better with mid and high frequencies.
So I have been wondering why the 1x80 from the old onkyo seemed more powerful than the 2x40 (with identical loads). And dynamic headroom seems the only logical explanation.
I know it could all happen in my head. But after amirms test I had high expectations for the fosi amp and really wanted to love it. And together with the HK amp I actually do like it a lot.
Maybe I'm missing some other explanation as to why the fosi seemed lackluster compared to the old onkyo?
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