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Benchmark AHB2 Review (Updated Measurements)

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 7 2.2%
  • 2. Not terrible (postman panther)

    Votes: 6 1.9%
  • 3. Fine (happy panther)

    Votes: 47 15.0%
  • 4. Great (golfing panther)

    Votes: 253 80.8%

  • Total voters
    313

DonH56

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I suspect so. For the past couple of years, I've had both the Benchmark and the NAD C298 and used them almost interchangeably, depending on circumstance. Recently, I used the NAD to review a loudspeaker which I generally enjoyed save for its notably skimpy bass performance <100Hz despite having a 10" woofer in a floor standing enclosure. I did not suspect the NAD but, to be sure, I switched over to the Benchmark and, to my surprise, the bass was restored to a great degree.

After I completed my writing, John Atkinson measured the loudspeaker and found that the speaker's EDPR (equivalent peak dissipation resistance) "drops below 1 ohm between 61Hz and 71Hz, with a minimum EPDR of 0.85 ohms at 65Hz." He says that it represents "a very demanding load for the partnering amplifier."

See full story at: https://www.stereophile.com/content/estelon-aura-loudspeaker
This is an excellent response that highlights several key points:

1. Not all amplifiers sound alike driving all loads (speakers);
2. Output impedance does matter (among other things); and,
3. Speakers can be more demanding than we think.

It also obviates any claims that the Benchmark cannot handle low impedances...
 

anmpr1

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I bought one of these a year or so ago, thinking - rather, hoping - it might be an upgrade on my ancient (but beloved) Nelson Pass-designed Forte 4 ...just 50 wpc pure class A,. I listen to almost exclusively Classical at high-res,... The Benchmark sounded good, but it was ultimately not in the same cosmos as the Forte in all sorts of ways. ...for super-discerning listeners this may still not be the answer.
Speaking of ancient, you should have been there when Steve Zipser, audiophile Illuminatus from the old rec.audio.high-end attempted to identify his expensive Class A Pass amps with an ancient Yamaha integrated.

I think we can be honest in saying that your Forte amp was/is probably not as good as the amp Zipser was using... I mean within the scheme of all things Nelson. But I'm sure your ears are probably better than the Zipser's were back then, and are definitely better than Steve's ears are now (may he RIP)... what with yours being hi-res and super-discerning.

Below is the write up:

__________________________________________

On Sunday afternoon, August 25th, Maki and I arrived at Zipser's house, which is also Sunshine Stereo. Maki brought his own control unit, a Yamaha AX-700 100-watt integrated amplifier for the challenge. In a straight 10-trial hard-wired comparison, Zipser was only able to identify correctly 3 times out of 10 whether the Yamaha unit or his pair of Pass Laboratories Aleph 1.2 monoblock 200-watt amplifiers was powering his Duntech Marquis speakers. A Pass Labs preamplifier, Zip's personal wiring, and a full Audio Alchemy CD playback system completed the playback chain. No device except the Yamaha integrated amplifier was ever placed in the system. Maki inserted one or the other amplifier into the system and covered them with a thin black cloth to hide identities. Zipser used his own playback material and had as long as he wanted to decide which unit was driving the speakers.

I had matched the playback levels of the amplifiers to within 0.1 dB at 1 kHz, using the Yamaha balance and volume controls. Playback levels were adjusted with the system preamplifier by Zipser. I also determined that the two devices had frequency response differences of 0.4 dB at 16 kHz, but both were perfectly flat from 20 Hz to 8 kHz. In addition to me, Zipser, and Maki, one of Zip's friends, his wife, and another person unknown to me were sometimes in the room during the test, but no one was disruptive and conditions were perfectly quiet.

As far as I was concerned, the test was over. However, Zipser complained that he had stayed out late the night before and this reduced his sensitivity. At dinner, purchased by Zipser, we offered to give him another chance on Monday morning before our flight back North. On Monday at 9 a.m., I installed an ABX comparator in the system, complete with baling-wire lead to the Yamaha. Zipser improved his score to 5 out of 10. However, my switchpad did develop a hang-up problem, meaning that occasionally one had to verify the amplifier in the circuit with a visual confirmation of an LED. Zipser has claimed he scored better prior to the problem, but in fact he only scored 4 out of 6 before any difficulties occurred.

His wife also conducted a 16-trial ABX comparison, using a 30-second phrase of a particular CD for all the trials. In this sequence I sat next to her at the main listening position and performed all the amplifier switching functions according to her verbal commands. She scored 9 out of 16 correct. Later another of Zip's friends scored 4 out of 10 correct. All listening was done with single listeners.

In sum, no matter what you may have heard elsewhere, audio store owner Steve Zipser was unable to tell reliably, based on sound alone, when his $14,000 pair of class A monoblock amplifiers was replaced by a ten-year old Japanese integrated amplifier in his personal reference system, in his own listening room, using program material selected personally by him as being especially revealing of differences. He failed the test under hardwired no-switching conditions, as well as with a high-resolution fast-comparison switching mode.
 

Danimacl

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Beautiful amplifier, definitely out of my price range. I think I’d just stick to the newer hypex designs.

I have been suggesting this forever, in my opinion as an electrician whose job in service is essentially just finding and fixing bad connections full time. If people want the best connections between their amplifier and speakers, banana plugs aren’t the best, even if they are convenient. 90% of high power connections which rely on spring loaded metal are total garbage. I personally would choose spades, bare wire under screwed under the binding posts, or ideally speakONs.

The audiophile community eventually figures out that the pro audio community is 10-20 years ahead of us regular consumers. Acoustic treatment, digital audio, shielded cables, digital amplification, balanced connections, DSP, Nuetrik speakONs… the list goes on.
 

pablolie

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Beautiful amplifier, definitely out of my price range. I think I’d just stick to the newer hypex designs.

I have been suggesting this forever, in my opinion as an electrician whose job in service is essentially just finding and fixing bad connections full time. If people want the best connections between their amplifier and speakers, banana plugs aren’t the best, even if they are convenient. 90% of high power connections which rely on spring loaded metal are total garbage. I personally would choose spades, bare wire under screwed under the binding posts, or ideally speakONs.

The audiophile community eventually figures out that the pro audio community is 10-20 years ahead of us regular consumers. Acoustic treatment, digital audio, shielded cables, digital amplification, balanced connections, DSP, Nuetrik speakONs… the list goes on.
I'd just say bananas are super easy. But yeah, plug and unplug them a lot and you'll wear them out... unless they are the locking kind. I use locking banana as well as spade connectors on either side of my main cables.
 

beagleman

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This is an excellent response that highlights several key points:

1. Not all amplifiers sound alike driving all loads (speakers);
2. Output impedance does matter (among other things); and,
3. Speakers can be more demanding than we think.

It also obviates any claims that the Benchmark cannot handle low impedances...
Not saying you are wrong, but amplifiers to not make any sound. just semantics....:)

I think you mean, not all speakers sound "the same" when driven by different amps, when impedance is crazy low or odd.
 

DonH56

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Not saying you are wrong, but amplifiers to not make any sound. just semantics....:)

I think you mean, not all speakers sound "the same" when driven by different amps, when impedance is crazy low or odd.
I went with the usual audiophile verbiage when discussing amplifiers. I am an engineer, grammar and such ain't my thang. If I (or you) were to nitpick everything I said we'd have a lifetime of work ahead (and behind) us.
 

beagleman

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I suspect so. For the past couple of years, I've had both the Benchmark and the NAD C298 and used them almost interchangeably, depending on circumstance. Recently, I used the NAD to review a loudspeaker which I generally enjoyed save for its notably skimpy bass performance <100Hz despite having a 10" woofer in a floor standing enclosure. I did not suspect the NAD but, to be sure, I switched over to the Benchmark and, to my surprise, the bass was restored to a great degree.

After I completed my writing, John Atkinson measured the loudspeaker and found that the speaker's EDPR (equivalent peak dissipation resistance) "drops below 1 ohm between 61Hz and 71Hz, with a minimum EPDR of 0.85 ohms at 65Hz." He says that it represents "a very demanding load for the partnering amplifier."

See full story at: https://www.stereophile.com/content/estelon-aura-loudspeaker
You would think for $20,000 they would have an actual speaker engineer that understands impedance and so on, but .85 EPDR and also having 18 ohms in the upper ranges, shows that very little thought was put into the actual engineering.

I know there are some lower impedance speakers on the market, ((As a former owner of Infinity Kappa 9s)) but that is a design flaw, or lack of engineering for sure.
 

Mike-48

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What do you think about this review ?


Do you know guys where I can find reliable measurements about the Bryston 4B Cubed so I can compare ?
My comments are completely subjective. Those who object to that, I suggest read no further.

I had the Bryston and Apollon (PuriFi 1ET400A) amps at the same time. I had owned the Bryston for a couple of years (and was happy with it) but bought the Apollons on spec during early days of the COVID pandemic as a birthday present to myself. I listened to each for weeks, back and forth and back again. I found them very difficult to distinguish from one another, not at all the big difference reported by the cited review. Finally, I concluded the Apollon 1ET400 might sound very slightly cleaner in the highs, so I sold the Bryston. Can I swear I picked the "better" amp (whatever that might mean)? No. I can say I haven't regretted the switch, that I don't think I lost anything by it.

To complete the comparison, I had the AHB2 in my system for an afternoon visit by a friend who owns one. Again, I found it difficult to distinguish from the Purifi-based competition. I didn't hear irritation or lack of power from either product. I think that both are excellent. I would recommend either of these lightweight amps to anyone, and if I were buying today, I'd probably choose the Benchmark for its ability to be repaired by the established US manufacturer. I am less certain of the value proposition of the Bryston, though I am convinced it is a fine audio amplifier.
 
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Gringoaudio1

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Next thing? We all know the landing was to be faked, that NASA commissioned Kubrick to direct the propaganda footage, and that he insisted on filming on location. The rest is history.
If you and all the people who liked this are serious then I will no longer spend any more of my time here with you fools.
 

anmpr1

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... if I were buying today, I'd probably choose the Benchmark for its ability to be repaired by the established US manufacturer. I am less certain of the value proposition of the Bryston, though I am convinced it is a fine audio amplifier.

Bryston has always been considered a reliable purchase. Their comparable amplifier is the 2.5b. Five large (USD) for the Canadian amp. Support-wise, Benchmark gives you five years of warranty, which is pretty good. Better than most. Bryston gives you 20 years-- probably the best in the business. Warranty is however dependent upon the company being there when you need it. Recall how the ReVox A77 came with a 'lifetime' warranty card (sans belt and heads).

By comparison, a company that has been around forever, McIntosh, will sell you their more or less comparable MC152 ($5,500.00) with a three year warranty. Of course for your extra McCash you get more in the cosmetic department, which could be the deal breaker, depending.
 

restorer-john

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It also obviates any claims that the Benchmark cannot handle low impedances...

Yes and no. We really have no idea what sort of levels @Kal Rubinson was pushing through the AHB-2/Estolon Aura combination and consequently what current demands were being made (or not).

I mean, you can run just about any amplifier into a <1R loudspeaker at a low(ish) level and not trip a protector/blow a fuse or bake a set of OPTs. With the Benchmark, it's a case of how high the demand is, for how long- transients are not an issue- continuous demands in BTL will shut it down fast.

But I do agree with all your points Don. The Estolon seems to have a rather extreme narrow range where the load is a bit difficult, but there's been plenty of loudspeakers worse in that regard and plenty of amplifiers that would take such a load also in their stride.

I am interested in exactly what was happening with the NAD vs the Benchmark as both are capable amplifiers. It would be very interesting to investigate wouldn't it?
 

pogo

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For the past couple of years, I've had both the Benchmark and the NAD C298 and used them almost interchangeably, depending on circumstance. Recently, I used the NAD to review a loudspeaker which I generally enjoyed save for its notably skimpy bass performance <100Hz despite having a 10" woofer in a floor standing enclosure. I did not suspect the NAD but, to be sure, I switched over to the Benchmark and, to my surprise, the bass was restored to a great degree.

After I completed my writing, John Atkinson measured the loudspeaker and found that the speaker's EDPR (equivalent peak dissipation resistance) "drops below 1 ohm between 61Hz and 71Hz, with a minimum EPDR of 0.85 ohms at 65Hz." He says that it represents "a very demanding load for the partnering amplifier."
This was to be expected, as the AHB2 does not control the woofers as well as the C298. This shows the tendency with lower impedances:

Damping Factor at 4ohm (63Hz/1kHz/14kHz)
AHB2: 48/45/19
C298: 833/769/559
Source: stereo.de

The reactive load tests of the AHB2 and the M23 (with high probability similar for the C298) also indicate this.
 
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restorer-john

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Bryston has always been considered a reliable purchase. Their comparable amplifier is the 2.5b. Five large (USD) for the Canadian amp. Support-wise, Benchmark gives you five years of warranty, which is pretty good. Better than most. Bryston gives you 20 years-- probably the best in the business. Warranty is however dependent upon the company being there when you need it. Recall how the ReVox A77 came with a 'lifetime' warranty card (sans belt and heads).

By comparison, a company that has been around forever, McIntosh, will sell you their more or less comparable MC152 ($5,500.00) with a three year warranty. Of course for your extra McCash you get more in the cosmetic department, which could be the deal breaker, depending.

Bryston, McIntosh and Benchmark. Doesn't get much better for made in the USA amps does it?
 

anmpr1

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Bryston, McIntosh and Benchmark. Doesn't get much better for made in the USA amps does it?

For the 'mainstream', probably not. Of course there is Boulder, whose 'baby' amplifier (comparable to the AHB2/2.5b/MC152) is $25,000.00. And from there their the prices skyrocket.

Boulder began by selling 'reasonably' price gear--circuits based on Deane Jensen's 990 'discrete op amp', but somewhere along the line the company decided they had to play in an altogether different ball park.
 

anmpr1

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Not a joke, I knew a guy who believed the moon landing was faked by Hollywood. This was back in the 1970s and he was old, dead now but there are some who still believe this.

It's like Jesse Ventura always said--People think that pro-wrestling is fake, but the real fake sport is baseball. Haven't you ever wondered why the inning ends right when it's time to air the commercial?
 
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