Benchmark AHB2 Power Amp: The Quietest and Cleanest Amp on Planet Earth?

[AJ Soundfield]

The trouble is, if you can't trust your own listening sessions

Well, you can Rich, as they are valid for you under your own listening conditions.
I can't stress enough, blind listening tests can only tell how something sounds.
It most certainly can't predict how something will be "experienced", which goes well beyond sound. Price, street rep, flashing lights (), glowing blue LEDs, etc, etc have a profound effect. I've posted these innumerable times
https://www.pnas.org/content/105/3/1050
And dear to me https://www.aes.org/e-lib/browse.cfm?elib=19405
Should be to Harman dealer Amir, but alas http://seanolive.blogspot.com/2009/04/dishonesty-of-sighted-audio-product.html
etc, etc,

you cant trust honorable reviewers (they exist), you can't trust SINAD, then all that is left is to assume that all products are the same.

- Rich

That's quite a stretch. What it means is that you can trust yourself to choose what suits your entire perceptual experience best.
The poor correlation between 'SINAD", THD, etc to perception most certainly doesn't mean all products sound the same. There are plenty that do...just not based on poorly correlated metrics.

cheers

 

[AJ Soundfield]

Another thing about Amir is he either has, or had some ties to Revel, so it's no surprise that he prefers them.

He does and is hopelessly biased, but lets be clear, the Salon 2 is king of the hill within the paradigm of low sensitivity, forward radiating monopole box speakers...about 99% of the market, until shown otherwise.
At one point anyone could bring on a challenger to the Harman shuffler lab for a fee. Not sure if this still holds true.

cheers

 

[Sonnie Parker]

That is one reason I wanted to try out a pair of Revels... they all get good reviews by so many different publications. I was looking for that neutral speaker (from my other thread) and figured I'd try to find a pair of 208's... no such luck, then figured why not the new 228's.... no such luck, but as luck would have its way, the 328's landed. Who knows... I could have a room full of Revel speakers this time next year.

I really do want to know how the Benchmark AHB2's will fair with the 328's, so I'm going to try my best to make it a point to pair them up.

 

[RichB]

That is one reason I wanted to try out a pair of Revels... they all get good reviews by so many different publications. I was looking for that neutral speaker (from my other thread) and figured I'd try to find a pair of 208's... no such luck, then figured why not the new 228's.... no such luck, but as luck would have its way, the 328's landed. Who knows... I could have a room full of Revel speakers this time next year.

I really do want to know how the Benchmark AHB2's will fair with the 328's, so I'm going to try my best to make it a point to pair them up.

It will be interesting to see how you like these speakers, after experiencing so many.

My brother-in-law bought F206's (maybe 5 years ago). We auditioned and bought them from a local dealer that drove them with a NAD integrated amp. The room was like a giant pillow, rugs, curtains, suspended ceiling, too dead for my tastes. The NAD did not do these speaker justice, it got harsh when turned up.

At home, he had a pair of Outlaw M2200 class-G monoblocks. I liked these amps at modest volume but not when turned up to where the music was in the mid 80s. I bought over a Parasound A21 and level matched and the A21 had no issues at the same volume levels with the tracks we played. He ended up buying an A21.

Now that we are both immunized, I am going to setup a listening session with the MiniDSP to compare the AHB2 to the A21 driving these speakers. He likes it loud and the F208s sound really good in is modest room, 13x15x8.
His system is using an Oppo UDP-105 as the preamp which is a nice solution and has a ML Grotti servo sub which was fairly easy to blend with the F208s without bass management.

Now that I think of it, I may have to bring 2 AHB2s

I am looking forward to your impression of the 328Bes. Maybe it was fate that you meet

- Rich

 

[Sonnie Parker]

I moved all the other posts to their own thread, since they were more about blind testing and to prevent derailing the AHB2 thread.

Blind Testing Amps

My brother-in-law bought F206's (maybe 5 years ago). We auditioned and bought them from a local dealer that drove them with a NAD integrated amp. The room was like a giant pillow, rugs, curtains, suspended ceiling, too dead for my tastes. The NAD did not do these speaker justice, it got harsh...

www.avnirvana.com

 

[RichB]

Just a note, the AT525NC is bit unusual. It is a Hypex NCore amp driven by a linear power supply.
Playing a 0 dBFS sine-wave the power varied (from memory) from 2.72 volts to 2.84, which if my math is correct, .34 dBV. I am not saying that is audible but it is past the accepted .1 dB range.

This is a different amp with its own design goals, efficient, Multi-channel configuration form 2 to 8 channels, transient headroom, etc.
It performs as expected, it does not measure that same and does not have the tolerances of the AHB2.

Some think it is impossible to hear the difference between amps that measure differently. That is a valid view backed by experience, but not my view.

- Rich

 

[AJ Soundfield]

Just a note, the AT525NC is bit unusual. It is a Hypex NCore amp driven by a linear power supply.
Playing a 0 dBFS sine-wave the power varied (from memory) from 2.72 volts to 2.84

Then you have a broken amp or a broken test

 

[RichB]

Then you have a broken amp or a broken test

Because it does not match your ideology.

There is a respected reviewer on this site that has made similar claims.
Thankfully, we have not seen the same criticism directed at him.

For some reason, I don't find our interactions intellectual nor productive.

- Rich

 

[AJ Soundfield]

There is a respected reviewer on this site that has made similar claims.

Links to said statements are helpful

 

[RichB]

Links to said statements are helpful

There are many reviews of the AHB2 that include statements similar to mine.
Google, read them, and derided them to your hearts content.

- Rich

 

[AJ Soundfield]

Just a note, the AT525NC is bit unusual. It is a Hypex NCore amp driven by a linear power supply.
Playing a 0 dBFS sine-wave the power varied (from memory) from 2.72 volts to 2.84

Then you have a broken amp or a broken test

There are many reviews of the AHB2 that include statement similar to mine.
Google read them, derided them to your hearts content.

 

[dlaloum]

I'll be putting them up for sale once I get the Magtechs.

Did the Magtech's ever turn up?

Did you get a chance to compare AHB2 to the Magtechs?

Also - given your penchant for stats.... no history with Quads?

 

[NBPK402]

I figured I would start at the lowest setting and see if it will be loud enough for me, and I suspect it will be. I have it set lower that what my currents amps require right now in the HTP-1, since it has adjustable gain.

When I get the SHD... not sure yet how that might match up.

Years ago I had some ML Sequel IIs and we found out that you can hit a certain power level and it just doesn't get any louder. We found this out driving them with some big Pro amps... I do not know what happened to the power but it did not increase SPL at a certain level, sounded great regardless of how much more power you use...maybe it is the electronics in the bass section?

 

[ddude003]

Years ago I had some ML Sequel IIs and we found out that you can hit a certain power level and it just doesn't get any louder. We found this out driving them with some big Pro amps... I do not know what happened to the power but it did not increase SPL at a certain level, sounded great regardless of how much more power you use...maybe it is the electronics in the bass section?

It is hard to say where the bottle neck would be... My guess would be that the amplifier and the speakers were not matched well given the impedance curve of the speakers (map) verses what the amplifier expects (map)... Most likely squealing high frequencies as the amp tries to double watts and double again as the speakers dive into the sub 2ohm range... The old power paradigm versus voltage paradigm... Or maybe it had to do with the gain structure between the source, preamp and amp...
My MLs and McIntosh are pretty well behaved into ear-bleeding levels... Because Autoformers...

 

[Asere]

Interesting I ran into this thread as I have been eyeing this Benchmark amp recently. I am curious to try it since it is so quiet from what I was told. Currently I have the Parasound HCA 1500A amp powering my Magnepan LRS at 315w @4 Ohms and current capacity of 60 amperes per channel. The Benchmark has less wattage so not sure since the LRS demands power.

 

[ddude003]

@Asere

ASR suggests that the Impedance dips down to 3 ohm at ~500Hz... https://www.audiosciencereview.com/forum/index.php?threads/magnepan-lrs-speaker-review.16068/ Not sure how well that would work out for the Benchmark... You could always contact Benchmark and ask... Also would want a trial period so you could see and hear for yourself in your own Room and the rest of your kit...

It looks like its time to suggest reading this paper http://www.atma-sphere.com/en/resources-paradigms-in-amplifier-design.html
Please read and reread the last paragraph of section 3 The Power Paradigm...

 

[dlaloum]

Interesting I ran into this thread as I have been eyeing this Benchmark amp recently. I am curious to try it since it is so quiet from what I was told. Currently I have the Parasound HCA 1500A amp powering my Magnepan LRS at 315w @4 Ohms and current capacity of 60 amperes per channel. The Benchmark has less wattage so not sure since the LRS demands power.

I don't think it (the speaker) actually requires massive power, it just requires massive current, and an amp that is stable at its low impedances...

Some amps get unstable at low impedances, other amps just run out of "puff" (current).

But if you calculate out using the SPL efficiency specs for the speaker, you will find that you probably don't need massive power.

Having said that, often it is the amps with massive power that are stable into the low impedance loads!! (which reinforces the massive power myth!)

I run my Gallo Reference 3.2's (which drop down to 1.6ohm) with Crown XLS2500 amps capable of 440W@8ohm, 775W@4ohm and 1200W@2ohm - yeah they cope with low impedance loads without any issue whatsoever!!

However my 1980's vintage Quad 606 amps sound pretty much identical to the Crowns.... their spec sheet specifies "unconditionally stable into ANY load" - and the power / impedance chart shows that their capacity is 135W@8ohm, but only 90W@2ohm.... when you calculate the SPL / Voltage equivalences the 90W@2ohm is equivalent to around 22.5W @ 8ohm.... - they sound very good!

So you need to have ENOUGH power to be able to achieve the target SPL in the frequencies that are most difficult (low impedance points / high phase angles) .... taking into account your headroom requirements - and anything beyond that, is never used.

So yes... I have an amp capable of 1200W, in a situation where an amp capable of 90W is demonstrably sufficient...
On the other hand, the XLS2500, cost me only US$250, used.... There is no way I could find an amp capable of handling my speakers properly at that price new.