Benchmark ABH2 Replacement

[dlaloum]

It’s perfectly possible for amplifiers to sound different, one of them has to be adding audible distortion, which of course you might enjoy.
The Benchmark measurements are exemplary so either the Accuphase is adding or it is just cognitive bias.
Amir has measured the Accuphase 270 which was rather a mixed bag.

Review and Measurements of Accuphase E-270 Amplifier

This is a review and detailed measurements of Accuphase E-270 Integrated Amplifier. It is on kind loan from our friends at Gig Harbor Audio. It is their demo unit so I have to return it on Tuesday. So if you need something else to be measured, ask right away! The E-270 was released in 2017 I...

www.audiosciencereview.com

Keith

The distortion output by an amplifier is directly related to the load attached to it.... put different speakers on any given amp, and the result differs... the possible permutations and combinations are infinite.

Given multiple amps working well within their design/rated performance envelope, they "should" (!) sound the same.

But most high end speakers (more so than mainstream speakers!) trade off things such as ease of drive and/or efficiency in exchange for other advantages - so you will get dramatic dips of impedance and increased phase angles... the things that stress amps... and differing amp designs will "misbehave" differently when they come in contact with such.... making them sound different.

In some cases this can be identified where an amplifier is measured into 1ohm and 2ohm loads... sadly, this is very rare.
Which leaves us in the dark as to what happens (especially in distortion terms) when a specific amp interacts with a difficult to drive speaker.
And the "misbehaviour pattern" could potentially be pleasing with one amp, and disturbing with another... that becomes a subjective evaluation.

In the absence of reliable consistent testing at the extremes of speaker load levels, we remain subject to subjective evaluation..... it is our only available tool - our ears.

I have experienced definite differences between amps on my speakers (which I know dip to 3ohm in the mid bass, and to 1.6ohm in the highs) - the "good" amps - all sound alike (of the ones I have experienced)...

I am surprised to hear of the AHB2 being audibly outperformed - but there are distinct advantages to the type of over-engineering available at the price levels Accuphase lives at....

The Harbeths (based on the impedance phase chart for the 7ES-3-XD - found here: https://www.whathifi.com/reviews/harbeth-compact-7es-3-xd ) is a benign load which either amp should handle with ease.... which leaves the difference between them as a mystery. (confirmation bias is always a possibility, and the accuphase gear is beautiful... where the AHB2 is more "industrial").

 

[dlaloum]

Yet for some reason, Accuphase amps as a breed seem to have a silky velvet kind of 'tone' in the systems I've heard them used in. I don't think it's especially natural, as real-live-instruments, especially brass and drums, can HURT with their intensity, even allowing for the dilution that comes when recording and mixing them, but it's damned alluring...

Irrespective of the 'sound' these amps may or may not add to the proceedings, Accuphase gear LOOKS so beautiful if presented singly (and common as muck displayed in quantity on a trestle table as I saw a few years back at a local show ). We all should know how important 'eye'fi' is to audiophiles, even if they deny it

Anyway, my suggestion would have been to buy another Benchmark amp and bridge them!!! FAR more power available then and still able to drive lowish impedance loads I believe. I love the C7-XD version (hated the previous ones) and again, a change to the current SHL5+-XD (which now sounds like a bigger version of the current C7-XD) might have been something to consider.

I'll put my 'dealer hat' back into retirement now. Enjoy, whatever

Bridging mostly exacerbates the audible issues caused by difficult speakers... it only provides benefits where higher V / W is what is desired, and the speakers are an "easy" load, which even by doubling how hard they are to drive (ie: halving the impedance seen by the amp) - still keeps them well within the amps performance envelope.

I have very seldom come across issues which are related to a lack of power/V in a setup.... especially in this day and age where a 100W amp is pretty much par for the course.... back in the days when man amps were 25W or 50W it was more of an issue!

 

[Joesax]

No keep them if you enjoy them and aren’t looking for something better or interested in spending money. It’s an excellent amp.

 

[KellenVancouver]

So why the replacement? Well I bought new speakers. Then decided to get a dedicated streamer which led to a new DAC...

Pray tell, which dedicated streamer did you get? I'm pretty fed up with Node 2i (BluOS a pain) so hoping you'll share what you switched to and reasons. Thanks!

 

[Joesax]

I listed my new system in a previous post. The Streamer is the Aurender N20.

 

[Joesax]

Oh reasons. Well it is my first dedicated streamer. Was using my MacBook before. Why this one? Many reasons.

Aurender Streamers to my ears sound very refined. Plus they have a variety of connection options and pay very close attention to isolating the internal components from each other and reducing noise which improves the sound. They also accept up to two internal SSD drives I believe up to 4 or 8 TB each. I use a single drive to store all my ripped CDs. So it’s a server as well. Finally they have excellent clocks or as with the N20 the ability to accept and sync with an external clock which is what I do. I sync with the Femto Clock in the MSB DAC. That made a noticeable improvement to the SQ. Finally I liked their Conductor app and the overall build quality. The unit itself weighs 29 pounds so it is solid piece of equipment.

 

[TLEDDY]

Oh reasons. Well it is my first dedicated streamer. Was using my MacBook before. Why this one? Many reasons.

Aurender Streamers to my ears sound very refined. Plus they have a variety of connection options and pay very close attention to isolating the internal components from each other and reducing noise which improves the sound. They also accept up to two internal SSD drives I believe up to 4 or 8 TB each. I use a single drive to store all my ripped CDs. So it’s a server as well. Finally they have excellent clocks or as with the N20 the ability to accept and sync with an external clock which is what I do. I sync with the Femto Clock in the MSB DAC. That made a noticeable improvement to the SQ. Finally I liked their Conductor app and the overall build quality. The unit itself weighs 29 pounds so it is solid piece of equipment.

If, perchance, you still have the Benchmark amps, I would be interested in purchasing them!

Tillman

 

[Joesax]

I only have one and I just listed it for sale on US Audiomart 2 days ago.

 

[DSJR]

Bridging mostly exacerbates the audible issues caused by difficult speakers... it only provides benefits where higher V / W is what is desired, and the speakers are an "easy" load, which even by doubling how hard they are to drive (ie: halving the impedance seen by the amp) - still keeps them well within the amps performance envelope.

I have very seldom come across issues which are related to a lack of power/V in a setup.... especially in this day and age where a 100W amp is pretty much par for the course.... back in the days when man amps were 25W or 50W it was more of an issue!

I fully accept your musings here, but bridging my amps into a Harbeth-like impedance curve *subjectively* made my similar impedance curve Spendors sound 'more of the same' and in any case, the Benchmark amps I'm certain are less bothered by lower impedances (the C7-XD I doubt drops below 6 ohms anywhere in the audio range).

Again and subjectively, Accuphase amps are characterised by a sweet silky tone that I feel isn't dictated to by the luscious looks. Don't care if it's my brain making it up (I don't think it is, not entirely).

 

[Purité Audio]

David you are just repeating ‘old wives tales’ is there any evidence that Accuphase amps have ‘sweet silky tone’ and if ( highly unlikely) why do they.
This parroting of un digested information has to stop.
Keith

 

[Purité Audio]

The distortion output by an amplifier is directly related to the load attached to it.... put different speakers on any given amp, and the result differs... the possible permutations and combinations are infinite.

Given multiple amps working well within their design/rated performance envelope, they "should" (!) sound the same.

But most high end speakers (more so than mainstream speakers!) trade off things such as ease of drive and/or efficiency in exchange for other advantages - so you will get dramatic dips of impedance and increased phase angles... the things that stress amps... and differing amp designs will "misbehave" differently when they come in contact with such.... making them sound different.

In some cases this can be identified where an amplifier is measured into 1ohm and 2ohm loads... sadly, this is very rare.
Which leaves us in the dark as to what happens (especially in distortion terms) when a specific amp interacts with a difficult to drive speaker.
And the "misbehaviour pattern" could potentially be pleasing with one amp, and disturbing with another... that becomes a subjective evaluation.

In the absence of reliable consistent testing at the extremes of speaker load levels, we remain subject to subjective evaluation..... it is our only available tool - our ears.

I have experienced definite differences between amps on my speakers (which I know dip to 3ohm in the mid bass, and to 1.6ohm in the highs) - the "good" amps - all sound alike (of the ones I have experienced)...

I am surprised to hear of the AHB2 being audibly outperformed - but there are distinct advantages to the type of over-engineering available at the price levels Accuphase lives at....

The Harbeths (based on the impedance phase chart for the 7ES-3-XD - found here: https://www.whathifi.com/reviews/harbeth-compact-7es-3-xd ) is a benign load which either amp should handle with ease.... which leaves the difference between them as a mystery. (confirmation bias is always a possibility, and the accuphase gear is beautiful... where the AHB2 is more "industrial").

The AHB2s haven’t been ‘outperfomed’ look at their measurements.
There are two possibilities either the Accuphase amps are adding audible distortion which the op prefers or cognitive bias and there is no actual difference whatsoever.
Keith

 

[dlaloum]

Having a glance at both the Benchmark and the Accuphase specs - with the speakers discussed here, I can see no reason why they would sound different.

The Accuphase has a bit more power, and is specced/rated down to 2 ohm - so it has a good solid power supply.

But short of a proper in situ comparison - that is all that I can say.

 

[solderdude]

Accuphase and Benchmark will not sound the same:

Accuphase

Damping Factor 4 Ohm at 63Hz/1kHz/14kHz:

167/142/84

Benchmark

Damping Factor 4 Ohm at 63Hz/1kHz/14kHz:

48/45/19

When I have a 4ohm signal source and short it with 0ohm (only theoretically possible), with 0.02ohm or 0.08ohm there is no real difference in damping current as that is determined by the source impedance (4ohm)

To give an example...(handily forgetting about XO filters and cable resistance)
Suppose the source has a 63Hz tone and produces 1.5V open voltage for instance.
In the ideal case the damping current is 1.5V/4ohm = 0.375A
In the Accuphase case the damping current is 1.5V/4.02ohm = 0.373A
In the AHB2 case the damping current is 1.5V/4.08ohm = 0.367A

There is a 0.14dB difference in electrical damping.

 

[caught gesture]

I always find it somewhat ridiculous the people who will embrace wholeheartedly one aspect of science (like the science behind the engineering of an amplifier), and then totally disregard another scientific field (like the science behind how the brain functions vis-a-vis cognitive biases). Non-scientific people deciding that they have the knowledge/training and authority to discard one whole field of scientific study. Bizarre.

 

[pogo]

When I have a 4ohm signal source and short it with 0ohm (only theoretically possible), with 0.02ohm or 0.08ohm there is no real difference in damping current as that is determined by the source impedance (4ohm)

However, this assumption does not apply to a transient signal and high volume in the real world.
Each turn of the voice coil couples individually and proportionately, so the resistance is distributed.

 

[Kal Rubinson]

Non-scientific people deciding that they have the knowledge/training and authority to discard one whole field of scientific study. Bizarre.

Unfortunately, it is too common.

 

[MusicNBeer]

Two things are possible.

1) The amps may indeed sound different for some reason. Linear distortion such as frequency response differences due to output impedance, amp bandwidth, etc. Nonlinear distortion for some reason. Benchmark unit is not performing up to spec possibly. Who knows.

2) The perceived differences are placebo due to sighted comparison.

With both possible, those arguing, regardless of which side, should not assume they are 100% correct.

 

[solderdude]

However, this assumption does not apply to a transient signal and high volume in the real world.
Each turn of the voice coil couples individually and proportionately, so the resistance is distributed.

Its a bit simplistic and phase as well as inductance and XO is not taken into account either.
I assume the message came across about DF (which is a weird number in essence)

 

[shuppatsu]

Two things are possible.

1) The amps may indeed sound different for some reason. Linear distortion such as frequency response differences due to output impedance, amp bandwidth, etc. Nonlinear distortion for some reason. Benchmark unit is not performing up to spec possibly. Who knows.

2) The perceived differences are placebo due to sighted comparison.

With both possible, those arguing, regardless of which side, should not assume they are 100% correct.

While true, the burden of proof lies with the person making the extraordinary claim that two exceptional amps sound different from each other. At least on this website.

 

[dlaloum]

While true, the burden of proof lies with the person making the extraordinary claim that two exceptional amps sound different from each other. At least on this website.

Non viable without substantial measurement instruments and analysis - most people don't have the gear nor the analytic experience.

A subjective experience is still a valid data point.

The much-discussed Harman preference curves, are a collation of subjective data points.