Review and Measurements of Benchmark AHB2 Amp

[Sal1950]

Edit: yes, the current iteration has a certain rugged industrial functional charm, but in my opinion is in no way pretty. I have several

And it needs some big honkin VU meters too.

 

[D700]

I don't disagree at all.
But on the other hand there are many with much less sensitive speakers, huge rooms, or just more demanding SPL levels.
A higher power stereo model would fill their needs at a lower cost than having to purchase 2 for bridging.
Just sayin

Couldn't they just make it go to 11?

 

[antcollinet]

Couldn't they just make it go to 11?

Just turn up everything louder than everything else.

 

[HalSF]

Sal, I think there is a market, but I wonder whether Benchmark would sell more amps to audiophiles if Siau made them look prettier.
A more powerful amp that looked prettier and still measured wonderfully well would be well-received, I imagine.
Still, I am NO businessman Maybe not a financial go-er?
Edit: yes, the current iteration has a certain rugged industrial functional charm, but in my opinion is in no way pretty. I have several

Aesthetic criticism of audio component appearances often puzzle me when the component in question is a clearly attractive, non-ugly and unobjectionable design. "Prettier" is such a subjective and personal thing — and in audio it often means debatable stuff like more extravagantly retro or super-minimalist and Apple-like. The AHB2 looks to me almost exactly like it should given its serious, ultra-utilitarian, measurement-driven value proposition, and it's hard for me to imagine that a tarted-up appearance would translate into better sales.

 

[MattHooper]

Aesthetic criticism of audio component appearances often puzzle me when the component in question is a clearly attractive, non-ugly and unobjectionable design. "Prettier" is such a subjective and personal thing — and in audio it often means debatable stuff like more extravagantly retro or super-minimalist and Apple-like. The AHB2 looks to me almost exactly like it should given its serious, ultra-utilitarian, measurement-driven value proposition, and it's hard for me to imagine that a tarted-up appearance would translate into better sales.

I’m really happy with the performance of my benchmark gear - my DAC and LA4 preamp.
But for me, it’s the ugliest two channel gear in my rack, so I tend to hide it a bit. In fact, I even have a bit of black velvet covering my deck, so it just disappears in the shadows of the rack.

 

[Sal1950]

Aesthetic criticism of audio component appearances often puzzle me when the component in question is a clearly attractive, non-ugly and unobjectionable design.

I find the aesthetic design very pleasing.
But I must admit the first time I saw one in person I was surprised by it's small size.
I'm just an ole timer and still feel more comfortable with traditional 17" rack mount size for serious gear.
YMMV

 

[misterdog]

Like this perhaps.

 

[Sal1950]

Like this perhaps.

Well kinda. it would look fine mounted in a rack.
But silly just sitting in the open on normal gear shelving

 

[digitalfrost]

I think a lot of hifi gear is unnecessarily large. It might have been neccessary back in the day but if you open up most modern devices with big enclosures, it's just a lot of air inside. Of course if that is what you have already and you want stuff to match it, I can see the issue, but really why should I waste the space. Look at a Sony CDP-101 which is pretty full of stuff and open up any modern CD player. It's a joke.

Efficiency gains by class D aside, the move from through-hole components to SMD and ICs saved a lot of space. I have all my components in 1 rack of an Ikea Kallax. That is 2 DACs, a phono pre, two power amplifiers and an audio interface. I can see the appeal of having a hifi shrine and displaying the components proudly, but really all that space is just not neccessary anymore. If I had to buy from scratch today, aside from going active with the speakers, I'd prefer half-rack size for sure.

Would this amp be better if Benchmark made a 17" wide version of it?

The first stereo I got from my grandfather, it came with its own rack and the devices were much wider than even 17".

 

[Sal1950]

Would this amp be better if Benchmark made a 17" wide version of it?

Not at all.
But we all know that visual bias can easily effect what we hear.
If small components look best to you, all else being equal, they will sound better.
I'm still most comfortable with the old standards.
YMMV

 

[Reddoc]

a clearly attractive, non-ugly and unobjectionable design. "Prettier" is such a subjective and personal thing

I would think design beyond pure function does play a role in presenting a device to the market. That doesn't mean it "should" but you yourself point out the idiosyncrasies of taste perfectly.

 

[Angsty]

Not at all.
But we all know that visual bias can easily effect what we hear.
If small components look best to you, all else being equal, they will sound better.
I'm still most comfortable with the old standards.
YMMV

View attachment 464537

They’re back…

ADCOM GFA-555se Audio Power Amplifier

The ADCOM GFA-555se audio power amplifier offers exceptional value and superior performance. Experience unparalleled sound quality with ADCOM.

adcom.com

 

[mcdonalk]

I replaced my 30+ year old Mark Levinson 333 stereo amp with two new AHB2's about six months ago, and I was happy with the change. I believe that I heard an improvement. However, I recently tried out a new Bryston 4B3 stereo amp at home and decided to keep it, replacing the dual mono AHB2's (which I still have), and I am also happy with that change.

The 4B3 seems to sound less thin than the AHB2's.

The dollar cost of two AHB2's and one 4B3 are comparable.

The only explanation that I can think of for my preference is that the 4B3 is actually rated to drive a 4ohm load and actually delivers, whereas the mono AHB2 is not so rated and possibly does not deliver as well. My initial AHB2 investigation consisted of correspondence with Benchmark on this issue, and they stated that in spite of not officially rating the AHB2 in mono mode for a 4ohm load, it would nevertheless drive a 4ohm load effectively.

I lieu of having the means to actually measure these two amps for comparison, I must depend on analysis of the published specifications for a possible explanation. And, the specifications for the two components differ in my application.

My speakers have an impedance curve that sometimes dips below 4ohms.

 

[Angsty]

If you got the Mark Levinson re-capped, you’d likely be happy with that, too. If ss amps are operating in their linear range, there will be vanishing audible difference. The difference between the 4B3 and the AHB2 may be less of an audible difference than one of expectation.

I have a 4B-ST and NAD C272, both re-capped. I cannot reliably tell the difference between them when they power Thiel CS6 speakers at my preferred listening volume. The Thiels are known to be a low impedance speaker with a mild phase angle.

This result surprised me because the Bryston has the higher continuous power rating and the better build quality. But, Julian Hirsch anticipated this result decades ago.

 

[Sal1950]

They’re back…

ADCOM GFA-555se Audio Power Amplifier

The ADCOM GFA-555se audio power amplifier offers exceptional value and superior performance. Experience unparalleled sound quality with ADCOM.

adcom.com

Actually they never went away. The Adcom.com site has always been there showing some products, but strangely I've never seen them advertise anyplace?

 

[mcdonalk]

The ML333 was "recapped" about 4 years ago along with a major repair at the authorized service facility in LA. Its rated S/N is significantly less than the other two amplifiers. Maybe that is a clue.

I expected the AHB2's to sound better than the 4B3 based on the former's innovative technology, so my expectations did not play out as I had expected. I wanted to prefer the AHB2's. But I don't really expect anyone here to believe me.

I still am using the Benchmark preamp, though.

 

[Poufflee]

The ML333 was "recapped" about 4 years ago along with a major repair at the authorized service facility in LA. Its rated S/N is significantly less than the other two amplifiers. Maybe that is a clue.

I expected the AHB2's to sound better than the 4B3 based on the former's innovative technology, so my expectations did not play out as I had expected. I wanted to prefer the AHB2's. But I don't really expect anyone here to believe me.

I still am using the Benchmark preamp, though.

Don’t discount your own listening experiences with the AHB2. Sometimes an upgrade clicks with our ears and sometimes it does not. All the engineers and physicists in the world can put tons of effort into designing electronics along the best principles and measurements we have, but we can’t control for how the sound gets into your head, and for how you perceive it.

Subjective preference is real, valid, and appreciated, as long as we recognize it clearly as subjective.

 

[Sal1950]

I expected the AHB2's to sound better than the 4B3 based on the former's innovative technology, so my expectations did not play out as I had expected. I wanted to prefer the AHB2's. But I don't really expect anyone here to believe me.

The only thing I would question is that you could actually hear any difference between the 2 excellent modern amps if listened to under tightly bias controlled double blind conditions. Close your eyes and that perceived "thinness" of the Benchmark would likely disappear.

 

[yanm]

I replaced my 30+ year old Mark Levinson 333 stereo amp with two new AHB2's about six months ago, and I was happy with the change. I believe that I heard an improvement. However, I recently tried out a new Bryston 4B3 stereo amp at home and decided to keep it, replacing the dual mono AHB2's (which I still have), and I am also happy with that change.

The 4B3 seems to sound less thin than the AHB2's.

The dollar cost of two AHB2's and one 4B3 are comparable.

The only explanation that I can think of for my preference is that the 4B3 is actually rated to drive a 4ohm load and actually delivers, whereas the mono AHB2 is not so rated and possibly does not deliver as well. My initial AHB2 investigation consisted of correspondence with Benchmark on this issue, and they stated that in spite of not officially rating the AHB2 in mono mode for a 4ohm load, it would nevertheless drive a 4ohm load effectively.

I lieu of having the means to actually measure these two amps for comparison, I must depend on analysis of the published specifications for a possible explanation. And, the specifications for the two components differ in my application.

My speakers have an impedance curve that sometimes dips below 4ohms.

The AHB2 is rated 518W at 4 ohm bridged mono. Or am I missing something?

 

[yanm]

The only thing I would question is that you could actually hear any difference between the 2 excellent modern amps if listened to under tightly bias controlled double blind conditions. Close your eyes and that perceived "thinness" of the Benchmark would likely disappear.

I agree that they should be indistinguishable under a tightly controlled double blind test.

Also the 4B3 has 23 and 29 dB gain settings, whereas the AHB2 has 9.2, 17, and 23 dB gain settings. I assume, the sighted test has been made with the 23 dB setting on both amps to have the same SPL.

I wonder how accurate are those gains though: a fraction of dB hotter on the 4B3 and a fraction of dB lower on the AHB2 will make the 4B3 sounds better.

Assuming the gain is set by 0.5%-accurate resistors in both amps and that the gains are by design exactly 23 dB, the error in voltage gain is at most 0.5%. So worst case, there is a 0.5% difference between the two amps voltage gain. As the SPL is driven by power and not voltage, the difference in power/SPL is about 1% or 0.04dB SPL.

Actually, Stereophile´s AHB2 measurements show the 23 dB gain measured at 22.9 dB, so the accuracy of the gain is clearly worst than 0.5% (more like 1%). Assuming 1%, the worst case difference in dB SPL becomes 0.09 dB. Still small, but maybe already perceptible as a sound quality difference.

Edit: added some back-of-the-envelope calculations
Edit 2: added Stereophile measurements of gains