Benchmark ABH2 Mono Block Configuration

[Thetiminator]

Hi

I’ve posted this inquiry in another forum as well with some interesting responses. So I’d welcome any experience from this forum as well

I've owned the Benchmark ABH2 Amp for a few years but am now considering one two alternative upgrade paths:
A New Amp or adding a second AHB2. If I purchase a new amp so far I like the Bryston 3BCubed which is a dual mono design with 200 watts into 8 ohms or possibly the 4BCubed at 300 watts. In either case this is more power than the single ABH2 at 100 watts into 8 ohms. However adding a second ABH2 increases the power per channel to 380 watts .
So much for raw power. What about overall sound quality? The Bryston 3BCubed got an excellent review on Absolute Sound as an amp that would require significantly more $$ to better. Another review I read easily preferred the Bryston 43Cubed (300 watts per channel) over the ABH2.
I'm in the process of completely upgrading my system after several years of the same components. I will shortly have:
An Aurender N20 Streamer into an MSB Discrete DAC with dual power supplies feeding the single ABH2 which drives my Harbeth C7es-XD speakers.
Everything will be new except the older ABH2. Hence the consideration of an amp upgrade.
Now Benchmark will tell you that adding a second ABH2 is only needed when the single amp clips. Other than that there is no sonic benefit to adding a second. I Ffnd that hard to believe. I would think having a second would offer improved soundstage, separation and possibly better performance from the speakers. So my question is:
Have any of you added a second ABH2 and if so what were the overall sonic benefits if any? Also any opinion or experience on the Brystons vs the Benchmark? Or any suggestions of a better upgrade path would be welcomed.
jfrmusic

Hi JFR
I’ve had many power amps over the years, usually a bit higher up the price range, but I did have the Benchmark as a stop gap. I found the same sound signature as you, it did have good clarity etc. but it definitely isn’t any giant killer. Unfortunately, hifi is like everything else, you get what you pay for. It is a good amp for the money, but more money will better it.
I can’t recommend anything specific as every system is different, and what worked well in my system might not in yours but my advice would be to audition a few second hand/demo amps from a dealer. It’s worth paying the return postage.
Two Benchmarks aren’t going to sound any better than one, unless they can’t drive your speakers properly, which I would doubt. In the end you’ll be in for £6k of benchmark, where that would get you a very nice used/demo £10-£12k amp, which should be of much higher quality (SQ wise).
Finally, I would hold off until you get the MSB in the system, that could sound more natural and sweeter than what you have at the moment and solve your problem…

 

[lordcloud]

My AHB2 experience has been the exact opposite of Thetiminator's.

I believe it takes a significant amount of money to "better" the sound quality of a pair of AHB2s, and adding a second one noticeably improves the sound to my ears.

The second AHB2 didn't change the sound, it just made everything bigger, easier, more effortless sounding. I would highly encourage adding a second amp!

I would also say that if you're wanting to improve the sound of the AHB2, then maybe what you're really wanting to improve is the sound of a component(s) around it, as the AHB2 is one of the more transparent components you'll hear.

 

[Majkel]

Hi

Hi JFR
I’ve had many power amps over the years, usually a bit higher up the price range, but I did have the Benchmark as a stop gap. I found the same sound signature as you, it did have good clarity etc. but it definitely isn’t any giant killer. Unfortunately, hifi is like everything else, you get what you pay for. It is a good amp for the money, but more money will better it.
I can’t recommend anything specific as every system is different, and what worked well in my system might not in yours but my advice would be to audition a few second hand/demo amps from a dealer. It’s worth paying the return postage.
Two Benchmarks aren’t going to sound any better than one, unless they can’t drive your speakers properly, which I would doubt. In the end you’ll be in for £6k of benchmark, where that would get you a very nice used/demo £10-£12k amp, which should be of much higher quality (SQ wise).
Finally, I would hold off until you get the MSB in the system, that could sound more natural and sweeter than what you have at the moment and solve your problem…

I completely disagree with that. The 2xAHB2 is a very serious contender, very much so. So much so that in my system and for my preferences, it outperformed the Boulder 866, Air Tight ATM-1E and Kora TB 400. To say that this is an amplifier that sounds like it costs is not a very credible opinion, precisely because Benchmark offers excellent value for money and you have to spend a lot to beat it.
At 8 ohms in bridged mode, it delivers 380 WPC of pure, undistorted power, and you can really hear it. This is my opinion, as someone who has been involved in this hobby for 30 years, who has access to expensive and very expensive amplifiers, and yet has decided on a full Benchmark stack.

 

[Hear Here]

Hi

Hi JFR
I’ve had many power amps over the years, usually a bit higher up the price range, but I did have the Benchmark as a stop gap. I found the same sound signature as you, it did have good clarity etc. but it definitely isn’t any giant killer. Unfortunately, hifi is like everything else, you get what you pay for. It is a good amp for the money, but more money will better it.
I can’t recommend anything specific as every system is different, and what worked well in my system might not in yours but my advice would be to audition a few second hand/demo amps from a dealer. It’s worth paying the return postage.
Two Benchmarks aren’t going to sound any better than one, unless they can’t drive your speakers properly, which I would doubt. In the end you’ll be in for £6k of benchmark, where that would get you a very nice used/demo £10-£12k amp, which should be of much higher quality (SQ wise).
Finally, I would hold off until you get the MSB in the system, that could sound more natural and sweeter than what you have at the moment and solve your problem…

Interesting that those that disagree with you are AHB2 owners! I wonder how many other amps they home demo'd before making their purchases.

I owned one for several months when I was looking to replace SETs to power my speakers. I bought the Benvchmark unseen and unheard as it was then a new amp. It was being raved about by the owner of similar speakers to mine (Avantgarde) so I just bought it on his advice.

Unfortunately, in my systrm it was drearily dull - the sort of music rendition that prompts you to turn down the volume. This for me is the kiss of death with any equipment - I want music rendition where one it tempted to turn up the volume!

This unfortunate purchase prompled me to start a multi-amp home demo session involving a dozen ss amps of Classes A, AB and D in the £3-8K range. I bought or borrowed amps from Sugden, Mark Levinson, Valvet, Bakoon, Lyngdorf, Quad, GamuT, Micromega, NAD and Accuphase. The Benchmark wasn't the worst but there were others so much better in my system. The Benchmark has some great features such as its measured accuracy, huge S/N ratio, adjustable gain, etc, but let down by its dullness! With less exciting speakers than mine, the Benchmark may have been better matched.

 

[lordcloud]

Interesting that those that disagree with you are AHB2 owners! I owned one for several months when I was looking to replace SETs to power my speakers. I bought the Benvchmark unseen and unheard as it was then a new amp. It was being raved about by the owner of similar speakers to mine (Avantgarde) so I just bought it on his advice.

Unfortunately, in my systrm it was drearily dull - the sort of music rendition that prompts you to turn down the volume. This for me is the kiss of death with any equipment - I want music rendition where one it tempted to turn up the volume!

This unfortunate purchase prompled me to start a multi-amp home demo session involving a dozen ss amps of Classes A, AB and D in the £3-8K range. I bought or borrowed amps from Sugden, Mark Levinson, Valvet, Bakoon, Lyngdorf, Quad, GamuT, Micromega, NAD and Accuphase. The Benchmark wasn't the worst but there were others so much better in my system. The Benchmark has some great features such as its measured accuracy, huge S/N ratio, adjustable gain, etc, but let down by its dullness! With less exciting speakers than mine, the Benchmark may have been better matched.

I think this makes sense, and I can see it being the viewpoint of a number of audiophiles that hear the AHB2s, as I believe most audiophiles are wanting to hear their systems versus hearing their recordings, and are looking for their system to sound a certain way or ways.

The AHB2, in my opinion, isn't really the amp for most audiophiles. But will fit in well with the type of audiophile that is wanting to get as close to a transparent system as possible.

When I put my Atma Sphere M60s in the system, I love how they sound. But it's clear that they embellish certain frequencies a bit in comparison to the AHB2s. And I love it. I love how they sound. But the AHB2s just have much less of a sound.

 

[Majkel]

Interesting that those that disagree with you are AHB2 owners! I wonder how many other amps they home demo'd before making their purchases.

I owned one for several months when I was looking to replace SETs to power my speakers. I bought the Benvchmark unseen and unheard as it was then a new amp. It was being raved about by the owner of similar speakers to mine (Avantgarde) so I just bought it on his advice.

Unfortunately, in my systrm it was drearily dull - the sort of music rendition that prompts you to turn down the volume. This for me is the kiss of death with any equipment - I want music rendition where one it tempted to turn up the volume!

This unfortunate purchase prompled me to start a multi-amp home demo session involving a dozen ss amps of Classes A, AB and D in the £3-8K range. I bought or borrowed amps from Sugden, Mark Levinson, Valvet, Bakoon, Lyngdorf, Quad, GamuT, Micromega, NAD and Accuphase. The Benchmark wasn't the worst but there were others so much better in my system. The Benchmark has some great features such as its measured accuracy, huge S/N ratio, adjustable gain, etc, but let down by its dullness! With less exciting speakers than mine, the Benchmark may have been better matched.

I'm sorry, mate, but I wrote down exactly which amplifiers I listened to (and that's only a small part, because there was also Leben, Sugden, English Acoustic and many others that I don't remember anymore). Benchmark blew them all away. However, combining Benchmark with high-efficiency horns is, to put it mildly, a big mistake. What you need here is a perfect set for 300B, 2A3 or 211, and then the magic happens.

 

[lordcloud]

I'm sorry, mate, but I wrote down exactly which amplifiers I listened to (and that's only a small part, because there was also Leben, Sugden, English Acoustic and many others that I don't remember anymore). Benchmark blew them all away. However, combining Benchmark with high-efficiency horns is, to put it mildly, a big mistake. What you need here is a perfect set for 300B, 2A3 or 211, and then the magic happens.

I've heard the AHB2 on high efficiency horns and it sounded amazing. I honestly think it's more about everything else with the Benchmark, than the Benchmark itself.

You're not going to get the midrange emphasis of a tube amp that people love on horns, so you'll want to get that in another component.

 

[Hear Here]

I'm sorry, mate, but I wrote down exactly which amplifiers I listened to (and that's only a small part, because there was also Leben, Sugden, English Acoustic and many others that I don't remember anymore). Benchmark blew them all away. However, combining Benchmark with high-efficiency horns is, to put it mildly, a big mistake. What you need here is a perfect set for 300B, 2A3 or 211, and then the magic happens.

Interesting comments, though I had previously been using SETs that featured PX-25, 845, 300B and other tube amps with other valves. I had decided to move away from tubes after retiring and expecting to spend far more time listening to music. The owner of Avantgarde Trios had owned numerous costly amps but said the Benchmark topped the lot. It was his recommendation that influenced me to buy it for my own Avantgarde speakers.

Why do you say "combining Benchmark with high-efficiency horns is, to put it mildly, a big mistake". The speakers are high sensitivity and the AHB2 is relatively low powered. Why should they not be a good match? Why do you think that several of the other amps I tried sounded so much better in my system and offered as exciting a listen as the SETs?

 

[Majkel]

Interesting comments, though I had previously been using SETs that featured PX-25, 845, 300B and other tube amps with other valves. I had decided to move away from tubes after retiring and expecting to spend far more time listening to music. The owner of Avantgarde Trios had owned numerous costly amps but said the Benchmark topped the lot. It was his recommendation that influenced me to buy it for my own Avantgarde speakers.

Why do you say "combining Benchmark with high-efficiency horns is, to put it mildly, a big mistake". The speakers are high sensitivity and the AHB2 is relatively low powered. Why should they not be a good match? Why do you think that several of the other amps I tried sounded so much better in my system and offered as exciting a listen as the SETs?

Is the Benchmark low power? Is 100WPC at 8 ohms low power in your opinion? Your speakers will be perfectly happy with 8 WPC from a 300B or 2 WPC from a 2A3, and there will be room for beautiful colour and colouration, the so-called even harmonics that tube enthusiasts love so much and which I have a feeling you also like very much. The Benchmark is an amplifier that has no sound signature. It's just a wire with amplification, and many people don't seem to like that.

 

[Hear Here]

Is the Benchmark low power? Is 100WPC at 8 ohms low power in your opinion? Your speakers will be perfectly happy with 8 WPC from a 300B or 2 WPC from a 2A3, and there will be room for beautiful colour and colouration, the so-called even harmonics that tube enthusiasts love so much and which I have a feeling you also like very much. The Benchmark is an amplifier that has no sound signature. It's just a wire with amplification, and many people don't seem to like that.

In the ss world. 100 watts is pretty modest amplifier power. You, yourself seem to need more as you are bridging (or bi-amping) using 2 x AHB2s.

I've owned a number of SETs in the past but decided to move to ss if I could find an amp that offers as good or better sound, without trying to mimic the SET sound. A long audition session, starting with the Benchmark, led me to the NAD M33 with its excellent Class D Purifi Eigentakt amp. Recently I've moved to the NAD M66 (streamer preamp) and a pair of Atmasphere Class D monos.

I'm currently not entirely happy with the M66 (and don't use many of its main features), so thinking of changing back to an all-in-one - the soon-to-be-released NAD M33 V2. Very similsr to the V1, apart from a better DAC and second-generation Eigentakt amp. Hopefully they won't ditch some of the original M33's features that they've done with the M66. Alternatibely (as I don't use analogue), the Mark Levinson 519 streamer preamp or another beast that does everything digital up to the preamp stage.

 

[Dustin Symanski]

I have an AHB2 in my office, I use it every day. For it's price it is fantastic. I would never use it in bridged mode (I have tried a pair of them). If you need more power get a more powerful amp. If the AHB2 is the only amp you are considering and you must "maximize" its potential, then use a pair of them and just don't use second channel. Get an XLR shorting block and pug it into the unused input. I think that is a bit wasteful but it is loads better sounding than putting that little amp in bridged mode.

 

[audiobomber]

use a pair of them and just don't use second channe

Or biamp vertically (one amp per speaker; one channel to woofer, one channel to mid/tweeter.

 

[Hear Here]

Or biamp vertically (one amp per speaker; one channel to woofer, one channel to mid/tweeter.

Do you get more power, hence higher potential volume, if you connect that way? I think not. Each channel is still faced with the same load.

 

[audiobomber]

Do you get more power, hence higher potential volume, if you connect that way? I think not. Each channel is still faced with the same load.

You don't get double the power, but you get double the current capability vs. one amp, and half the load vs. monoblocking. I have had much success with vertical biamping in the past in my system, using a pair of 50W stereo amps and 4-ohm 89dB/1m speakers. My only experience with monoblocking was in a friend's system, with a pair of Bryston 3B-STs driving B&W 802 Nautilus speakers. The improvement when I converted to vertical vs. monoblock was shockingly better.

 

[Republicoftexas69]

You don't get double the power, but you get double the current capability vs. one amp, and half the load vs. monoblocking. I have had much success with vertical biamping in the past in ,y system, using a pair of 50W stereo amps and 4-ohm speakers. My only experience with monoblocking was in a friend's system, with a pair of Bryston 3B-STs driving B&W 802 Nautilus speakers. The improvement when I converted to vertical vs. monoblock was shockingly better.

Had the same experience with my Gold Note PA-10 amplifier, moved to mono-blocks 2x PA-10 and it was a marked improvement.

 

[Kal Rubinson]

I think this makes sense, and I can see it being the viewpoint of a number of audiophiles that hear the AHB2s, as I believe most audiophiles are wanting to hear their systems versus hearing their recordings, and are looking for their system to sound a certain way or ways.

The AHB2, in my opinion, isn't really the amp for most audiophiles. But will fit in well with the type of audiophile that is wanting to get as close to a transparent system as possible.

When I put my Atma Sphere M60s in the system, I love how they sound. But it's clear that they embellish certain frequencies a bit in comparison to the AHB2s. And I love it. I love how they sound. But the AHB2s just have much less of a sound.

I think you nailed it.

 

[Audiohertz2]

Or biamp vertically (one amp per speaker; one channel to woofer, one channel to mid/tweeter.

Actually this is the worse way to biamp a speaker system …!

 

[audiobomber]

Actually this is the worse way to biamp a speaker system …!

I should have mentioned, vertical biamping requires two identical amps, otherwise coherence suffers.