Benchmark AHB2 Amplifier, opinions and competition

Benchmark has been "sold Out" of the AHB2 for a while. Just curious if a new version is coming pretty soon. 

If anyone is passively biamping, such as hifidream, I highly recommend the vertical biamping scheme. One amp for each speaker, one channel running the low frequencies, the other channel running the tops. To my ears, this is always more open, dynamic and detailed. Does not cost a penny to try it. There are others besides myself who prefer it, so I am not alone in making the recommendation. Enjoy ! MrD.

One amp for each speaker, one channel running the low frequencies, the other channel running the tops. To my ears, this is always more open, dynamic and detailed.

That's because in vertical bi-amping all the energy stored in the power supply of the one amp is devoted to just one bass driver, and the other amp the other bass driver.
Horizontal is compromised, as the power supply in one amp has to service both channels bass drivers.
And bridging the amp is just wrong, unless you want/need very high wattage, but be prepared to "take a hit" on all the other parameters that make an amp a good one.

Cheers George

There was a review I read on the AHB2 that compared it to the Chord TToby. I have NEVER even heard of this Chord amp and yet according to this reviewer I think I would prefer it as its Warmer/Sweeter etc.  I cant even find a review of this Chord amp or literally anything on the Web.  I am intrigued. Its a little more expensive...like 1K more. Might be something to consider if you can audition one.

The review mentioned above.
https://audiobacon.net/2019/03/29/benchmark-ahb2-stereo-power-amplifier-review/

Rather interesting that Benchmark is out of stock.
https://benchmarkmedia.com/collections/amp/products/benchmark-ahb2-power-amplifier

I found it interesting the amp is out of stock thru Benchmark direct. Back ordered at B&H. Maybe some issue with part shortages or manufacturing plant. One would think that if a new version was close, one would hear something at recent audio shows

It’s ironic that I bought the Benchmark not having yet read the reviews but out of expediency, simply needing to quickly replace my broken amp out for repairs.
You can imagine how thrilled I am after hearing it and reading the glowing reviews cited above.  Also it appears I got lucky in obtaining one before the shortage.

Perhaps they are selling a ton of them because they just kick @ss and people are catching on. 

@mrdecibel Your suggestion is excellent advice. I don’t know why that never occurred to me. While I don’t have an issue with clipping, I like the principle of having more power if needed and having the same load on the amps. Since I bought two at the same time they have consecutive serial numbers and would share the same part lots. They should sound identical. . . As you said it’s free to try, and it makes logical sense. Just got to move a few cords around. I’ll try to rearrange it tomorrow! I wonder if I’ll hear difference. That’s one reason I like this forum. I feel you can always learn things! 

Thanks,
Steve 

hifidream
While I don’t have an issue with clipping. Since I bought two at the same time they have consecutive serial numbers and would share the same part lots. They should sound identical. . . As you said it’s free to try, and it makes logical sense.

From Magnepan: "The MG20.1 has optional bi-amplification and bi-wire capability."

Seeing you have Magnepan 20.1 and have enough watts with one amp, I suggest you vertically bi-amp the two amps, one channel on the ribbon tweeter and the other channel on the bass panel, of each speaker, with each amp.
http://www.av2day.com/wp-content/uploads/2014/05/biamp2.jpg
It will sound far better than bridging the amps, and give you the best sound using two identical amps.

Cheers George

Thanks George. I understand it completely and agree it should sound better. I’ve always had it arranged where one amp is playing the lows for both speakers and the other amp plays the highs. I think my idea was that both channels will have the same draw on them and thereby reduce harmonic distortion etc. but most amps would operate in driving a high/low  scenario and are designed to do so. Was my thinking totally off? 

Thanks,
Steve

hifidream
Was my thinking totally off?

Yes Steve, the AHB2 has one power supply for both channels.
By having one amp playing one speaker, one channel for highs and the other for lows, then the total power supply’s stored energy (joules) of that amp has all it’s energy available for just one bass driver on big transients. Instead of sharing it for two bass units horizontal bi-amping the way you have it. The highs don’t take much out out the supply. Buy vertically bi-amping these instead of horizontally, you should hear a marked improvement in the lower mids and bass, highs should remain the same.

It would be a different story if the stereo amp was true dual mono construction, with 2 transformers and completely dual mono power supply. Then it would make no difference if it were vertically or horizontally bi-amped.

Cheers George

Got it. Makes sense!

- Steve

I may just have to try one and be done with it

You won’t be sorry.

Music direct backordered as well

Very popular Amp. Check with Benchmark when they will have another run made. Assuming your speakers have a well designed cross over, vertical bi amping will make very little difference while strapping the amps mono will give you much more headroom and make the system sound more effortless. Here you will notice the difference! Try running the amps both ways and let us know what you think. When you can get them:-(

@mijostyn

Benchmark products measure as good as or better than anything else. They are reasonably priced too.

If accuracy or highest fidelity is important then Benchmark are go to reference products.

That said, I like my PS Audio DSD DAC and tube amps too - so owning Benchmark reference products does not preclude owning less accurate but more “musical” products - but Benchmark sure make a nice affordable reference in any setup.

If you don’t like the sound of your speakers or other gear when coupled with a reference product then you really should take a hard look at that gear. It should always sound good with a reference source or amplification even if your setup sounds even better with a component that caters to your taste.

I am waiting for my second AHB2.

I live in Singapore and have placed the deposit back in early March, with the local benchmark dealer for the amp (AHB2)....still waiting.

I wrote in to benchmark and learnt that next shipment should go out at the end April. I am hoping to get the delivery soon (in few weeks) and use it in mono with my ATCs. I am gonna try these in other configuration (as suggested above - dedicated amp for HF and LF). But I am using speakons, which might pose a bit of challenge to use the amps in anything other than mono, for the time being. 

And forgot to share: AHB2 is the sweetest amp I have ever listened to. This could be my last amp.

How sweet it is!!!

FYI I’ve been listening to my system for a couple of weeks after vertically bi-amping rather than horizontal bi-amping. There is defiantly more punch and immediacy! My wife commented on it. :)

@ssnkssnk the Speakon connections work great. 

Thanks,
Steve

FYI I’ve been listening to my system for a couple of weeks after vertically bi-amping rather than horizontal bi-amping. There is defiantly more punch and immediacy! My wife commented on it. :)

Yes, it's easy to understand, bass/upper bass is the most "power sapping" area from an amp in music.
 In vertical bi-amping the whole power supply of one  amp, is dedicated to just one bass driver instead of two, like in normal stereo or in horizontal bi-amping.
And forget about bridging, it just turns "good" amps into higher wattage "average" amps.

Cheers George 

Bringing this thread up due to PS Audio going direct, this, no more deep dealer discounts. I was hoping to have funds for the PSA BHK 250 by the end of the year. However, that has changed and now there’s only 2 weeks left for dealer orders. My preamp is the BHK pre. Before looking at the BHK 250 I was zero in on the following amps to replace my NuForce STA200:

1. ABH2

2. Carver 275

3. Rogue Stereo 100

4. Mac MC275 ( I would have to save until the end of the year)

5. PrimaLuna 

Looks like back at square one. However, I could possibly swing PSA class D M700 monos while I can still get a discount. 

I know the above amps all have have different characteristics. I’m running ZU Omen Defs ( I’ve auditioned small watt tube amps in my system...they Peter out at high volumes). 

Im wondering how the M700’s would compare to a single ABH2?

I can just say the Benchmark will not peter  out high volumes.
In fact it has a three-way gain switch which can accommodate any volume need.
Really excellent amplifier.  Certainly miles ahead of the NuForce which I’ve owned.

Thanks. The Nuforce has more than enough power. Sounds great, just lacks a bit of finesse imo. 

The Benchmark has finesse, clarity and musicality (whatever that means,)

I am considering an AHB2 but just made the switch from neutral tubes (Rogue Audio) to solid state and am not 100% happy.  I miss the transparency and midrange bloom of the tube amp.

Anyone make the switch from a tube amplifier to the AHB2 and how do you feel about it?  Thanks.  

My recent amp ownership has been Audio Research Ref 75 -> Luxman M900U -> Benchmark AHB2 -> Benchmark AHB2 Monos.

The Benchmark will not add bloom or warmth to the sound, in fact the entire point of the design is to not sound like anything and just get out of the way, i.e. to be transparent. To me it achieves that as well as anything I've heard.

The downside of that is that if you have problems upstream from the amp it's not going to do anything to hide them and will clearly show you what all your upstream components actually sound like.

If you want the amp to color the sound with bloom then you either need to stick with tubes or maybe try a warm and colored solid state amp like Luxman. The Luxman adds bloom but it's not the same as what you get with tubes and sounds more artificial to me. 

Bump for any more thoughts?

Benchmark is selling them as fast as they make them, along with the new preamp(s). There is a 3 week waiting period to get it. When I got mine a few years ago (not much people knew about it) there was no wait..

Just curious if the following speaker can be vertically bi-amped? There is a photo of the back of the speaker on the link below.

https://www.soundstageaustralia.com/index.php/reviews/110-follow-up-yamaha-ns-5000-loudspeakers-edit...

Recently researching for a new amplifier I read a long involved thread about the AHB2 that included a lot of technical discussion and some subjective comments about the sound quality.  
The AHB2 made my short list but I ultimately went in a different direction.  
The people that did not care for them had a common theme- lack of dynamics and excitement.  
Some people that liked the amp overall also thought that dynamics were not its strong point.  
FWIW.  

I don't  see how those speakers could be vertically bi-amped yyzsantabarba there's only one set of binding posts you could use monoblocks.

My Benchmark amp is about two years old. It replaced a First Watt F6.  About a year ago, I purchased a Benchmark LA4. It replaced a Audio by Van Alstine T10 RB tube preamp.  Awesome sound!

I am considering an AHB2 but just made the switch from neutral tubes (Rogue Audio) to solid state and am not 100% happy.  I miss the transparency and midrange bloom of the tube amp.

Anyone make the switch from a tube amplifier to the AHB2 and how do you feel about it?  Thanks.  <<
 

I have two stereo systems for music. Based on my recent experiment triggered by a house move, BM AHB2 is a great amplifier if your over all system is very high quality and with great musicality already in place. To be specific, my system A has a Harbeth Compact 7-ES speakers while the system B with B&W 702 S2.

The Harbeth’s sensitivity is 87db and 5-8 omhs in load Impedance. The B&W is 90db sensitivity, but load Impedance from 4-8 ohms. The rest of the components are Technics 1500 turntable, Audio Lab CD transport, Hi Fi Rose 250 Streaming Transport, DACs are Gustard X16 & Schitt Multibits. The preamp is PS Audio BHK Preamplifier with NOS tubes. All interconnects are balanced whenever available. Cables are Audioquest and Blue Jeans.

On paper it appears Harbeth is different to drive, but in practice all my amplifiers from PS Audio Steller S300, Rotel 1552 mk 2, MC MHA 150 to BM AHB2 can all handle it with ease. In particular BM AHB2 sounds the best, gives system A amazing soundstage, dynamics and resolution. It enhances the system’s strength without taking away its musicality.

On system B with BW 702 S2, it is a completely different story. The AHB2’s resolution and power make the system somewhat too  bright and fatiguing to listen to for my ears. It sounds the best with Rotel 1552 mk ii or the McIntosh (both AB class amplifier). The PS audio Steller S300 is also struggling as B&W proves difficult to drive with many Class D amplifier.

Hope this helps.

 

 

 

 

 

 

 

 

 

I can highly recommend the LSA Voyager GaN 350 @~ $2500