Is the Benchmark AHB2, in mono mode, really better than my Mark Levinson No. 536 monoblocks?

[RichB]

Power increases significantly in bridged mono but other than that I would expect them to sound the same. If you have a very low impedance speaker, especially if it’s inefficient, then you may find them running out of current when playing loud. I checked with Benchmark and they said my 4 ohm TADs would be fine in bridged mono. I’ve have not had any issues whatsoever.

When an amp is bridged, the voltage swing is doubled, which quadruples the power, but the current availability remains the same, therefore the caution on using bridged amps on very low impedance speakers. Note either the voltage or the current or both will eventually reach a limit with every amplifier, it’s just that when one bridges, the weaker link is likely the current. AHB2s have enough current to deliver 500 watts into 4ohm, which is more than enough for most.

Fortunately, the amp has very sensitive clipping lights with separate indicators for voltage and current clipping.

- Rich

 

[MaxBuck]

Please allow me getting out of the scope of this thread, as an interlude...

Palm Springs area!! I know you get enough clean (green) electricity from wind.

In July 2018, I drove into your place from San Diego La Jolla Research Triangle area for amateur panoramic photo challenge of the windmill power plant spectacular view;
View attachment 212315

These wind generators are most prevalent in the pass north and west of Palm Springs, on the way to Beaumont and Riverside. If you drive east on I-10 from Palm Springs to Phoenix, you'll see several massive photovoltaic generation farms. This is truly the epicenter of sustainable power generation in the USA.

 

[PGAMiami]

Fortunately, the amp has very sensitive clipping lights with separate indicators for voltage and current clipping.

- Rich

Yes and I’ve only had the clipping lights turn on once in over a year of use. That was essentially caused by user error. Volume was maxed out on my DAC and a very loud track with synthetic bass was playing. Under normal and loud conditions, using 4 ohm TAD R1s they don’t ever clip.

 

[mdunjic]

Amplifier SINAD list ASR + 3rd parties

docs.google.com

If buying new, Purifi, Hypex, and Benchmark are really the only ones that matter these days in terms of the objective best, and thankfully they have comparatively sane prices compared to overpriced audiophile grade junk. Win/win. Also the new upcoming Chinese products like Topping for lower power outputs are making their appearance. Buying one of these according to your power needs and you will be happy, period, and they will all sound the same as long as it can provide the power. There are few exceptions to this suggestion, but any deviation from this is buying for looks, vanity, brand/reputation, warranty, etc.- NOT sound quality and engineering up to modern reproducible standards. While the Benchmark is a great product, I generally suggest Purifi or Hypex as they are top tier performers and you will barely pay more than $1-2k for stereo amplification, unless you want to buy from a premium brand with a premium chassis which may cost more. Dual mono benchmark or maybe the Mcintosh is the only real "upgrade" from Purifi from the things we have 3rd party measurements for, and these still have some cons over a cheaper Purifi/Hypex amp such as costing 6-8x the price and larger/heavier units to deal with.

Shift your time, energy and wallet to measuring your room with and worrying about DSP/EQ, proper sub integration, and potential room treatments if possible. These things will actually better your sound, and it will be significant. Spending 5, 10, and even 20 grand on power amplification is passé unless you're running some sort of cinema in your home or running a venue, and at that stage you would want to be upgrading to something like Genelec active speakers/subs at which point what amplifier you're using ceases to matter anyway.

I (just as an experiment) replaced two of my Quad 909s (I had them in my system in last 15 years, as bi-amping setup) with Audiophonics Hypex NC502MP based stereo amp (driving each speaker's bass driver units) + 2 x Audiophonics Hypex NC500MP based monoblocks (each driving it's own speaker's mid+highs) ... complete overkill in terms of wattage lol ... but the total cost of these amazingly performing Audiophonics (1 x stereo + 2 x monos) power amps is less than $2000 CAD. So, why not get almost unlimited power, with ultra low distortion, and ruler flat frequency responses ... all for less than $2000 CAD? I use Benchmark LA4 as pre-amp and this is all I need. That unit in itself is more expensive than all of these Audiophonics Hypex based class D power amps combined lol

It's not that I didn't like Quad sound (it's great, I like it, and I still have the Quads) but they are getting too hot for my room, and I was curious about these cooler running Hypex class D power amps ... lot more power per channel now, cool-ish running and even lower distortion than my old Quads ... what more can you ask for?

 

[40th Anniversary]

Interesting comments. Reading through the comments I'll make a "bad analogy" of amps with cars. Let's say amps are cars. Those who do not own cars get around just fine with their built in TV speakers. Those who have cheap entry level cars are those with soundbars. Those with mainstream vehicles, like Ford, Chrysler, Toyota, or Honda use AV receivers as amps, with various sizes and features. Entry level "luxury" such as the Acuras, Cadillacs, Lexus will go to separates and get maybe a Parasound A23 or equivalent. Those who want even more like the Mercedes, BMW, and Audi would be like Parasound A21. The JC-5 would be like the higher end Luxury/sport vehicles. I'm thinking my JC-1 monos would be like a Porsche 911. Higher end amps would be like Ferraris. Then the really high end Boulder Amps would be like Bugatti.

If the Benchmark AHB2 were a car, I'm seeing the Benchmark AHB2 as a Tesla Model S Plaid.

Now, is a pair of AHB2 in bridged mono better than using 1 stereo AHB2? Has anyone tried this and hear a difference?

I did that today: I bridged a pair of AHB2s to smaller Triangle 40th anniversary Comète.
There were improvements that will lead me to keep them in mono bridged mode and now I'll need a third amplifier for my living room system.

1. The stereo separation between right and left channels was clearly improved. This was the biggest change that I initially noted.
2. There was more detail to the sound.
* I did reduce the sensitivity from medium to low when moving to "mono" mode.
* The amplifiers remain dead quiet.
3. There was more bass, but the changes were subtle.
I am pushing the limits of my speakers and there is only so much bass output capability. More testing with bigger speakers is needed.
4. There was a "bit" more depth to the soundstage.
5. The overall sound was more "present", "open" "forward" and dare I say "effortless".
* The soundstage changed its signature. Because there was "more" there, the soundstage remained but was bigger at times with more detail presented.

Bottom line: the aggregate of all these changes on my smaller, less demanding speakers was a surprise and a bigger improvement than I anticipated.

I was expecting a similar sound, just louder, maybe more slam and bass as more power is available.

Contrary to expectations, an air of refinement and openness is what was presented along with the above noted improvements.
I now expect stepping back to stereo mode with one (1) amplifier is going to create a void that will be difficult to adapt to when I know that the pair of "mono" AHB2s sound appreciatively better.

 

[pogo]

There was more bass, but the changes were subtle.

This should now be the case, no matter at what volume.
So this has nothing to do with the output power

 

[PGAMiami]

Cancel your order and get better speakers.

I replaced Constellation Centaur monos with a pair of AHB2s. Never looked back. Everything got better. Before that the Centaur were the best amps I owned in a list that included Spectral DMA 360, MSB, Levinson, Cello and Pass. The Benchmark sound every bit as smooth as the Cello and Pass, but with transparency of Spectral. Btw, the Benchmark in mono outperform the XA25 on every parameter. They may clip harder, but at a much higher power level. Within their power rating, they have essentially no distortion from zero watts up to clipping. There are even folks using them with headphones.

 

[Killingbeans]

1. The stereo separation between right and left channels was clearly improved. This was the biggest change that I initially noted.

You could hear an improvement to this?:

I'd probably also hear an improvement when upgrading to dual bridged amps, but with numbers like that, I'd have no problem convincing myself of it being caused by expectation bias.

 

[sq225917]

Crosstalk already some 60db better than anyone's HRTF, but we have a winner that can hear a further reduction to zero. Bless you.

Sometimes one just has to accept that what we think we perceive is simply impossible.

 

[40th Anniversary]

You could hear an improvement to this?:

I'd probably also hear an improvement when upgrading to dual bridged amps, but with numbers like that, I'd have no problem convincing myself of it being caused by expectation bias.

I’ll have to re-listen to the amps again. That is one measurement I did not seize on when I read the thread. It was the first characteristic change to the sound that I noted.

 

[40th Anniversary]

You could hear an improvement to this?:

I'd probably also hear an improvement when upgrading to dual bridged amps, but with numbers like that, I'd have no problem convincing myself of it being caused by expectation bias.

I’ll have to re-listen to the amps again. That is one measurement I did not seize on when I read the thread. It was the first characteristic change to the sound that I noted. Ok

Crosstalk already some 60db better than anyone's HRTF, but we have a winner that can hear a further reduction to zero. Bless you.

Sometimes one just has to accept that what we think we perceive is simply impossible.

Maybe something else in the sound presentation has changed to make me perceive the improvement to L-R. That and the more present and forward soundstage are noticeable.

 

[Killingbeans]

It was the first characteristic change to the sound that I noted.

No wonder. It's also the most obvious thing to expect when switching to monoblocks.

Our brains can d¤¤k with us in so many ways, it's not even funny.

 

[40th Anniversary]

No wonder. It's also the most obvious thing to expect when switching to monoblocks.

Our brains can d¤¤k with us in so many ways, it's not even funny.

I’m easily « dooked »! LoL! When I switched material, Some tracks improved, some were the same. It depends on the recordings.

 

[40th Anniversary]

AHB2: Another 40th anniversary speaker tests, this time with Dynaudio Special 40s: and my test measurement ears hard at work. LoL
I'm going to focus on previous comments made by others with regards to my perceived Left-Right improvement scenario that I earlier reported after going dual "mono" with my AHB2s.

1. In stereo mode, My Dynaudio SP40 provide good bass, but the soundstage is blasé relative to the Triangles Comète speakers.
The Dyns and the Triangles are doing different things. I love them both but for different reasons.
2. With the dual mono AHB2s powering the Dyns, there is a "huge" improvement in soundstage as compared to one AHB2 in stereo mode.
I give the edge to the Comètes for Soundstage (both in stereo and dual mono mode), but the Dyns are now very close and they provide a deeper bass response.
3. There is clearly more bass in dual mono mode. This is easily evident with Dave Brubeck's Take Five CD that I was using as reference material tonight.
4. The sound is more forward and present with more detail, as perviously reported.
This was noted with the Comètes. And those Pianos, oh my! And the brass instruments, oh my!

5. The Left-Right imaging is much better with the dyns in mono mode, and they better the Triangles in this manner as well. An easy improvement to report with the Dyns.
If the amplifiers offer no better specifications in dual mono operation from what is being reported, I have to come up with an explanation for what I am hearing!

So here goes a theory: there is so much more detail coming through, a more forward presentation and a wider soundstage, that certain sounds or instruments that remain in the background in stereo mode get projected to the front in a disproportionate manner in mono bloc operation. This impact is more easily discernible with the Dynaudio speakers.

There is certainly more air and again, I hear better representation of instruments left to right, even percussions.

To think that a 100 watt (8 ohm) amplifier should be enough power for the type of speakers I am using becomes an expensive hobby as I'm coming to grips with the fact that using 2 AHB2 in dual mono mode is a clear improvement in sound quality and totally justifiable for my ears....even with the extra $$ needed to further the sound quality.
It's not a diminishing return based on the improvements I've noted, but it's not cheap as well.

And as Benchmark clearly states, going in "mono" mode improves the Signal to noise ratio by 3 db with no increase in distortion. I certainly don't hear more noise and I don't think I could correlate the distortion changes with the numbers (Sinad of 120 to 130 db) being so low; that makes the AHB2 unique. I love reading about and discovering this amplifier.

 

[PGAMiami]

AHB2: Another 40th anniversary speaker tests, this time with Dynaudio Special 40s: and my test measurement ears hard at work. LoL
I'm going to focus on previous comments made by others with regards to my perceived Left-Right improvement scenario that I earlier reported after going dual "mono" with my AHB2s.

1. In stereo mode, My Dynaudio SP40 provide good bass, but the soundstage is blasé relative to the Triangles Comète speakers.
The Dyns and the Triangles are doing different things. I love them both but for different reasons.
2. With the dual mono AHB2s powering the Dyns, there is a "huge" improvement in soundstage as compared to one AHB2 in stereo mode.
I give the edge to the Comètes for Soundstage (both in stereo and dual mono mode), but the Dyns are now very close and they provide a deeper bass response.
3. There is clearly more bass in dual mono mode. This is easily evident with Dave Brubeck's Take Five CD that I was using as reference material tonight.
4. The sound is more forward and present with more detail, as perviously reported.
This was noted with the Comètes. And those Pianos, oh my! And the brass instruments, oh my!

5. The Left-Right imaging is much better with the dyns in mono mode, and they better the Triangles in this manner as well. An easy improvement to report with the Dyns.
If the amplifiers offer no better specifications in dual mono operation from what is being reported, I have to come up with an explanation for what I am hearing!

So here goes a theory: there is so much more detail coming through, a more forward presentation and a wider soundstage, that certain sounds or instruments that remain in the background in stereo mode get projected to the front in a disproportionate manner in mono bloc operation. This impact is more easily discernible with the Dynaudio speakers.

There is certainly more air and again, I hear better representation of instruments left to right, even percussions.

To think that a 100 watt (8 ohm) amplifier should be enough power for the type of speakers I am using becomes an expensive hobby as I'm coming to grips with the fact that using 2 AHB2 in dual mono mode is a clear improvement in sound quality and totally justifiable for my ears....even with the extra $$ needed to further the sound quality.
It's not a diminishing return based on the improvements I've noted, but it's not cheap as well.

And as Benchmark clearly states, going in "mono" mode improves the Signal to noise ratio by 3 db with no increase in distortion. I certainly don't hear more noise and I don't think I could correlate the distortion changes with the numbers (Sinad of 120 to 130 db) being so low; that makes the AHB2 unique. I love reading about and discovering this amplifier.

These do sound great in bridged mono. As I wrote previously, I’m using 4 in bridge mono in an active biamp, and the results are stunning. It took some time to set up the Pass XVR1 as the active crossover, and during this time, I used the 4 amps in an simple vertical biamp. In this setup all 4 see the full spectrum of music and all are generating voltage at all frequencies. However, they are only providing current for the band pass of the speaker that each amp is connected to. In other words, the amps driving the woofers are not delivering power above the frequency range of the woofer. Conversely, those driving the mid and tweeter are not delivering power at the frequencies below the midrange. So even without the active crossover, the demands placed on the amps are diminished, especially for the ones driving the mid and tweeter. So taken sequentially a single AHB2 sounds great, two in mono sound better, 4 in a vertical biamp better yet, 4 in an active biamp much better even.

 

[40th Anniversary]

These do sound great in bridged mono. As I wrote previously, I’m using 4 in bridge mono in an active biamp, and the results are stunning. It took some time to set up the Pass XVR1 as the active crossover, and during this time, I used the 4 amps in an simple vertical biamp. In this setup all 4 see the full spectrum of music and all are generating voltage at all frequencies. However, they are only providing current for the band pass of the speaker that each amp is connected to. In other words, the amps driving the woofers are not delivering power above the frequency range of the woofer. Conversely, those driving the mid and tweeter are not delivering power at the frequencies below the midrange. So even without the active crossover, the demands placed on the amps are diminished, especially for the ones driving the mid and tweeter. So taken sequentially a single AHB2 sounds great, two in mono sound better, 4 in a vertical biamp better yet, 4 in an active biamp much better even.

That is crazy! But I love it! Good business for Benchmark as well. Having 2 amps is expensive enough for me now. But hey, maybe down the road.....

 

[PGAMiami]

That is crazy! But I love it! Good business for Benchmark as well. Having 2 amps is expensive enough for me now. But hey, maybe down the road.....

Yes, 4 are expensive, but much cheaper than the pair of Constellation Centaur they replaced. I sold the Centaurs and never looked back, and the added bonus is with 4 Benchmarks my room doesn’t overheat like it did with the Centaur.

 

[pogo]

If the amplifiers offer no better specifications in dual mono operation from what is being reported, I have to come up with an explanation for what I am hearing!

The difference you hear just in the bass range is due to the halved amp DF, see also here: Link

 

[Geert]

The difference you hear just in the bass range is due to the halved amp DF, see also here: Link

Which is not true, this statement has been refuted on this forum a zillion times by different experts (with supporting theory and research). Pogo only shows up on this forum to troll about DF.

 

[PGAMiami]

Which is not true, this statement has been refuted on this forum a zillion times by different experts (with supporting theory and research). Pogo only shows up on this forum to troll about DF.

The difference almost certainly has nothing to do with DF as in either case, stereo or mono, the DF on the AHB2 is more than adequate. Instead the difference is coming from essentially quadrupling the power. DF is the ratio of the impedance of the load divided by the impedance of the source. The impedance of the AHB2 is very low. When you bridge then the load sees two source is series, and therefore the impedance is doubled and the DF is cut in half. But it’s so high to begin with that this doesn’t affect the sound.