Review and Measurements of Benchmark AHB2 Amp

[restorer-john]

I played on a small set of speakers, with a Maratnz PM-80 MKII SE wit ha few friends, while trying out different equipment. We then tried the AHB2 with an old high end Denon pre amp - cant remember the details of it. But the Benchmark started clipping easily, before we found out that you need to adjust the load on the rear. But still, there was no real improvement in sound. Maybe the Denon was not up to the job. But maybe, sometimes even good specs, does not equal better sound.

Certainly don't be quick to dismiss the PM-80. It was a great value high powered integrated from Marantz. I have a comprehensive review of it someplace (IIRC it was in Australian HiFi) and it exceeded it specifications significantly in all areas. It's stereo power output is in exactly the same league as the Benchmark. I recall it hit over 300W/ch (or close to it) into 2ohms.

The only downfall with the original PM-80 was the voltage stage driver IC. They are unavailable (easily) when they fail. The PM-80Mk2/SE used a much better power amplifier stage which was completely discrete with optical (optocoupler) based bias switching and rail switching for the Class- A.

In short, the Benchmark may have an order of distortion lower than the Marantz, but other than that, the PM-80mk2SE would certainly not have been embarrassed in any technical way.

But it was built in a different era. Through hole and point to point harnesses. Bowden linkages to remote switches. It's an integrated with tons of functionality. The Benchmark is two boards, sandwiched together in a compact, modern form factor. The Benchmark is a work of art inside, that's for sure.

 

[cbnbmore]

The AHB2 no doubt has the look of a well planned and executed design. With the use of high end parts it’s easy to see why they measure and sound as excellent as they do.

 

[Renan]

Looks like a cheaper alternative amp to Benchmark is Denafrips Hyperion amp with 80 watts rms into 8ohms class AB, 0.00078% THD+N and 125 dB S/N ratio.
Attached link: https://www.vinshineaudio.com/product-page/denafrips-hyperion-poweramp

 

[digitalfrost]

Looks like a cheaper alternative amp to Benchmark is Denafrips Hyperion amp with 80 watts rms into 8ohms class AB, 0.00078% THD+N and 125 dB S/N ratio.
Attached link: https://www.vinshineaudio.com/product-page/denafrips-hyperion-poweramp

Why have I never heard about this thing before and why does it have such good specs? What is their magic? @amirm should test this.

 

[amirm]

Why have I never heard about this thing before and why does it have such good specs? What is their magic? @amirm should test this.

Someone should contact them first to send me one.

 

[D700]

Its certainly winning the capacitor wars. Tidy kit as well.

 

[digitalfrost]

Someone should contact them first to send me one.

Maybe someone just wrote them a mail suggesting they send some your way.

 

[Renan]

Denafrips has a very good review from 6moons that they gave them the Blue Moon award. Attached is the Denafrips Hyperion together with preamp Hestia review link: https://6moons.com/audioreview_articles/denafrips2/5/

 

[anmpr1]

Out of curiosity: is there still a critical mass of manufacturers who adhere to this FTC rule in 2019? I remember in the golden age of car audio there was CEA-2006...

I don't think the regulation is a requirment, anymore. In any case, the test protocol was always questionable, from a 'real world' standpoint. Prior to its adoption, David Hafler (among others) was a big critic. The original idea was to stop manufacturers from using idiotic, made up power ratings claiming huge numbers that had absolutely no relationship to the actual amplifier's capability.

FWIW, I have a David Hafler/Ed Laurent kit, a tube design from the late '50s. Modern up to date parts. Dyna rated them (EL34 mono amps) at about 40 watts. From an FTC standpoint it would probably be a 15-20 watt amp. But it sounds as powerful as my 100 watt/channel Yamaha SS, in real life and on real music. The FTC rule was ridiculous for tubes. Why would you want to stress tubes ala FTC protocol? What is that supposed to tell you?

Of course neither the Dyna nor the Yamaha sounds nearly as good or as powerful as my AHB2. I wouldn't pay much attention to the FTC protocol. Again, it was just an ad hoc thing that was made up to control out of control advertising claims, not to get to the bottom of what constitutes good amp design.

PS: from a quick search it appears that the original rule is not in effect, but has been revised. It now includes active speakers, or subwoofers. I don't know how it applies to multi channel AV type amps. I'm all for accountability in advertising. It's just that the FTC rule has to be seen within the context of advertising, and not whether an amp that passes the test is necessarily better than one that won't.

 

[anmpr1]

I don't think the regulation is a requirment, anymore. In any case, the test protocol was always questionable, from a 'real world' standpoint. Prior to its adoption, David Hafler (among others) was a big critic. The original idea was to stop manufacturers from using idiotic, made up power ratings claiming huge numbers that had absolutely no relationship to the actual amplifier's capability.

FWIW, I have a David Hafler/Ed Laurent kit, a tube design from the late '50s. Modern up to date parts. Dyna rated them (EL34 mono amps) at about 40 watts. From an FTC standpoint it would probably be a 15-20 watt amp. But it sounds as powerful as my 100 watt/channel Yamaha SS, in real life and on real music. The FTC rule was ridiculous for tubes. Why would you want to stress tubes ala FTC protocol? What is that supposed to tell you?

Of course neither the Dyna nor the Yamaha sounds nearly as good or as powerful as my AHB2. I wouldn't pay much attention to the FTC protocol. Again, it was just an ad hoc thing that was made up to control out of control advertising claims, not to get to the bottom of what constitutes good amp design.

PS: from a quick search it appears that the original rule is not in effect, but has been revised. It now includes active speakers, or subwoofers. I don't know how it applies to multi channel AV type amps. I'm all for accountability in advertising. It's just that the FTC rule has to be seen within the context of advertising, and not whether an amp that passes the test is necessarily better than one that won't.

PSS: I came across another discussion that indicates the FTC rule only covers consumer Hi-Fi gear. Not professional oriented products, or musical instrument amplifiers. If that is so, it would be interesting to know the status of a product like the AHB2, which straddles the pro-consumer fence, or amps such as Crown, which are strictly pro-oriented.

 

[headshake]

Looks like a cheaper alternative amp to Benchmark is Denafrips Hyperion amp with 80 watts rms into 8ohms class AB, 0.00078% THD+N and 125 dB S/N ratio.
Attached link: https://www.vinshineaudio.com/product-page/denafrips-hyperion-poweramp

What a beast! So this is $50USD cheaper than an ncore DIY kit to my door and the only labour is taking it out of the box? Hmmm.

The "18 pieces of large reservoir capacitors (147,600uF)" ...oh my goodness. The Outlaw audio 2200 mono's have 20,0000uF. The "AT6007 7 channels (fully loaded) with 59,400 microfarads capacitance per channel."

Another review (that was prob translated):
https://www.denafrips.com/single-post/2019/05/29/Hyperion-Review

The current on tap from the amp seems high, so although 80 watts per channel into 8 ohms does not sound like much, there is drive and no little authority to the sound. There is a weight and body to the sound, a corporeal character that is really fleshy with vocal-heavy tracks, and is especially pronounced with bass notes; however, I have to turn up the volume when compared to my PS Audio M700 monoblocks (350 watts per channel into 8 ohms, 700 into 4), so for example for the similar approximate output at 50 on my preamp steps using the M700s, I have to go to 75 using the Hyperion.

ABH2 specs:

Ok, so this is where the Hypex DIY nc400 kit and the Denafrips Hyperion fall off a little for me: No trigger. I don't want to be a human trigger for amp power.

They all prob have different levels of falt protection. I'd bet the ABH2 has more.

TRIGGER I/O

• 12 VDC 200 mA current-limited output to trigger turn-on of remote devices
• DC input for slaving to remote devices
• Input responds to 3.3 V logic and higher, VIL = 1.26 V, VIH = 2.7 V
• Absolute maximum input voltage = 30 VDC
• Absolute minimum input voltage = -0.3 VDC
• Input Impedance = 20 k Ohms

PROTECTION CIRCUITS

• Fully Electronic, No Relays
• Mute Sequencing
• Distortion Detection
• Short Circuit Detection
• Over Current Detection
• Over Temperature Detection
• SOA Detection (Output device safe operating area)

 

[RichB]

Online, power calculators are not very good at determining the actual power requirements.
My Salon2's are 86 dB at 2.83 volts (about a watt) but since they hover around 4 Ohms, assume 2 watts.

To get a better handle, I measured the volume setting -31 on XMC-1 delivers approximately 2.83 volts (1kHz, 2khz, 50hz) at my seating positions which is about 10 feet from the speakers. My room is 4500 cubic feet, 30 ft. long with openings on the rear-left and rear.

Here are my typical listening levels and power:

Background Music: 0.5 watts
Typical Music: 2 watts
TV: 4 watts
Movies: 8 watts
Movies too Loud: 32 watts
Music Loud: 64 watts
Clipping Tests: 128 watts

Two Benchmark AHB2's are driving the Salon2 bi-amped.
According to my measurements and the AHB2 clipping indicators, I do not clip these amps at any level I care to listen.

When I had the ATI AT6000's their clipping indicators would light at -6 that support the accuracy of these values.

- Rich

 

[Sal1950]

Ok, so this is where the Hypex DIY nc400 kit and the Denafrips Hyperion fall off a little for me: No trigger. I don't want to be a human trigger for amp power.

Get one of these then. I use two of them to control the 5 Adcoms in my system. Turn on the pre/pro and the whole system comes up.

 

[dkfan9]

Get one of these then. I use two of them to control the 5 Adcoms in my system. Turn on the pre/pro and the whole system comes up.

So powering down amps like this is not bad for them in the long run? Possibly I'm biased by TVs and other electronics that generally do not like this.

 

[DonH56]

Most electronics have a switch that removes the power, same as the box does. And every power amp I've seen. Some have a soft-start circuit but they all just switch off power. Some have a standby mode, which you would lose, mainly to keep the trigger circuit alive (in the case of power amps) so nothing to lose in your case.

 

[Sal1950]

Possibly I'm biased by TVs and other electronics that generally do not like this.

Todays TV's are "smart" devices, meaning they are computer controled. And like computers you wouldn't want to just kill power to them on a regular basis, not to mention having to wait for some boot-up period on startup. Power amps are just dumb devices and none of that would apply.
Forgot to link, at $25, very cheap.
https://www.adafruit.com/product/2935?gclid=EAIaIQobChMIi9fB2dya2gIVEp7ACh3tMQZWEAQYAiABEgJUQvD_BwE

 

[RichB]

Todays TV's are "smart" devices, meaning they are computer controled. And like computers you wouldn't want to just kill power to them on a regular basis, not to mention having to wait for some boot-up period on startup. Power amps are just dumb devices and none of that would apply.
Forgot to link, at $25, very cheap.
https://www.adafruit.com/product/2935?gclid=EAIaIQobChMIi9fB2dya2gIVEp7ACh3tMQZWEAQYAiABEgJUQvD_BwE

OLED TV's run compensation cycles in standby when the TV has at least 4 hours use. So, do not cut the power if you want them to perform well. For Amps, I prefer connecting them directly to the wall.

- Rich

 

[dkfan9]

Ok good to know--killing power at the device isn't inherently bad, it's all dependent on the device's requirements, and most "dumb" devices have no special power down requirements. Thanks all

 

[Sal1950]

OLED TV's run compensation cycles in standby

Is that when the supposed fix for their ability to image burn-in the screen runs?
I'll be sticking with LED for now due to this issue.

 

[RichB]

Is that when the supposed fix for their ability to image burn-in the screen runs?
I'll be sticking with LED for now due to this issue.

Each technology has its advantages.

OLED compensation cycles have more to do with residual images, banding in low APL areas.
It is not burn-in which is really uneven wear. If you watches stations with tickers, news most of the time, LCD is a better choice.

OLED is better than Plasma for IR and wear. For most, it is not an issue.
OLED's perfect black-levels and accurate color tracking provide an SOA viewing experience.
They are wonderful.

- Rich