Review and Measurements of Benchmark AHB2 Amp

[scott wurcer]

An Otari MX50 with various 15IPS tapes was also used.

Last week we listened to a meticulously restored Otari at 15ips and universally preferred simple transfers to tape of SACD downloads to the originals. The system was almost totally bespoke valve based amplification/speakers. The general opinion (this was not blind) was that the low frequency HD issues with tape played a role.

 

[JP]

Kevin's?

 

[scott wurcer]

Kevin's?

Yes

 

[Frank Dernie]

Last week we listened to a meticulously restored Otari at 15ips and universally preferred simple transfers to tape of SACD downloads to the originals. The system was almost totally bespoke valve based amplification/speakers. The general opinion (this was not blind) was that the low frequency HD issues with tape played a role.

Did the recording take the peaks a good bit over 0dB VU?
The bass uneveness is one thing but I know a tape overload emulator is a very popular limiter on the Metric Halo discussion group.

 

[oivavoi]

Large woofers reproduce percussion instruments in a convincing way that smaller drivers never do (unless you have a big array of them.) Power compression is real. Modern midwoofers can sound pretty amazing but they will never give you what a big cone can.

I think Earl Geddes theorized that power compression caused by VC heating could be a source of subharmonic distortion, where tones lower than the input are created by the heating and cooling of the motor. Interesting to think about.

The tactility of bass in large drivers is one of those things which conventional measurements don't do a great job of representing; it's not a FR issue or a directivity issue but it's very real. Low distortion in the 30-120hz area is a good place to start but I think it's more than that.

This aligns with subjective experience. What's your personal definition of "large" in this case? And how low in frequency do you think this really starts to matter?

 

[solderdude]

universally preferred simple transfers to tape of SACD downloads to the originals

So the distortion (changes made whatever they may be) by the tape recording/playback was subjectively, and not blind, preferred over the original and recorded from the same DAC that was used for the original signal ?

Could the same effect be created by emulation in DSP when the tape characteristics were analyzed and implemented including wow/flutter/scrape effects ?

 

[PaulD]

Could the same effect be created by emulation in DSP when the tape characteristics were analyzed and implemented including wow/flutter/scrape effects ?

Yep, it's been done... There are many options in the pro audio world, from Slate, Waves etc...

https://slatedigital.com/virtual-tape-machines/

https://musicproductionnerds.com/best-tape-emulation-plugins

https://www.waves.com/plugins/j37-t...1aWwbAXooT40&irgwc=1#butch-vig-billy-bush-j37

https://www.waves.com/plugins/krame...rgwc=1#eddie-kramer-on-the-kramer-master-tape

 

[scott wurcer]

So the distortion (changes made whatever they may be) by the tape recording/playback was subjectively, and not blind, preferred over the original and recorded from the same DAC that was used for the original signal ?

Not sure of all the details but the playback chain was the same in both cases, no obvious overload issues. A this point something interesting to explore. There is nothing un-scientific about a preference for some subtle effects in the signal chain as long as one accepts that that is what is going on.

 

[pma]

And even technically worse is often subjectively preferred as "better". We know that, right?
BTW, nice to meet you, Scott.

 

[Xulonn]

Large woofers reproduce percussion instruments in a convincing way that smaller drivers never do

 

[solderdude]

There is nothing un-scientific about a preference for some subtle effects in the signal chain as long as one accepts that that is what is going on.

Yes, there is nothing wrong with preference as long as one does not say it IS better, unless one has a preference for technical perfection.
Everyone has preferences.

One should be very clear one prefers it or it sounds better to them.
Saying the ACA is better than the AHB2 (to keep things on topic) is provable incorrect.
One can safely say one prefers the ACA or likes it more.

 

[scott wurcer]

And even technically worse is often subjectively preferred as "better". We know that, right?
BTW, nice to meet you, Scott.

Yes, I like to save the ridicule and sarcasm for actual anti-science. I've met too many folks that I respect with a vast knowledge of music and extensive listening experience who have listening preferences that include devices that get scorned by certain crowds.

IMO if you are dealing with what is in the end a subjective matter there is nothing like sharing the exact same experience and discussing it. Here I mean experiences that are not exactly reproducible like a meal on a given night at your favorite restaurant rather than say a book or a film. In the case here we all listened in the same space to the same thing. I have done the same thing in the past where, for instance, folks were waxing ecstatically about a system while the heavy bass was actually modulating the room lights and obviously grossly distorting.

 

[HammerSandwich]

View attachment 39824

What cute little woofers! Here are a 15" & its big brother:

SMSG-50

 

[restorer-john]

And for scale:

 

[RayDunzl]

I could get an AHB2, but then my 10"x17"x45" Fortress of Power shrine just wouldn't look the same..

Or a pair of those subs and just cover up everything. They'd fill all but two feet of the wall.

 

[VeerK]

Is the THX technology used in the AHB2 a proprietary collaboration between Benchmark and THX? I’ve just been spoiled with the new THX887 for my headphones and am looking at a similar solution for my speakers. The AHB2 looks amazing, but I’m curious if any other companies are allowed to use THX tech in their amps, like headphone amp manufacturers are.

The numbers are ludicrous, as a speaker enthusiast, I need this or another power amp using this tech in my setup. I’ve been designing my own speakers for a while now, half tempted to grab 3 of these for a full digital crossover and DSP implementation, if only my wife wouldn’t kill me.

 

[amirm]

Is the THX technology used in the AHB2 a proprietary collaboration between Benchmark and THX?

The complete design is proprietary and the two companies did work collaboratively to develop AHB2. The THX part alone can be gotten from THX. Note that it is not a module/chip solution but a design.

 

[VeerK]

The complete design is proprietary and the two companies did work collaboratively to develop AHB2. The THX part alone can be gotten from THX. Note that it is not a module/chip solution but a design.

Thanks for the clarification Amir, what I’m taking from this is that we may see more speaker amps in the future with the THX badge, but that’s not necessarily an indication of AHB2 level performance.

 

[amirm]

I am surprised that there has not been more takers as there were with headphone amps. Hopefully this will resolve in the future.

 

[cookiefactory]

I am surprised that there has not been more takers as there were with headphone amps. Hopefully this will resolve in the future.

Benchmark occupies an interesting niche in that they straddle the audiophile and pro markets. It’s my observation as a layman is that the pro market audience (which values transparency) has largely moved to active systems.

On the audiophile side, the premium is placed on “sounding good” (see PSAudio’s justification for their poorly measuring DAC). Making ambiguous “nice sounding” gear for huge comparative margins is probably a lot more profitable than competing on objective benchmarks, especially against the ABH2 (at $3K).