Review and Measurements of Benchmark AHB2 Amp

[GXAlan]

Indeed he would. I honestly don't understand the stubborn persistence some members have when it comes to trying to find every different which way to claim that high-frequency ultrasonic noise from amps can somehow become lower-frequency ultrasonic noise that will damage speakers or compromise frequency response in ways that don't show up in Amir's measurements. I feel like we've been over this repeatedly, and every time the outcome is the same - an endless parade of "but this could theoretically happen" and "this used to happen in the old days" and "this can happen if an amp breaks or is designed in a certain way" that the modern amps we're discussing are not designed. At some point it just seems to become FUD.

+1

High frequency ultrasonic noise is a part of SACD and no one has damaged their tweeters with SACD.

 

[RichB]

+1

High frequency ultrasonic noise is a part of SACD and no one has damaged their tweeters with SACD.

View attachment 297270

I believe the discussion is whether ultrasonic noise could modulate into the audible range, not the necessarily unexpected tweeter fires

SACD - A massive increase in file size with added distortion that also prohibits DSP processing (without conversion to LPCM).
This is euphonic distortion to be proud of.

- Rich

 

[tmtomh]

I believe the discussion is whether ultrasonic noise could modulate into the audible range, not the necessarily unexpected tweeter fires

Well, I think that's part of the difficulty, actually - often when someone addresses the concern about damaged tweeters, a response comes in saying it's really about IMD; and when IMD is addressed, the tweeter-blowing issue comes up again. It's a bit of whack-a-mole.

 

[GXAlan]

I believe the discussion is whether ultrasonic noise could modulate into the audible range, not the necessarily unexpected tweeter fires

SACD - A massive increase in file size with added distortion that also prohibits DSP processing (without conversion to LPCM).
This is euphonic distortion to be proud of.

- Rich

According to the PK Metric, maybe.

Two reasonable DACs with a large PK Metric when tested with real music...

I've previously shown that my SA-11s2 and Panasonic UB9000 sound similarly and measure similarly with DeltaWave. In this post, I'm sharing some preliminary data showing a) a measurable PK Metric difference between two reasonable DACs with real music b) the DAC with a ~10 dB worse 1 kHz SINAD...

www.audiosciencereview.com

 

[PGAMiami]

+1

High frequency ultrasonic noise is a part of SACD and no one has damaged their tweeters with SACD.

View attachment 297270

I believe the original question was essentially why Amir looks at ultrasonic noise. Btw, he includes this test in many of his reviews of both source components and amplifiers.

As I understand the answer is that this noise may sometimes cause problems downstream, a DAC may hamper a preamp, a preamp may hamper an amp or an amp may hamper a speaker. Key word being “may” instead of “will”. Well designed components should not be affected by this noise, but not everything is well designed.

This noise is usually not high enough in amplitude to cause problems or become audible in any way. But still he measures it, I suppose as a best practice test., like a dr taking your temperature at your physical.

Also, it can affect other test results as it may impact sensitive test equipment.

 

[pogo]

Is there already a Reactive Load Test of the AHB2 available, as it is carried out recently (e.g. NAD M23)?

 

[pogo]

In bridge mode this would also be very interesting.

 

[PGAMiami]

Although this is a purely subjective observation, I found that bypassing the ferrite core inductor based LPF that is in my speakers and implementing the LPF with an active crossover ahead of the AHB2 resulted in much better sounding bass. Maybe it’s placebo effect, but no matter how good the amplifier‘s reactive load performance may be, from the actual driver’s perspective, the speakers LPF is also in the circuit.

Also, placing my speakers closer to the front wall corners and relying on DSP to EQ the bass boost worked very effectively. DSP now has 10-15 db of attenuation in the low bass, which just adds to the overall bass headroom. The walls are all heavily treated to minimize reflections from the mid bass up.

 

[boomtheroom]

I’m using bridged AHB2s on TAD R1s. They are a match made in heaven. Absolutely no problem driving these, have never clipped the amps even at levels you would not want to listen to, even using the R1s full range without subs watching things blowing up in a home theater set up

you got a youtube chan demoing this combo... would love to hear...

 

[Jimster480]

you got a youtube chan demoing this combo... would love to hear...

Without a masterful ADC; you can't hear the difference.

 

[xaxxon]

I’m using bridged AHB2s on TAD R1s. They are a match made in heaven. Absolutely no problem driving these, have never clipped the amps even at levels you would not want to listen to, even using the R1s full range without subs watching things blowing up in a home theater set up

ahb2's don't clip. They will protect long before they clip. Also, their watt outputs into different loads are well documented, so the volume of your speaker is kind of irrelevant. Anyone can just look up how many watts they'll put out.

I have 5 ahb2's. They're great.

 

[pogo]

their watt outputs into different loads are well documented

So far I have not seen a reactive load test!?

 

[xaxxon]

So far I have not seen a reactive load test!?

it's on their website.

 

[RichB]

So far I have not seen a reactive load test!?

stereophile has them, if you look.

 

[pogo]

I was thinking more of something like this: Link

 

[RichB]

I was thinking more of something like this: Link

Those are good measurements. Clearly, there is an interest in the AHB2, why not buy one and send it to ASR?

- Rich

 

[Angsty]

Those are good measurements. Clearly, there is an interest in the AHB2, why not buy one and send it to ASR?

- Rich

See the first post in this thread.

 

[yanm]

See the first post in this thread.

BTW, isn’t @amirm using a AHB2 for one of his setup? May be worth to update the AHB2 review / first page with the reactive load test information at some point.

 

[PGAMiami]

BTW, isn’t @amirm using a AHB2 for one of his setup? May be worth to update the AHB2 review / first page with the reactive load test information at some point.

As I understand, the clipping indicators on the AHB2 would be triggered if the amp starts to distort. I've never seen that happen in my room under real world situations with movies and music with TAD R2s, then again I have 4 in bridged mono biamping the R2s. Only time my amps clipped was one time when the volume was maxed out in error and deep bass techno started to play at levels no one would want to listen to. My friend with a pair of amps in bridged monos with TAD CR1s (that are less efficient than CR1s) also has never seen them clip. The TADs are not particularly difficult loads, but they are not easy either. These are easily the best amps I've had, including many 10x the price.

 

[Doodski]

As I understand, the clipping indicators on the AHB2 would be triggered if the amp starts to distort. I've never seen that happen in my room under real world situations with movies and music with TAD R2s, then again I have 4 in bridged mono biamping the R2s. Only time my amps clipped was one time when the volume was maxed out in error and deep bass techno started to play at levels no one would want to listen to. My friend with a pair of amps in bridged monos with TAD CR1s (that are less efficient than CR1s) also has never seen them clip. The TADs are not particularly difficult loads, but they are not easy either. These are easily the best amps I've had, including many 10x the price.

Very nice gear setup! How are those TADs when the bi-amping is used and adjusted for tone control?