Benchmark AHB2 / Class D Purifi Eigentakt / Mark Levinson 333 - Listening impression & Conclusion

[Phorize]

I have a PhD in Neurosciences from MIT/Harvard, I think I know better what science is than you. You are a cultist.

Then you’ll know exactly why controlled tests are a necessity.

 

[BDWoody]

I have a PhD in Neurosciences from MIT/Harvard, I think I know better what science is than you. You are a cultist.

You have a couple weeks off. Have a nice holiday.

 

[SIY]

Sure, no problem with that. The problem is measurements dont get the whole picture. Things like soundstage and microdynamics and not really captured. Even Amir does a sound test. Ask him why

Where in the world did I mention measurements?

Controls. Come back when you've done a valid listening comparison.

edit: sorry, I missed Brad stepping in. And the humor.

 

[caught gesture]

I have a PhD in Neurosciences from MIT/Harvard, I think I know better what science is than you. You are a cultist.

Attempted authority bias alert!

 

[Phorize]

I have a Tufty club badge, I didn’t notice any difference when I had Hypex/Purifi and the AHB2 here apart from the price of course.
Keith

In his defence I did find significant audible differences between my accuphase e202 and my purifi amp. My e202 was f@&king heavy and went thud everytime I moved it around. In contrast my March p452 makes no sound at all when I move it. That said if I tap it on top it makes a mid frequency, light percussive sound that diminishes when i stop tapping. It’s as plain as day to my ears,

 

[BDWoody]

On extraordinary claims? Absolutely. No controls, the claim is equivalent to the claims of alien abductions with anal probing.

I wonder if they charge extra for that...

 

[BrokenEnglishGuy]

In his defence I did find significant audible differences between my accuphase e202 and my purifi amp. My e202 was f@&king heavy and went thud everytime I moved it around. In contrast my March p452 makes no sound at all when I move it. That said if I tap it on top it makes a mid frequency, light percussive sound that diminishes when i stop tapping. It’s as plain as day to my ears,

Well, the accuphase is not clean as the purifi in the measurements, that can explain the differences.

 

[Phorize]

You have a couple weeks off. Have a nice holiday.

Aw, I was starting to like @Gueco. He didn’t like @Willem though, no sirree!

 

[BDWoody]

Aw, I was starting to like @Gueco. He didn’t like @Willem though, no sirree!

He needs to put the blazing guns away.

 

[Lord Victor]

I just want to say I compared the purifi with the benchmark at my home and reached the same conclusion as the original poster: the purifi is compressed and has a hard time driving my kef r3. The benchmark is a better amplifier, better dynamics and better presentation. The ahb2 is lot more musical (the forbidden word)

As much as my recent listening tests where I level matched with a multimeter would suggest no audible differences between amps, my earlier subjective tests matching by dB meter did seem to suggest the Purifi was somewhat “boring” or “compressed” sounding, so I’m rather curious about this… wish I had the option to listen to them compared.

 

[mocenigo]

I just want to say I compared the purifi with the benchmark at my home and reached the same conclusion as the original poster: the purifi is compressed and has a hard time driving my kef r3. The benchmark is a better amplifier, better dynamics and better presentation. The ahb2 is lot more musical (the forbidden word)

The Kef r3 have a horrible impedance, dipping to 3ohm and less at 40hz and 150hz with a large argument in the impedance. It may be that the Purifi has trouble there, even though it should be very stable up to 2ohm. The fact that these are also very low sensitivity speakers mag play a role

Of course assuming the comparison was properly controlled.

 

[sq225917]

I'd love to amps measured driving speakers.

 

[rdenney]

like you do before you have an opinion? LOL

(Edit: This response isn't just for Gueco, but also for whoever the anthill-kicking cabal sends next week. )

It's not a matter of whether people have opinions, it's a matter of figuring how 1.) whether those opinions hold up when we don't know which alternative is being played, and 2.) whether there is any reasonable explanation that could be analyzed to support that opinion.

Let's say, without any justification, that what you heard was real. What could cause that outcome? Well, firstly, what gain setting did the Benchmark use? Is there any chance that the source was overloading the input buffer of the amp? The two amps have different gain structures, so something must be done to correct for differences in levels, and that something could also cause problems. The Purifi amp has about 13 dB of gain, plus 14 dB from the EVAL input buffer, if that's what your amp used. The AHB2 has 9, 17, or 23 dB of gain, depending on settings. So, there's just no way the two amps will put out the same sound level without adjusting levels, and even the slightest difference will color our perceptions. Studies have shown that tiny variations in loudness, if broadly applied across the spectrum, change our perceptions even when so tiny we can't tell that one is "louder" than the other. That can be as little a 0.1 dB, we are given to understand.

Dynamic compression usually means an amp is running out of headroom (or the speakers are). What did you do to ascertain whether that was happening? It means the louder bits aren't as loud compared to the softer bits, and that can be measured. Those evaluations and measurements are data. Without data, you simply cannot say "The benchmark is a better amplifier, better dynamics and better presentation. The ahb2 is lot more musical (the forbidden word)". You could say you liked it more, but can't explain why. You could also perform some controlled testing to demonstrate that you can distinguish the amps reliably, and then make some measurements and perform some analysis that might explain why.

But the way you say it is a conclusion not in evidence, and the result misleads people without justification. The preponderance of all the evidence suggests that your perceptions are biased by differences in gain that are not being fully corrected.

Rick "who has opinions, too, but looks for reasons before declaring them" Denney

 

[thewas]

I have a PhD in Neurosciences from MIT/Harvard, I think I know better what science is than you. You are a cultist.

I am actually a musician, I play trumpet and piano. I love how cultists with no sound experience think measurements are everything and thats science for you.

Impressive curriculum vitae!

 

[SIY]

Impressive curriculum vitae!

He's also married to Morgan Fairchild. Who he's seen naked.

 

[MaxBuck]

He's also married to Morgan Fairchild. Who he's seen naked.

That actually would impress me more than any of the other resume items, if true.

 

[Digital_Thor]

When searching for small differences in amplifiers. Wouldn't it be better to use a more neutral speaker?
https://www.stereophile.com/content/bowers-wilkins-802-d3-diamond-loudspeaker-measurements

 

[sq225917]

If searching for small differences I'd suggest no speaker would suffice.

 

[tedmingo]

I have these 3 amplifiers and am curious how they compare in my environment.

Equipment setup:

CD/SACD player: Oppo BD105

Stereophile’s Test CD2 , Track 15 pink noise, , for level matching the three amplifiers​

Volume set 72dBC on track 15 before playing songs B - F​

Volume set to 82dBC on track 15 before playing songs G-H​

​

Standard Music :​

• B - SACD Norah Jones, Come away with me
• C -SACD Andrea Bocelli, Melodramma
• D -SACD Dire Straits, Walk of Life
• E -SACD Pink Flyod, Time
• F -CD Ultimate Demonstration Disc: Chesky Records’ Guide to Critical Listening, Track 3 Spanish Harlem

Life Classical Recording Music:​

• G - SACD Telarc Tchaikovsky 1812 overture, Track 7 Cossack Dance from Mazeppa
• H -SACD Telarc , Donald Runnicles , ORFF Carmina Burana , track 10 were diu werlt alle min

Blu-Ray Movies:​

• I -John Williams Live in Vienna, Track 19 Imperial March , watching in 2ch mode
• J -Patriot, Uncompressed LPCM Audio track, Scene 6

Apple TV 4k:

• 1. Streaming Apple music (various pop songs Taylor Swift, Marron 5, etc)
  2. YouTube podcast (for center channel compare)
  3. HBO Max Movies (for center channel compare)

Pre-Pro Anthem AVM50v, XLR audio input from oppo.
802D3 Speakers (Front) , HTM1D3 (Center) , old DM640i (Surround back)
Amplifiers under test:

1. Mark Levinson No 333
2. Benchmark AHB2
3. VTV Purifi Eigentakt EVAL-1

Listening Impression (Stereo 2ch mode):

• For songs B-F , level match volume based on Track 15 pink noise (A1 above) , resulting in typical music volume swings around 80dB-86dB. They all sound good. The Benchmark and Levinson sounds very similar in tonal balance, my son (blind test) could not tell them apart. The Benchmark AHB2 sounds very clean on E) Time , the ring sounds the clearest. On v vocal on AHB2 sounds a little bit less weight (Andrea Bocelli voice sounds less vibrato) compare to others. Levinson sounds very similar to AHB2 but the vocal is is more full and the bass has more weight. The Class D Purifi Eigentakt tonal balance has stronger mid-bass/low midrange so the vocal sounds more forward and closer but the upper treble is rolled off. The sound of cymbals are not as clear and not as distinct compare to levinson 333 or benchmark. AHB2.
• For songs G-I, volume knob has to increase by 10dB (A2 above) to compensate for the recording sound level. The Class D Purifi Eigentakt sounds compressed (lack impact), at loud level, the sounds of each instruments are not as delineated, and the high frequency triangle and cymbals are not very clear in comparison to benchmark AHB2 or levinson 333. Both levinson 333 and benchmark AHB2 sounds very similar, but when the dynamic sound peak at 94dB, the 333 sounds more at ease and each individual instruments details are more distinct (more details of cello vibration and triangle resonance) than the AHB2.
• It is hard to tell apart AHB2 vs 333 but easy to identify the Class D Purifi once we have heard all three on the same or specific songs. The Class D Purifi has rolled off treble and forward midrange that is its strong signature (by comparison, it sounds neutral/normal on its own when there is nothing to compare). This roll off treble reminds me on my previous Krell KSA-200s sonic signature.
• The life recording song G-H has very wide dynamic (55dB – 94dB swing). Since my son played at the orchestra, I know what orchestra sounds like sitting in front rows. In my observation, to reproduce this life-like sounds of life orchestra is probably the most demanding for high resolution speakers and amplifiers. When playing loud level , songs G-I , the old Levinson still sounds the best.
• When playing loud dynamic music song G-I, we heard changes in Class D Purifi tonal balance, the peak sounds certain instruments are level off compare to AHB2 or 333. Could the Class D PWM sampling be manipulated so the peak musical waveform dynamic is lost to bias for more midrange clarity ? Or is there soft clip mode where certain peak music waveform is “clipped” so they sound “compressed” . I don’t know but what we heard is a more compressed dynamic relative to AHB2 or 333 on song G-I.

Listening impression (Movie, using it to drive center channel)

• Playing with K-M, AHB2 (mono bridge mode) and 333 sounds the same.
• Playing with K-M, even level matching with AVM50v built-in level calibration (per SPL meter), the dialogue still sounds louder with the Class D Purifi. It correlates with our stereo experience where purify midrange is more forward sounding but less treble.
• This Class D Purifi amp is good match for center channel or a PA system, it accentuates midrange voice (in comparison, sounds "neutral"/normal when listening to it without any comparison). So the dialog is more clear (e.g. comparison on streaming podcast from apple TV).
• Try watching the Blu-ray Patriot movie Scene 6; It has both uncompressed 5.1 PCM and standard Dolby Digital 5.1. The dialogue on Dolby Digital 5.1 is more clear due to compression (special effects, music, weapons sounds are compressed) . However, if one has dedicated room , speakers and amps, one would want to watch it in uncompressed PCM for more immersive and open sound.

My personal conclusion:

1. Class D amplifiers have improved a lot of the years but Class D Amps are still no match to good design Class AB Amp.in term of sound quality and dynamic handling
2. Benchmark AHB2 is more versatile (good for all music) and more dynamic than the Class D Purifi Eigentakt
3. Class D Purifi Eigentakt is suitable for center channel, its slight compression and unnatural bias toward midrange makes dialogue more clear It is not an ideal amp for life classical music reproduction.
4. Mark Levinson 333 is the best despite its old age. It is the most life-like, with more weight on vocal , and more at ease when playing life recording classical orchestra at higher volume level
5. There needs to additional scientific measurements that can explain why the benchmark AHB2 sounds better than Purifi Eigentakt in my environment and why the levinson sounds more dynamic and detailed on loud classical music. Traditional SINAD, THD , IMD measurement using sinewave do not have the musical waverform complexity and can not explain the contrast of what we heard among these amplifiers in our environment. What we heard can not be explained with just THD measurement as they all sound good (not distorted) but different. As below certain THD, the delta is not audible.

I am a Benchmark fan. I use it to drive a pair of Revel F208's. When I describe the sound of the AHB2 I usually start with how it does not sound. It's the quietest amp I have ever heard. For me an amp should be virtually distortion free, ruler flat and get out of the way.

 

[Mosfet]

I am a Benchmark fan. I use it to drive a pair of Revel F208's. When I describe the sound of the AHB2 I usually start with how it does not sound. It's the quietest amp I have ever heard. For me an amp should be virtually distortion free, ruler flat and get out of the way.

When you say 'quietest', are you referring to background noise such as a total absence of 'hissing'?