VAC 452 iQ review in Stereophile

An extremely enthusiastic subjective review by Michael Fremer - the kind of review that makes people say "I want them!" - followed by a measurement sections showing disappointing very poor measurements of signal to noise ratio by John Atkinson. Should we conclude that poor SNR improves sound quality? ;) The recent review of the new Dan D'Agostino Master Audio Systems Momentum HD line preamplifier also shows a similar behavior - much improved sonics compared to the previous version, but extremely poor measurements of signal to noise ratio, much worst than the ones of the previous model.
 

Comments

JackD201

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#2
Did they show the spectra of the noise my friend? In a analysis of even small (peanut) military tubes shows great linearity in the upper and mid octaves and oise rises down below where the ear is less pitch sensitive and we perceive the vibrations more with our bodies and even hair follicles. It is a case where SNR by itself is useful but needs qualification. This has been central to the tube vs SS and even between PP and SE.

My thinkig is that good electronics will always have good linearity regardless of topology in the critical "ear" portion of the hearing experience. The low frequency area is much more subjective because it is a matter of texture rather than intelligibility. Wet or Dry? Most people like some creaminess down below, I really have to put that another way.

In any case, I want my speakers to be as linear as I can afford but am very flexible when it comes to electronics SNR for the reasons above.
 

Carlos269

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Mar 21, 2012
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#3
An extremely enthusiastic subjective review by Michael Fremer - the kind of review that makes people say "I want them!" - followed by a measurement sections showing disappointing very poor measurements of signal to noise ratio by John Atkinson. Should we conclude that poor SNR improves sound quality? ;) The recent review of the new Dan D'Agostino Master Audio Systems Momentum HD line preamplifier also shows a similar behavior - much improved sonics compared to the previous version, but extremely poor measurements of signal to noise ratio, much worst than the ones of the previous model.
It seems like linearity is no longer the emphasis in boutique designers’ design goals and that they are now “voicing” their equipment for a desired sound. They appear to have also learned a lesson from Halcro, who designed equipment with almost unmeasurable THD (Total Harmonic Distortion) but that not many found musical; and they have now embraced principles of psychoacoustics, where distortion improves detail retrieval and perciveability. This is part of the tools of the trade in the mastering studio world and an unspoken practice in high-end audio, where gullible deep pocket audiophiles are swindled with promises of precision and high-fidelity, while being sold distortion.

Have a read at the following article and see how it reflects the current state of high-end audio:

Analogue Warmth

Some of these much heralded “trophy” gear and designers are cooking the books.
 
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Ron Resnick

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#4
It is personally (and idiosyncratically, I realize) very interesting to me that Michael liked the VAQ 452 iQ as much he did, compared to his reference darTZeel NHB 468s. I enjoy reading about how and where Michael calibrates various tube, hybrid and solid-state amplifiers on his spectrum of sonic attributes.

At this level of top-of-the-line amplifiers I think it is totally a matter of personal subjective preference. In my brief comparison at MikeL's of older generation VAC 450s and his then-reference darTZeel NHB 458s a couple of years ago I would have chosen the VACs as my "keepers" and MikeL clearly preferred his 458s.

Also interesting to me is that Michael apparently preferred these new VACs over the VTL Siegfried IIs he compared directly to his darTZeel 458s several years ago, as I sense that he did not rave about the Siegfried IIs quite as effusively as he praised the VAC 452 iQs. Putting it differently, I read this review as suggesting that Michael enjoyed the VAC 452 iQs compared to the 468s relatively more than he enjoyed the Siegfried IIs compared to the 458s.

Consistently, it seems, Michael Fremer and MikeL both ultimately come down on the solid-state side of the tube/solid-state dividing line on the amplifier spectrum. I still come down on the tube side of that line.

Of course Michael was using different speakers then, so these idle speculations may be entirely spurious and invalid.
 
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Holli82

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Jun 7, 2010
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#5
Ron,

I agree with you. I think it all about synergy.
 
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Holli82

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#7
no, I don't think so. I believe synergy > measurement. I guess we can agree that we disagree.
 

bonzo75

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#8
I don't see how a big push pull amp from AR, VTL, or VAC, can sound better than a good SS amp in an all out system (i have never heard VAC outside a show, just my assumption it is on the lines of, but different from AR, VTL, or CJ). In all the latter 3 cases I would prefer them to a not so good SS, but not to a good SS. In a system like Mike's, I see no chance for the other 3 to compete with the Dartzeel. Now if such a system gets set around another high quality SS amp like dagostino, boulder or audionet Heisenberg, that is different and would be a good competition
 

JackD201

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Apr 21, 2010
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#9
It seems like linearity is no longer the emphasis in boutique designers’ design goals and that they are now “voicing” their equipment for a desired sound. They appear to have also learned a lesson from Halcro, who designed equipment with almost unmeasurable THD (Total Harmonic Distortion) but that not many found musical; and they have now embraced principles of psychoacoustics, where distortion improves detail retrieval and perciveability. This is part of the tools of the trade in the mastering studio world and an unspoken practice in high-end audio, where gullible deep pocket audiophiles are swindled with promises of precision and high-fidelity, while being sold distortion.

Have a read at the following article and see how it reflects the current state of high-end audio:

Analogue Warmth

Some of these much heralded “trophy” gear and designers are cooking the books.
Well, to a point. If the core function of a system is to deliver information, we are talking about the degree of communication while the presentation is second, albeit a close second. In other words ideally there would be the least possible drop off in data then the rest as you imply is gravy. There must be a baseline and that to me is low level linearity. If a system cannot convey the sweetness or sharpness of small tones and transients, there is little hope for anything but brute force sound events. If this sounds like the first watt principle, I guess it is. Just viewed within musical context.

As far as tailoring sound goes, it is a universal reality. Know your market, build for your market, make a living. Same goes for music production. I remember one lab session where 6 of us were given 12 tracks to mix. None sounded remotely alike at the end of the session. I went for a clean, polished sound and was pleased with myself. My classmate went to town and grunged the MF-in bass guitar up and I'll be damned if I didn't like his better. I missed the context of the song, which was about a girl who'd been cheated on. My lady was contemplative, his was Lorena Bobbit already thinking of heading to the kitchen LOL

I any case, I cringe when accuracy in and of itself is touted as the selling point of anything except a design or measuring apparatus. As far as I am concerned, Enjoyment is the bottom line and SNR, like watts, without context is just another number.
 

Alpinist

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#10
I find it disappointing that amplifiers such as the VAC 452IQ and the dartZeel NHB-468, while sounding better than their predecessors, do not measure nearly as well, based on JA’s measurements. The NHB-468’s for example could only deliver 205 watts into a 4 ohm load. This would not even be sufficient to drive my Vandersteen 7 Mk2’s. I think these are too large trade offs for some improvement in sound quality.

Ken
 
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bonzo75

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#11
How much did the 458 deliver into 4 ohms?
 

Ron Resnick

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#12
I find it disappointing that amplifiers such as the VAC 452IQ and the dartZeel NHB-468, while sounding better than their predecessors, do not measure nearly as well, based on JA’s measurements. The NHB-468’s for example could only deliver 205 watts into a 4 ohm load. This would not even be sufficient to drive my Vandersteen 7 Mk2’s. I think these are too large trade offs for some improvement in sound quality.

Ken
I agree that the below-specified output into 4 ohms for both the VAC 452 iQ and the darTZeel NHB-468 is puzzling.
 

Mike Lavigne

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#13
It is personally (and idiosyncratically, I realize) very interesting to me that Michael liked the VAQ 452 iQ as much he did, compared to his reference darTZeel NHB 468s. I enjoy reading about how and where Michael calibrates various tube, hybrid and solid-state amplifiers on his spectrum of sonic attributes.

At this level of top-of-the-line amplifiers I think it is totally a matter of personal subjective preference. In my brief comparison at MikeL's of older generation VAC 450s and his then-reference darTZeel NHB 458s a couple of years ago I would have chosen the VACs as my "keepers" and MikeL clearly preferred his 458s.

Also interesting to me is that Michael apparently preferred these new VACs over the VTL Siegfried IIs he compared directly to his darTZeel 458s several years ago, as I sense that he did not rave about the Siegfried IIs quite as effusively as he praised the VAC 452 iQs. Putting it differently, I read this review as suggesting that Michael enjoyed the VAC 452 iQs compared to the 468s relatively more than he enjoyed the Siegfried IIs compared to the 458s.

Consistently, it seems, Michael Fremer and MikeL both ultimately come down on the solid-state side of the tube/solid-state dividing line on the amplifier spectrum. I still come down on the tube side of that line.

Of course Michael was using different speakers then, so these idle speculations may be entirely spurious and invalid.
did you notice Fremer never actually names his reference dart 468's in the review. he only refers to them as his reference amps. that's a first in my recollection. my guess is this was a conscious decision by someone for some reason. i would have been interested in overhearing the discussion that led to that move.

i enjoyed the VAC 450 Statements in my system and could have easily lived with them happily. it's a great amp, and likely the 452 IQ monos are better. but i think ultimately they held my system back from doing everything i want. and now with the 468's my expectations are even higher.

but at the level of these amps we are splitting hairs and system synergies and sonic preferences are very much at play. and my system has particular possibilities i like to access fully.
 
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Mike Lavigne

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#14
How much did the 458 deliver into 4 ohms?
the 458's are manufacturer rated as 800 watts into 4 ohms.

Atkinson's measurements;
Defining the clipping point as the power when the THD+N reaches 1%, the NHB-458 clips at 530W into 8 ohms (27.2dBW), 900W into 4 ohms (26.5dBW), and 1025W into 2 ohms (24.1dBW).
 

Ron Resnick

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#15
did you notice Fremer never actually names his reference dart 468's in the review. he only refers to them as his reference amps. that's a first in my recollection. my guess is this was a conscious decision by someone for some reason. i would have been interested in overhearing the discussion that led to that move.

. . .
The 468s are listed in Michael's Associated Equipment list.
 

Carlos269

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Mar 21, 2012
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#16
did you notice Fremer never actually names his reference dart 468's in the review. he only refers to them as his reference amps. that's a first in my recollection. my guess is this was a conscious decision by someone for some reason. i would have been interested in overhearing the discussion that led to that move.

i enjoyed the VAC 450 Statements in my system and could have easily lived with them happily. it's a great amp, and likely the 452 IQ monos are better. but i think ultimately they held my system back from doing everything i want. and now with the 468's my expectations are even higher.

but at the level of these amps we are splitting hairs and system synergies and sonic preferences are very much at play. and my system has particular possibilities i like to access fully.

How does 205 Watts into a 4 ohm load enable the Dartzeel 468 amplifiers to allow for possibilities to be accessed fully, when they are rated at 800 Watts into a 4 ohm load but fail to deliver less than 205 Watts? Scratching my head. Sounds like someone has been .......................

Redefining the clipping THD% criteria is totally specmanship. Scientific measurements are based on a reference yardstick, not on one that moves to make the specifications look better. There are standards for a reason, to serve as a datum for analysis.

You can’t put lipstick on a pig and claim that it’s not a pig.
 
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Mike Lavigne

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#17
I find it disappointing that amplifiers such as the VAC 452IQ and the dartZeel NHB-468, while sounding better than their predecessors, do not measure nearly as well, based on JA’s measurements. The NHB-468’s for example could only deliver 205 watts into a 4 ohm load. This would not even be sufficient to drive my Vandersteen 7 Mk2’s. I think these are too large trade offs for some improvement in sound quality.

Ken
if you read the manufacturers comments section of the 2019 Stereophile issue with the 468 review, this 4 ohm output issue gets addressed.

Herve Deletraz writes.......

the difference in maximum output measured power is mainly due to the fact that our main internal power supply is filtered but not regulated. AC main voltage at Michael's home presumably dropped a little during sustained power tests.. Our design is centered around an AC voltage source of 125 volts. a difference of 6-7 volts would have a significant difference on the output power, enough to explain the difference.
 

Mike Lavigne

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#18
my speakers are 97db, with a nominal 7 ohm load. they mostly run at 1-2 watts output with the 458's or 468's.

when i'm really cranking it i see steady state levels of 25-75 watts and occasional peaks of 200-300 watts.

i've been at shows with Herve where is pushed 458's and 468's to 1200 peak watts with 86db efficient speakers.
 

Mike Lavigne

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#19
do the math on 200 steady state watts and a 97db efficient speaker. it would be like putting your head inside a jet engine.
 
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Mike Lavigne

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How does 205 Watts into a 4 ohm load enable the Dartzeel 468 amplifiers to allow for possibilities to be accessed fully, when they are rated at 800 Watts into a 4 ohm load but fail to deliver less than 205 Watts? Scratching my head. Sounds like someone has been .......................

Redefining the clipping THD% criteria is totally specmanship. Scientific measurements are based on a reference yardstick, not on one that moves to make the specifications look better. There are standards for a reason, to serve as a datum for analysis.

You can’t put lipstick on a pig and claim that it’s not a pig.
Carlos, not sure the 468's are for you.
 

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