Just read the Fremer review of the Ypsilon Hyperion...interesting

[morricab]

A linear distortion is only impacting the amplitude of the signal. If phase or frequency are impacted by the distortion (such as new harmonics or sidebands etc.) then it is by definition non-linear as these new bands are being created by higher order effects. I also cannot see how these memory effects could be purely linear and not affecting the frequency domain. Temperature effects in transistors are never linear...as transistors themselves are also highly non-linear...why would secondary effects suddenly be linear??

I misspoke here. Phase changes are still considered linear distortions...a non-linear distortion is when new frequencies are created.

 

[awsmone]

That’s correct phase changes are linear , the sine wave is unchanged

An example of thermal non linear changes is the drop/increase in THD as Audio amplifiers warm up, this is variable between different amplifiers

I should point out, some musical instruments develop higher order harmonics as they get louder, not just amplifiers Lol

And we haven’t even talked about FMD and AMD of speakers

 

[KeithR]

Hello Keith,
I ask because both pairs of Zu’s that were measured by Stereophile according to JA had “awful... cumulative spectral-decay (and) waterfall plot(s)”, “the drive-unit (of the Essence) is in breakup at and above 2kHz, with a large suckout evident in the presence region” and the Essence's anechoic frequency response looked like this:

Though the Zu’s are certainly lower in price to the Hyperion, among other speakers of a similar price bracket (or less) it measures rather poorly in comparison. If it’s possible Zu Audio owner's subjective enjoyment of them is not hampered by their objectively poor performance, wouldn’t it also be possible that MF could also derive significant subjective enjoyment from the Hyperion despite their objective performance?

After all, in conclusion, JA stated thus: “I suspect that Zu's designer has carefully balanced the individual aspects of the Essence's design so that the musical result is greater than the sum of its often disappointingly-measuring parts.”

Thank you - I do believe the Zu Essence sounds like it measures as the ribbon/FRD interface wasn't smooth (spirit has said it as well). It was the Wilson Audio Witt for Zu Audio and not a successful design.

I believe JA stated that the issues with the amp in question are or will be audible in many systems, so that's the issue.

 

[853guy]

Thank you - I do believe the Zu Essence sounds like it measures as the ribbon/FRD interface wasn't smooth (spirit has said it as well). It was the Wilson Audio Witt for Zu Audio and not a successful design.

I believe JA stated that the issues with the amp in question are or will be audible in many systems, so that's the issue.

Hi Keith,

Those quotes were taken from both reviews - neither the Essence nor Soul Supreme measure objectively well (not even at their price point), and the high-frequency behavior of the Supreme also is extremely ragged as can be seen in its plot.

Again, I'm curious as to whether JA's comments on the benign nature of these objective anomalies when heard subjectively is what accounts for the discrepancy between AD and HR's experience relative to JA's measurements, and is therefore applicable to Zu Audio speakers exclusively; or can also be extended to account for MF's enthusiasm for the Hyperion and Wavac, even in spite of the price differential between the latter and the former.

That these objective anomalies may be audible is perhaps less pertinent than whether or not they are deemed by the ear/brain's mechanism to be objectionable. Again, anomalies exist in all gear - and at all price points. Audibility should not be conflated with non-preferrable.

Best,

853guy

 

[spiritofmusic]

I’m pretty much the go to guy on WBF re Zu.
FWIW, I do know that chief designer Sean Casey was never totally happy w the Essence.
Ironic for the name, it never captured the “essence” of Zu.
I run the TOTL Definitions 4, and am fully aware the spkr is pretty wilful and characterful.
It requires a lot of care to get right.
A decade of ownership in, two pairs of the Definitions, 2 and 4, major mods to the 4, new room, new optimisation, and I’m wrangling a very impressive sound.
Just don’t show me the measurements.
Fascinatingly there is a video of a long conversation btwn JA and Sean, w Sean talking his design philosophy, and JA absolutely extolling the new Zu Druid VI.
I can only assume Zu sounds better than ever, and measures better too.

 

[awsmone]

I believe JA stated that the issues with the amp in question are or will be audible in many systems, so that's the issue.

I am not sure where JA said that

My interpretation of JA was that he philosophically didn’t like a “tailored” amplifier but preferred a neutral setting, did he mention it would be audible and in what sense audible?

MF in his review constantly pointed out he did not here a Tubey sound

My comment semantically is

Is adding feedback tailoring
Or is not adding feedback tailoring ?

 

[BruceD]

My comment semantically is

Is adding feedback tailoring
Or is not adding feedback tailoring ?

Hmmm--My amp has a switch on the front panel that adds NFB +3dB and 50Hz+3dB

But I cannot discern any sonic difference upon either implementation

Should I?

BruceD

 

[awsmone]

I suppose it depends on the amplifier and the speakers?

As it effects the amplifiers behaviour as well as how it interacts with the speaker

I have had two amplifiers you could adjust the feedback on, and lower feedback was preferable

 

[BruceD]

I suppose it depends on the amplifier and the speakers?

As it effects the amplifiers behaviour as well as how it interacts with the speaker

I have had two amplifiers you could adjust the feedback on, and lower feedback was preferable

Right on then!--I'm on a mission to listen intently to each switch change--I have zero then the two other settings

I won't bore you with any results

Unless I hear any differences--fair or foul!

BruceD

 

[morricab]

I am not sure where JA said that

My interpretation of JA was that he philosophically didn’t like a “tailored” amplifier but preferred a neutral setting, did he mention it would be audible and in what sense audible?

MF in his review constantly pointed out he did not here a Tubey sound

My comment semantically is

Is adding feedback tailoring
Or is not adding feedback tailoring ?

Well, for sure the Hyperion is no more tailored than Lamms, which by the admission of the designer are adjusted to fit a particular model that Mr. Lamm has supposedly developed. That would definitely fit the definition of tailored. But so what, if the goal is to make things sound better to humans then it has to be tailored because amplification devices do not make Zero distortion. However, adding feedback is also tailoring and it is tailoring to get the lowest possible distortion from a static measurement and/or to make the amp more stable and damn the consequences sonically.

Of course, Bruno Putzeys has the opposite philosophy, that if you use ENOUGH feedback (by this he means somewhere around 80db) then everything starts to get rather perfect. He would argue that a lot of amps don't sound good because they don't use enough feedback and cannot suppress the distortion well enough. I get the feeling that he is an all or none guy regarding feedback and anything in between makes bad sound. However, having heard a number of ncore designs now, I would not agree with Putzeys idea of great sound...

The Hyperion measures relatively good from a psychoacoustic perspective and likely the distortion is truly inaudible from this amp as the low order harmonics are well below 1% most of the time and the high order ones are essentially non-existant at lower power. At higher power (and thus high SPL) the audibility of distortion is much lower so when some high order peaks creep in at 200 watts it doesn't really matter so much. I think the amp fits reasonably well with what Cheever and Hiraga outline as being a good sounding amp.

 

[morricab]

I suppose it depends on the amplifier and the speakers?

As it effects the amplifiers behaviour as well as how it interacts with the speaker

I have had two amplifiers you could adjust the feedback on, and lower feedback was preferable

That was the same with my VAC 30/30...zero feedback was always the better sounding option.

 

[morricab]

Right on then!--I'm on a mission to listen intently to each switch change--I have zero then the two other settings

I won't bore you with any results

Unless I hear any differences--fair or foul!

BruceD

good luck!

 

[awsmone]

I had vac 200 and that was my experience better more holographic organic midrange , but bass was less tight a little flabby ok on classical not so good elsewhere

 

[morricab]

I had vac 200 and that was my experience better more holographic organic midrange , but bass was less tight a little flabby ok on classical not so good elsewhere

The VAC 30/30 actually has very good bass...even on a somewhat demanding speaker like the Thiel CS3.7.

 

[KeithR]

I am not sure where JA said that

My interpretation of JA was that he philosophically didn’t like a “tailored” amplifier but preferred a neutral setting, did he mention it would be audible and in what sense audible?

JA said Fremer may not hear it because he was only using a few watts. I took that to believe he felt it was audible on regular speakers.

I've owned no NFB amps, both tube and ss. What Brad is peddling isn't always true and I feel he is (extraordinarily) biased to the point of finding pseudo science (ie. Cheever's master thesis comparing a Hafler and diy 1.5 SET amp) to support his claims while ignoring others (Nelson Pass for one). My favorite amps on 101db Zu speakers were Quad Jubilees or Forties, Valvet Class A monos, and Dartzeel. And every SET amp under 20 watts wasn't enough power and had crappy bass or such boosted 2nd harmonic that I was hearing distortion. The irony is that I'm not anti-SET actually - in fact have been eyeing a Solista to scratch a long-term itch - but putting them on inefficient speakers is a recipe for disaster and belies the entire SET point. So when I see JA confirm measurements for this SS amp that is meant to drive inefficient speakers, I fail to see the point.

Curiously enough, I now have a Ref 75SE on my current Devores Gibbon Xs which SET fans who have visited my room love. Go figure?

 

[morricab]

JA said Fremer may not hear it because he was only using a few watts. I took that to believe he felt it was audible on regular speakers.

I've owned no NFB amps, both tube and ss. What Brad is peddling isn't always true and I feel he is (extraordinarily) biased to the point of finding pseudo science (ie. Cheever's master thesis comparing a Hafler and diy 1.5 SET amp) to support his claims while ignoring others (Nelson Pass for one). My favorite amps on 101db Zu speakers were Quad Jubilees or Forties, Valvet Class A monos, and Dartzeel. And every SET amp under 20 watts wasn't enough power and had crappy bass or such boosted 2nd harmonic that I was hearing distortion. The irony is that I'm not anti-SET actually - in fact have been eyeing a Solista to scratch a long-term itch - but putting them on inefficient speakers is a recipe for disaster and belies the entire SET point. So when I see JA confirm measurements for this SS amp that is meant to drive inefficient speakers, I fail to see the point.

Curiously enough, I now have a Ref 75SE on my current Devores Gibbon Xs which SET fans who have visited my room love. Go figure?

I am not peddling anything and there is no pseudo-science behind my discussions...please feel free to be specific enough to have a proper debate,. I have been quite specific, siting findings from a number of sources, including Pass, Cheever, Boyk and Sussmann, Crowhurst, Geddes and others. Do you even know I am saying to say that it is or isn't true? Do you? What is pseudo-scientific in comparing to extremes of amplification? If you want to map out the boudaries of a scientific problem this is often exactly how you do it. One that objectively measures very poorly and one that objectively measures very good to test the hypothesis that your metric, which says the objectively poor measuring one sounds better to a collection of people, more accurately predicts this than standard THD and IMD measurements. While this is not a conclusive study, it he did not invalidate his hypothesis that the amp that stays closest to his definition of aural harmonics will be the better sounding amp to MOST people. The results are consistent (if not exactly) with other engineers and scientists who have thought about this issue of correlating sound quality with measurements.

Specifically, which claim from Pass am I ignoring? His anecdote that some people prefer 3rd harmonic to 2nd harmonic? Something else? He has his opinion based on experience but it is not a fact borne out by controlled studies. He might be right or there might be something more hidden behind. I agree with a lot of what he says regarding distortion and how it builds up in circuits (particularly IMD). BTW, none of this contradicts Cheever.

I am almost certain that what you were hearing was not 2nd order distortion. More likely transformer saturation. I do not advocate using low powered SETs on unfriendly speakers and the truth is that a lot of SETs have design deficiencies (like too small output transformers...that's the most common one I would say) to save costs, because although the designs are relatively simple, the parts costs are high...if you want to do it right. A good 30 watt SET can get very satisfactory results on a 90db speaker. FWIW, I run my SETs primarily on horns or other high sensitivity, SET friendly speakers and I have never owned one that was less than 20 watts. Your over dramatizing the "disaster" of putting a moderate powered SET on normal speaker is grossly overblown and tells me that you never really tried it. It does not belie the point that most listening, even on a 90db speaker, is with 1 watt or less and the naturalness of a SET can still easily shine through, particularly the 3d presence and microdynamic liveness.

If you look at this amps measurements, it can produce several hundred watts into 2ohms with less than 1% THD, which is primarily low order harmonics...will you hear this when the amp is close to clipping? Hell no. At normal levels, where there is only few watts peak, the distortion is much lower and quite benign overall. Not sure why this can't drive difficult speakers successfully... please explain why you think so. Ironically, a lot of big speakers that this amp would be used with are MORE sensitive than the smaller siblings in their lineups...this is true for Wilson and for Focal and probably many other brands...bigger drivers are usually more sensitive not less sensitive.

Cheever correctly points out that the sensitivity to distortion decreases as the SPL increases...it is SPL dependent. That is why distortion increasing with power is not a problem at all as long as that distortion character remains constant and primarily low order. It seems that the Hyperion is fitting this ok.

Please be specific as to what no NFB amps you have owned.

Scratch that SET itch by all means...just make sure you choose wisely and don't put them on a 83db Vandersteen or similar... for a 20 watt SET I have found that 90db and up works fine in a moderate sized room sitting 3-4 meters away.

I have heard the latest Audio Research stuff at a local dealers several times now...not impressed so far...

 

[KeithR]

Please be specific as to what no NFB amps you have owned.

Scratch that SET itch by all means...just make sure you choose wisely and don't put them on a 83db Vandersteen or similar... for a 20 watt SET I have found that 90db and up works fine in a moderate sized room sitting 3-4 meters away.

I have heard the latest Audio Research stuff at a local dealers several times now...not impressed so far...

Brad - you've advocated for SETs on panels, electrostats (even Apogee), and other hard to drive speakers like Thiel.

I've probably owned more amps than you in the past five years (17-18 by last count) and listed them before. You can use the search function. There were several 75lb SET monos in that period with huge OPTs. I have more than put the legwork into this arena - and honestly I thank you for your posts years ago that turned me into thinking more about amplification and the role of feedback.


I will say Nelson Pass is leagues better than some EE with a Masters thesis (who never had a job in audio for the past two decades), but you can't seem to get that. And ironically Jack Roberts sold his beloved Wavac three years ago and has never looked back. I've owned his SITs as mentioned before.

I have wanted a Solista because of how it looks - really no other reason. Honestly, I'm pretty sure I won't like the sound as the Viva room seemed extra-euphonic to me in the past on T&F speakers. But, I prefer to do my bidding at home in my system where things aren't complicated by unfamiliar gear. My speakers are 92db/flat 8 ohms but I don't consider them particularly SET friendly.

My good friend who loves SET (and has owned/had 50 or so amps through his house - most recently the Luxman 300B SOTA job) believes the Ref75SE is the best ARC amp since the 1970s and exhibits almost no crossover distortion to his ears.

 

[awsmone]

It does seem to me we can argue all day about the measurements, but the real question is how it sounds

It does occur to me that all amplifiers produce the same total level of distortion at 1% clipping

This amplifier it’s a lot of power 200w with 100 in class A

So the question is will it drives your speakers before it clips

If you don’t like the sound you won’t buy it

If specs were the main driver for purchases we should all run out and buy Benchmark ahb2 but funny I don’t see it mentioned on these pages, maybe the owners are having too much fun to bother to blog, all the reviews were excellent

 

[BruceD]

Right on then!--I'm on a mission to listen intently to each switch change--I have zero then the two other settings

I won't bore you with any results

Unless I hear any differences--fair or foul!

BruceD

Tested and rested:

CD used one of my favs -The Living Past CD MM9401--I like it as it was recorded and stamped direct from the live tape feed.

A: 0 --Sound full dynamic, attack,decay and voice soars as I remember excellent

B: +3bB -- Slight constriction of the above with hint of hardness on the vocal-- slight shrinking of soundstage(?)

C: hz +3dB---More of B now "digititus horrendous" evident --vocals strident--no roundness /fullness to the presentation --no cigar

Yes zero setting wins the day

Funny though in the 80's I owned couple of ER A75 Class A Amps with more feedback than a FleaB Gold seller--they sounded pretty good

Go figure !

Apologies to Poster--back on topic folks

BruceD

 

[morricab]

Brad - you've advocated for SETs on panels, electrostats (even Apogee), and other hard to drive speakers like Thiel.

I've probably owned more amps than you in the past five years (17-18 by last count) and listed them before. You can use the search function. There were several 75lb SET monos in that period with huge OPTs. I have more than put the legwork into this arena - and honestly I thank you for your posts years ago that turned me into thinking more about amplification and the role of feedback.


I will say Nelson Pass is leagues better than some EE with a Masters thesis (who never had a job in audio for the past two decades), but you can't seem to get that. And ironically Jack Roberts sold his beloved Wavac three years ago and has never looked back. I've owned his SITs as mentioned before.

I have wanted a Solista because of how it looks - really no other reason. Honestly, I'm pretty sure I won't like the sound as the Viva room seemed extra-euphonic to me in the past on T&F speakers. But, I prefer to do my bidding at home in my system where things aren't complicated by unfamiliar gear. My speakers are 92db/flat 8 ohms but I don't consider them particularly SET friendly.

My good friend who loves SET (and has owned/had 50 or so amps through his house - most recently the Luxman 300B SOTA job) believes the Ref75SE is the best ARC amp since the 1970s and exhibits almost no crossover distortion to his ears.

You have been through a lot of amps in the last five years...I have had my fair share...but several were for review. Seems you are not satisfied with how most sound...in that we could agree as I think most amps, regardless of topology, are not very good.

Yes, in moderate sized rooms they work very well. The Thiels surprised us. They worked great with two or three different 25-35 watt SETs. No two ways about it. In fact one guy who heard it went and bought Line Magnetic monos for his CS3.7s (same model my colleague has). The later Apogees were pretty easy 4-6 ohm loads and ok sensitivity...works well with 30 watts... if you haven't tried it... Electrostats sounded very good this way too (3 pairs of Acoustats a pair of STAX and Audiostatics tested out).

Which SET monos please? Why don't you provide names?

You are making the classic mistake of science vs. engineering. Nelson is an engineer and a good one. Cheever is coming up with an analytical test for correlation with measurments. He doesn't have to have the engineering chops of Nelson to be good at coming up with ideas on how to evaluate amps. I haven't heard a Pass amp yet that I would want to own...including this XA30.8.

IMO, Viva's also sound somewhat colored. In this we can agree...at least what I heard in show demos. What are your speakers exactly?