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Bruno Putzeys reaches out to the subjectivists

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oivavoi

oivavoi

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Actually this looks like it would prove no problem in gain structure. The PA2 has several adjustments for setting system gain structure anyway. One is setting input sensitivity of the PA2 at either +4dbu or -10 dbv. Which is about a 12 db difference between those two. The 26 db gain of the amps is about right for you. If fed the max Oppo output into the amps directly it would be outputting between 200 and 250 wpc into 8 ohms. That would drive your speakers somewhere around 109 db give or take a few if they are 86 db sensitivity. If your normal listening is the level you describe you might well be just about perfect with +4 dbu settings on the input of the PA2.

Thanks!
 

cjf

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Im not sure I fully understand what you are saying here but it sounds like you are describing mains buzz 50 or 60hz on top of connection issue.

This catagorically is not the fault if the hypex amps.

As blum mentioned the Ayre very high input impedance and practically no input filtering.....mmmmm......dont live near any transmitters do you? Probably best to keep your mobile phone away from it also. Its not a good idea to have the input open that wide IMO, open to all sorts of RF getting in there including that from some DACs / CD players.


Think the penny has dropped. The Hypex class D amps oscillate at about 400khz....

Change the pre amp and I will bet your problems all go away. Its a radio receiver not an audio pre amp :)

Well, I'm not sure I agree with you on it not being the fault of the Hypex Amps. I have owned 3 different flavors of Hypex Amps thus far and had the luck of actually having all 3 of those flavors in my house at the same time side by side. I don't think many other people can say they have had the same opportunity for testing these components as myself. All 3 were built by at least 3 different people at different times using different hardware and Internal cabling combinations and all 3 have the same problems..in my house. Whatever parts or build techniques that are common among those 3 Amps are most likely what's to blame. To me that makes for a pretty strong case that it is indeed something about these Amps...again in my house.

With that said, I have found and lived with combinations using these Amps that do work just fine. Also, none of these issues exist in any form when using more mainstream Amps in my house. For example, every Pass Labs amp I have owned and now currently own never had such issues with any of the same equipment. Same goes for the Classe Amps I have owned.

All this goes back to possibly designing these Hypex Amps in a bubble or only testing them via simulations, software or relying on a select group of others most likely heavily committed to the DIY world and not as likely to use the more mainstream "hi-end" equipment. In my mind if you take two components (PreAmp & Speakers) required to complete the playback chain which are built by other highly regarded/respected manufacturers and pair them to 3 different Amps all from the same manufacturer which share the same common design elements and discover a set of issues that dont exist when you pair those same (PreAmp & Speakers) to a multiple other Amps from different manufacturers then who is the manufacturer most likely doing something wrong? I doubt anyone would argue the fact that the Ayre KX-R Twenty, Magico or any of the Pass Labs XA.x series Amps are best of breed equipment. If your product doesn't work with these brands then your doing something wrong somewhere and it needs to be addressed if you want your product to survive.

Anyway..this is all just one mans experience/opinion so take it for what you feel its worth. :)
 

Blumlein 88

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Well, I'm not sure I agree with you on it not being the fault of the Hypex Amps. I have owned 3 different flavors of Hypex Amps thus far and had the luck of actually having all 3 of those flavors in my house at the same time side by side. I don't think many other people can say they have had the same opportunity for testing these components as myself. All 3 were built by at least 3 different people at different times using different hardware and Internal cabling combinations and all 3 have the same problems..in my house. Whatever parts or build techniques that are common among those 3 Amps are most likely what's to blame. To me that makes for a pretty strong case that it is indeed something about these Amps...again in my house.

With that said, I have found and lived with combinations using these Amps that do work just fine. Also, none of these issues exist in any form when using more mainstream Amps in my house. For example, every Pass Labs amp I have owned and now currently own never had such issues with any of the same equipment. Same goes for the Classe Amps I have owned.

All this goes back to possibly designing these Hypex Amps in a bubble or only testing them via simulations, software or relying on a select group of others most likely heavily committed to the DIY world and not as likely to use the more mainstream "hi-end" equipment. In my mind if you take two components (PreAmp & Speakers) required to complete the playback chain which are built by other highly regarded/respected manufacturers and pair them to 3 different Amps all from the same manufacturer which share the same common design elements and discover a set of issues that dont exist when you pair those same (PreAmp & Speakers) to a multiple other Amps from different manufacturers then who is the manufacturer most likely doing something wrong? I doubt anyone would argue the fact that the Ayre KX-R Twenty, Magico or any of the Pass Labs XA.x series Amps are best of breed equipment. If your product doesn't work with these brands then your doing something wrong somewhere and it needs to be addressed if you want your product to survive.

Anyway..this is all just one mans experience/opinion so take it for what you feel its worth. :)

One could just as easily say the fault lies with Ayre for designing in a bubble. It was the only problem preamp you encountered. I believe you said two or three other pre-amps worked fine with hypex amps. As far as anyone knows there is no other preamp on the planet that causes this issue other than the Ayre. How is any company to test every conceivable combination? Yes some aspect of hypex design doesn't play well with Ayre. That hardly justifies the other conclusions you are drawing. If someone investigated the output with that configuration beyond just what it sounded like it might be obvious what was going on, and a fix might also be possible. Hypex amps are out there in the many thousands at least, and don't suffer some regular problem or it would have been heard about by now. The Ayre is not unique, but highly unusual to have a 2 megaohm input impedance. Which is why I suspect that has something to do with the issue. It is possible one could have simply paralleled a 47 kohm resistor to ground at the Ayre input and solved the problem while introducing no other problematic issues for either piece of gear. If Ayre had this problem with very many amps, it would be no big deal to have a switch for that in case it becomes a problem.
 

Sal1950

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Anyway..this is all just one mans experience/opinion so take it for what you feel its worth.
cjf, Have you ever considered having an exorcist visit of your listening room?
I remember the highly irregular issues you had with speaker cabling and your Magico speakers.
With all this expensive gear you have going in and out of your system are you searching for some ultimate synergistic combination or is this just a big hobbyist experiment? Between the Hypex, Pass, and Classe amps you mentioned I would challenge you to identify them apart in a bias controlled blind listening test. (pops and clicks ills cured).
Why not just settle on a combination that works and pleases you, then just listen to the music.
 
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March Audio

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Well, I'm not sure I agree with you on it not being the fault of the Hypex Amps. I have owned 3 different flavors of Hypex Amps thus far and had the luck of actually having all 3 of those flavors in my house at the same time side by side. I don't think many other people can say they have had the same opportunity for testing these components as myself. All 3 were built by at least 3 different people at different times using different hardware and Internal cabling combinations and all 3 have the same problems..in my house. Whatever parts or build techniques that are common among those 3 Amps are most likely what's to blame. To me that makes for a pretty strong case that it is indeed something about these Amps...again in my house.

With that said, I have found and lived with combinations using these Amps that do work just fine. Also, none of these issues exist in any form when using more mainstream Amps in my house. For example, every Pass Labs amp I have owned and now currently own never had such issues with any of the same equipment. Same goes for the Classe Amps I have owned.

All this goes back to possibly designing these Hypex Amps in a bubble or only testing them via simulations, software or relying on a select group of others most likely heavily committed to the DIY world and not as likely to use the more mainstream "hi-end" equipment. In my mind if you take two components (PreAmp & Speakers) required to complete the playback chain which are built by other highly regarded/respected manufacturers and pair them to 3 different Amps all from the same manufacturer which share the same common design elements and discover a set of issues that dont exist when you pair those same (PreAmp & Speakers) to a multiple other Amps from different manufacturers then who is the manufacturer most likely doing something wrong? I doubt anyone would argue the fact that the Ayre KX-R Twenty, Magico or any of the Pass Labs XA.x series Amps are best of breed equipment. If your product doesn't work with these brands then your doing something wrong somewhere and it needs to be addressed if you want your product to survive.

Anyway..this is all just one mans experience/opinion so take it for what you feel its worth. :)

Having an amp input with no filtering is asking for trouble and that appears to be what youve got.

Its difficult to blame the hypex and I have not heard of anyone else experiencing problems of this nature with them
 

cjf

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cjf, Have you ever considered having an exorcist visit of your listening room?
I remember the highly irregular issues you had with speaker cabling and your Magico speakers.
With all this expensive gear you have going in and out of your system are you searching for some ultimate synergistic combination or is this just a big hobbyist experiment? Between the Hypex, Pass, and Classe amps you mentioned I would challenge you to identify them apart in a bias controlled blind listening test. (pops and clicks ills cured).
Why not just settle on a combination that works and pleases you, then just listen to the music.

Haha..yes it wouldn't surprise me at all if there are a few Ghosts and Goblins floating around this place. The house is 125yrs old after all :D

I suppose all the gear swaps over the last two years could be considered a search for the ultimate synergy to the extent my wallet would allow. You may or may not believe this but I'm pretty certain I could easily pick out the sound characters blindly between the Hypex and the Pass Labs amps I have on hand. They really do sound quite different, especially the XA30.5 I have used recently. My new long term amps are the XA60.8's and I'm very happy with them and their universal compatibility with any gear/cable I chose to hook up to them. No exorcisms or other tweaks necessary. They just work as it should be but this is apparently too much to ask of the Hypex amps as I have come to learn the hard way.

At this point I have settled on a combination that I feel I can live with for the long haul...well at least in terms of the Amp/Speaker/Cabling combo :)
 

watchnerd

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Having an amp input with no filtering is asking for trouble and that appears to be what youve got.

Its difficult to blame the hypex and I have not heard of anyone else experiencing problems of this nature with them

Not to mention I doubt guys like NAD would build their new Master series around the Hypex nCore if it was massively flawed.
 

Sal1950

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You may or may not believe this but I'm pretty certain I could easily pick out the sound characters blindly between the Hypex and the Pass Labs amps I have on hand.
Well not having any engineering background but taking into account the circumstances documented in your cable thread, driving your Magico's I would guess it is definitely possible for amps to sound quite different. In the terms used in that thread (unusual load) the Magicos present a very irregular load for a amplifier to control. No disrespect but I would tend to consider a crossover that difficult to drive to be a broken design. Looking at what you had to come up with in cabling make them behave suggests to me that things just shouldn't be done this way.
YMMV

For those that don't remember the thread it's here.
http://audiosciencereview.com/forum...rs-and-cables-connected.291/page-4#post-19107
 
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Thomas savage

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Well @cjf you've got the right amps now, the high end audiophile world does seem to churn out weird designs that are at odds with sensible / practical design and being so throw up all sorts of weird little issues. Like your magico problem that became a speaker cable issue :confused: and now a preamp issue that's in effect now a amp issue...:confused:

Iv been there myself over the years, always something strange happening, it's just 'esoteric ' designs that seem only to work in the minds of the guys who think them up . In the real world their design choices cause many strange happenings, and thusly a whole load of super expensive tweaks are avalible to help ' solve ' them.. I think this is what happens when a talented designer spends too much time on their own, away from being in a bigger company and getting challenged on their ideas they seem to indulge and go off piste :D

I always fancied those pass lab amps you have.. plenty of audiophile kudos with those :)
 

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I had Pass Labs, I don't believe their current delivery is all that wonderful, i.e. When the speakers impedance dips/halves the amps output does not double.
I have compared the Hypex to many other designs ,they are IMO right up there ,completely silent and efficient.
We have the Benchmark AHB2 at the moment that is a hybrid design, another superb amp.
Keith
 

Thomas savage

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I had Pass Labs, I don't believe their current delivery is all that wonderful, i.e. When the speakers impedance dips/halves the amps output does not double.
I have compared the Hypex to many other designs ,they are IMO right up there ,completely silent and efficient.
We have the Benchmark AHB2 at the moment that is a hybrid design, another superb amp.

Keith
IMG_0764.JPG
 

Purité Audio

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Hypex you purchase directly from Hypex, but I rate them, the only really 'suspect' Class D I have had here was the SPEC amps from Japan, I did write to the manufacturer on several occasions but the design ws not changed.
Keith
 

Sal1950

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I always fancied those pass lab amps you have.. plenty of audiophile kudos with those :)

If there was a High Fidelity Hall Of Fame, Nelson Pass would most certainly deserve a place there. From his early days with Threshold to the designs for Adcom, etc; and now with Pass Labs/First Watt, IMO he has brought some of the best of the best in amps to High End Audio. Not to be forgotten is his continued work and contributions to the DIY community.
Thanks Papa ;)
 

Bruno Putzeys

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If I was trying to sell amplifiers that used a huge amount of negative feedback, I, too would write something similar. It's good marketing.
I wonder if anyone's ever thought of the possibility that I might have turned to designing low distortion amplifiers that have lots of feedback because they work better than the ones that don't? It's a lot easier to to design non-feedback amps and waffle about those than to learn how to do feedback and then try to sell amps to a populace that, on the whole, is suspicious of feedback. People seem to think that I just happened to have high-feedback amps handy by chance, and needed to flog them. Does anyone have the faintest idea how complicated this stuff gets, particularly as applied to class D amplifiers? Seriously, trying to make a quick buck by designing and selling amplifiers with a lot of feedback in the current audiophile market would not count as a rational way to get rich.

There is no question that he is wrong about the statements you quoted. He leaves no place for sighted listening to be wrong. As noted, he has to make a living and that has a way of corrupting one's views.
You're misreading me. All I'm saying is that if someone has a particular listening experience, I've no business denying that. But I don't have to assume that the explanation given by that person is the right one either. Almost all of the time psychological factors fully cover the facts. Just not always. And in those proverbial 99% of cases where a sonic claim turns out to be spurious, there's no point in me making a big poohaa about it, is there?
People closer to me are actually annoyed by this marked tendency I have to reject any form of audiophile claim out of hand, and only to investigate when pressed hard.

If you read his earlier articles, interviews and see his ideas from a decade or so back when he was with Philips they read like some completely different person vs newer interviews since he has his own high end company or worked with people like Grimm. The answer is extremely simple. His work and design ability is at a very high level. Nevertheless, he has become the Smart Engineer.
I didn't know I was that famous in my Philips days. When I started there, I subscribed to every single item of audiophoolery around. It was a slow and painful process to extricate myself from that and attain a degree of rationality. What helped massively is that as I became more conventional (i.e. measurement driven) in my design approach, the stuff clearly started sounding better too. I'm now very much in the "meter reading" camp. And indeed as mentioned somewhere, I haven't based amp design decisions on listening tests for a long time. Anyway, listening tests should only serve to refine one's measurement procedures, not the actual designs directly. But where some of my fellow rationalists and I part company is when they keep insisting that any amp with a THD below some ridiculously high number is automatically perfect. Mind you, there's probably a lot of truth in this when you insert a simple static nonlinear transfer in an otherwise blameless signal chain, but most distortion isn't like that.

Play the game, say the right thing, spend more time developing an aura of mystery rather than spilling out the hard numbers. It opens up pocketbooks.
I wasn't aware that I was that reticent on hard numbers. But if by playing the game you mean "break it to people gently without chasing them away" I'm totally in with that and I have to admit I've put in the effort to learn how to do that. At least in writing - in speech I'm still as blunt as ever.
For instance, most of the audiophile public is so dead set against rational design (using measurements to diagnose and feedback, DSP and whatnot to cure) that they wouldn't even countenance exposing themselves to a quick listen. The problem is that it's not 100% imaginary: some of them have heard atrocious amplifiers that they were told had low distortion and a lot of feedback (at 10Hz perhaps they did), and drew far reaching conclusions from that. If you want to stand any chance of winning them over, the least thing you can do is to give them a cogent explanation for that experience if there is one (there is, I think. Read the F word). Then they might let you invite them in for a listen. You can call that playing the game if you want. You can also call it giving people a modicum of respect. All I know is that calling people silly sods for not agreeing with you in full without as much as offering an argument is not going to advance any of science, society, or your job security if that's of any value to you.

http://www.brunoputzeys.be/r4.php
Apparently Mr. Putzeys isn't big on the influx of refugees in his part of the world.
If you need it spelled out: it's religion I have a problem with. All of them. But since people being religious is part of reality, one can't just wish it away. So politically I'm a secularist. Folks who laud the West on its Judaeo-Christian roots have got it spectacularly wrong. The West only really came out of the bush when it discovered secularism. That's what we ought to defend. Concerning refugees and other immigrants, I'm actually strongly in favour of taking in more of them. I think it's unbelievably unjust that the place where you're born should have such an impact on your chances in life. But, as they are coming of their own volition that would be an excellent opportunity to ask them to sign up to that particular value that keeps this European ship afloat. Sadly we can't do that with the people who are already here.
 
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watchnerd

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I wonder if anyone's ever thought of the possibility that I might have turned to designing low distortion amplifiers that have lots of feedback because they work better than the ones that don't?

Having a good idea and recognizing the need to market the good idea, because people aren't getting it, are not contradictory aims.
 

BDWoody

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By reputation he's not famed for PR rehtoric, in fact the opposite so I'd view his comments with a good deal less cynicism personally.

It would be great if he popped in here but that's extremely unlikely unfortunately.

He was also quite clear that where conflicts exists, it's likely in testing methodology or focus, not on magical properties that can't be explained.

I think he's trying to walk a fine line, but he's not someone to be dismissed out of hand.

And, it's true that these people DO hear these things... The fact that they are almost guaranteed to hear whatever they are told to hear isn't really the point. He is 'feeling their pain' and doing something about it.

I also wonder how many truly excellent engineers haven't done any research into psychoacoustics and hearing, so assume what everyone else assumes...?
 

scott wurcer

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I didn't know I was that famous in my Philips days. When I started there, I subscribed to every single item of audiophoolery around. It was a slow and painful process to extricate myself from that and attain a degree of rationality. What helped massively is that as I became more conventional (i.e. measurement driven) in my design approach, the stuff clearly started sounding better too. I'm now very much in the "meter reading" camp. And indeed as mentioned somewhere, I haven't based amp design decisions on listening tests for a long time. Anyway, listening tests should only serve to refine one's measurement procedures, not the actual designs directly. But where some of my fellow rationalists and I part company is when they keep insisting that any amp with a THD below some ridiculously high number is automatically perfect. Mind you, there's probably a lot of truth in this when you insert a simple static nonlinear transfer in an otherwise blameless signal chain, but most distortion isn't like that.

I tried a lot of things but I never bought into any of the far fetched explanations or the "hear that which can't be measured" stuff. The lack of simple intellectual curiosity about what could be going on always annoyed me.

The simplistic THD + N only view is a problem part of which is an attitude (IMO) that if it is not a canned AP test it is not to be trusted. There are many ways of exercising amplifier (or DAC for that matter) behaviors that require custom bench fixtures and someone who understands what is going on.

BTW Bruno if you see this I was wondering... Someone sent me a PPT presentation of yours without any of the commentary. In it it appeared that you showed fractional sample delay in an FIR filter reducing the Gibbs ringing. I had published an article in Linear Audio where I found that some classes of filters (RIAA de-emphasis in particular) could be realized with dramatically reduced number of coefficients and Gibbs effect while also being minimum phase. I saw no downside at all but none of our DSP guys including Bob Adams ever saw anything like this.
 
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Sal1950

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