Why the Harman mono speaker test was wrong for dipole planers

[amirm]

The somewhat tardy realisation, on my part, that you are also in fact a 'Pedlar of Boxes', the portfolio of which would seem to place certain of your wares in competition with Martin Logan, does afford me an altogether other prism through which I may view your considerations on this subject matter.

I don't peddle anything much less speakers to audiophiles. My company is a custom electronics company and does not deal with the audience in this forum.

When we first started though, we thought we have that side of the business. We created a high-end theater with two parallel systems, one based on Wisdom Planar Magnetics and a JBL System at less than half its price:

We then put a screen in front of it for video and had the makings of a very nice blind AB test. Our $110K investment in that Wisdom system came crashing down on our head. On some tracks it would sound wonderful but on many others, it would sound just wrong. I spent months with the company going back and forth but the problem was endemic to the design. They had never measured the performance in anechoic chamber, nor had done any controlled testing. We walked away from each other and we got back to selling those ugly JBLs instead.

So put away your insulting accusations please. I have no financial interest in any of these discussions. Argue the research if you can. Otherwise your comments are waste of forum bandwidth.

 

[DaveC]

It will take me a while to locate references to give you. For now, the first piece of data was as you guessed it, at Harman. They pre-tested drivers as you did and found noticeable difference. But once in an enclosure, the effect almost vanished. It was noticeable as a tiny variation and that was likely inaudible. Since then, I have run into other people analyzing the same but in a quick search I could not find it. If I come across it, I will post.

Edit: just did a quick search online and ran into one of the articles I had read: http://www.audioholics.com/loudspeaker-design/speaker-break-in-fact-or-fiction

"The compliance of the air enclosed within the enclosure is significantly less than the driver's suspension compliance, therefore the enclosure has the dominant influence where it comes to determining things such as system resonance. Thus, owing to the physics of the enclosed box loudspeaker system, any pre/post differences in driver suspension mechanical compliance are constrained from having as large an effect on parameters such as resonance frequency, etc as intuition might lead one to believe it should.

Taken together, it's clear the volume of air confined within the sealed cabinet of the enclosed box loudspeaker system moderates any measurable and/or audible changes that might arise as a consequence of driver compliance changes."

Sure, IF the compliance of the air in the enclosure dominates the driver's suspension compliance but this is not always the case... my woofers are going into a 5.5 cu ft vented enclosure... How about OB woofers, I suppose they would have a very audible break-in since the air contributes almost nothing...

 

[Argonaut]

Is it your opinion that the 'Audible' considerations of a number of professional reviewers, together with many several hundreds of customers, that presumably auditioned ML transducers against other brands and design topologies before purchase, is not valid 'Research' and that the latter were just too stupid to realise that you might have saved them from themselves if Only they had also worshiped at the alter of Harman car audio!

 

[Purite Audio]

Just because you have discovered the speakers measure poorly shouldn't spoil your enjoyment of them .
Keith.

 

[Gregadd]

You have put the cart before the horse. They have worked out what sounds good to people, and they produce speakers to that standard.

I think not. I recall Sean complaiing that sales were(my word)lackluster. His marketing people had opined upon listening to his products, parapphrasing, How do we sell that? He said he was considering hiring some Bose salesman because tey had more sales success. All indciations they are having trouble pusihing thier theoryand tproducct. The exceptoin is of course the car audio market, That involves a captive audience.

WIth respect to thier study. I said repeatedly it did not involve a random choice of subjects. I beleive then he cannot apply it to the genral public. That is the best he can claim is that is what the test subjects prefer. Harmon remans a non-issue in the high end marketplace. They wish they could compete with Martin Logan.Theeir reseach does however make for an interesting intellectual discussion.

 

[DaveC]

I think not. I recall Sean complaiing that sales were(my word)lackluster. His marketing people had opined upon listening to his products, parapphrasing, How do we sell that? He said he was considering hiring some Bose salesman because tey had more sales success. All indciations they are having trouble pusihing thier theoryand tproducct. The exceptoin is of course the car audio market, That involves a captive audience.

WIth respect to thier study. I said repeatedly it did not involve a random choice of subjects. I beleive then he cannot apply it to the genral public. That is the best he can claim is that is what the test subjects prefer. Harmon remans a non-issue in the high end marketplace. They wish they could compete with Martin Logan.Theeir reseach does however make for an interesting intellectual discussion.

Product quality may not be the most important thing when it comes to marketing luxury goods...

IMO... Harman doesn't have all the answers but they do have some of them so their products are very good but it's possible to surpass them. I don't think Revel/ML has come all that close to TAD, for example. The difference? Designers with a more complete understanding of what makes for good sound, and resources. Not everyone can make 6.5" vapor-deposited beryllium cones...

 

[Argonaut]

I don't peddle anything much less speakers to audiophiles
So put away your insulting accusations please. I have no financial interest in any of these discussions. Argue the research if you can. Otherwise your comments are waste of forum bandwidth.

I am sorry!!! Are you claiming that there are NO products within the ML range that do not compete, in application, with~

http://www.madronadigital.com/Products/audio/audio.html

 

[Gregadd]

Perhaps worthy of note is that once Peter Aczel heard and tested one of Linkwitz' speakers, they became his reference, and have remained so through multiple redesigns and upgrades. Please don't take this as an endorsement for The Audio Critic, though

Let's go a litlle furhter . Before Peter "lost his mnd"hjis refernce was the Beveridge 2sw. Akso he was quite a Qaad fan and had good things to say about Martin Logan CLS. Electrstaics hold legenfary status in high end audio. The KLH Nine and.Soindlab A-1 for example. How about considering something other than libear distrotions. How about the time domain?

 

[Kal Rubinson]

Do they test burn-in using these facilities and double blind listening tests? Quoted from their site OM104 owner manual.

Dunno but Peter Barton (of PSB), another NRC alum, said this about burn-in during an interview for Soundstage.com:
"Barton has examined his own speakers to test this. He has taken a Stratus Gold loudspeaker, built and measured some ten years ago, and re-measured it today. The deviation is slight, perhaps 1/4dB at most. Although that deviation can possibly be heard, it is certainly not a huge difference that one may attest to hearing. Instead, Barton surmises that the difference in sound that people are hearing over time is conditioning of the brain. He cites experiments done with sight that indicate the brain can accommodate for enormous changes fairly quickly and certainly within the hundreds of hours that audiophiles claim changes occur in. Could this apply to hearing, too? Barton thinks that more often than not, what happens is that the changes in perceived sound that are attributed to component break-in are simply the brain becoming accustomed to the sound. He warns listeners not to fool themselves."

 

[Gregadd]

No one says you have to listen during breakin. Just let it play and do soemthing else.

 

[microstrip]

Dunno but Peter Barton (of PSB), another NRC alum, said this about burn-in during an interview for Soundstage.com:
"Barton has examined his own speakers to test this. He has taken a Stratus Gold loudspeaker, built and measured some ten years ago, and re-measured it today. The deviation is slight, perhaps 1/4dB at most. Although that deviation can possibly be heard, it is certainly not a huge difference that one may attest to hearing. Instead, Barton surmises that the difference in sound that people are hearing over time is conditioning of the brain. He cites experiments done with sight that indicate the brain can accommodate for enormous changes fairly quickly and certainly within the hundreds of hours that audiophiles claim changes occur in. Could this apply to hearing, too? Barton thinks that more often than not, what happens is that the changes in perceived sound that are attributed to component break-in are simply the brain becoming accustomed to the sound. He warns listeners not to fool themselves."

Just to remember that typical measurements will not show burn-in effects. It is reported that most are due to the burn-in of passive components of crossovers, mainly the capacitors.

 

[rbbert]

...Electrostatics hold legendary status in high end audio. The KLH Nine and Soindlab A-1 for example. How about considering something other than linear distrotions. How about the time domain?

Preaching to the choir here. I owned Acoustats for almost 20 years, and probably still would if the company were around to support the Servo-Charge amps.

 

[DaveC]

Dunno but Peter Barton (of PSB), another NRC alum, said this about burn-in during an interview for Soundstage.com:
"Barton has examined his own speakers to test this. He has taken a Stratus Gold loudspeaker, built and measured some ten years ago, and re-measured it today. The deviation is slight, perhaps 1/4dB at most. Although that deviation can possibly be heard, it is certainly not a huge difference that one may attest to hearing. Instead, Barton surmises that the difference in sound that people are hearing over time is conditioning of the brain. He cites experiments done with sight that indicate the brain can accommodate for enormous changes fairly quickly and certainly within the hundreds of hours that audiophiles claim changes occur in. Could this apply to hearing, too? Barton thinks that more often than not, what happens is that the changes in perceived sound that are attributed to component break-in are simply the brain becoming accustomed to the sound. He warns listeners not to fool themselves."

The majority of break-in is accomplished in the first hours, so if the speakers had been used at all before the measurements were taken, which is probable, then the test is pretty much useless. Also, drivers may be tested at the factory before leaving and the test period may vary between manufacturers if it's done at all. Easily measurable T/S parameters change quite a bit in the first hours of driver use, enough to certainly result in a change of overall speaker performance that would be pretty obvious and easily measurable.

That's not to say acclimation isn't a factor, I'm sure it plays a part but burn-in is also a real phenomenon. I'm pretty surprised this is even a debate to be honest, it seems like it's common knowledge that drivers change quite a bit from brand new over a period of time. I've even seen driver specifications that say T/S parameters taken after 2 hours of use.

 

[DaveC]

Just to remember that typical measurements will not show burn-in effects. It is reported that most are due to the burn-in of passive components of crossovers, mainly the capacitors.

Everything burns in to some degree...

 

[Blizzard]

The majority of break-in is accomplished in the first hours, so if the speakers had been used at all before the measurements were taken, which is probable, then the test is pretty much useless. Also, drivers may be tested at the factory before leaving and the test period may vary between manufacturers if it's done at all. Easily measurable T/S parameters change quite a bit in the first hours of driver use, enough to certainly result in a change of overall speaker performance that would be pretty obvious and easily measurable.

That's not to say acclimation isn't a factor, I'm sure it plays a part but it's also a real phenomenon. I'm pretty surprised this is even a debate to be honest, it seems like it's common knowledge that drivers change quite a bit from brand new over a period of time. I've even seen driver specifications that say T/S parameters taken after 2 hours of use.

Kinda like a pair of shoes breaking in. I don't think this is a myth. Although it levels out after full break in. I recently tested a pair of bookshelf speakers I built around 1997. I have tortured these so much over the years the voicecoils were even smoking 1 time. You probably could have overlaid the plots from 1997 and they would have looked like 1 line. Old school Focal quality

 

[Don Hills]

Sure, IF the compliance of the air in the enclosure dominates the driver's suspension compliance but this is not always the case... my woofers are going into a 5.5 cu ft vented enclosure... How about OB woofers, I suppose they would have a very audible break-in since the air contributes almost nothing...

Doubling the Vas can give a significantly different response for ported enclosures. It makes no significant difference for OB.

 

[Robh3606]

Have you done so amirm?

Are they posted somewhere?? I would like to see them if I could.

Rob

 

[Robh3606]

Just to remember that typical measurements will not show burn-in effects. It is reported that most are due to the burn-in of passive components of crossovers, mainly the capacitors.

Hello Micro

Do have any experience with what actually happens to parts that are burned in?? I do, ran a part screening department for parts to be used for military and commercial satellite programs. They degrade over time and the capacitance values shift a bit and the DF leakage will get worse. So you could possibly see a shift and it would be measurable in the frequency response depending on how much value drift there is over time.

Hello Dave

That's not to say acclimation isn't a factor, I'm sure it plays a part but burn-in is also a real phenomenon. I'm pretty surprised this is even a debate to be honest, it seems like it's common knowledge that drivers change quite a bit from brand new over a period of time. I've even seen driver specifications that say T/S parameters taken after 2 hours of use.

Depends not always typically FS will change and get lower as the suspension breaks in. So the driver should measure high and then work into the published values. That is what you would expect. That said I have measured FS on drivers right out of the box and they were right on spec. Re-maeasured them and did not see a significant change which frankly surprised me. You expect the designer to account for T/S changes this when they do the crossover and mainly the box design for a bass reflex enclosure.

Rob

 

[Kal Rubinson]

Just to remember that typical measurements will not show burn-in effects. It is reported that most are due to the burn-in of passive components of crossovers, mainly the capacitors.

Why would I remember that? Why would changes in passive components that affect sound not be measurable?

 

[Blizzard]

Why would I remember that? Why would changes in passive components that affect sound not be measurable?

Everything is measurable with the right equipment and knowledge. Only thing is some of this equipment hasn't been invented yet.