Why the Harman mono speaker test was wrong for dipole planers

[Kal Rubinson]

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.

If the majority of the break-in effects happen so early, they would not likely to have any influence on the listener. To be a significant issue, as some maintain it to be, it must occur over a significant interval of time and in the hands of the purchaser, not just during factory testing.

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.

Heating can be an issue. FWIW, I think most people agree that there are significant changes in early use. The contentious issue is whether there are audible/physical changes over weeks/month which, curiously, seem always to be positive.

 

[Robh3606]

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

Hello Blizzard

Are you kidding?? We are talking resistors capacitors and Inductors no surprises here.

Rob

 

[Blizzard]

Hello Blizzard

Are you kidding?? We are talking resistors capacitors and Inductors no surprises here.

Rob

If a human ear can hear it, it can be measured.

 

[Robh3606]

f a human ear can hear it, it can be measured.

Ok but what hasn't been invented yet?? That is what I was wondering. Especially with respect to the effects of changes due to aging/burn in with passive components. Any decent simulator like LEAP will show you the effects due to any value changes.

Rob

 

[microstrip]

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

Typical speaker measurements are acoustical - they do not have resolution enough to show differences in passive components.

 

[Purite Audio]

Typical speaker measurements are acoustical - they do not have resolution enough to show differences in passive components.

Distortion in an amplifier for example would be reflected in the speakers measurements.
Keith.

 

[esldude]

Distortion in an amplifier for example would be reflected in the speakers measurements.
Keith.

Or could be found at speaker binding posts with more accuracy.

 

[Robh3606]

Typical speaker measurements are acoustical - they do not have resolution enough to show differences in passive components.

Well we are talking about changes due to burn in no?? Parts drift as they age and there is a measurable difference before and after. Why do you think it can't be seen in a frequency response measurement?? Here is what a standard value change looks like in a simulator in this case LEAP. This shows the change from a 2.4 to a 2.7 or about 10% change in value. If it can be seen with the simulator you can most definitely measure it. Green is 2.4 and Blue is 2.7

Rob

 

[FrantzM]

If a human ear can hear it, it can be measured.

I am with you but some maintain with a passion verging on devotion that it isn't the case

 

[FrantzM]

If the majority of the break-in effects happen so early, they would not likely to have any influence on the listener. To be a significant issue, as some maintain it to be, it must occur over a significant interval of time and in the hands of the purchaser, not just during factory testing.

Heating can be an issue. FWIW, I think most people agree that there are significant changes in early use. The contentious issue is whether there are audible/physical changes over weeks/month which, curiously, seem always to be positive.

Excellent post ... but we are tip-toeing into the religion of burn-in and emotions run high there

 

[microstrip]

If a human ear can hear it, it can be measured.

We agree.
However three questions arise: 1. Can the numerical values resulting of the measurement be correlated systematically with sound quality? 2. Was it done before with success? 3.Can it be done currently with reasonable resources and expense?

 

[DaveC]

If the majority of the break-in effects happen so early, they would not likely to have any influence on the listener. To be a significant issue, as some maintain it to be, it must occur over a significant interval of time and in the hands of the purchaser, not just during factory testing.

Heating can be an issue. FWIW, I think most people agree that there are significant changes in early use. The contentious issue is whether there are audible/physical changes over weeks/month which, curiously, seem always to be positive.

It depends on the suspension used in the driver and how loud and at what frequencies are used to break-in the driver. Considering everyone agrees there are dramatic changes the first few hours, I'm not sure how it's discounted so easily (and without good supporting evidence) that break-in can happen over many hours, especially if the driver isn't pushed anywhere close to it's Xmax.

Now that you mention it, I'm not sure if the 2-hour thing was to get the driver's suspension broken-in, get the motor heated up or both.

Anyways, I've experienced drivers that don't change much during break-in and what changes do happen, happen early on and I've had drivers that take hundreds of hours to loosen-up and for the bass to fully express so I don't think there's any hard and fast rule to apply, it's going to be different with different drivers and different suspension designs and materials.

 

[Rodney Gold]

So , after all this voluminous research and to and fro quoting , how come we arent all listening to the same speakers based on this "irrefutable" research? Maybe cos its not the be all and end all...
Those who want to opt in to it..cool.. those that dont , dont deserve to have it thrust down their throats at every opportunity.. its like a broken record, playing the same 10 seconds of music ad infinitum.

 

[Purite Audio]

So , after all this voluminous research and to and fro quoting , how come we arent all listening to the same speakers based on this "irrefutable" research? Maybe cos its not the be all and end all...
Those who want to opt in to it..cool.. those that dont , dont deserve to have it thrust down their throats at every opportunity.. its like a broken record, playing the same 10 seconds of music ad infinitum.

I suspect it is because it is relatively difficult for an ordinary listener to compare a number of different designs in their room at the same time.
Also I believe only a very small percentage of listeners today understand or even care to look at measured performance if indeed manufacturers provided that information and finally product placement and marketing play a huge part in the decision to purchase.
Keith.

 

[DaveC]

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

The change in Fs is a result of the suspension breaking-in, as you said, the direct measure of suspension compliance is Vas which will change more than Fs and the change in Vas also affects other parameters too.

I'd expect drivers to all be different depending on the design, materials and how much the drivers were tested at the factory, if at all.

 

[Kal Rubinson]

Typical speaker measurements are acoustical - they do not have resolution enough to show differences in passive components.

That assumes a narrower definition of measurable than I was inferring. We can measure the entire speaker and its individual components electronically as well as acoustically.

 

[microstrip]

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.

There are many effects reported with dielectrics due to burn-in - e.g. if you get two similar lots of some types of capacitors and burn-in one of them for an amount of time at half rated voltage, this lot will sustain higher voltage in average before breakdown than a non burn-in lot.
The main question is how these effects can result in audible signals. The same way some people say that there is no audible difference between a proper 16 bit and a 24 bit recording, many people will tell you that this signal level differences will not be audible.

I have found that JBL, Vandersteen and Infinity manufacture(d) high-end speakers that used batteries to polarize the film capacitor dielectrics. It would be nice to know if their users feel there is difference in sound quality with and without batteries. But I can guess we will never have an official firm statement from Harman on this matter.

 

[Kal Rubinson]

Again, why are the subjective effects of burn-in always reported as being positive?

 

[microstrip]

That assumes a narrower definition of measurable than I was inferring. We can measure the entire speaker and its individual components electronically as well as acoustically.

OK, I was not considering disassembling and chopping the speaker. So we are not strictly debating speaker burn-in any more, but generic component burn-in.

 

[Groucho]

Again, why are the subjective effects of burn-in always reported as being positive?

Because of the genius designer who designed it that way.