Axiom Home Page Forums General Discussion Technical Questions Equipment Burn-In -- A Scientific Test

hello everyone,

I have an idea that can help prove/dis-prove any myths about speaker or other equipment burn-in. You know how in reviews of Axiom speakers, they show us graphs showing the decibel to frequency response, well, wouldn't this graph change if the speakers did in fact change after, say, 100 hours of listening? A lot of people believe a speaker gets better after 100 hours, if not more. Some also believe the same for wires and even electronics, such as DACs and amps. Personally, I am a disbeliever, I think it has more to do with the person getting used to the sound, and not the sound getting better. This is why I want to know if there is information out there where someone or some company has done response graphs with the speakers brand, then after, say, 100 hours, then 1000 hours, and compare them to see if they are in fact different. Perhaps Axiom is up to the task? It would be the only way to scientifically conclude that break-in does or does not exist, and if it does, to what degree.

Any thoughts, suggestions?

gotta completly agree.....

well id say only a few hours are required to break in speakers, not 100 hours. two of my friends bought headphones (eyts er-6s) and they said after so many hours the bass got lower and the highs became more tame. since headphones and speakers basically use the same technology, i believe that speakers do need some time to break in. but yeah, a scientific test would be a great way to tell.

I'm all for it. I'd like to see the exact same tests done with speaker wire to see if there is an actual, audible difference. With speaker I can see there being a very slight change in lower frequency response as the surround and damper stretch out but whether or not this is audible is up to debate until we can get some real scientific numbers.

Ravi, you can find just a little bit of information on this topic near the end of an interview at the NRC with Paul Barton of PSB Speakers( soundstagelive.com/factorytours/psbnrc/ ). Paul gives his views on the matter and briefly describes tests he ran on his speakers when new and on the same speakers after 10 years( should be adequate "break-in"). No difference of audible significance was found.

amazing stuff JohnK!

thanks a lot!

now I'd like to see these tests with speaker cables, like danr suggested. However, I don't know how we could scientifically measure something like soundstange, or the transparency of the speaker. I guess that has a lot to do with off-axis performance.

Excellence article. It shows that bad speakers don't get good over time, people just get used to bad sound. The small changes noted are far too small to be audible. The brain adapts to changes or imbalances that are input by the senses. I'm also an amateur astronomer and familiar with optics and their flaws. One example of how the brain adapts is the eye. The lens of the eye isn't achromatic and actually produces a significant violet halo around the edges of bright-colored objects. The brain, however, is able to adapt to this chromatic aberration and alter how things are perceived. Do you ever see well-defined blue halos around objects? Probably not unless you wear glasses which introduce their own errors. This is the same with sound. I guess you could say that the brain has tone controls and an EQ built into it.

As for soundstage and imaging that seems to have a lot to do with baffle design and especially room acoustics (as seen in the article) and are difficult if not impossible to quantify. If we could then one could easily predict or model how one speaker design would perform and how to optimize it. Then after a while nearly all speakers would be nearly identical if one particlular design or model worked best.

Ravi and danr, on the question of speaker wire tests, these have been done on occasion in the past. Note that in Roger Russell's article on speaker wire( sundial.net/~rogerr/wire.htm )he describes the 1983 Stereo Review and 1994 Audio tests. I read these back-issues at the library and doubt that they're available online.

As JohnK mentioned, someone must have tested this out before. I would be shocked if speaker companies have not done some 'break in' testing since it is a real buzzword in the world of audio.

I just saw a customer comment the other day, on a company website, regarding his high end interconnect cables and how he talked about their 'break in' after 200h, 500h and so on. Apparently he heard quite precise changes in the mids, highs, etc. after 200h but that the real smoothness never really came about until the 500h mark. Then he went on to mention how he was using a 1500w home baseboard heater to do the break in.
One can only begin to wonder...

I completely agree with Danr on the brain perception concept.
Blind testing. It's about the best option the industry has to find out the truth.

The tests noted by Russell appear to be listening tests. I want to see graphed frequency-response tests using the same equipment they use for testing speakers. Measurements can be taken of several different speaker models using several different type of cabling in anechoic chambers.

Everybody might also want to check out http://sound.westhost.com/cables.htm

Here is a hilarious quote from a section on the link:

"What we do is kind of dirty and stinky," he said. "We say we are starting with a 12 AWG zip cord, and we position a technician behind each speaker to change the cables out." The technicians hold up fancy-looking cables before they disappear behind the speakers. The critics debate the sound characteristics of each wire. "They describe huge changes and they say, 'Oh my God, John, tell me you can hear that difference,'" Mr. Dunlavy said. The trick is the technicians never actually change the cables, he said, adding, "It's the placebo effect."

This one is the most thorough examination of cable theory I've seen yet.

i saw that same article about the bluff they pulled - kool
hey some people still believe elvis is alive

Here are some speaker parameters and their percentage change after a 3 hr. burn-in. These figures are from Partsexpress when they tested 3 randomly chosen woofers from an OEM batch.

Seem that these changes are significant.

(sorry about the format - just look close: parameter/value before/value after/pct change)

Before Break-In Average Post Break-In Average Percent Change
----------------------------------------------------------------------------------------
Re(Ohms) 2.441 2.467 1.04%
Fs(Hz) 31.557 28.307 10.30%
Qms 9.826 9.547 2.84%
Qes 0.514 0.427 17.05%
Qts 0.489 0.407 16.79%
Mms(g) 124.773 133.903 7.32%
Cms(mm/ N) 0.205 0.237 15.71%
Vas(L) 33.050 38.087 15.24%
BL 10.770 11.737 8.98%
Le(mH) 2.546 2.480 2.57%
Sd(sq.m) 0.034 0.034 0.0%

Is there a link to this 'study'?

I would love to hear a pro comment on whatever these values listed are.

PartsExpress.com Then search for the Titanic MKII 10 inch woofer. Download the white paper from there. Also check out the glossary for a quick reference on the params.

Searching on "Thiel Small parameters" should yeald tons of sites with basic information.

Have fun!

In reply to:

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I'd like to see the exact same tests done with speaker wire to see if there is an actual, audible difference.

---

One may measure differences between cables, but that alone says nothing about audibility. Also, the "exact same" tests are too simple to uncover differences between cables.

It should not be difficult to find published cable measurements as there have been many studies. The problem is, what kind of measurements are you looking for? Cables measurably differ in R, L, and C, but it cannot be easily correlated into how they will sound.

Considerations for setting up equipment to measure cables:

http://www.audioasylum.com/audio/cables/messages/41579.html
http://www.audioasylum.com/audio/cables/messages/41456.html

In reply to:

---

Blind testing. It's about the best option the industry has to find out the truth.

---

Although listening perceptions can be influenced by factors other than acoustic change, it does not automatically follow that blind listening is more reliable.

Yes:
"Cable Bibliography"
http://www.audioasylum.com/audio/cables/messages/12102.html

No:
(lists articles from professional journals)
http://www.audioasylum.com/audio/cables/messages/6127.html

Yes R, L, C, No everything else:
http://home.pacbell.net/drquad/jdunlavy.html

Review of Harrison and Duncan's "The Great Cable Test":
http://www.st-and.ac.uk/~www_pa/Scots_Guide/audio/cableshift/cp.html

Funny thing.
There seems to be alot more true scientific, journal articles proving no difference between cables and more unpublished, non-peer reviewed magazine articles that say there is a difference.
When i read words like 'digital jitter' i pretty much quit reading the article and know a salesman is in the house.
Sorry but this is one scientist that will stick with 50 cents a foot 12 gauge 99% copper wire as opposed to the $10 a foot, 12 gauge 99% copper wire.Blind testing. It's about the best option the industry has to find out the truth.

Adriel, I have to agree with chesseroo here. There have been too many instances in which cable differences have been described in extravagant terms which then disappeared a few minutes later when the listening became blind.

You appear to be somewhat subject to audio mythology. I recall your 2/15 post in Questions and Comments where you described a ringing in your ears and a metallic taste in your mouth while listening to the M2s. I gave the first reply( as Anonymous)with some helpful suggestions. This is a field which is rife with exaggerations and outright lies. Don't be fooled.

It's not that perceptions can be influenced by other factors, it's that they are influenced by other factors. The differences I'm looking for are in response tests. I don't care if the difference is good or bad, too subjective, just different. In order for one cable to sound different than another the sound coming out of the speaker it is connected to must be different. Once a change is noted, determination of the cause can then be done. If we know what causes what then one can say that one cable with these characteristics will sound like this with this type of speaker and so-on. Right now even the people that do believe in huge difference can't agree on what sounds best with what. Until true statistical analysis of the differences and similarities between blind test results and electrical characteristics of wire is done then this debate will always raise the blood pressure of both sides.

Daniel

Now there's a test.
How far will one's blood pressure go in attempting to determine if there is a difference by listening to the same damn test song 30 times over!?
ha

The quick links I provided are not intended to be comprehensive nor representative. I would expect anyone interested to conduct his or her own research.

Perhaps you can explain the animosity towards the words "digital jitter". It is measurable, it is an issue that digital audio IC manufacturers need to design for, and lastly it can be affected by the choices of end users. The existence of charlatans should not lead one to discriminate against the entire science.

Hey chess,

190/110 then your head explodes, unless of course you duct tape your head first.

CAV104

Such unprofessional and condescending comments as these are the reason why I chose not to respond to any of the comments in the older thread referred to. They are unacceptable in tone. Those who can't get the point across without resorting to personal, condescending language are not worth responding to. I'm all for disagreement, but at a professional level.

As for solid state equipment burn-in, I can believe that there is some initial change, then change for the worse 10-15 years later when the caps dry out. Whether or not the change is entirely audible is another matter.

I'll be modifying a mass-market grade SACD player shortly, installing new capacitors (BG NX-HiQ) on its output coupling caps after the DAC and also after the op-amp. New high speed soft recovery diodes (Harris TO-251) installed on the power supply diode bridges are a possibility, although this could be complicated due to the surface mount board. I'll make an effort to record its output on several songs both before and after modification, as well as weeks and months into the modification. Sine wave tests are possible but not appropriate in this case, since the purpose isn't to establish any technical specs but rather to record any sonic change in music. These modifications are common, and the Black Gates in particular are said to improve bass response when installed as coupling capacitors as they "break-in". If such is the case, the change in bass should not be difficult to document.

I surely don't read anything condescending in JohnK's writing.
Are you sure you were reading the right post?

Blind testing. It's about the best option the industry has to find out the truth.

Well Chess I guess it probably depends on the recording. I sure hope that person would pick something he/she liked. Thirty time? A hundred probably would barely be enough, unless of course you had many people participating in the test.

Daniel

Oh believe me when i tell you that i don't want to ever hear any of the songs on either of my 2 test cds anymore.
They were great for playing out the ranges of music on different components but with so much auditioning, i'm just sick of those songs.
I think i ruined some of them for myself. Some were my real favorites.

I never get tired of any movie or music track, no matter how many times I've seen or heard it. I would be a good test subject because I can endure lots of repetition, especially if it's a kick-ass track or movie. Hell, if I've seen the Star Wars movies less than 600 times all the way through I would be very, very surprised. And that's not counting the number of quick looks. I've worn out two sets of VHS trilogy sets in just the past few years. I can't wait until Nov 12 when Ep II is released on DVD. I've listened to Megadeth's "Tornado of Souls" about 100 times in the past few days as well and can listen to it another 100 times. Those are just two examples. Good thing DVD's and CD's don't wear out 'cause they cost more.

Daniel