As I am a dedicated sceptique I never believed in loudspeaker break-in. Until recently I bought a 6.5inch speaker with a specified open air resonance of 120Hz - but I measured 155hz
Monitoring speaker current with a DVM I adjusted frequency to the minimum and set amplitude to several mm excursion. It took some seconds and current began to rise. I adjusted frequency to the minimum again - 1 oder 2Hz lower. Continuing this game you could watch the resonant frequency drop. Meanwhile I switched to 30Hz sine and set the excursion to about 3mm for 15min. After that the speakermagnet was warm and the fundamental open air resonance had dropped to 122Hz!
For me there is no mystic about that. All in all it is the same effect with a new pair of shoes
Whether there is an audible difference or not I cannot say because I have only a single speaker of that type, so there was no chance for a direct comparision.
Interesting point is that after that "treatment" the driver approaches the specs of the fab.
Monitoring speaker current with a DVM I adjusted frequency to the minimum and set amplitude to several mm excursion. It took some seconds and current began to rise. I adjusted frequency to the minimum again - 1 oder 2Hz lower. Continuing this game you could watch the resonant frequency drop. Meanwhile I switched to 30Hz sine and set the excursion to about 3mm for 15min. After that the speakermagnet was warm and the fundamental open air resonance had dropped to 122Hz!
For me there is no mystic about that. All in all it is the same effect with a new pair of shoes
Whether there is an audible difference or not I cannot say because I have only a single speaker of that type, so there was no chance for a direct comparision.
Interesting point is that after that "treatment" the driver approaches the specs of the fab.
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After that the speakermagnet was warm and the fundamental open air resonance had dropped to 122Hz!
For me there is no mystic about that. All in all it is the same effect with a new pair of shoes
The spider will soften up most.
The outer cone will over time wear a bit where it flexes.
I have seen old speakers be a slightly different colour where the outer cone has worn away.
Eventually the outer cone will wear away and split.
One day I measured 40mpg on my car. The next week I measured 26mpg! Could both be right? Maybe it is not a mystery?
I doubt you measured that at all, it stinks of a just made out "example" pulled out of the blue, but if you actually did, please post a proper description of your experiments, how you measured each value.
What you suggest can be applied to yourself:
Publish your work, subject it to peer review. I bet your methodology will be laughed at.
This method is fast and easy, but wrong. You are entering into a creep suspension problem (see AES papers).
You should measure the same loudspeaker before and after playing. And yes, there is a difference in resonant frequency before and after playing.
If you insist. (Actual data from my car in the image)The 40mpg was a ~100mile drive at 55mph
The next reading was mixed driving over a longer period.
Both readings are "correct"
Basically, with my silly example I was saying that the usefulness or relationship between any two measured numbers may be tenuous at best. There are so many ways to make mistakes or false assumptions when interpreting data. If all one looked at were the two mpg points and didn't know what the conditions were, one could think that I suddenly had a large drop in mileage due to some problem.
In the loudspeaker realm, I have measured a driver after running it a while and found a drop in Fs only to measure it later and the Fs raised again. I am sure you have done the same. There is temperature to control for - rather important especially with rubber....
Sometimes people are so keen to prove something that they don't consider confounding factors at all....
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Guess I'll answer my own question; here's good data:
http://www.gr-research.com/burnin.htm
From that data and the discussion that follows, my own newly-modest conclusions are that there are likely some changes to most of the kinds of springy materials used in drivers and these take place (a) over long time periods of use, (b) if you really stretch them a lot beyond what is normal music excursion, and/or (c) may or may not be barely audible.
But I will stick with my assertion that as a human testing paradigm, it's got the features that lead to self-delusion.*
Ben
*Some subjective testing paradigms - such as double-blind ABX - are quite trustworthy and are legitimate ways to evaluate gear. That would be quite applicable here, you just buy three subs and store one for 30 years and then compare it to the two you've been using in your stereo. Check for rodent bite holes on the spider and decomposition on the surround
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Note that even when measuring parameters with a computer, the values are derived and there is error because of many things - the equations assume linearity and the speaker isn't, etc.....
In the GR Research data, note the changes in Mms and Bl, both of which one would expect to be constant. For one test, the driver suddenly gained ~15% Mms and 10% Bl.
Say you measured the same driver with several different weights attached. You might not expect to get different parameter results with the different weights, but you will. Different input levels, same effect.... The devil is in the details.
In the GR Research data, note the changes in Mms and Bl, both of which one would expect to be constant. For one test, the driver suddenly gained ~15% Mms and 10% Bl.
Say you measured the same driver with several different weights attached. You might not expect to get different parameter results with the different weights, but you will. Different input levels, same effect.... The devil is in the details.
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Yes. good point. Noticed that too but some variation is normal even in others carefully conducted measurements. Those variations moved up and down and didn't offer a coherent picture of systematic bias.
If there are any changes to the driver over time, the problem is the design and choice of materials. I think starched cloth spiders and other aspects of the century-old Rice-Kellogg voice-coil-and-cone driver model need rethinking.
B.
Ben,
There have been a number of changes due to "rethinking" century old transducer tech, including double (and triple) spiders that use materials other than starched cloth. Although shorting rings are not exactly new, incorporating them and Klipple- optimized magnetic structures (and multiple layer voice coils on both sides of the former) has decreased distortion, as has incorporation of semi-exotic materials such as carbon fiber and kevlar for cones.
Although there are many speakers that are 60 (or more) years old that sound fine, there are new speakers employing current tech that sound (and measure) considerably better.
Time waits for no-one...
Art
Just as voodoo misinformation is problematic, so are people who poo-poo real things by lumping them in with voodoo. I've measured meaningful (20%) Fs changes in a number of drivers with break-in. It's more pronounced with vintage high efficiency drivers with pleated surrounds that have been sitting, but those too loosen back up, and I've seen it with current production subs as well. Thiel's method makes plenty of sense, they were (don't know about the current units since Jim's death) very well engineered speakers, not voodoo at all. I believe they used driver matching and that would make having the drivers in a "final" broken-in state important for the matching to be meaningful.
Let's just suppose that ardent proponents of breaking-in can shake their drivers violence or longly or violently and longly enough to record before versus after measurement differences.
Do the changes of the freed-up drivers remain or do they fall back closer to the initial state after a short while? If a driver was played for 20 years at normal levels or even with an occasional playing of the 1812 Overture, would any change be measurable?
Would lots of drivers change in the first moments out of the packing box and playing music at normal levels, once the factory dust has been blown off and then be stable?
As in the case of the link I posted, can anybody hear reliably in ABX testing hear the difference when the resonant frequency drops by a Hz or three without having any effect what so ever on the rest of the sound compass?
And so on.
Ben
Do the changes of the freed-up drivers remain or do they fall back closer to the initial state after a short while? If a driver was played for 20 years at normal levels or even with an occasional playing of the 1812 Overture, would any change be measurable?
Would lots of drivers change in the first moments out of the packing box and playing music at normal levels, once the factory dust has been blown off and then be stable?
As in the case of the link I posted, can anybody hear reliably in ABX testing hear the difference when the resonant frequency drops by a Hz or three without having any effect what so ever on the rest of the sound compass?
And so on.
Ben
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1-3hz wouldn't matter on a small mid, or even much on a sub. But it can be bigger than that. As mentioned, 20% is not uncommon. Pretty big difference from 50hz to 40 particularly in a vented enclosure. Also potentially audible are stiction artifacts, if the suspension has stiffened, softening it up may make it cleaner near rest level. There are multiple factors at play, driver suspensions can and do change over time, usually stiffer, sometimes softer. But the specification creep related to age is very slow, so if they get a regular workout in normal use, they ought to largely stay "broken in".
There is a very simple, easy-to-follow and foolproof procedure for breaking in speaker drivers:
- connect up speakers and start playing music
- start a diyAudio thread on "how to break in speakers"
- wait for thread to finish
That's it! Your speakers are now broken in!
There must of been something between then and the AC outlet otherwise it would put them through a wall.
second I dont see much point in doing that when its straight current that would put and leave woofers in max excursion wouldnt it?
Since buying new kicker subs back in mobile days they came with a break in method that seemed to make sense and work I apply it to all new speakers. Listen at a modest listening level and turn up your amps for 30 second intervals gradually increasing power and duration. You can tell when they begin smoothing out, use discretion and play it by ear.
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Originally Posted by Bare:
Years ago Vandersteen used to (no Idea if they still do this) line up a fresh shipment of Drivers .. all wired in series and plugged the assembly into a wall plug.
For a Week!
Apparently the 60hz did a good job of 'prelimary' break in.
1) 60 Hz AC provides a nice sine wave signal if the power provider has a decent AC generator.
2) Household 60 Hz AC is typically 120 volts, a single B&C 18SW115-4 (a four ohm woofer) can handle that power for several seconds (I proved that with repeated operator error ).
Connecting enough multiple drivers of any impedance or "watt" capability in series to AC mains outlet is perfectly safe, providing you don't touch the live mains leads .
Art
Years ago Vandersteen used to (no Idea if they still do this) line up a fresh shipment of Drivers .. all wired in series and plugged the assembly into a wall plug.
For a Week!
Apparently the 60hz did a good job of 'prelimary' break in.
SS4927 (what's the # signify?..),
1) 60 Hz AC provides a nice sine wave signal if the power provider has a decent AC generator.
2) Household 60 Hz AC is typically 120 volts, a single B&C 18SW115-4 (a four ohm woofer) can handle that power for several seconds (I proved that with repeated operator error
). Connecting enough multiple drivers of any impedance or "watt" capability in series to AC mains outlet is perfectly safe, providing you don't touch the live mains leads
.Art
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Ben,
My, you axe so many ??.
1) I don't know how you can "shake their drivers violence", perhaps I need a refresher course in Canadian technical writing..
2) The drivers I have "broken in" remained broken, ie. the Fs did not increase after the suspension (soft parts) loosened up.
3) That would depend on the orientation of the driver (vertical, horizontal, facing up or down) and the driver's suspension. I have owned many drivers that have not changed a whit in 20 years, and some that sagged 3mm in 3 years.
4) Depends on what you consider "normal levels". I have "broken in" drivers with levels equal (or in some cases, greater than) their rated power, and the suspension loosened up. Had I used one watt (loud enough for "normal levels" in a house) a 1700 watt B&C woofer's TS parameters would not have changed after taking it out of the box and playing it for several years. Fortunately, well established, reliable speaker manufacturing companies test their drivers after "break in", at an expected power level, so my experience with B&C, Eminence, Electro-voice, JBL, etc. has been their published TS parameters are correct, with allowance for the usual unit to unit manufacturing deviations.
5) I have been using GPS rather than a compass since 1987, so can not give you an answer to ? # 5.
6) Yada yada yada, whatever..
Luv ya, baby,
Art
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