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Old 6th February 2004, 02:14 AM   #1
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Default Driver 'break-in' period

I've read elsewhere that some drivers require a break-in period. Is this all drivers?
They were talking Lowthers full range stuff.

How about my 15" PA woofs? How about the compression tweeters?

What should I expect over the next year? [these are outdoor speakers only, not a lot of use].

They were talking 100 hours plus. I was not aware of the extent of it

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Cal
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Old 6th February 2004, 03:22 AM   #2
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I have one direct experience that supports the idea of speaker breakin. When I first put my TAD 4001's into service they sounded compressed and lifeless. Needless to say I was very disappointed (although I got them for less then nothing. Another story.) I continued to play them in hopes they would come around. They did in about the 3rd week. Not over night, but almost. In a matter of a few days they were sounding more open and un-strained. The dynamics came last, but bests of all they never lost the smoothness.

So is breakin for real. For my subs, maybe, my mid-basses, maybe, my mid-horn compression drivers, definitely.
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Old 6th February 2004, 11:29 AM   #3
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For low frequency drivers I point the thing facing upward in free air and apply just enough low voltage AC from a transformer to make it hum at say 50% of Xmax, maybe a little more. I did a pair of 12" 50 watt paper cone woofers last weekend with a peak to peak displacement of about 9-10 mm. I let it run for about 2 hours.

I read a Philips app note from about 1983 that was saying that under these conditions the majority of the settling-down of the speaker parameters e.g. Fs and Vas occur in the first 30 minutes. I did one overnight once and didn't realise that one of the flexy wires had a bad mechanical resonance at 50Hz and after many hours of this treatment the connection between it and the voice coil wire became intermittent and sort of fuzzy sounding. It was a dirt-cheap speaker though.
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Old 6th February 2004, 12:39 PM   #4
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This question comes up a lot. Many people have opinions based on aural memory (which is notoriously bad even with experienced listeners)

See this link.
http://groups.google.com/groups?hl=e...e+Search&meta=
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Old 6th February 2004, 01:06 PM   #5
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So what Dick Pierce says is gospel ?!

Has he ever noticed that for a reflex (the most used principle currently) tuning both VAS and fs have great influences ?

Regards

Charles

BTW: Please look at note #6 on the following data-sheet of a well-known manufacturer: http://www.jblpro.com/pages/pub/components/2206.pdf
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Old 6th February 2004, 04:36 PM   #6
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Break-in changes are do not always show up in tech specs. The T-S params may stay the same but the tonal quality of the driver may be drastically different.
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Old 6th February 2004, 04:54 PM   #7
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Quote:
The T-S params may stay the same but the tonal quality of the driver may be drastically different.
I have never seen or heard anything proving this statement, and my own measurements have disproven it.

Quote:
Has he ever noticed that for a reflex (the most used principle currently) tuning both VAS and fs have great influences ?
Actually, if you look at Changes in Cms, which causes complementary changes in Vas iand Fs (Vas increases and Fs drops by the square root) - you often need to cause a change of 30% or so to cause a change of 1 dB in the bass.
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Old 6th February 2004, 05:19 PM   #8
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Quote:
Dick Pierce
This occurs within the first 20-30 seconds when using high-level sine waves at resonance.
Quote:
JBL 2206H Specifications Sheet
6. Thiele/Small parameters are measured after 2 hour exercise period using a 600 W AES power test and will reflect the expected long term parameter values once the driver has been installed and operated for a short period of time.
I wonder how long it would take with "normal" program material at "normal" listening levels for various length listening sessions. A few days, maybe a few weeks?
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Old 6th February 2004, 05:50 PM   #9
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Quote:
Originally posted by Ron E


I have never seen or heard anything proving this statement, and my own measurements have disproven it..
Many people have noticed speakers character changing after a break-in period. My ears have proven it to me and others used their ears to agree. A sine wave is no test of a speakers sound reproduction capability. It does nothing to show impulse response that is critical to the 'sound' of a driver. Impulse response appears to increase with a break-in. I have no imperical data, but ears know what sounds more real. Auditory memory might not be accurate but the ears knows what sounds right, that does not change over time.
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Old 6th February 2004, 08:04 PM   #10
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Here's an alternative explanation for you. Your ears get used to the sound. It takes some time to do this, but the ears do it automatically.
I have experienced this many times.

When you are used to sound as it is reproduced by a reference transducer, what you notice most early on when switching to another transducer is the differences between the two. Switch from a too-bright speaker to one that has a more neutral balance and the neutral one will sound dull..... etc...

An analogy is the difference in light quality between different types of light (incandescent, fluorescent, sodium, etc...). THe eye adjusts for this automatically after a few minutes. The film cannot adjust automatically to these differences as the eye would, so pictures taken with film balanced for daylight look yellow when the light source is sodium or incandescent, and the pictures look blue when the light source is mercury or fluorescent.

Objective measurements are like the film. It's all about perception.
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