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New speaker "playing in" period?


solo4652
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http://barefacedbass.com/technical-information.htm

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For breaking-in new woofers:[list]
[*][url="http://barefacedbass.com/uploads/images/page_images/BAREFACED%20-%2025Hz%20Sine.mp3"]25Hz Sine Wave.[/url]
[/list]
When a high performance pro-audio woofer is fresh out of the box its suspension is very stiff. This means that the woofer is over-damped in the low frequencies compared to its design parameters, resulting in thinner bass response and lower efficiency. It also means that the woofer is under-damped in the mid and high frequencies, resulting in worse control of the higher frequency break-up modes and thus a harsher sound. During the first few hours of high SPL use the suspension loosens up and settles into its long-term design parameters.
Unlike a brand new car you do not need to baby the loudspeaker whilst it's still 'running in' and in fact the louder you play it, the quicker it'll loosen up (but don't be silly, modern amps are powerful!) Play a few loud gigs or rehearsals and your cab will reach its destination tone and performance. Alternatively, play the 25Hz sine wave above through your rig, with the volume turned up so that the air movement from the port feels like a desk fan on low, not like a hair dryer on high. If you have a steel grill cab you'll see the woofer(s) moving about 1/2". Leave it like that for as long as you can bear the rumble - three hours will get you a good distance along the break-in curve, which is reversal exponential, so the first five minutes make as much difference as the last fifty minutes.
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Running in a loudspeaker is not about being careful when it's new, it's realising that the suspension is stiff when new which restricts the bass response - it just saves you have to gradually turn down the lows during your first few gigs. If you're running in non-Barefaced cabs I wouldn't recommend driving them to the amount of excursion or you risk damaging them.

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[quote name='xgsjx' timestamp='1354191042' post='1883266']
IIRC, Ampeg suggest playing pre recorded music (such as a CD) at a reasonable volume for several hours before first use.
[/quote]

Well, the Promethean and I have gone through my CD selection and we've decided on Joss Stone's latest CD. We're going to play that this afternoon through the CD player on the TV and then I'll use the combo for the first time. Is that what you meant?! :)

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[quote name='solo4652' timestamp='1354192322' post='1883297']
Well, the Promethean and I have gone through my CD selection and we've decided on Joss Stone's latest CD. We're going to play that this afternoon through the CD player on the TV and then I'll use the combo for the first time. Is that what you meant?! :)
[/quote]
Tough call - 25Hz rumble or Joss Stone's latest?

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[quote name='solo4652' timestamp='1354192322' post='1883297']
Well, the Promethean and I have gone through my CD selection and we've decided on Joss Stone's latest CD. We're going to play that this afternoon through the CD player on the TV and then I'll use the combo for the first time. Is that what you meant?! :)
[/quote]

I would have chosen more than 1 CD for several hour's listening myself. :P
Though with my Markbass combo, it was just several hours of me playing my bass at home & then off to rehearsal a few nights later.

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I'm sorry, but running your speakers in is a completely pointless exercise. It's an audio myth. Your speaker is not a car engine. Sure, you'll soften up the suspension of your drivers but the lower resonance frequency (Fs) will be balanced by an increase in compliance (VAS) and there will be no difference in the sound of your cab. Of course, if you're expecting to hear a difference, chances are you will hear one. Then there is the matter of whether you can actually tell whether the sound has changed (even if it has) when there is a long gap between listening tests.

A year or two ago when this subject was being discussed on here I measured the Thiele-Small parameters of a factory fresh Eminence 3012LF. Then I ran it in and measured again. Of course, the parameters had changed but when I modelled the frequency response in a box there was no difference. I published the results and they should be on this site somewhere.

I didn't realize at the time that greater minds had done this before me.

Just play the cab and stop farting about. :D

[Edit] I would add that there is a greater chance of damaging your speaker by playing a very low test tone through it (at a frequency that the cab is not designed to handle and where the driver has very little excursion capability) than playing through it normally.

Edited by stevie
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[quote name='hamfist' timestamp='1354254132' post='1884113']
I think we should all also consider a decent running in period for new cables. They can be very dellicate until properly broken in. ;)
[/quote]

Should we have a running in period for the electrons :blink:

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[quote name='stevie' timestamp='1354207585' post='1883657']I'm sorry, but running your speakers in is a completely pointless exercise. It's an audio myth. Your speaker is not a car engine. Sure, you'll soften up the suspension of your drivers but the lower resonance frequency (Fs) will be balanced by an increase in compliance (VAS) and there will be no difference in the sound of your cab. Of course, if you're expecting to hear a difference, chances are you will hear one. Then there is the matter of whether you can actually tell whether the sound has changed (even if it has) when there is a long gap between listening tests.[/quote]

I wouldn't recommend doing this with our cabs if it didn't make a difference - I deal in truths, not pointless audio myths. Cms is the fundamental parameter which changes, raising Fs and lowering Vas. In a typical bass cab this will result in an increase in output between 50Hz and 100Hz - you can measure this and you can model this. And you can hear it! The lowering of Vas means you'll often get more output below 50Hz with a fresh woofer because it goes deeper in a small box, but as the sum total of output from a typical bass guitar and typical bass amp has much much lower output in the sub 50Hz region than the 50-100Hz region you'll hear a fresh woofer as having noticeably less bottom than a loosened up one.

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Just to back up Alex, I had a bit of a problem accepting my BF cabs to start with, frankly disappointed. Lots of email exchange with Alex, I eventually followed his instructions, left the 25Hz on for around 5 hours with the resulting nausia for the inhabitants in our part of the road (I placed the cabs face down to reduce this especially unpleasant effect). This and lots of use anyway (could be either or a combination) and the cabs are much warmer and cleaner sounding.

Of course I have no measurements etc but they have settled down to now be my essential equipment. I would go so far as to say transformed, bass control now more likely to face 10 rather than 2 O'Clock. Loosening (as opposed to 'running in' which implies going easy on it) is definitely recommended, if the use of the 25Hz signal speeds this then, great.

Running in of a car has to do with machined surfaces being (microscopically) rough and thousands of microscopic welds joining and being ripped open every second as the peaks in the surfaces rub against each other. The wear effect of this can be reduced by offering only light loads to the rubbing parts until they have more gently worn away the peaks. (Modern machining and oils has made this process practically redundant, but its still worth not thrashing a new or even cold engine.) There is no such rubbing in a speaker with the moving parts magnetically suspended. As mentioned, its to do with speeding the loosening of the cone suspension.

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[quote name='4 Strings' timestamp='1354272503' post='1884263']
Running in of a car...
[/quote]The running in of a car isn't a very good analogy. The wearing in of a pair of new unwashed jeans or leather shoes is, because they get softer with use, as do the suspensions on drivers. Like Alex I don't recommend breaking in drivers just because I think it might be beneficial, it's because I've measured the results of break in, literally hundreds of times. I very much doubt that the wags who say it doesn't do anything have any data to back up their assertions.

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4String, have you considered that your experience could be down to listener break-in?

Expectation bias is a very strange thing. I remember being convinced of the superiority of my £100 interconnect cables until I recommended them to a friend and we compared them with the free ones that came with his amplifier. Of course, in those days when you got a new item of hi-fi equipment the first thing you did was to bin the free cables supplied and replace them with a pair from a boutique maker made from 99.999 percent oxygen-free silver-plated copper.

When I first took my swish cables home I plugged them in and was convinced they sounded better. After all, they looked better, a very knowledgeable salesman had assured me that they would sound better, they had good reviews in the hi-fi press and were manufactured by a company with a million dollar turnover making all kinds of scientific claims that sounded very convincing.

Expectation bias, you see? A few years later when I compared them to my friend’s cheap cables, I wasn’t aware which was which - and guess what? I couldn’t hear any difference. Nothing at all. They sounded identical.

I’m curious about two things.

1. If breaking a speaker in makes a difference, why is it always a difference for the better?

2. For all the people who claim to hear a difference in their speakers after break-in (where there is no measurable difference in the system frequency response) why doesn’t anyone notice a difference in their speakers after they’ve been playing them for a while? After all, driver parameters change as the voice coil gets hot and this has a very real effect on frequency response that you can in fact measure.

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