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Old 19th November 2003, 04:34 PM   #1
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Default Speaker "break in"

I'm wondering if my PA subs (EV SB180s- have the EVX180B 18" drivers in them) need to be broken in. I bought them many months ago but never really cranked it.

They're rated at 600 watts continuous, 2400 peak. I'm driving them in stereo mode with a Crown Macro-Tech 5000VZ amp, approx 1350 wpc cont. I bought these subs when Mars went outta business and they were pretty much never used. I drove them lightly (relatively speaking) in my house, but yesterday I decided to turn them up for maybe 30 seconds or a minute. I noticed for one there was a strong smell, like "new driver smell" if that makes any sense. Today I turned on the system again and I noticed that wow, it seems as though the bass got punchier. To make sure I made sure I played the same tracks with the same level patterns as indicated on both the amp and the mixer. I wonder if such PA subs actually need a break in time since they are rated to take 600 watts continuously for hours on in.
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Old 19th November 2003, 05:13 PM   #2
markp is offline markp  United States
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Speakers do need a break-in to get the full bass output. Put them face to face but wired out of phase and turn it up. This will let them break-in without having to hear the loud music. A 24 hour break-in period is considered normal.
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Old 20th November 2003, 10:30 AM   #3
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Actually music is probably not the best source for breaking in, as you need lots of power to get the suspension moving - breaking in is all about loosening up the new tight suspension, not heating up voice coils. Better would be low frequency sine wave, say around 10Hz - this could even be generated from PC sound card. A level of even 30W will produce large visible motion and loosen things up quickly - it is also a lot quieter !

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Old 20th November 2003, 04:03 PM   #4
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I couldnt find my test CD with all the sinewaves, so I instead hooked up a pink noise generator and turned the crossover down low and turned up the volume. Also wired the subs out of phase but dang it was still pretty loud and everything was shaking. I should probably leave it like this for a while but listening to the pink noise rumble is really annoying. Maybe ill try to find that test CD. I think its workin though, I can smell the speakers still .
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Old 20th November 2003, 05:04 PM   #5
markp is offline markp  United States
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Quote:
Originally posted by eRiCdWoNg
I couldnt find my test CD with all the sinewaves, so I instead hooked up a pink noise generator and turned the crossover down low and turned up the volume. Also wired the subs out of phase but dang it was still pretty loud and everything was shaking. I should probably leave it like this for a while but listening to the pink noise rumble is really annoying. Maybe ill try to find that test CD. I think its workin though, I can smell the speakers still .
Remember to put them face to face to cancel better.
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Old 20th November 2003, 09:18 PM   #6
Ron E is offline Ron E  United States
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Break-in is a myth.

Speakers don't need high power break-in.
If you can smell them, you are probably making them too hot. Pink noise has a higher duty cycle than most music and it is quite a torture test.

If the speaker suspension loosens a bit in the first few hours of play, Fs goes down and Vas goes up, the two changes cancel out and frequency response changes very little, if at all. A 20% change in stiffness, which is quite a lot, makes a difference of perhaps 1dB in a sensitive box alignment.

Please note that many of the changes one sees in parameters after long use are reversible, and stiffness in particular is very temperature dependent.

I measured a woofer, it had an Fs of 35Hz, I played sine tones through it at Fs for a couple hours and Fs dropped to 31Hz. A couple hours later, Fs was back to 35Hz. I measured later on a cooler day (only ~10degrees cooler) and Fs was 43Hz.
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Old 20th November 2003, 09:21 PM   #7
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Ruler breaker.....What you are really doing is the equivalent of the diesel motor exhaust emissions test. You rev the motor up to max revs then (hopefully) the govener comes in, in the meantime the electronics is snifling it's rear end. There a condition for this, that the OH cam belt won't snap. Same with your speaker system.
There's an awesome power in this.........600W speaker system used on a 1.2kw amp and for testing on sine waves is inverse logic. One risks destroying the lot. Forget the peak power figures.

I don't trust Mosfet amps (whatever name) from the Orient. 've repaired too many and most (whatever the brand) have basically the same circuitry. To get 1.2Kw p.c the bridging technique is used with perhaps 4 mosfet output stages thrown in with some fancy current limiting. Beware, this most likely works after the speaker has gone for launch.

If I have got this one right, there used to be a golden rule in the industry that speaker music ratings (cont) should be rated 4 times max amplifer power. That seems to be ignored.
Using a CD with mixed tone is fine, but remember the continuous aspect. You don't hear all the sounds and it's those often do the damage.
Sine wave testing is risky for the speakers and usually exceeds IEC ratings. An 18" can tolerate alot of stick, but I don't like anything but good music even from new speakers. I would avoid digital for playing around with speakers at very high electrical levels without an LF interlock. Why one might ask. If LF warbling starts or instability at only a few Hz, then these mosfet amps will send this right through the system with the damaging effects of DC.
That is probably one of the reasons that speakers stand up very well with tube amps, as the o/p transformer will attenuate sharply at a low cutoff frequency. The small peerless 8" baskets off my 150W tube amp cope very well with the best steel band & reggae music (Tabu Combo) ,and that's a real test for the speakers and I haven't burnt them out yet..

Not all speakers need a run-in.... that is a misnomer. There will aways be some ageing but:-

Modern Hi Speakers with neoprene surrounds NO. The suspension and spiders is already highly compliant, made by modern processes.

Older speakers with paper surrounds with dusty paper cones will benefit from a good excursion, but don't overdo. A paper cone speaker with "honk" if overloaded. They are more fragile. Keep the cone dirty. The extra mass of crud reduces the resonance freq and smoothens the sound. Once the corrugated surround has limbered up, also expect a 15% reduction of resonant freq.

Musical instrument/PA speakers are entirely different. They have to be weather proofed, have designed stiff cones and hard sprung centering spiders to stand the rigours of bad handling and overloading. The cone surrounds and cones usually have a higher resonant frequency.

rich
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Old 20th November 2003, 09:40 PM   #8
markp is offline markp  United States
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That's funny, why do almost all quality speaker manufacturers post their drive specs after a 24 hour burn in? Heres a hint, it makes a difference. I've tested brand new drivers and again after a burn in and the specs change, not a lot, but enough to make a diffrence in box design. The spider is what breaks in the most on rubber surrounded drivers. On tweeters with ferofluid, the fluid spreads out more evenly after a few hours of use smoothing out the response. The variation in Fs RonE was talking about is more likely a change in barometric pressure and a sealed box that has not been allowed to equalize internal pressure(through a small hole or such). Believe what you wish but it does make a differnce!
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Old 20th November 2003, 11:09 PM   #9
Ken L is offline Ken L  United States
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Quote:
Originally posted by Ron E
Break-in is a myth.
Ron E is a myth _big grin_

Driver break-in is real. Not in all circumstances, but in some.

Ask any Lowther owner.

Of course you could say that Lowther owners are a myth also. _even bigger grin_

I guess they _are_ kind of "mystical"

Mythical, mystical - whatever

regards

Ken L
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Old 20th November 2003, 11:28 PM   #10
Ron E is offline Ron E  United States
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That's funny, my measurements were free air

Hint: Fs is a free-air parameter.

Belief is your department, not mine.
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