Breaking in drivers |
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JonB67
Young Croc Joined: 22 April 2016 Location: UK Status: Offline Points: 1376 |
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I don't think anyone's saying they don't change, and the numbers make interesting reading.
Does it make difference doing it in free air vs in box other than time frame?
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Timebomb
Old Croc Joined: 11 October 2004 Location: Lancaster Status: Offline Points: 2716 |
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Ive never tried running in drivers in a cabinet, it would make a lot of noise and take more power to reach xmax.
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James Secker facebook.com/soundgearuk
James@soundgear.co.uk www.soundgear.co.uk |
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jbl_man
Moderator Group Joined: 12 January 2005 Location: London. Status: Offline Points: 11154 |
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^ This. "Breaking in" drivers is complete nonsense. All you are doing is shortening the life expectancy of said driver. Breaking-in is one of the more stupid ideas circulatiing in the insane world of the hifi nutter, where almost everything from a mains fuse to a turntable needs, in their minds,"breaking in". |
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djeddie
Old Croc Joined: 26 April 2004 Location: Bristol Status: Offline Points: 4125 |
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^ This. Both of them.
Most TS parameters have a tolerance anyway, some as much as ±20%. Also temperature, humidity etc etc have an effect on wht's measured. |
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Chas n Dave : it's like Drum and Bass but with beards. E=mc² ±3dB
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jbl_man
Moderator Group Joined: 12 January 2005 Location: London. Status: Offline Points: 11154 |
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Only thing i would advise with brand new drivers, allways stick an ohm meter on them before putting them in a cabinet...a few years back,a pair of new P Audio 18inch drivers straight out the box,one meaured 9 ohms,the other 5. So much for quality control!..Of course one was much louder than the other.
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Robbo
Old Croc Joined: 05 December 2005 Location: Shropshire Status: Offline Points: 4221 |
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When loading a brand new driver into a cabinet also check the phasing with a PP3 9v battery as sometimes they can be out of phase from new and also double check any driver that has been re-coned as I have seen a lot of these out of phase over the years.
I do tend to agree with Timebomb that new drivers are very slightly lower in volume when new---We once doubled the size of one of our touring rigs back in the eighties with new drivers inside new cabinets and on the first gig, all of the newer cabinets were stacked on one side of the PA in the venue as they were first out of the truck. When the rig was run up to a usable volume with our normal mono test tracks you could actually hear that the bass was slightly down on that one side and the two mid sections on that side were also very slightly down---HF was fine and this was easily adjusted by increasing bass and mid sends on the FOH Xover by a notch or two from our usual settings---Most people would not have even noticed the difference in a gig situation. The following night the Xover settings were returned to normal and everything was fine from then onwards. |
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Peter Jan
Young Croc Joined: 16 December 2008 Location: Belgium Status: Offline Points: 1019 |
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Same here, thousands of drivers in the last 40 years or so and never ever ran one in. What's the point ? Using them for a few hours in their first outing does just that. It's not that they will perform any better or longer after a "break-in". I get asked often whether speakers need to be broken in, usually followed by the expression : "like car engines ? ". My answer is always : Speakers are not car engines, totally different mechanics going on there. For second hand speakers, new old stock, reconed, ex demo or whatever the story that goes with them, I suggest to check impedance and phase, check for voicecoil rubbing, cone deformation, if the cone can move back and forth the same amount (and without any noises), things like that. New in the box, some speaker suspensions sag hard after barely a few years on the shelve and others don't move a hair after decades, no matter the climate conditions they were in. So don't worry about breaking in ( it's nonsense ), but DO check the basics. |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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Breaking in the drivers in the box is like breaking in a brand new pair of shoes. If you and I wore the same shoe size, the shape of our foot would differ if we swapped a pair of broken in shoes in terms of comfort. So the end result would not be the same on the overall shape of the shoe. Bear in mind if you are not playing a significant amount of 30 Hz and below, you may not hear huge difference in the sound if the majority of the bass propagating is 40 Hz. On the flip side, if you are into a lot of punchy (80 Hz) bass, a broken in driver will not sound as fast (highly dynamic) once broken in as it increases the lag time. So, the results are debatable if breaking in a loudspeaker is a good or bad thing pending on your musical taste. One thing is certain, all loudspeaker's suspension will loosen up within time. The most simplest way to get an idea on the difference in sound is comparing a woofer with a 0.2 Qts versus a woofer with a Qts of 0.3 A 0.2 Qts broken in woofer will never achieve the sound of a broken in woofer of a Qts of 0.3 However, it may achieve the sound of a brand new in the box woofer offering a Qts of 0.3 Best Regards,
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Elliot Thompson
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IanD
Registered User Joined: 17 January 2009 Location: London Status: Offline Points: 400 |
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Except that by breaking a driver in you're not changing either BL or Mms which have by far the biggest effect on the frequency response, you're changing Cms which has far less effect in most enclosures (sometimes almost none). Qts (or Qes) is a derived parameter which depends on all three factors, Fs is derived and depends only on Mms and Cms. If you don't believe me take a typical driver in any simulator and change just Cms by +/-20% while keeping BL and Mms the same (Q and Fs will change) and resimulate. Now try the same but changing just BL (affects response everywhere) or Mms (affects response in mass-controlled region), the effect on response is *way* bigger.
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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What is changing is the fs. Any of the three (VAS, fs, Qts) that creates a change will alter the sound. The VAS, fs, and, Qts are the primary figures. Best Regards,
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Elliot Thompson
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IanD
Registered User Joined: 17 January 2009 Location: London Status: Offline Points: 400 |
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Nope, the four fundamental physical parameters which actually vary are BL/sqrt(Re) (driving force), Mms (moving mass), Cms (suspension stiffness), and Sd (diaphragm area) -- all the others like Fs and Vas and Qes may be useful for speaker design (which is why manufacturers specify them) but they are derived from the basic four. For example if Cms changes then Vas and Qes and Fs change, but if BL and Mms and Sd are unchanged there will be little change in the speaker response, the efficiency is unchanged because this only depends on BL, MMs, and Sd. If BL or Mms changes then the efficiency changes, this has a big effect. Most box designs (reflex, bandpass, horn) are pretty insensitive to compliance changes but very sensitive to mass or BL changes -- which is a good thing because it's easy to produce speakers with well-defined BL/Mms/Sd but much harder to get consistent (and stable over time and temperature) compliance. Go and try a speaker simulator that lets you alter the fundamental properties and calculates the derived ones if you don't believe me... ;-)
Edited by IanD - 28 March 2020 at 6:20pm |
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concept-10
Young Croc Joined: 17 May 2016 Status: Offline Points: 1292 |
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Funny isn't it Elliot, we as in this forum lost a very valid member (kyle) recently, Why? because he was fed up with your constant rubbish, you have never shown one photo of anything you have built, not one, yet you spout the most complete drivel, every time you post your crap you get shot down because you are just plain having sex wrong, this thread is perfect because everything you have said has been shot down yet people still follow your advice, many here are older and wiser than me, but I have been doing this sinse 1979 and I know for a fact you talk utter shite, so from another sound man it's good bye forum.
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