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Author
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Topic: How common are blown speakers?
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Steve Guttag
We forgot the crackers Gromit!!!
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Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 05-09-2009 05:48 PM
Mike,
We got into the reconing business due to blown speakers and it comes/goes in spurts. Generally right before the big seasons (gee I wonder why ).
We have specialized in Altec, JBL and EV repairs (factory certified and only use their genuine parts on those).
Altec drivers often come in from just plain age! Some have had the driver, from being in the same position so long, just sag and the voice coil rubs.
Others are over driven.
JBL's are a much rarer driver to fail, as a group. The bulk that we see are the 2245H as used in the original 4645 (as Scotty would say...no stinkin' A, B, C or D). Those recones fall into two categories...foam rot and overdriven (to the point the voice-coil leaves the gap).
Some recone the 2245H as a 2242H (pleated surround)...the bass will suffer if you do but you will not see foam rot again. Many folks do not appreciate just how much power is required to play subwoofers in a digital sound world (film or DCinema). One MUST use the continious PINK NOISE spec when figuring out subwoofer power handling since that most closely resembles what a subwoofer receives...unlike the other channels. In some films, it can be sustained for quite a long time too.
Well a JBL 2245H is really just a 350-watt driver. It plays down flatly to 20Hz though. In most typical 200-300 seat theatres...you best have 4-8 of them if you want them to survive. In fact, if your room is 60-feet deep (speaker to rear seat)...you would need 6 4645s to play at spec. It would be a very good subwoofer system if you did...and it would play deeper bass than most systems offered today...but most seem to think 1 or 2 subs is all you need...idiots.
The other JBL drivers we see are often from their "econo" line of speakers (3000 series)...they are low-cost for a reason...the parts are not up to the job nearly as much. Most folks though want to believe they can pay less and get everything. Net result...BLAMO....and it probably didn't sound too good either.
Lastly...there are the mechanical damage JBLs...something went through the cone...oh well...accidents do happen.
EVs almost always suffer from two things...cheapass construction/design or over driven.
EV's specs are probably the most accurate...if someone would read them. If driven within their range, they will do okay (they still will sound like EVs though). But seriously...some of their driver constructions really suck....pleats tear apart, insufficient adhesive area to hold the spider...you name it. Their voicecoils are also rather understated, except in the EVX line. Most of their drivers handle far less power than people seem to think they do. We have received numerious speakers from the "pro" world where some schmuck believe the salesperson and bought the cheapo speaker and can't figure out why it blew up (and some blew up real good too).
Ashley amps have contributed quite a bit to our recone business. You can always spot an Ashley failure...the voice coil burns completely off the voice coil former. I always make a point of telling the customer when I see that failure to "repair or replace" their Ashley amp...they are amazed that I know who made their amp....you see a few dozen failures like that...you see a trend.
Surround speakers are another story. I've had the odd one here and there fail for seemingly no reason. I think most are made on the cheap since when one adds up the total cost of the surround channel, it is likely the most expensive channel.
By and large, however, if you properly design a system, use good quality speakers (pick your favorite)...and design the system such that the speakers are driven within their actual power handling, failures are a very rare thing...just like any other component within the system.
Steve
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