Field Replacable Speaker Cones

Dennis Manuel · Post by **Dennis Manuel** » 20 Aug 2000 9:34 am

A speakers efficiency comes from many different design features, one of them being voice coil to magnet tolerance. I think that a "Field Replacable Cone" would be less efficient than a "Factory Replaced Cone" because the tolerance would not be as close. Has anybody had any experience with this?
Please respond. Thanks in advance.

Jack Stoner · Post by **Jack Stoner** » 20 Aug 2000 11:26 am

There's no problem with the Peavey BW replacement. When you replace the "cone" you replace everything, the spider, cone voice coil. The only reused part is the bolt on magnet. You effectively have a new speaker.

Dennis Manuel · Post by **Dennis Manuel** » 20 Aug 2000 8:23 pm

Thanks for the response everyone but I don't think we are talking about the same thing.
My concern is this; When the gap between the voice coil and the magnet is increased, as in a field replacable basket, I would think sonic qualities will be lost because of the larger gap. The closer to the magnet the better the efficiency.

Jack Stoner · Post by **Jack Stoner** » 21 Aug 2000 2:13 am

With sound engineering design I wouldn't think that is a problem. On cheap speakers anything is possible, even if the magnet is close to the voice coil.

On high end speakers, such as JBL, or Black Widow, Electro Voice, etc., your question is not a concern. It is only a concern on the cheaper speakers and they are generally not used for professional speaker systems.

Some of the "cheap" speakers are used by some to achieve specific sounds, but other than that I can't think of a reason to use a lower grade speaker.

If you're really concerned about it, do some homework and study up on speaker design and engineering.

Bill Crook · Post by **Bill Crook** » 21 Aug 2000 5:03 am

On the BW replacement baskets, the "GAP" is the same as the old one. Thats the beauty of the BW transducer, you can be assured of a perfect fit,(be sure to tighten all three bolts the same,as much as possible) Like Jack saids, "your question is not a concern. It is only a concern on the cheaper speakers."

Cairo Zoots · Post by **Cairo Zoots** » 22 Aug 2000 7:55 am

Dennis-I've always held that JBL's closer tolerances and flat wire technology helped to maintain their dominance. Especially noticeable in higher fidelity applications. Several other factors contribute to the spkrs performance, and one of them is the ability of the coil to dissipate HEAT, since this one of the real enemies. Cz

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ree-oo-dee-doo

Keith Hilton · Post by **Keith Hilton** » 22 Aug 2000 12:26 pm

Wonder if Peavey has the Patent on a field replaceable speaker cone? I don't remember any other company doing this.

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[This message was edited by Keith Hilton on 23 August 2000 at 07:48 AM.]

Rich Paton · Post by **Rich Paton** » 25 Aug 2000 10:07 pm

I do repairs part-time for a local lighting & sound contractor/dealer/service center. Repaur customers often bring in Peavey speakers and compression drivers (mosty ones abused in disco and DJ systems, but that's another whole thread in itself).
I can go to the shelf, locate & grab the Peavey part, and have the speaker or driver fixed ready to go, usually in less time than it takes to write up the service order. Usually no labor is charged to the work, which is very good for customer relations.
To me, that really speaks (no pun intended) an awful lot for Peavey's concept & implementation of the repair of their speakers.
I wish that I could do such a repair on the two JBL 15" model 2235 subwoofer drivers which I need to re-cone for my home listening/studio system.
Even at dealer cost they will run me nearly $150 to re-cone them, and will take an hour or more just to strip the old adhesives and cones from them.
In addition to needing access to the genuine factory repair parts, the process requires stocking and using noxious solvents, exotic adhesives, alignment fixtures & tooling, special non-magnetic tools, and plenty of careful and tedious work.
The JBL's are an excellent product, but a real pain in the rear to repair properly.
Regarding effiency, the actual difference in the field-repairable Peavey speakers and similar products (Altec, JBL, E-V, etc.) is really too small to be a much of a factor in the speakers' performance, if indeed it is actually an issue at all. I doubt it.
Cairo is right on in his assessment of the differences, but since the products are used in different applications, that's really a matter of "Apples & Oranges".
BTW, it's very rare to see a JBL or Electro-Voice musical instrument loudspeaker
come in for repair, or Peaveys used in that role either. It's mostly PA stuff and much, much damage is due to inappropriate usage and
occaisionally defects in amplifiers such as D.C. leakage to the output. A very large percentage of failures are due to operating speakers with inadequate clean output power for the task, as distortion in the output signal places severe abuse on the speakers. Here's some very useful info on the subject: http://www.jblpro.com/pub/technote/lowpower.pdf
Hey Cairo...how are you (& the Teac) doing?[This message was edited by Rich Paton on 25 August 2000 at 11:22 PM.]

Donny Hinson · Post by **Donny Hinson** » 26 Aug 2000 1:26 pm

Maybe the "looser" tolerences in these "field-replaceable" speaker assemblies is the reason that my Peavey amp doesn't sound as powerful as my Fender. The Peavey's 260 watts is blown away by the Fender's 160 watts.

The speaker efficiency could have a LOT to do with this. This isn't a slam against Peavey, nor is it an invitation to another "tube vs. solid state" debate.

It's just an observation...plain and simple.

Rich Paton · Post by **Rich Paton** » 27 Aug 2000 11:47 am

OK...I'll ask the boss about this (the field replacable vs. factory repairable drivers) efficiency factor., I'm sure he knows something about it. It is an interesting thought.

Mike Brown · Post by **Mike Brown** » 29 Aug 2000 1:19 pm

The efficiency and the gap tolerances on a Peavey Black Widow are very tight. After all, we are talking about milled parts, so why wouldn't the tolerances be as precise as possible?

The magnet gap on a Black Widow speaker is .064 with plus or minus .0015 tolerance. This is extremely tight in any speaker.

The coil wire "is" rectangular as opposed to a round shape in order to obtain maximum magnetic field in the gap. There is 14,000 gauss of energy in the gap of a BW speaker.

When the VC wire is heated, it increases in size by .010 of an inch. Again, there has to be a minimum gap size due to this fact or the VC excursion would not be smooth and probably result in speaker failure. The quality of voice coil materials would also have a lot to do with the efficiency of a speaker.

Donny, as far as comparing a Fender and Peavey amp that have totally different specs, it's near impossible to say that "one is blown away by the other". They both have to be on a same level playing field in order to come up with an honest conclusion.

A couple of weeks back, there was a post about what speaker sounded better. Well, as most of you know, a speaker sounds it "best" after it is broken in, just like a pair of shoes. When you first try a pair of shoes on, they are usually stiff. After you wear them awhile, they become comfortable. Then, after years of use, they become worn and loose. Same thing with a speaker. After all, a speaker is a mechanical/expendable device that will wear down. At some point it time, the shoes will wear their best and at some point in time, the speaker will sound its best.

Mike Brown
Peavey Electronics Corporation