jps@wucs2.UUCP (James Sterbenz) (08/02/88)
I'm not sure about posting this to sci.electronics, but there isn't
a sci.electroacoustics :-), and I thought I might reach some of those
who don't read "wreck.audio"
I've got a pair of Electro-Voice EV14-A speakers, purchased in 1974.
The woofers are 10" acoustic suspension type, and the ring of foam
which supports the paper cone has deteriorated very badly (i.e. holes).
The cone itself seems fine.
I called E-V, and they sent me a replacement pair of woofers, pure
junk. These sound far worse, than with the old ones (with holes). They are
poorly constructed, have a magnet that must be measured in grams :-),
and are made in Taiwan.
I talked to a technical type at E-V, who said that E-V hadn't made any
acoustic suspension speakers in 12 years, they just stocked something
to send to people who ordered replacements (after all, I didn't ask
for a QUALITY replacement (my words, not his :-).
So two questions: Has anyone had experience with rebuilding speaker
cones. I'm more interested in finding out if I should try to find
someone who can do it, rather than trying it myself (although it
may be fairly simple since its only the foam that is in bad shape.
Any suggestions for a good 10" woofer that would be compatible with
the EV14-A. It's a 2-way, but I don't remember the crossover frequency
offhand. How critical is the enclosure geometry in acoustic suspension
systems?
--
James Sterbenz Computer and Communications Research Center
Washington University in St. Louis 314-726-4203
INTERNET: jps@wucs1.wustl.edu
UUCP: wucs1!jps@uunet.uu.netmnw@trwrb.UUCP (Michael N. Washington) (08/02/88)
In article <904@wucs2.UUCP>, jps@wucs2.UUCP (James Sterbenz) writes: > > I've got a pair of Electro-Voice EV14-A speakers, purchased in 1974. > The woofers are 10" acoustic suspension type, and the ring of foam > which supports the paper cone has deteriorated very badly (i.e. holes). > The cone itself seems fine. > > So two questions: Has anyone had experience with rebuilding speaker > cones. I'm more interested in finding out if I should try to find > someone who can do it, rather than trying it myself (although it > may be fairly simple since its only the foam that is in bad shape. > > Any suggestions for a good 10" woofer that would be compatible with > the EV14-A. It's a 2-way, but I don't remember the crossover frequency > offhand. How critical is the enclosure geometry in acoustic suspension > systems? > James Sterbenz Computer and Communications Research Center > Washington University in St. Louis 314-726-4203 > INTERNET: jps@wucs1.wustl.edu > UUCP: wucs1!jps@uunet.uu.net I don't have Electro Voice speakers, but I too have an acoustic suspension speaker that the surround suspension had died. I tried to repair it, but it just kept tearing. Finally, I just pulled off all of the suspension foam. It plays, but not very well. My speaker is an Advent circa 1974. It too has a 10" woofer, but is built on a 12" frame, so this woofer may not fit your E-V's. Anyway, I wrote to Advent. They will sell me a woofer to replace my old one. Seems a shame since my woofer cone seems fine. It would be simple just to replace the foam, but there wouldn't be any MONEY in doing that. At any rate, I will order the woofer and replace it. Meanwhile, I have a perfectly good speaker without the foam surround, doing nothing. You may wish to check with Advent to see if they would sell you a woofer if it will fit your enclosure. They are in Illinois and are a subsidary of Jensen International. Address: Advent Division of Jensen 4138 North United Parkway Schiller Park, Illinois 60176 "Live Long and Prosper!" Michael N. Washington -- "Live Long and Prosper" Michael N. Washington -- "Live Long and Prosper" Michael N. Washington
rdp@atexrd.UUCP (Dick Pierce) (08/04/88)
In article <904@wucs2.UUCP> jps@wucs2.UUCP (James Sterbenz) writes: >I'm not sure about posting this to sci.electronics, but there isn't >a sci.electroacoustics :-), and I thought I might reach some of those >who don't read "wreck.audio" > >I've got a pair of Electro-Voice EV14-A speakers, purchased in 1974. >The woofers are 10" acoustic suspension type, and the ring of foam >which supports the paper cone has deteriorated very badly (i.e. holes). >The cone itself seems fine. > >I called E-V, and they sent me a replacement pair of woofers, pure >junk. These sound far worse, than with the old ones (with holes). They are >poorly constructed, have a magnet that must be measured in grams :-), >and are made in Taiwan. > >So two questions: Has anyone had experience with rebuilding speaker >cones. I'm more interested in finding out if I should try to find >someone who can do it, rather than trying it myself (although it >may be fairly simple since its only the foam that is in bad shape. > >Any suggestions for a good 10" woofer that would be compatible with >the EV14-A. It's a 2-way, but I don't remember the crossover frequency >offhand. How critical is the enclosure geometry in acoustic suspension >systems? > As the engineer in charge at Precision, I have had quite a bit of with reconing drivers. It is not a job that is easily done without the precision fictures necessary. Usually, the job is done in several steps: 1. After the old cone is removed and all the glue areas thoroughly cleaned, the voice coil is inserted into the gap with a jig that simultaneously centers it radially and axially in the gap Glue is applied to the vc and the basket where the spider is attached, and the spider is then put in place. 2. Glue is now applied to the voice coil where the cone attaches and to the periphery of the basket where the spider attaches. An assembly consisting of the cone, surround and tinsel leads is then lowered over the voice coil and clamped in place. 3. The voice coil leads are soldered to the tinsel leads, and the dust cap is glued in place. All of this requires the right adhesives and fixtures, and is not a simple home job. The alternative solution is to replace the woofer. In this case, indeed a good knowledge of the cabinet parameters is necessary to find the right replacements. Also a 10 inch 2-way system is really stretching the capabilities of both the woofer and the tweeter a bit much, especially given that EV undoubtedly used a paper cone in the woofer. Newer drivers have far better capabilities in this respect, so the system may need significant changes to work right. The end results, if done properly, may well be significantly better than what you originally started with, but it's not clear that its worth the effort. Incidentally, the deterioration you discovered is quite common amongst polyurthane foam surrounds from a variety of manufacturers. This is due to the fact that the kind of foam they use is conducive to mold and mildew growth, which simply eats the foam. Newer surrounds use an ether-based foam which is hostile to such growth, and is somewhat more UV resistant (making it somewhat longer living in cars). There is no visible or performance difference between the two (at least while both are intact :-)). -- Dick Pierce EPPS, Bedford, MA ----
al@qiclab.UUCP (Al Peterman) (08/05/88)
>In article <904@wucs2.UUCP>, jps@wucs2.UUCP (James Sterbenz) writes: >> >> So two questions: Has anyone had experience with rebuilding speaker >> cones. I'm more interested in finding out if I should try to find >> someone who can do it, rather than trying it myself (although it >> may be fairly simple since its only the foam that is in bad shape. >> There are many places that can recone speakers. I used to have torn and worn out speakers reconed all the time. In Minneapolis there is a company called Market Speaker that specializes in recones of decent quality speakers. Figure about $2 per inch of cone diameter ( a good 10 inch will be about $20) depending on the type of surround. I know there are other such operations in most major cities, ask at musical electronics dealers or look in the yellow pages. Seattle and Chicago have such companies, I don't know about your city. A complete recone will replace the surround, cone, voice coil, and suspension spider. You really have to do it all to get a properly centered job. If all else fails, you can purchase reconing supplies and try to do it yourself, but there are special jigs and weights that make the job much easier and more accurate that would be too expensive for a one time job. If you need information you could contact: Market Speaker 293 Snelling Avenue St. Paul, MN (612)-645-7174 -- Alan L. Peterman Aero Air Hillsboro, OR (503)-640-3711 wk (503)-684-1984 hm Airborne N33291 Cessna Cardinal RG Net !tektronix!(psu-cs,reed)!qiclab!al
del@Data-IO.COM (Erik Lindberg) (08/05/88)
> > I've got a pair of Electro-Voice EV14-A speakers, purchased in 1974. ... > cones. I'm more interested in finding out if I should try to find > someone who can do it, rather than trying it myself (although it ... > Any suggestions for a good 10" woofer that would be compatible with > the EV14-A. It's a 2-way, but I don't remember the crossover frequency As another user pointed out, simply replacing the foam surround at home will probably not result in anything that sounds good. I have had some speakers re-coned at Speakerlab, with good results. Cost was significant, though less than the cost of new speakers, and was worth it in this case because of the odd characteristics of the speakers. If you decide to replace the speakers with new units, you could very likely end up with a better sounding system at more expense and hassle. Speakerlab sells some high quality speakers and crossovers. They may be ale to match your boxes exactly, or provide both woofers and crossovers to go with them. They do a large volume of mail order business. They are certainly not the cheapest place in town for equivalent quality components, but in some cases it is worth while to pay a little extra for experience and technical expertise. They have reasonably technical people available for phone consultation. I would suggest that you call them and tell them your situation and get their recommendation on a course of action. -- del (Erik Lindberg) uw-beaver!tikal!pilchuck!del
del@Data-IO.COM (Erik Lindberg) (08/05/88)
<blush> OOPS! Forgot to include the phone number for Speakerlab in my previous posting, you probably don't know it right off the top of your head :-) Speakerlab 6307 Roosevelt Wy NE Seattle, WA (206) 523-2269 -- del (Erik Lindberg) uw-beaver!tikal!pilchuck!del
jps@wucs2.UUCP (James Sterbenz) (08/09/88)
In article <120@grace.atexrd.UUCP> rdp@grace.UUCP (Dick Pierce) writes: >In article <904@wucs2.UUCP> jps@wucs2.UUCP (James Sterbenz) writes: >>[question about deteriorating acoustic suspension cones] >[procecdure to recone] >Incidentally, the deterioration you discovered is quite common >amongst polyurthane foam surrounds from a variety of manufacturers. >This is due to the fact that the kind of foam they use is conducive >to mold and mildew growth, which simply eats the foam. Newer >surrounds use an ether-based foam which is hostile to such growth, >and is somewhat more UV resistant (making it somewhat longer living >in cars). There is no visible or performance difference between the >two (at least while both are intact :-)). Thanks, but a couple of follow-up questions: When did the ether-based foam come widely into use? I also have a pair of Genesis 3+ speakers (8 years old). These are not acoustic suspension, but have a foam-like support ring, although it seems more rigid than the Electro-Voice foam was. Is this likley to deteriorate in the next several years? Do you know of any way to protect the suspension ring (e.g. some sort of chemical to smear on the ring ... Armor-all is great stuff, but who knows what it'll do to your speakers :-) ). -- Teo Computer and Communications Research Center Washington University in St. Louis 314-726-4203 INTERNET: jps@wucs1.wustl.edu UUCP: wucs1!jps@uunet.uu.net