Repair FAQ
This Repair FAQ page is…
We are just getting this page started, but will post a couple items for now…
——————————————————–
Q: How big is my woofer?
A: Now, we can just hear some of you “pros” out there snickering, but this is actually a common question, and not really a bad one.*
Generally, woofers are “sized” by measuring the frame diameter. This can “get a little weird” when non-round shapes are used, but, generally, for round woofers, the size is rated as the following links show:
Image of 12″ woofer: http://praudio.com/site/wp-content/uploads/2010/02/woofer-diaexample-500-85.jpg
Larger image of 12″ woofer: http://praudio.com/site/wp-content/uploads/2010/02/woofer-diaexample-1024-90.jpg
* Attempts have been made in loudspeaker industry circles to categorize speaker size by diaphragm size, rather than frame size, because sometimes manufacturers will build a smaller cone than usual into a largish frame. A classic example is the old “Large Advent” speaker’s woofer, which was really a 10″ driver built into a 12″ frame. In the other direction, sometimes a large diaphragm is “crammed” onto a frame smaller than usual for such a diaphragm. Then there are dome type-drivers, where the whole point of the design is to have a smallish radiating element (the dome) for good dispersion of mid or high frequencies. But, especially in days past, most of these were built on frames quite a bit larger than the diaphragm: A 1″ dome tweeter might well be built on a 4″ diameter faceplate. But if the manufacturer called that unit a “4-inch dome tweeter”, without a picture or drawing, people could be VERY confused as to what it really was… Still, most woofers are categorized by the frame diameter (roughly), with special exceptions sometimes being made for ”oddball” designs like the Large Advent woofer. (It usually IS called a 10″ driver, despite it’s oversize 12″ frame.)
——————————————————–
Q: I’m confused. What are the correct designations for the dimensions of a woofer suspension?
A: Don’t feel bad. Most of the recone parts suppliers, not to mention “refoam kit” sellers, both on eBay and elsewhere, seem to be oblivious to loudspeaker parts makers’ industry standard designations. The most critical match, in most cases, is how the outside edge of the cone body matches up with the “inner crease” (or sometimes called “inner corner”) of the roll. Yet if you ask some eBay seller if their roll matches up with your cone, and furthermore ask them to give you the specific dimensions you need, not some platitude, well… Good Luck!! We have made up a drawing, showing the industry standard designations, which are simple and make sense (except for slight confusion if you are talking about the actual inside diameter of a voice coil at the same time you are talking about how that coil fits your cone.)
(Click image to enlarge)
(The drawing shows a “flat attachment” of the roll to the body, on the left side, and an “angle attachment” of the roll to the body, on the right side. No cone is made this way, we just wanted to condense everything into one drawing, similar to a drawing we saw on one of the cone manufacturers website.)
Further discussion, information on how to go about measuring Roll I.D., etc., accurately, and a picture of a woofer showing these measurements are here.
Paul can almost understand some bloke selling on eBay not knowing what’s what (though he doesn’t forgive them!) What on Earth is going on with most of the the recone parts suppliers, though, just defies comprehension…
——————————————————–
Q: Does PR Audio sell recone kits?
A: We don’t really sell recone “kits”, because in order to do so, we’d get into either:
1) Shipping glues that fall under various “hazardous substances” restrictions, and the time involved with the paperwork / meeting shippers’ and gov’t requirements (which would be reflected in your cost) just gets out of hand… Some of the proper adhesives are pretty specialized (esp. the high temperature glues, various treatments, etc.), and one can’t just run down to a hardware store to pick them up.
Or,
2) Selling pre-assembled cone-spider-coil assemblies. Someone like JBL can do this, because they only have a relative few models to cover, some with common parts, and, more important, they have jigs (or just extra structures, for that matter) that they can build the cone-spider-coil assemblies on. Since they use the same baskets for a lot of models, etc., they don’t have to have all that many jigs. But, for someone like us, we’d have to have a unique jig for literally hundreds if not thousands of different speaker (driver) designs that have been made in the last 50 years or so. And until we got one of each model in, we would likely NOT have all the information to fabricate a jig for it’s recone kit. One jig might handle several of JBL 12″ models, for example, but we’d probably have to have a shelf of jigs just for ALL the different 12″ designs JBL has had over the years. So, selling pre-assembled cone-spider-coil assemblies is generally not practical or cost effective, either. 
(Taken as a whole, in the speaker business, very few things are really “standardized.”)
There is also very definitely an “experience” factor, in reconing, and there are a lot of “little things” (which can have a big effect) to look out for. (We like to think our experience and attention to details are two of our strong points!)
——————————————————–
Q: Can we bring you a speaker and have you recone it while we wait?
(Sort of like taking your car to the tire store for new tires.)
A: Occasionally, simple repairs can be done in a short time, but a recone job “while you wait” is difficult at best, for a couple reasons. First, for some very well known / widely used speakers, such as the ElectroVoice EVM 15B (or L), or the JBL 2226H series, we keep parts in stock. But there are so many different drivers “out there”, that even with a large part of a 40′ x 64′ building devoted to speaker parts inventory and related items, the odds that we will have all the parts for your speaker(s) in stock are iffy at best. More important to the success and best functioning of your reconed speaker, it’s really best at a couple points in the assembly to give adhesives time to fully cure. In particular this means that about 3/4 of the way through, we set the unit(s) aside 10-12 hours (usually overnight). Then we come back and run an initial operational test: If ok the driver tests ok, then we finish up the driver & run a final, higher power test.
While a (formerly) large driver manufacturer such as Credence, who Paul used to work for, starting with a completed “structure”, can run a woofer down the production line in 1/2 hour or less, that’s not the full story: Even at Credence, we ended up rechecking all drivers with a final / higher power test, after an overnight “full cure” time.
If we stocked specific “kits” (preassembled coil / cone / spider) for all the models out there, the reconing time would be reduced, but we’d still want a few hours to do the job. And, we don’t even want to think about what size building we’d have to have, just to store all those kits! The cost of our inventory (some of which, like cones with foam rolls, would deteriorate with time), would be pretty forbidding, too. That would really drive up our costs, which would drive up our customers’ costs.
Note however that if you are within “driving distance” (50 miles? 100 miles?*) to drop your speakers off, get to meet us, etc., that is fine! Just set up an appointment, first, please. We have a FedEx online account, and the corresponding rates for “ground” or “home delivery” are not too bad, for up to medium-large size, medium weight packages. So, having us ship your reconed speakers back to you may be an option. (We’ll figure up a couple examples on shipping costs and add them here, soon.) We can also set up FedEx pickups for you to send us your speakers, in some cases, if that will help.
*We’ve had customers come from even further, or “bend” trip routes to come by, by considerably more, though of course that is not the norm!!)
——————————————————–
The above and much more information on driver repair and reconing is available on our Driver Reconing FAQ page.
——————————————————–
This page has useful information and tips regarding woofer and mid-bass edge / roll / surround replacement, what to look for, and what to watch out for.
More coming soon!
