QuestionQUESTION: Hey Cleggsan you briefly mentioned in your profile Loudspeakers do you happen to know anything about yorkville EF508s they might be CDN im not really sure. either way my horn started cutting in and out this morning and its something i'd like to fix myself if at all possible? could the driver be blown? or could something be loose i have it all taken apart and it looks pretty connected im not exactly sure what i am looking for. i noticed when i boosted the power on the amp it would come back for 5- 30 seconds? if this is totally irrelevant to anything you've worked with sorry for bothering you, but if you have any knowledge of loudspeaker main boards/crossover coils etc. or know anybody who does it would be greatly appreciated.
Thanks!
ANSWER: Yes, I know about them. Good merchandise.
The symptoms you describe are exactly like when the voice coil is going bad. It is almost always from overdrive or overpowering the system.
These speakers are sensitive to too much audio power, especially the tweeter which is only a 1.4" voice coil and rated for only about 100w. The woofer is a 15 inch unit driven directly into its 8 ohm voice coil. It is not a horn design, by the way, as they claim, as the conical reflex port above the 15 incher is not long enough or wide enough to produce any real horn effect; what it does though, is aim the upper base forward a little and provide some acoustic loading for the Q factor of the woofer parameters.
So, you could have an intermittent open in either voice coil. The 15" is easy to detect by putting an ohmmeter on the connections to the voice coil and manually pumping the cone. Doing so will excite the coil connections and you will likely see the continuity go in and out. Sometimes the problem is a break or melted solder connection of the flex wires that go between the binding post and the coil (at the spider connection to the cone). Often it can be resoldered.
The tweeter unit is more difficult to diagnose because of its smaller size and inability to easily see down into the works. But the principle is the same. If the tweeter only is open then you would hear the sound cutting in and out only for the high frequencies, of course.
If you are located in a large city there are usually loudspeaker repair shops that can replace the voice coil.
These speaker systems are made in Canada and I think the company can supply you with replacement parts if necessary. Don't know the pricing but a 15" woofer of this variety could cost $$$$$.
Here are your reference pages:
http://www.yorkville.com/products.asp?type=71&cat=31&id=13
and
http://www.yorkville.com/downloads/quickparts/qp-ef508-all.pdf
I don't know what their return policy is or if they will replace free of charge; but you should call them and find out.
My guess is, after considering the above comments while typing them out is: The woofer voice coil has a broken wire or it has come loose from the coil form and needs to be repaired. The best strategy is, if the manufacturer cannot replace it, to have a speaker repair shop fix it up for you. Cost should be nominal even if you have to ship it off to their lab. For example, there is a good repair shop in Atlanta, GA and most big cities would have a similar shop.
Let me know if you need more.
PS: I notice they have a recone kit for the 15" woofer that you can find on their parts list download. It may be a way of repairing if the 15" inch unit is the problem. Cost would be much less than a whole new driver unit.
---------- FOLLOW-UP ----------
QUESTION: the voice coil going from to much audio output sounds very reasonable actually that's probably what is happening. I live in a fairly large center with general music stores, but i think I'm looking at around 60 just for them to open it up and look inside a bit. the 15 inch woofer still works just fine its just my mid to highs that cut in and out on this speaker could you suggest any places to look for bad wires/connections? I will take a look around town to see if there is maybe a specialty shop, and i have contacted the company as well thank you very much for your wise advice.
ANSWER: Do you have a vom or ohmmeter? You can check the wiring out in a flash.
But, I am nearly certain the problem is an open voice coil in the woofer (or tweeter or both). And the best strategy under this case is to pull the 15 incher out and take just the driver into a repair shop (or obtain the recone kit from the manufacturer). Checking the woofer (once out of the box) is a 30 second test!
You did not give me your location, but maybe a possible solution is to find someone who can repair the unit (call them) and ship it off to them.
http://www.speakerdoctor.com/
Above is an example of the kind of service you are looking for.
---------- FOLLOW-UP ----------
QUESTION: hey no i don't have a vom or ohmmeter, but i happen to know a few electricians would they have on handy? right now i have the woofer out Im not sure what you mean by its driver? should i just take the woofer in without any wires attached? I am in sask. canada there are music shops like b-sharp music/long and mcquade that encompass all instruments, but i will look out for a specialty shop. the horn seems to be attached to the cabinet with some sort of glue though? so the wires going up to it are a little harder to check but they feel plugged in.
Answer
Loudspeaker Exploded
You must find a shop that does cone and voice coil repairs.
Yes, take the driver in by itself. They do not need any connecting wires. The speaker driver unit is a stand alone device.
While you have it out, just gently push on the cone from both sides so the force is uniform and see if you hear any rubbing sound when the cone goes in and out. If so, the voice coil is probably damaged. The voice coil is attached to the cone and is fashioned such that it is surrounded by the big magnet on the back side of the basket of the driver.
See the attached exploded view of a loudspeaker so you can understand the parts of it. The voice coil is attached at the apex of the cone and the spider and is embedded into the magnetic gap.
The horn is part of the cabinet construction; it has nothing to do with the electronics; it is woodwork only.
So, look for a firm that does loudspeaker repair, cone replacement or voice coil repair. An ordinary music shop, tv or audio repair shop will not have any understanding or tools/parts for this kind of work. Just google for "loudspeaker repair service" in your town or area. If they do not have on in SASK you may have to ship the driver to a place in another city. Or, if you contact the manufacturer they may have such repair services.
All the best.
