Best resources for self-teaching speaker repair?

[econeditor]

Through some fault of my own, I have recently acquired several pairs of speakers--Polk 7b's, Ohm K2's, and EPI T/E 100's--none of which sound quite right. Nothing is audibly not working, but they each sound less dynamic/more muddled than I think they are supposed to sound. It's probably time for me to teach myself how to diagnose and fix these puppies up. I know there is a lot of information on the internet on how to do so, so much so that I'm not quite sure where to begin. I'd appreciate any suggestions or pointers on the best videos/tutorials on the basics of speaker repair, especially for a newb such as myself.

 

[rickb119]

If none of them sound right, I'd first question everything else (source, amp, IC's and speaker cables). Beyond that, the next logical step would be to recap the speakers. Several how to video's out there, and a veritable plethora of different caps available, ranging in price from to cheap to .

What amp are you using?

 

[econeditor]

Thanks! I've got a NAD 3020b integrated amp, and an Exposure 2010s power amp, and have run speakers off both. The NAD itself could probably use some reconditioning, but the reason why I'm looking at the speakers is that I also have a pair of OLAs that sound reasonable with my set-up.

Would love pointers to good how-to videos on recapping.

 

[C Hart]

Recapping is very easy. Just pul the woofer, find the crossover inside, note the capacitor values, buy new ones from Parts Express or wherever, clip out the old and solder the new ones to the existing connections. I am pretty bad at soldering but manage to get clean connections in probably a dozen speakers over the past year or two since I started. I would start with the EPIs. I don't have that model but I believe it's just one 10uF cap, same as my 100Vs.

 

[rickb119]

Google *recapping vintage speakers*. That pulls up several videos, as well as many AK threads on recapping. Recapping is pretty easy, if you know how to solder. If not, it's not hard to learn, although it does take a little practice. Amazon has several cheap irons and kits (includes solder) that would probably suffice. Add some small gauge, solid core wire, and start learning. (Probably some how to solder videos out there too.)

Everyone has their own opinions as to which caps to use. For inexpensive speakers, use (relatively) inexpensive caps. Many use Dayton's (Parts Express), although I don't care for them. I'd probably go for something like the Clarity CSA/ESA 250v. Or, for a little less $, the Clarity PX 250v. If you can't find the right value, caps are additive in parallel. I.e., a 3uf and a .5uf = 3.5uf (when connected in parallel).
https://www.partsconnexion.com/claritycap-film-capacitors.html

Here's a little *light* reading of one persons opinions of different caps. Again, some are very pricey.
https://www.humblehomemadehifi.com/Cap.html

 

[macyjrm]

YouTube is your friend. Use the search function to seek vids on speaker repair. In fact look for vids specific to what you want to repair.

 

[C Hart]

Regarding quality and audibility, I can't hear the difference between two properly functioning capacitors of the same rating. Also, speaker manufacturers used the cheapest commodity non-polar electrolytic caps in most speakers, and certainly in the EPIs and the Ohms you have. They get old and go out of value and any new brand/model is a big improvement. Unless you have a real golden ear, I recommend starting with inexpensive audio quality caps such as Daytons.

 

[RTally]

I would start with the EPI speakers. They are the simplest to work on. I suggest searching on each speaker to see what can be done with them. The Polks have many mods (some simple, some not) in addition to the requisite recapping.

More than likely, if the speakers sound muffled, they need to be recapped. If the original electrolytic caps are still installed in vintage speakers, they should be replaced. It makes little sense to test because most do not have the requisite test equipment to check capacitance value and ESR at audio frequencies. Since the caps need to be removed to test, might just as well install new ones.

I prefer to recap one speaker and then A/B test it side-by-side against the other, unrecapped speaker. This will help with determining if the recap was successful and worthwhile.

The EPI and Polk woofers should have the magnets epoxied in place to avoid magnet shift. The Polks are notorious for this. And it is recommended for the the EPI woofers, too.

 

[RTally]

Also, it is sometimes informative to test the frequency response of speakers, before and after recapping.

I play noise through the speakers and use a phone app (Decibel X) to measure the frequency response. Pink and white noise files are easy to find on the web. The phone apps are a simple way to see what is going on. It is a rough tool with limited accuracy, but fine for seat-of-the-pants testing.

For the really muffled sounding speakers I often see a very noticeable rolloff or step decrease in the higher frequencies that is flattened out after recapping. The difference is more noticeable when testing the speakers side-by-side, one recapped, one original.

 

[econeditor]

I would start with the EPI speakers. They are the simplest to work on. I suggest searching on each speaker to see what can be done with them. The Polks have many mods (some simple, some not) in addition to the requisite recapping.

Thanks! Of the three, the EPIs are probably in the best shape, though still would likely benefit from recapping; and are a good pair to experiment on since they're the ones I paid nothing for.

 

[RTally]

Thanks! Of the three, the EPIs are probably in the best shape, though still would likely benefit from recapping; and are a good pair to experiment on since they're the ones I paid nothing for.

I have 5 different models of EPI / Epicure speakers. They all needed to be recapped 'cuz they used inexpensive caps back then. The T/E are slightly newer than mine, but I am sure that similar caps were used.

As long as you can solder, they are simple to recap.