Another Recapping Project: Canton Ergo 22DC Speakers

Canton Ergo 22DC speakers and SVS 3000 Micro subwoofer.

Do you collect vintage audio gear? Or maybe you just have some stuff you've been using for years and it seems to work just fine. Over all the years you've been using that gear, the electrolytic caps have been slowly degrading, maybe doing the same to the sound, but so slowly you haven't noticed. If the gear is more than 20 years old, it's a good idea to replace all the electrolytic capacitors. Yes, even in speakers. Most speakers have at least one nonpolar electrolytic capacitor in the crossover. If you're not sure, open it up and take a look.

My brother recently gave me a pair of Canton Ergo 22DC speakers that look and sound great, but they are over 20 years old. I opened one of the speakers up and found two 12 uF and one 1000 uF nonpolar electrolytic caps. One of the 12 uF caps measured poorly on my LCR meter. I checked with Canton to see if I could buy replacements from them and the answer was a polite "no- they are no longer available". 

I did some searching and was unable to locate 12 and 1000 uF caps that matched the original part's 5% tolerance. However, I found 10% tolerance parts replacements at Madisound Speaker Components. The new parts are made by a company in Taiwan called MDL and are specifically for audio, whatever that entails. The original parts were rated for 23VAC (I know, weird, right?) and the new ones for 100V. It's OK to go up in voltage, but don't go down! They should last another 20 years.

I checked the new caps with an LCR meter and it showed the 12 uF caps to be 11.6 uF with ESR of  0.06 Ohms at 10 kHz, and the 1000 uF caps read about 991 uF at 100 Hz with <0.1 Ohm ESR, so all were within the 5% tolerance of the original parts.

If you're ever thinking about recapping an amplifier or other piece of gear, and not sure you have the skills, try recapping speakers first. It's pretty easy and hard to mess up!

If you can't find nonpolar capacitors that match the capacitance in your speaker, you can always make a non polar cap by connecting two polar electrolytic caps back to back. For example, if you need a 5 uF non polar cap and can't find one, get two 10 uF polarized caps and wire them like this:

You can connect the caps either way: + to + or - to -. The final value is 1/2 of each cap's value (use the same value for both!). Final voltage rating is the same as each cap's rating- if you use 50V caps, the nonpolar cap will be a 50V cap.

Surgery

In most speakers, you can get at the crossover by removing the bass driver. Just figure out how to take off the grilles without damaging the speaker cabinet's finish and you're half-way there. In the Cantons, the little logo badge at the bottom front pulls out revealing a spot where you can get your fingers under the perforated steel grille to lift it off the speaker.

The patient, prepped and ready for surgery.

Remove the logo badge and the grille.

Take out the woofer- Torx #15 tool required for this speaker.

The stuffing, removed from inside the speaker

The crossover board, held in place by the nuts on the screws that pass through the inductors.

The crossover out of the box- no need to disconnect either the drivers or the input terminals.

I used a desoldering pump and a soldering iron with a large tip to remove the old capacitors, inserted the new ones and soldered them down, and finally clipped off the leads. You don't have to worry about polarity with these caps!

The three new capacitors soldered in and ready to reassemble. Bolt the crossover back in place, replace the stuffing (very important!), screw the bass driver down, vacuum the fuzz off the front panel, and replace the grille.

The total time required, start to finish, was about 15 minutes for one speaker. The new caps cost about $15 per speaker. As long as the adhesives in the drivers hold out, and I don't do anything stupid with the amplifier driving them, they should last another 20 years.

Like Radiohead says, "Everything in its right place..."