February 2011

Factory Tour: Orange Country California Speaker Repair
Article By Jeff Poth

  A couple years ago, I had a great Craigslist find- JBL SR4725 PA speakers. These house a 2226h woofer and a 2426h compression driver, on a 2370 horn. They were rather inexpensive, I believe $100 or $150, with the caveat that the compression drivers had blown diaphragms. This was an easy sell- MSRP for the raw drivers is on the order of $400/per. These are serious woofers and compression drivers. Upon testing, the titanium diaphragms of the 2426h were definitely blown, and needed replacement. Being in Southern California, I am fairly local to OC Speaker repair, so spoke to their manager on duty and scheduled a brief tour. As you, my faithful readers, remember, I'm something of a repairer myself (see DIY article here), though not in any commercial way, and thus was very interested to see the facility and what sort of toys they have.

OC speaker is one of the largest speaker re-coning facilities in the world, and has a large inventory of loudspeaker drivers, parts, and accessories. They are authorized dealers for JBL and Eminence (and others), and authorized service center for most major brands of loudspeaker. They are in a pretty decent sized facility, at 8000 square feet, nestled in a nice little industrial park in Garden Grove, CA. This is a family owned operation, with the Sunda clan at the helm, and has been in operation since 1968.

Upon entry to the facility, I poked around the showroom, The showroom was well-stocked, but only reflected a small selection of their inventory. Very cool stuff, and I loved the wall of woofers. These are "Real" woofers, not the car audio nonsense from Best Buy. Big motors, high power handling, high sensitivity, big boxes.

On To The Inside Scoop
I introduced myself, and was given a tour with Bryan, one of the owners. We moseyed on into the back, where the shipping, receiving, and final speaker assembly (putting it back together once you've fixed a woofer) took place. A lot of speakers move through this place!

There is an energizer for recharging AlNiCo woofers. The repair article has a little more information. Essentially, overdriven AlNiCo woofers tend to lose magnetic strength. This requires recharging, and the pic below is the machine that performs this service. It can be a major issue, as much as 3dB sensitivity can be lost.

There is a heck of a lot of inventory, with a huge number of completed drivers on the shelves, as well as cone, dustcap, diaphragm, and voicecoil assemblies. If it is a loudspeaker, they likely have the parts that fit, even if the factory parts are unavailable.

No shortage of parts here, eh? And they also have a number of jigs assembled to allow custom fabrication when the need is there. Most loudspeakers use fairly common/similar parts, so adaptation is usually fairly close to the original. Some exceptions exist, naturally, like woofers with heavy coatings (JBL's coated woofers come to mind, Hartleys too). Shown is a jig for sizing/shaping dustcaps:

Basic Woofer Anatomy
A typical loudspeaker is made of a frame, magnet assembly, cone, surround, spider, voice coil, voicecoil former, and dustcap. The surround is the suspension component visible from the front of the driver, attaching the cone to the frame. The role of this is primarily to keep the cone centered in the X and Y axes, (imagine the cone tilting) and seal the enclosure volume rather than leaving a gap around the edge of the woofer. Most surrounds provide only very little restoring force, until the cone is at its excursion limits. The spider provides most of the centering force in the Z-axis (woofer stroke, the in-out motion), and looks like a folded concentric ring of cloth. The voicecoil is the wound copper (or aluminum, or copper-clad aluminum) around the voicecoil former (think toilet paper tube).

Work Area
All of these parts have to be assembled, naturally, so there's a dedicated workshop space. Don't mind the mess- it's a dirty job. I was able to spend a little time observing, caution and compressed air are used to ensure that everything comes out squeaky clean. There are appropriate signal generation and electrical testing abilities in addition to skilled techs, who made the job look easy (not a shocker, when you've done thousands you'd better be good!).

That's All!
They did a great job of replacing my 2426h diaphragms per JBL spec'ed procedure, and I left having seen more woofers than I've ever seen in my life. A very fun trip for yours truly, and a great facility. I can wholeheartedly recommend their services, and a friendly staff to boot.

Orange County Speaker
12141 Mariners Way
Garden Grove, CA 92843

Voice: (800) 897-8373
Website: www.speakerrepair.com