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JBL Vintage Speaker Restoration Done Right by Simply Speakers

by August 03, 2009
JBL Pro III before

JBL Pro III before

There is an old axiom I love to live by, “if it ain’t broke, don’t fix it”. Just because your speakers are old, doesn’t mean they can’t still perform as good and sometimes better than the models that replace them from the very same company. Such was the case with a pair of JBL Pro III professional monitors I’ve had since my post-college days when I was a budding audiophile but not yet an Audioholic. These speakers are small and unobtrusive but they put out quite impressive sound for their size. They are also very efficient designs meaning they play “LOUD” with little applied amplifier power. Their cabinets are covered in rubber material and they have metal grills. The Pro IIIs are a front ported enclosure with a 5 ¼” treated paper woofer with foam surrounds and a 1” titanium dome tweeter. Although the speakers in all of my reference systems are superior in terms of bandwidth and overall sound quality, these little gems work great for portable audio applications when I travel. When I am not traveling with sound, I use them as my primary speakers for my desktop computer where I stream music from Pandora.com and Rhapsody.com while I write my articles for Audioholics.com.

Recently I’ve noticed they were simply not sounding as good as I remembered. The bass was weak and I heard a lot of buzzing emanating from the woofers. When I popped the grills off it was obvious what was going on. Dry rot. Before butyl rubber took over as the primary choice of woofer surrounds, most companies utilized foam. Foam is actually more efficient than butyl rubber but there are no free lunches. The problem with foam, especially in humid climates like Florida, is that they deteriorate over time. Considering I had these speakers for over a decade, it only makes sense that the inevitable would happen to my cherished little JBLs.

At this point I had two options:

  • Buy new speakers
  • Get these speakers reconditioned

control1pro.jpgI initially started down the path of the first option, searching JBL’s own website for a replacement to these speakers. What I found instead was a watered down version (Control 1 Pro) that appeared very similar but utilized a cheap ¾” mylar dome tweeter. I didn’t care for this option so I went to eBay and searched out the used market. I found a few pairs of Pro IIIs just like mine but noticed upon closer inspection some of the woofers had the dry rot problem as well. Basically even if I bought a good used one from a consumer, how long would it be until the woofers dry rotted on me again?

It was at this moment that I decided to pursue my second option. I did a Google search on refoaming kits and came across a company known as Simply Speakers. Not only did they offer refoaming kits but they also offered the option of mailing in your speakers to have their professional staff do it for you. Since I don’t have the steadiest hands (hence why I am an engineer and not a surgeon), I opted for having them restore my speakers for me. Instead of simply sending in the woofers, they insisted I send in both speakers fully assembled so they could inspect the crossovers and tweeters. As I was getting ready to ship them out, I realized their location was about a 1 hour drive from me so I opted to hand deliver them and meet the folks behind Simply Speakers.

What I didn’t realize until I stepped into their place was that I had dealt with them before. Back when I was in college I worked for a hifi shop called Cooper 4 Stereo where I assembled systems for clients, repaired electronics and installed gear in people’s homes. I used to frequent Simply Speakers to get vintage McIntosh woofers refoamed. They changed locations so I didn’t realize it was the same company.

SSstore3.JPG     SSstore4.JPG

Simply Speaker Storefront with fully restored vintage speakers from JBL, Cerwin Vega, Infinity and many others

I always admired the work they did, as did their customers whom in a way felt like their precious speakers were re-birthed after they were fully restored by Simply Speakers. Some people have an affinity for vintage speakers and electronics just like they do for cars. I totally understand that as I still have a place in my heart for old JBL speakers. After all the JBL LX-44s were considered my first truly high end speaker system that I owned and spent a summer working at Publix supermarkets when I was in high school to afford them. Why ditch something you're so fond of just because it needs a little tender loving care?

With that I handed off my Pro IIIs to the staff at Simply Speakers where I could instantly tell they were very serious about taking good care of them and restoring them to their original working condition. I got a good warm fuzzy from them and was excited to see and hear the end results.

I had a few special requests of them that went beyond simple refoaming.

  • Use a foam guard sealer on the new surrounds. This increases the surround life expectancy while also tightening up the response a bit to actually help improve the driver performance over its original condition.
  • Replace the electrolytic capacitor in series with the tweeter with an equivalent value polypropylene one. This decreases frequency response variations because the latter dielectric has tighter tolerances. Poly caps also last a lot longer as they aren’t as susceptible to rotting out like electrolytics. This is more critical for high frequencies so only the tweeter cap was replaced, not the electrolytic on the woofer.

Editorial Note on Foam Surrounds:
Simply Speakers utilizes a poly-ether based foam rubber material for their refoaming kits. This has a much longer life expectancy than the original foam used by the manufacturer which was a polyester based material. Simply Speakers also warranties their refoaming on home audio for 7 years and automotive for 1 year.

They had no problems with my request and asked to give them a couple of weeks to get these speakers fully restored. I left the JBL’s with them and proceeded to enjoy the 4th of July weekend with my family at the wonderful beaches in Clearwater, Florida. When I got back from my mini vacation, I received an email confirmation from Simply Speakers acknowledging the work being done and the return shipping address they would mail my speakers back to once the work was completed.

During the restoration phase, I asked them to send me some before and after pictures to monitor their progress along the way. This is not something they normally do for customers but I wanted to concisely document the process and show our readers what these guys were all about. About two weeks later I received an email (with photos upon my request) that the work was completed and that my speakers would be shipped back to me. I received my speakers the next day!

JBL Pro III  Woofer Foam.JPG       JBL Pro III New Foam.JPG

Dry rotted surrounds and nasty electrolytic cap in the tweeter HPF (left pic);
Restored woofers and new polypropylene caps being ready to installed (right pic)

JBL Pro III Woofers Foam Sealer Applied.JPG      JBL Pro III New Caps Installed.JPG

Foam sealant and new surrounds on the woofers (left pic);
Clean install of the new capacitors (right pic)

JBL Vintage Speaker Restoration Continued

When my speakers arrived back, they also included an itemized list of services performed in the bill of receipt.


So for under $90, I got my pair of vintage JBL speakers fully restored to factory brand new condition, perhaps a little bit better. They definitely looked much cleaner and newer thanks to the courtesy cleaning of the cabinets they performed prior to shipping them back to me. Before I brought my speakers to Simply Speakers for restoration, I pulled a nearfield measurement. I wanted to compare the before and after response which is illustrated below.


JBL Pro III before (purple trace) /after (brown trace) Frequency response
(mic 6” from acoustics center, 1/6th octave smoothing)

Granted this wasn’t a very precise measurement as I couldn’t assure the mic was in the exact same position both times but it does show a clear improvement in bass response below 100Hz after the fix. The high frequency response looks slightly elevated which could be a result of the lower ESR capacitor that is now used in the tweeters HPF.

Wrap Up

JBL Pro III Completed.JPGIt was time to hook these babies back up and hear the end results. I did the listening evaluation prior to my measurements so I could eliminate any bias based on the before and after results. I pulled up my favorite artists on Pandora and let it rip. I immediately noticed the much tighter and cleaner bass response the JBL Pro III’s were reproducing. The speakers played loud and clear and I heard no hint of woofer buzz or distress like I had before. I subjectively felt the top end may have been somewhat more lively but without doing a direct A/B comparison there was no way of telling.

Overall I was very pleased with the results. Restoring my JBL Pro III’s gave me a new appreciation for how good these little speakers really are. We tend to get so caught up in upgrading our A/V gear to the latest and greatest, but sometimes it pays to hang on to something that was well engineered. Simply Speakers did a first rate job from start to finish. They treated me with utmost respect and courtesy despite this was a low wage job for them. They proved to me that it’s hip to be vintage. If you’ve got some old speakers lying around that you’re fond of in need of a little TLC, I highly recommend Simply Speakers as your #1 choice for the task.

About Simply Speakers
Simply Speakers was formed in 1992 as a result of a need in our area of Florida for a factory authorized loudspeaker service center. We saw potential to gather a national and worldwide audience with advertising in national magazines like Stereo Review, Audio and Popular Science. Over time, we have built a loyal following for our customers who wish to maintain their vintage audio speakers. We offer services to electronic repair centers and consumers from our area and around the world. Our specialties include speaker refoaming (edge replacement), speaker reconing (full rebuild, including voice coil, spider, cone, surround and dust cap), replacement woofers, midranges, tweeters, horns, and diaphragms. Finally, we sell a line of replacement foam edge kits, recone kits, grill fabrics, and accessories.


About the author:
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Gene manages this organization, establishes relations with manufacturers and keeps Audioholics a well oiled machine. His goal is to educate about home theater and develop more standards in the industry to eliminate consumer confusion clouded by industry snake oil.

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