Andy E.

After reading Joe Taylor's reply post to JCP1990S4's thread about the everpresent problem with the 2-ohm rear speakers, I decided to tackle the job myself and restore my stereo's dignity. After all, at 18 years running the old lady deserved a refresh. https://rennlist.com/forums/928-foru...-speakers.html

I consulted Best Buy's website for the Pioneer 4-ohm units that Joe recommended. I knew that a 4-ohm speaker probably wouldn't sound as good as the original 2-ohm units but my choices were either to re-cone the originals or to go with new. I also wanted to keep the factory stock Porsche CD-2 head unit and matching amp with no visible signs of speaker enhancement or modifications (ex: buldging speaker grilles/logos, cumbersome boxes, bazookas, etc...).

As I scanned Best Buy's website, I came across the JBL Grand Touring series GT0-628 6.5'' 2-way speakers. I clicked on the specifications tab to verify if the mounting depth would be an issue and lo & behold, I saw the 2-ohm impedance rating!! (Wally P, I told you that I'd find them one day!!)

I picked them up on Saturday and using my Dremel with both the cut-off wheel as well as the large milling attachments, they fit perfectly into the stock housings and grilles! Here's Best Buy's website showing the GTO-628: http://www.bestbuy.ca/catalog/prodde...07&catid=20114

The install was a success although as one member had mentioned that over 75% of the old speaker housing must be whittled away using the Dremel in order to fit the new speakers within. Much patience is required while doing this procedure as it's very easy to remove too much of the old housing material and be stuck with a system that doesn't work. Here are some pictures that I snapped along the way. Sorry for the lo-res as they were taken with my cell phone.

First picture shows the final look of the speaker housing/basket after the milling job:

Andy E.

This picture shows the back-side of the speaker nestled within the housing:

Andy E.

Frontal view of JBL onto ring:

Andy E.

Using screws provided with speakers, they're screwed into the housing ring where they get cut as flush to the ring as possible:

Andy E.

The trimmed screws are then touched up using a black touch-up paint applicator:

Andy E.

Snapping oem speaker grilles back on to check fit and finish:

Marine Blue

Nice write up and nice find on the speakers. Did you have to modify any of the speaker/car wiring to install the speakers?

Another question, are new housings readily available so stock speakers can be reinstalled at a later date?

How do the new speakers sound compared to the previous?

utjmac

Great write up! I'm sure I'll need this solution once I replace the Blaupunkt low power tape player that's installed now. How'd they sound once hooked up?

Andy E.

Thanks guys. The wiring was untouched and all the oem plugs were saved as I did manage to retain the crossovers that were screwed into the back of the old speakers. They were wrapped in a fire-retardant heat-resistant ventilated sheath and tucked into the panel void directly below the speaker.

The speaker housing and loudspeaker itself are molded into one unit and cannot be purchased separately. The speakers must be sacrificed (to be performed while playing a well-known African ritual theme song) and the curved housings (baskets) retained so that the new speakers can be re-fitted.

I had read all the older posts about overmodding on the highs and I was concerned about retaining the tweeters on the new units. If I had cut out the old tweeters and mids, I would have lost some of the crisp sound that's associated with a component system like ours. In the end, I kept everything including the tweeters on the new JBL's. The sound is great although if you're expecting bass as in the case with a subwoofer, you'll be greatly disappointed.

At the same time, I swapped out the door speakers with some Alpine SPS-400 4'' 4-ohm units. Yes, you read right, the door speakers are in fact rated at 4-ohms. Our systems have a mish-mash of 2-ohm, 3-ohm & 4-ohm speakers which makes it a car stereo shop installer's nightmare. The last shop I went to didn't even want to be bothered and quoted me an entirely new system including head unit, amp and speakers. "Too much trouble.." he said.

The combined sound of both the JBL's as well as the Alpines is excellent.

Bill Ball

You might try some experiments with sealing/baffle materials in the cavity behind the new JBLs to improve bass response. I had some success by stuffing the area pretty tight with polyester (available from crafts stores like Micheals) when I did a mod like yours. Or some large pipe insulation from Home Depot/Lowes can be used to create a seal between the inner and outer walls. Not all speakers respond well to this. Some MB Quarts I used did, while JL Audio woofers I tried did not.

Andy E.

Unfortunately, the Best Buy link expired so I've included the technical specs of the JBL speakers. The speakers were purchased for $129.99 CDN which should amount to something like $25 US.

Marine Blue

Thanks Andy.

Are the modifications you made to the new speaker housing or the existing speaker housing?

Andy E.

Actually Bill, I was thinking of Dynamatting that same void behind the speaker in hopes of extracting every last decibel of good sound that this system has to offer. I'll try some closed-cell pipe insulation first as Dynamat doesn't come cheap.

Afshin, the speaker housings that I refer to are always the old ones. The new speakers are traditionally mfd using a metal type of basket as opposed to the existing units which are made from a dense molded glass-fibre type of plastic.

Bill Ball

The idea is to try to make a sealed chamber or close to it (small port) in the large open cavity behind the woofer. I don't know how you'd do that with Dynamat. Gobs of polyester stuffed tight seemed to work better than the pipe insulation tube for creating a seal in here. Some people have filled the area with aeresol foam inside large trash bags suffed down in there, which also reduces tire noise from the rear wheels. That could be hard to reverse but could be much more effective.

Nice job on cutting out the stock speaker to use as mounting rings. When I did this with my Dremel, it came out a lot cruder.

Andy E.

Bill, If I was to use a thick foam ring that I could sandwich in between both panel walls, would I then need to Dynamat or "insulate" the exposed metal panel in back? In other words, should the exposed metal panel become insulated to improve acoustics?