JoeTaylor

Hi Andy,

What a great write up and beautiful speakers. Looks like it worked out great.

4 ohm vs. 2 ohm speakers: In a speaker/amplifier combination, the reason for matching the speakers' impedance to the amp's impedance is to maximize power transfer between the two. A miss-match only reduces the power transfered to the speaker.

1988 OEM speakers: The speakers I removed or looked at in my car were all ITT OEM speakers at 4 ohm resistance. So when I was expecting 2 ohm speakers, there were none. Though each pair, door and rear speakers, were connected in parallel, for 2 ohms. See photos below.

Still, I think speaker technology has marched ahead and newer, aftermarket speakers will sound much better than the older ones.

VTY
Joe Taylor

meracus

2 ohm impedance is the worst thing that could happen to your auto sound ......... yet everyone braggs about it

Andy E.

Bose boasts about their 2-ohm component systems that come standard in the Infinity. Go figure...

Andy E.

Thanks Joe. Had it not been for your write-up, I would not have stumbled upon the JBL speakers.

Heads up: From what I've been able to gather from the PET parts program, the service manual diags as well as other sources, the 10-speaker sound system with the 2-ohm/3-ohm/4-ohm speakers was available as standard equipment on all 1989+ models. The 10-speaker sound system may have also been available in 1988 as an option only; hence your all-4-ohm 8-speaker system.

Whew, try saying that in rapid succession....

JoeTaylor

Hi Andy,

You're welcome Andy.

By the way, 2-ohm, 4-ohm or 8-ohm speakers, it doesnt matter as long as it matches the internal impedance of the amplifier for max power transfer. Its not a quality issue as Andy can attest to.

Joe

meracus

2 ohm speaker are low impedance , the lower the impedance the harder it is to drive , and they say nominal 2 ohm , wonder how the speaker behaves at 60-100 hz probably 1 ohm , this is very close to shorting , the amp will spur out more power but it will enter high thd teritory
looking at the specs jbl claims 94 db efficiency ( amazing ) but its not going to be at 1 metre off axis
shame there is a shortage of proper adaptor rings /mounting plates for cars ,usually the ones available look very childish ie plastic silver rings and gaudy designs aimed at the 17 years old headbanger , otherwise the world of audio is festooned with excellent drive units that would kill any car hifi known to man for 1/4 of the price

Andy E.

One strange thing I found is how JBL placed a 4-ohm logo on the bottom left-hand corner of the box with a check mark next to it. This logo seems to imply to the consumer that it is 4-ohm compatible. What gives if this is a 2-ohm impedance rated unit?

meracus

the best speaker i tried and bought by the way are morel . they also look better than stock

WallyP

Really odd - the GTO-628 specs clearly say that these are 2-Ohm speakers, yet in the description it says, "True Four Ohm – GTO Series speakers can be safely driven by any head unit. "

They are $65 here - http://www.onlinecarstereo.com/CarAu...roductID=20784 - also available at about the same price at several different vendors.

$61.98 w/free shipping on eBay - http://cgi.ebay.com/JBL-GTO-628-CAR-...QQcmdZViewItem

Andy E.

Wally, thanks for pointing out the huge savings!

cjn928

I just did this set up today,Best buy around the corner had them.
NICE! thanks Andy!
I was going to send them out for reconing it was going to cost at least $120.
good upgrade from stock.

Andy E.

Glad it worked out for you CJ. The preparation on the old housings requires a lot of patience and skill with the Dremel.

You may notice that the highs are now slightly more pronounced with these 2-ways than before. I wonder if simply cutting the wires running to the built-in tweeters will eliminate some of this and resort to using them solely as woofers.

The elaborate "mil-spec" Porsche crossovers have been retained for the mid-speakers and tweeters on the rear shelves (fenders). Can anybody shed light on this subject?

cjn928

I thought about that, but there is a button on the tweeter that reads: 0db or -3db
At the store the rep installed the same speakers in a 1993 gts and replaced the doors with 5 1/4" pioneers(ts a1372r).The same dremel procedure required for them too, something to think about for the future,I have had enough 'dremeling' for now.
I also used the x-overs from the original speakers.
5 years ago I had a 86.5 that seemed easier to up grade the sound system.
with this car (1990 s4 from the original owner) seemed to be more let's say different.

Andy E.

CJ, after installing the JBL's I also decided to get at the door speakers. I had looked at the Pioneers and even brought home a set but they wouldn't fit due to the massive magnets. They probably would have fit but definitely needed some sheet metal trimming of the door panel; something I wasn't interested in doing.

Finally, I took home a set of Alpine SPS-400 4" speakers in a 4-ohm configuration. The fit was tight but all went well without the requirement for spacers.

Strat_928

One note - I just bought the Infinity 6/5 CF series to do the same thing in my 83, and the specs above are REMARKABLY similar. So they are an option in 2011. 55.00 from Amazon but you have to buy the grills separate. Still a good deal for reference series. I am going to use a Dremel etc to try and cut the old ones out and drop in the Infinitys. You need a 5 in hole for the speakers to fit in flush. I have 1 in extender rings, but they don;t really fit the speaker and I am going to try and get them in there without it. They come with a 1/8 in adapter ring and I will be top mounting them, so i am hoping I won't need the extenders anyway. I will let you know if it works or not. If I don't get back here to post just PM me if interested. I will try to take some pics as well.