2 ohm speakers - trial

[secondchance]

I found availability of aftermarket 6.5" (rear) and 3.5" 2 ohm speakers. And, naturally, had to see if replacement resulted in better performance.
So, I ordered a pair of PowerBass OE652 (2 ohm) and JBL GX328 (2.3 ohm).
https://powerbassusa.com/us/en/produ...65-full-range/
https://www.bestbuy.com/site/jbl-gx-...?skuId=6283624

6.5s arrived first. So, removed passenger side, rear speaker assembly and replaced OEM speaker with PowerBass unit. No modification was necessary and new unit dropped right in.

I turned off my sub, adjusted fader to rear only and used balance to compare OEM vs. replacement. End result - 27 year old OEM Bose sounded louder and better reproduced mid-range and low - much richer sound compared to replacement unit.

I thorized speaker enclosure voluum and port tuning optimized for Bose unit are responsible for higher quality of sound especially at low frequency range.

I have not yet tried front speaker yet. Maybe, I won't even waste time trying it out. Namely, since fronts with 3.5" is challenging even more for the fronts and careful design in volume and tuned port done by Bose most likely cannot be beat.

It was worth trying but in the end, my assumption 10 years ago, despite all negative sentiments over OEM system, within the restraint of space for good size speakers (especially up front), careful tuning of Bose is tough to beat.

I remember Chevrolet/Bose marketing of new for 84 Bose system later enhanced and labeled as Bose Gold, with EQ being optimized for Corvette interior and all that. Maybe be this is true. What I know for certain after this trial is by carefully designing air volume behind the speaker and tuned port, Bose successfully optimized sound level and successfully increased low frequency production despite relatively tiny/small speakers. However, in my opinion, what is lacking, especially if you opted for exhaust headers and straight though exhaust, is sound volume. Best way to counter this is 1997 to 2002 Cadillac Bose 100W amplifiers. C5 Corvette Bose amps are also 100W but has more wires/pins at the connector and may require sorting out wiring at the connector. Cadillac Bose amps have same pins and are direct plug in substitution. I am running Cadillac 100W amps front and rear for about a year and have not noticed any ill effect. What it did was increase the volume level. I believe higher wattage amp running at lower volume (compared to lower wattage at higher volume) reduces distortion.

One additional mod to OEM speakers were Elmer's glue diluted with equal part water and 2-3 coats of mixture. This added additional stiffness to OEM paper cones resulting in more tight sound. Just be sure to dry the speaker thoroughly before turning them on.

In summary, we have viable substitute speakers if and when we blow Bose speakers and cannot find clean/low mile replacement. However, hold on to your OEM speakers (perhaps strengthened with Elmer's glue - homemade composite) and avoid unnecessary expenditure like I did.

Lastly, if not committed to keeping completely stock, subwoofer/subwoofers addition definitely adds richness especially when playing more recent vintage recordings with low frequency deep bass.
https://www.zr1.net/forum/showthread.php?t=26010

[Matt B]

That's an interesting approach. What's the impedance of the OEM chassis? Another thing I thought might be worth considering is to swap out the entire amp infrastructure. Not relevant to me as I intent to keep mine bone stock. But think about the following setup:

- Get this sound processor https://www.audiotec-fischer.de/en/h...ssors/dsp-mini
- top it up with this BT receiver https://www.audiotec-fischer.de/en/h...ec-bt-dsp-mini
- add a nice 4 channel amp like this one https://www.audiotec-fischer.de/en/h...lifiers/h-400x
- ideally add a high power cap to ensure a smooth and stable energy supply.

By the way I don't work for this company nor do I know whether they sell in the US. Just great products, amazingly capable and well thought out.
With that equipment on hand drop the old amps, add new professional wiring, squeeze amp and DSP into the tray behind right hand seat. The DSP has high power input, so you can plug in the OEM speaker wiring as sound source. Now your OEM enclosures will be powered by one central amp.
Now "all" you need to do is to use a proper microphone and a piece of software provided by Audiotechnik Fischer to be installed on you laptop. From here you can adjust all parameters of your system, e.g. latency per channel, equalization per channel, low (and high, if wanted) frequency cut (cutting super low will give you more room to squeeze our more power level), etc. You can literally adjust EVERYTHING.
The good thing about the Helix amp is its extremely high damping factor, i.e. the chassis will, when swinging back, be stopped very quick and effectively, there is no uncontrolled motion besides music which equals better "dryer" sound, more power and longer speaker life.
Also this setup gives you a seamless BT integration - forget CD and cassette, just connect your phone and enjoy APTX quality BT stream.

The best thing about this stuff is: once programmed properly you can share the setup. So if anyone else decides to go down the same road in his C4 he or she can just upload your file and enjoy the same sound. That's a pretty cool feature...

Again, I'm in no relation to this company, just a fan of what they do. There might be others around. And this is just an idea. I'm running the exact same combination (plus a proper woofer channel) in my Audi and you would not believe how capable it is. You can maintain all OEM speakers and radio, gain sound quality, get a perfectly centered stage, more power, better control (and thereby more speaker life), more flexibility, modern Bluetooth connection, etc.
IF I ever consider to upgrade my Z's audio, THAT's the way to go!