Only 87-up had the block off plate in the rear. 86 and below just had a hole for 4x6's. The later models had the 4x6 hole but also had a 6.5 inch hole plate. I would check that. If you have an 86 then it definitely won't work unless you have a sawzall.

I think his cab was a conversion not a stock porsche one.

 

A simple design for some Nakamichi SP-80 subs. Made them back in 1986.

 

The stereo system in the first three pics is install of all places in a pristine -low mileage 83 944 Callaway Turbo,witch belong to a Pelican member.Just tougth you guys will be interested to know,it's kind of OT but sending a couple pics of it. Hope__ ZP8ED__ don't mind me doing so ,they are so rare that it's worth looking at an almost perfect exemple .

 

You should really try and find some better car audio guys. At Sub bass frequencies the wave takes about 6M (30ft) to propagate so the initial advise you received isn't relevant. Its true at higher midrange freqs but not at sub bass freqs(in a car). The Dual Voice coil sub is a way to configure a combination of subs to create the desired load(impedance) to the amp. They don't magically combine left and right waves, as all sub bass sounds are mono anyway. I'm glad you are happy with your results but the logic you have been sold as to why is simply incorrect.

I have been involved heavily in car audio for over 30 years and can't believe how many ppl in the industry just don't know what they are talking about. Going for a sub on each side would result in great bass and would not present any standing wave issues.

I have just started building a box for a single 10 in the rear corner. It is designed to fit to the cover so I can still get access to the storage area underneath. It will end up with a carbon fibre fascia(front baffle) when its finished.


peace

 

my bad (not my installer)... you're absolutely right... it's a mono amp sending a single mono signal processed from both sides... i had him build me a speaker box and flip the on/off switch to on. it's clean w/ rich, deep bass.... as one of the guys mentioned, 1 sub already adds weight. i didn't really want more, so when my installer suggested i'd likely get the cleanest basswave from a single source, i said, "ok..." and whether he turned out to be right or wrong, is not something i've fought over for every last decibel. i'm convinced that it worked.

my home system deserves a listen... not running the B & W Nautilus sats and Krell subs, but what i am running is pretty close in the loudness department and not bad stuff for under $20 k. anyway, back to bed.

Nakamichi CD.
Audio Research tube pre amp
twin Sunfire Amps
JBL pro. "can't buy anywhere sats." get so loud you might die... original owner paid about 12 grand for these.
Ground Zero engineering subs.

 

my bad (not my installer)... you're absolutely right... it's a mono amp sending a single mono signal processed from both sides... i had him build me a speaker box and flip the on/off switch to on. it's clean w/ rich, deep bass.... as one of the guys mentioned, 1 sub already adds weight. i didn't really want more, so when my installer suggested i'd likely get the cleanest basswave from a single source, i said, "ok..." and whether he turned out to be right or wrong, is not something i've fought over for every last decibel. i'm convinced that it worked.

my home system deserves a listen... not running B & W Nautilus sats and Krell subs but,

Nakamichi CD.
Adcom signal processor
Audio Research pre amp (yeah, the one with tubes).
2 Sunfire 600 watt/channel stereo amps....
JBL pro. "can't buy anywhere sats." get so loud you might die... each consists of 1 8" midbass driver, 1 8" fullrange driver, 4" midrange and tweeter... just a few of these cabinets were made by JBL for recording studios..... original owner paid about 12 grand for these amazing loudspeakers.
Ground Zero engineering subs (just the drivers weight about 25 kg each). they might be the loudest 10" subs ever built and can handle 3,000 watts each... i was lucky enough to get a spare set to put in two more cabinets, but haven't gotten there yet. cheers.

 

Sounds like quite a set up you have for your home system. My brother had some rare JBL pro speakers when he was going to Uni(college). He sold them years later for a profit. I think that si what got me hooked on audio. The system in my 952 is going to be pretty simple by my standards, as I used to compete in Sound Quality competition. I was actually national champion, in pro class in 2007, and have been fitting systems for31 years now.

Just FYI a single sub won't give you cleaner sound waves compared to 2 or more, it would just have less output compared to using 2 or more. Sub bass is directionless, which is why sub/sat systems in home audio work so well. our brains just assume the bass is coming from the speakers we can locate(the sats).

It can be a little different in a car, as we may have sympathetic vibrations(like a panel vibrating) that will vibrate at a higher frequency and therefore give direction cues to the sub, and we may also need to cross the sub at a higher freq, to compensate for lack of midbass from our full range speakers, which can push them into the freq range that we get directional cues from.
peace

 

Those are nice subs. I have mostly vintage stuff and have no desire to get anything new. Car audio is pretty sorry sounding anyway, too accurate to say the least.
I have a couple of ADS 7" subs, of which I only use one, Nakamichi PA 500II amp. Nak sp seperates/ADS 320I w/ADS class A 50 amp. Good enough for me. Car audio is very intrusive and heavy in a Porsche - a quality set of full range components in the door is plenty.

 

that's the weakness of my sysetem. not enough bass from about 100~180 hz. but i have plenty of room in my sat amps to locate one more set of midbass drivers. it's just a matter of "where" to locate them in the car. i'm also reluctant to do it because of weight.

i'm thinking cross over the behind the seats speakers witch i believe are 6.5" midbass speakers at an even higher cutoff, like say, 120 hz instead of where they are now (i think they're at 100 hz now), and install 8" midbass drivers somewhere to deal specifically with making about 90 to 140 hz.

my system gets very loud now, but i think that adding two stout midbass drivers would be insane.

 

In my competition system, I built small boxes in front of the seats that housed 8 inch midbass drivers. These had speakers angled at the windscreen. now most of the competitors here, have copied this set up, as it helps with getting bass up front but also can improve sound staging.

As you are just trying to add midbass punch, you can get away with very small boxes. This improves power handling and helps with getting a solid kick. A lot of ppl dismissed my design till they heard it. Anyway its an option and will work better than fitting them in doors or behind seats. Midbass has a directional component so placement will effect how well they blend in.

will post some pics if i can dig them up

peace