officemanager

I just got the following from Focal in a request about using their 5" mini subs in custom door panels... but Alan at Orca Design [Focal's US design reps] also addressed the porting/free-air/sealed bass enclosure issue that runs around here like a proverbial chicken crossing Limerock...

He wrote:

Hello Chris,

Ported boxes do not sound good in cars because they have the wrong shape of frequency response.
A ported box is appropriate for really huge vehicles like Suburban, Excursion and full size vans.

Car acoustics have a rising efficiency below about 50 hertz dependant upon the interior volume.
Below about 50 hertz the efficiency rises at about 12 decibel per octave.
The ideal speaker would be a mirror image of the car acoustics.
This means a closed box with Qts = 0.7 and –3 decibel around 50 hertz.

Vented box speakers go lower than 50 hertz which cause an artificial bump, below the port tune frequency they roll off at 24 decibel per octave which reduces the deepest bass. Power handling also falls to only 10 watts below the port tune frequency.
This might be good for bass freak music but terrible for symphony, jazz and rock !
It would be much better to use an equalizer to make the “artificial bump” according to your personal taste.

The optimum sealed box for Focal 5WS is 180 cubic inches with –3 decibel at 86 hertz.
Considering maximum cone travel, subwoofer amplifier size should be75 watts.

Check out the new 8 inch 21V2 subwoofer. It is our smallest TRUE subwoofer.
Sealed box volume is 870 cubic inches.
-3 dB is at 41 hertz.
Considering maximum cone travel, recommended amplifier size is 200 watts.
ONE 21V2 woofer moves as much air as three 5WS woofers......

Also, consider the 165W or 165W3 systems.
The 6.5 inch woofer needs 870 cubic inches.
-3 dB is at 70 hertz.
Considering maximum cone travel, amplifier size should be 75 watts.
Maximum loudness is identical to one 5WS.

Alan

So for my 2 bucks

As to driver placement: I have 4 Focal 5ws' in a leather wrapped fiber enclosure on the rear deck of my Coupe and I have the rear seat/trunk option in my cabriolet and it's a no brainer the larger sub on the seat is better

<img src="http://ocdny.com/96%20porsche%20cab.%20064.jpg" alt=" - " /> <img src="http://ocdny.com/96%20porsche%20cab.%20052.jpg" alt=" - " />
Note amp rack rises to accommodate trunk placement.
<img src="http://ocdny.com/96%20porsche%20cab.%20026.jpg" alt=" - " /> <img src="http://ocdny.com/96%20porsche%20cab.%20027.jpg" alt=" - " />

I'm researching the new 8" 21V2 as possible for the rear [hinged] portion of the door panels [which hinged pocket area would of course need to be sacrificed and sealed] the question is whether the door affords the 870 cubic inches with 165w3's in the front end of it... But if it does I think I will have found the answer for my next 993 [i.e. some Rennlister's meticulously maintained 1997 Silver Turbo – PS I'm in the market.]

ammo_collector

Hey officemanager, have you considered the armrest for the rear passengers? Look at the second picture down from this link: <a href="http://www.usdaudio.com/sw/cars/porsche/page1.html" target="_blank">http://www.usdaudio.com/sw/cars/porsche/page1.html</a>

The 21V2's look like they would fit here and you wouldn't give up any rear seating or footing.

AKA

you definetly could use that sub for that application, but, you are going to be using it freeair. freeair sucks. YOU WILL NEVER GET THE LOWEND FROM ANY FREEAIR SETUP.

ammo_collector

From what I understand, Speakerworks did that enclosure as a sealed box.

officemanager

Thanx ammo_collector... I looked at your posted pix link... It's a good thought and I'm grateful... the problem is, as AKA says above [P.S. hi Doug], you can't fit the 870 cubic inches [0.5035 cubic ft] of sealed space you need for the 8" in there with, in my case, the cabriolet top mechanism...

That's also the problem with the 8" and 10" drivers attached to carpet wrapped Barra board everyone is laying [or even caulking] in their rear foot wells. They are, as Alan from Focal says above and Rennlist member 'Vinny '98 3.8 C2S' [who is a bass player] and whose post I read a few weeks ago said... 'making' a lot of noise in the low frequencies is easy... But a tight structured musical bass note is very hard thing to make... however once you hear it, like a Porsche it's a thing of beauty to be sought. And even if you can get it clear down below the fifty hertz line it's even harder to get it to climb evenly and smoothly up from below 50 to 250 and above... And it's never, ever going to happened with a free air install of a low woofer...

There is a cd of Janos Starker playing Bach on the cello [and I, as a rule, listen to Lynyrd Skynyrd, Buddy Guy and Weather Report alot more than I listen to Bach trust me] but you put that Starker CD on in my car and the hair on your neck'll stand up... it's like great sex the low

officemanager

Sorry Ammo_collector your post and mine crossed...
I havn't measured the space in the rear of the 993 coupe and turbo [my coupe is a 964] but if someone has done the volume calculation would you please post it... here or email me...

Thank

Chris Wolf
cr@ocdny.com

officemanager

Oops nothing below 50 cycles on that post above... Ahh now that my sub is back on I will continue... It's like great sex... the low frequencies of that cello just warp themselves around you and eventually [and especially with the tube amps] you and the cello are one. I have a few Kieth Jarret ECM recordings with Gary Holland where the acoustic bass does the same... And I will add... from a VBR MB3 not even from a CD.

Admittedly if 50cents is your source material then free air 12's are gonna be fine but everything from Jon Bonham's drumming through gratefully almost all new recordings [try Kenny Wayne Sheppard or Dave Matthews] need precision reproduction in the low frequencies...

But I suspect I'm preaching to the choir... if you didn't care about the fine points you'd all have the new Chrysler with the factory radio and none of you would be readed this at all. And if you were all looking for a cheap do it yourself kick for $200-400 dollars you'd all be standing over the new bypass valves in your Mitsubishi Eclipses right now instead of reading my rantings... [and PS I own 420hp twin turbo VR4 as my station car, so no hate mail from the Diamond Star crowd please...]

PPS I don't check the site as often as I should so email me directly if I can answer anything that would help you and you need a timely response...

jhb

As we are speaking of bass, a few years ago there was a post where some audio tuner put a sub somewhere in line with the heating ventilation system on a pre 993. Seemed clever, though I am not sure how efective it was. Any thoughts on trying to repeat for a 993.
What about a Bose wave tube type solution. But I guess bass is adirectional, and the problem is to find the space to mount it.

shattergard

Beautiful Sub: https://rennlist.com/forums/showthre...ight=enclosure

shattergard

Beautiful Sub: https://rennlist.com/forums/showthre...ight=enclosure

gonzilla

OMG, we get it already! Yeah, beautiful sub.

shattergard

Just trying to be helpful, I had only posted the photos one one thread

tankertoad

I was talking with Alan at the Audio Shoppe in Riverside Ca this week and he mentioned just that. In pre 964 cars, the antiquated suspension left a "smuggler's box" next to the gas tank. Alan puts subs in there and the sound waves enter the cabin from the recirculation ducting in the passenger footwell. Pretty trick but too bad we don't have smuggler's boxes...