I am going to be building a box for my new Alpine 12" Type R (4ohm DVC).

I have the MRD-M500 Alpine amp, which will pump around 285wrms into each Voice Coil.

What I would like to know is what kind of box I need to build to get nice, punchy tight bass. I am after SQ (that's why I'm posting here not in SPL), and will probably go in a sound comp or two when I'm done.

Just so you know, the rest of my system is:

Alpine 7894 HU
Alpine MRV-T320 (80wrms per channel)
Focal Polykevlar 165K2

So, do I need ported or sealed, and if so, how big...

I would work this out myself on the box building programs, but there are a few around, so I wouldn't know where to start... Any suggestions?

Your help is appreciated.
Valkyrie
ÜÆ

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'97 Mirage
V12 AccuClass-D MRD-M500
Type-R SWR-1221D

I'm just trying to keep da Peace!
[email="valkyrie@caraudioaustralia.com"]valkyrie@caraudioaustralia.com[/email]

I have been down this road......

My mate has a Pug 306 with one of these in a 50 litre sealed box, well a SVC one anyway. They are quite similar unlike some drivers which are fairly different SVC v DVC versions.

He gets quite good low frequency power out of it for a sealed box/low Q driver combo, and it is pretty tight too. Using a Kicker ZR240 bridged to drive it.

If you want it particularly "punchy", I would go a little smaller (a "classic" 1.5 cu ft, 42.5 litre) in a smaller boot/hatch.

Funny, he uses 165Ks (not K2s tho').....
Anyhow, I'd make 2 observations:
1. Build that enclosure STRONG and RIGID so that you can "tap tap" it anywhere and it sounds exactly the same. Very important for SQ.
2. Mount those Focals rigidly in DEAD doors, sealed up as much as practical for a good mid-bass to sub transition and get strong "up-front".

That's my thoughts. The word of Critter is NOT the gospel tho'....

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Mazda SP20 - NOT yellow,Dynamat Extreme and G Spot in front doors
HU - Alpine CDA-7876RB
Audison VRx 2.150EX front stage amp
JL Audio 500/1 Class D monoblock sub amp
Front Stage - Morel HCW 6.5 woofers, Morel MT2 tweeters, Morel MX2.2 x-overs.
Rear fill - stockies with power from HU (not that they get any)
Sub - Kicker S12L72 in 75 litre 30Hz slot-ported display box.
Stinger cables and connectors etc
TEAM AUDISON SQ WITH ATTITUDE

Thanks for the reply Critter.

Have you seen my install pics? I'm going all out totally SICK with the sound deadening! So yes, the mid bass sound be nice! (I hope that with all this effort it's good anyway)

ÜÆ

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'97 Mirage
V12 AccuClass-D MRD-M500
Type-R SWR-1221D

I'm just trying to keep da Peace!
[email="valkyrie@caraudioaustralia.com"]valkyrie@caraudioaustralia.com[/email]

one thing that i have also noticed is that if you use a low Q system and a nice low (even steep 24dB/oct) crossover point say 60hz or lower it tends to really aid in keeping the staging right...the larger vol and low Q aids in the subs low end extension and performance thru low freq range.

you can see the effects of what i mean simply by playing with your x/over points in any sub system.

why you say... well it tends to isolate the subs output to more the range of sound that we humans, with our very limited hearing senses, tend to have limited ability to hear(we just feel it) and also distuinguish directionally.. what this in effect does is stops very loud and powerful WELL AND TRULY REAR speakers from adding too much of an apparently locatable sound source behind!! and stopping the creation of a FRONT STAGE as is the goal in SQ reproduction. Given the quality of your front drivers you will have no trouble getting good linear low extension. with them mounted in well deadened doors and with on axis mids. They will most likely handle highpass set at 50-65Hz!!! keeping more of the freqs we can easily locate audibly up front!!!

an example of this is the /////Alpine AUS F#1 status demo car using it uses only 2 TYPE R TENS in a 30 litre enclosure each. For theses specific drivers this gives a Q=0.505... low... and the x-overs were 24db/oct set to 63Hz with a subsonic filter at 22hz...which again is way way low for tens and well and truly low based on their TS parameters quoted resonant frequencies. But for the effect of keeping the low frequencies ambient not so locateable it works...

But try for yourself and see what works best!!! experimentation for your own learnin and satisfaction is what counts not what the rest of us tell you!!!

im wonderin whether most of you out there will agree or agree in part. I know my theory on x-over points is what is in place in CYBERPUNKYS SETUP and we all know thats a damn hi quality setup!!!!

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TravGTi

1. SOURCE: Pioneer DEH-P6350
2. PROCESSOR: /////Alpine PXA-H600
3. POWER: /////ALPINE V12 MRV-F407
4. /////ALPINE V12 MRV-T407
5. HIGHS: FRONT= /////ALPINE DDDrive 6.5" F-SERIES Components
6. REAR=/////ALPINE S-Series 5.25" coaxials
7. LOWS: /////ALPINE DDDrive DDW-F30A 12"
8. IMPULSE POWER: Lightning Audio 1F Capacitor

the t/s specs are as follows i believe:
*Fs 27Hz
*Qts 0.38
*Vas 58L

i'd probably go with a ported box, say 1.5cuft tuned to a nice low 28Hz. will offer very good low extension.

sealed would be fine too, but probably not as 'low', and maybe 1.0cuft for that low total Q of 0.66.

hope this helps.

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/////ALPINE audison DYNAUDIO polkaudio OPTIMA Stinger LIGHTNINGAUDIO

Issues of harassment, conflict, vindictive allegations, or unfairness, personal or observed, should be reported to me via Private Messages or at [email="shiny_car@caraudioaustralia.com"]shiny_car@caraudioaustralia.com[/email]

The specs certainly "suggest" porting one of these.
Much as I am a porting nutter...., the small (shop) sealed box of 28 litres we tried in Al's Pug had no grunt and the bigger enclosure (admittedly a quality Oscar box) is heaps better for power and attack.

I'm also thinking, shiny, (much as I HATE to disagree with the "boss" )that whilst 1.5 cu ft/28Hz "looks" nice, it will be a mongrel to make a port for, VERY long with a decent port area. Twin drivers in a single 84 litre enclosure will work tho'.
Hehe, slot port.
Valkyrie, have a look at my box on the instal forum for an idea on how you might do that with a long slot (or technically, a duct in this case).

Good luck with it, it's gonna be nice really either way you go, Type Rs are good like that.

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Mazda SP20 - NOT yellow,Dynamat Extreme and G Spot in front doors
HU - Alpine CDA-7876RB
Audison VRx 2.150EX front stage amp
JL Audio 500/1 Class D monoblock sub amp
Front Stage - Morel HCW 6.5 woofers, Morel MT2 tweeters, Morel MX2.2 x-overs.
Rear fill - stockies with power from HU (not that they get any)
Sub - Kicker S12L72 in 75 litre 30Hz slot-ported display box.
Stinger cables and connectors etc
TEAM AUDISON SQ WITH ATTITUDE

quote:

---

Originally posted by Critter:
I'm also thinking, shiny, (much as I HATE to disagree with the "boss" )that whilst 1.5 cu ft/28Hz "looks" nice, it will be a mongrel to make a port for, VERY long with a decent port area.

---

don't worry, i'm the fool when it comes to designing boxes, esp bloody ported jobbies. i'm still on the steep learning curve for them.

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/////ALPINE audison DYNAUDIO polkaudio OPTIMA Stinger LIGHTNINGAUDIO

Issues of harassment, conflict, vindictive allegations, or unfairness, personal or observed, should be reported to me via Private Messages or at [email="shiny_car@caraudioaustralia.com"]shiny_car@caraudioaustralia.com[/email]

my box is .75 cu. ft each, so 1.5 cu ft in total
for the two, But my box is a dual chamber
Ben

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No Longer a 1976 RA23 18RG powered Celica!!!

2 Alpine Type R 12" SVC subs sitting in my room next to a couple of Clarion Vnet 4150's, Now all i need to do is decide on a car, then some speakers :(

With that much power..nearly double recommended id make it sealed...bout 1.5cuft
eg.1 12" type r in hatch DVC getting the whole jaycar 4x100wRMS bridged-2x300wRMS= 140dB

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Headunit: JVC KD-SX985
Mid bass: Kenwood KFC HQ 718320w 7x10's
Amps: Jaycar 100wRMSx4, Kenwwod KAC 628 100wRMSx2
Subs: Pioneer 12" TS-W1201C
Neons: 2x strobes,2x pulsing,2x antenna type and 2x12"

I agree sealed would be MUCH easier to build (since I have never attempted a ported), but would it get low enough? I mean, I am going for SQ so I want the flattest, lowest frequency output possible.

Would I get a VERY low freqency output with a sealed box? How big/small would it have to be?

Thanks
Valk
ÜÆ

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'97 Mirage

I'm just trying to keep da Peace!
[email="valkyrie@caraudioaustralia.com"]valkyrie@caraudioaustralia.com[/email]

You'll probably find that the gain you get by having the sub in an enclosed area (ie, car) will boost up yer sub bass a fair bit... those gain plots in WinISD etc don't take car gain into account, so even though the graph tapers off a lot in the sub bass region for a sealed box, in a car it will be boosted a fair bit.


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HU: Clarion DRX7675z
FRONT STAGE: Blaupunkt GT6 6.5" Splits
FRONT AMP: Coustic 240SE
SUB: JL Audio 12" W0-4
SUB AMP: Clarion Vnet 2100
WIRING: Aerpro 8GA power cable and home made UTP RCAs :P

Axis - "Muahahaha!"