Alpine Type-R

[bparker]

I'm getting a Type-R 12 (500W RMS dual 4ohm) and I was wondering what to go with in terms of a box, like sealed, ported, vented etc, and what are the advantages/disadvantages of down/backfiring? I'm looking for mainly SQ here.

[hari-bhari]

if ur looking for SQ, def go sealed. ported is louder but not as clean

[Duffman]

For that sub, sealed - 0.85 to 1.25 cubic inches.

SWR-1242D, right? I'm looking to get a pair of those in a downward-firing box.

[bparker]

a local audio shop here will make me a box for $60, should I get down or back firing? What are the differences?

[Duffman]

Downward-firing is the "new thing", has good sound and generally, more bass. They also look cleaner and the downward-firing ones have room on the box to mount the amp for a clean install. If you go that path, dynamat the bottom of your trunk, under the carpet, as you're gonna be pushing a decent amount of bass into the body.

You'll "feel" the bass more with a downward-firing box, but "hear" more bass with a regular box (and you're able to direct the sound better with a regular one). All depends on what kind of sound you want out of the system. Just make sure you go sealed - do NOT go ported or bandbass. That's way too clear of a sub to waste its clarity in a crappy box.

What amp are you running to it? Wiring DVC is fun, you generally either have to run 2 channels (for that one, 250x2 @ 4 Ohms) to one sub or one large amplifier wired to two subs to keep the ohm load balanced.

[bparker]

I have a kenwood bridgeable amp that will do 460x1 RMS at 2ohm (stable). I was thinking I could just wire up the coils in parallel to run it as 2ohm, right? i.e. connect each coil's pos/neg together, then run that to the bridge +/- on the amp

[Duffman]

As long as you know the speaker is capable of 2 Ohms. It'd be a crime to mess up an Alpine sub - Alpine being one of the foremost companies out there for clarity - by powering it wrong. What does the amp do @ 4 Ohms? The problem with a DVC sub is that if you have a mono-channel amplifier, it's difficult to match the impedance and utilize both coils. If you ran to one coil, sure, but then you'd be coming real close to the sub's peak... ouch.

The setup I came up with uses the Alpine MRD-M1005 and two Alpine SWR-1222D subwoofers - The M1005 puts out 1000w x 1 @ 2 Ohms, the 1222Ds take 250w RMS @ 2 Ohms. I can wire those to all run off that sub, use the full rated power for each coil, and still pull as a 2 Ohm load.

All depends on what you want to do with it. Post some specs and we'll see what we can "theoretically" wire out for ya.

[bparker]

well the alpine sub is a 1242D, and no documentation I can find says if the 500W RMS rating is at 4ohm or 2, I was assuming 2, but I'm not sure. Maybe someone can verify for me.

[Aotoyota]

if you have a SWR 1242D then it means that you have a dual four ohm woofer. with a 12 i would go about 0.9ft^3 sealed for sq. I currently have the ten in my car and that thing hits nice and accurate with a mrd-m605.

[bparker]

What I'm trying to find out is what will happen when I run the DVC in parallel as 2ohm to my amp. I figured that even if at 2ohm the sub did more than 500WRMS (if it's rated for that at 4ohm), the amp will only draw 460x1 RMS at 2 ohm so I should be fine running it at 2ohm, right?

[Duffman]

The SWR-1242D is a dual 4-Ohm sub... 250w RMS x 2 @ 4 Ohms. You will hurt the sub if you try to run it at 2 Ohms. The amp will handle it no problem, but using both coils of a sub on one amplifier will never give you the impedance the subwoofer was designed for. Simple math.

[bparker]

Then what about all the other people all over the net that even tell you how to do it in subs exactly like this if it's bad? No offense but please back yourself up.

[Duffman]

I'm just going by all the research I've done. Check cruchfield.com, they have an extensive knowledge base there that will give you plenty of information about wiring up subs and the impedance you'll get from different wiring combinations. Click here to see how these wiring combinations will affect your sub.

You've basically got two 250w subs built into one... with your unit, both 4-Ohm subs. If you take your power source and connect it to both coils in parallel (positive lead goes to both positive terminals and negative lead goes to both negative terminals), you're powering "two" subs and creating a 2-Ohm load. If you run the power in series (positive lead goes to one positive terminal, then from that coil's negative terminal to the other coil's positive terminal, then from that coil's negative terminal to the negative lead from the amplifier) you will create an 8-Ohm load. Now, if you ran two subs like that, you could make a 4-Ohm load with them. Click here for more information on how a DVC sub works. As the warning on that page states:

CAUTION: Some or all of these wiring options may not be compatible with your amplifier due to low impedance loads. Please check your amplifier owner's manual to determine the best wiring option. Also, be sure to maintain proper polarity to prevent damage to your amplifier/woofer system!

I'm not saying it's not "possible" - you could do it if you wanted, and make a 2-Ohm load (or 8-Ohm) and see what happens, but I don't think that's good for the subwoofer. If you have some examples of people who have taken a DVC sub with two 4-Ohm coils and make that one unit create a 4-Ohm load using one channel of input... please let me know, I'd like to see how it's done, since I've yet to figure any way to make it happen.

[bparker]

I read that crutchfield link and noticed the warning about with the ohm load. In my case, the amp IS 2-ohm stable and is designed to be bridged (it's a 2 channel amp, Kenwood KAC-7201), and the sub is designed to handle a 2-ohm load (not 100% sure, but I assumed this). According to crutchfield and others, wiring DVC parallel is a common thing, so I figured if that was something that would harm the sub, they'd say so somewhere, but I've not found anything stating that, but then again, I haven't found any documentation as to the actual 2-ohm performance of this sub. Since the amp puts out less than the max rms power of the sub (whether or not the sub actually outputs 500rms at either 4 or 2 ohm), I figured it wouldn't hurt as the amp would not pull that much all the time anyway. Still, I'm no audio expert, I just thought this was a little less complicated than it was made out to be. Let me know your opinion, and thanks for helping me out.

[Aotoyota]

500 will be fine. if u noticed my post i am running a mrd-m605...thats a 700wrms amp! i had the old type R (1041d) with 500 on it and it ran strong.