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Discussion Starter · #1 ·
Hello,

I'm new here, been browsing for a few months.

I have three Audiomobile MASS 2212's (D4) sitting around, & would like to put a couple of them to use in a vented cabinet primarily for HT use 80/20. Here's the parameters I found on the net:

Qts: 0.42 Qms: 5.80
Vas: 92L Qes: 0.45
Fs: 22Hz SPL: 90dB
Re: 7.6ohm Pe: 600w
Le: 0.507mH BL: 19.80
Xmax 20.0mm Diam: 12in
Z: 4.0ohm Sd: 0.046m^2
Mms: 160g

I understand using two separate cabs is best to smooth out the bass response, but since they're dual 4's that doesn't leave me too many options except to use a pro amp. Unfortunately, my TV stand's cabinets aren't large enough to house one without proper ventilation I'm afraid.

So, that leaves me a plate amp, or possibly the SA1000 since it measures a bit smaller (TV cabinet friendly)than PA amps. As far as the Dayton 1k watt plate amp I'm a little hesitant because of all the complaints of hum & it also doesn't produce a true 1k watts. The PE Bash 500 is another consideration, although it's only 500 watts.

It's a large Great Room (22'w X 25'd X 10'h) that also includes the kitchen & dining area. There's also a large 14' X 8.5' opening on the left side that opens up to the hallway/entryway & the rest of the house. The sub would be placed in the right side corner (only available corner) along the front media wall.

Enclosure size is really no concern because I will eventually go with multiple 15" or 18" drivers when more money presents itself. I would like to see how these pair of 12" subs perform first. I would prefer to keep the width & depth at a minimum as long as it doesn't hinder performance, height is not an issue. I think a large slot-ported design would be easiest to build, unless a large round port(s) is recommended over a slot. Tuning frequency I'm shooting for would be 18-20hz, depending on which amp is suggested.

Any & all advice is much appreciated! Sorry if I gave too much unneeded info, or if I left something important out please let me know.
 

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Discussion Starter · #3 ·
Thanks Mike!

Does the Bash 500 come from the factory with an 18hz 12db/octave high-pass filter, plus some boost in the 20hz-30hz region? As far as the slot port goes... would it be better to go with a wider cabinet to try to keep the port from having a 90*angle? Or is there really no way to get around a 90* bend? I was thinking in the ballpark of 18"-19" wide with 3/4" material, 1.5" baffle.
 

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I have two Crystal CMP subwoofers in one of my setups. I've always wanted a pair of MASS'.

I have a thread somewhere of the build. Let me find it.

I think the box is 3.6 cu foot tuned to 18hz. The subs share the same airspace.
 

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Discussion Starter · #10 ·
Thanks for the link! Very nice build, & just the opposite, I always wanted a Crystal CMP. :) Both were/are great subs. I've been contemplating getting a 15" or 18" recone on one or two of them.

I have a question about your Crown XLS 2000... does it have a non-defeatable 20hz high-pass filter? I'm curious, since you have an 18hz tuning, does that drop the level enough below tuning to NOT have a filter below the tuning frequency?
 

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Thanks for the link! Very nice build, & just the opposite, I always wanted a Crystal CMP. :) Both were/are great subs. I've been contemplating getting a 15" or 18" recone on one or two of them.
I asked PSI back in Feb 2012 if a 12" CMP could be reconed into an 18". He said "You 'could', but it's a little on the small/weak side of things for such a build. You would need to use a large enclosure, around 12-14ft"

SO, that is why I didn't go that route, didn't have that much space. If you ever want larger subs, post your MASS' for sale, I'd buy them if the price is right.
 

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I have a question about your Crown XLS 2000... does it have a non-defeatable 20hz high-pass filter? I'm curious, since you have an 18hz tuning, does that drop the level enough below tuning to NOT have a filter below the tuning frequency?
It has a HPF but it can only go down to 50hz, so I just leave it off.

I know conventional wisdom says you need a HPF right at or below tuning frequency but I've never had a problem. I have a book on this somewhere but in a ported enclosure, the air in the box acts as a 'spring'. The sub and the air/spring work together as long as you stay above the tuning frequency. Once you go below tuning frequency, the sub in the enclosure no longer uses the air, the sub is controlled only by the motor and suspension of the speaker. This is commonly referred to as the speaker 'unloading'. This can easily cause damage.

That is why in most cases, a foolproof way to go is build a sealed enclosure. You won't have as much output, but you can get away with a smaller box, don't have to worry about tuning/unloading/etc... I have two sealed SI 18's each getting 2100 watts and wow...

I have three ported boxes, 2x 12" subs tuned to 18hz, 2x 8" subs tuned to 25hz and a single 12" tuned to 26hz and have never blown/damaged one (yet).
 
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