acoustical stuffing / sound dampening subwoofer cabinet REL BRITANNIA B1 subwoofer

As auxinput states, internal bracing is the best and first way to combat enclosure resonance. Braces stiffen the enclosure walls, raising their resonant frequency above the frequencies the sub is asked to produce. Internal stuffing "tricks" the box into thinking it’s internal volume is greater than it actually is (by slowing down the sound), and needs to be matched to the driver’s needs in relation to that volume. Both too much or too little for any given application are possible.

Sonic Barrier is a fair enclosure wall damper, but a superior product to achieve that end is NoRez, sold on the GR Research website.

Thanks for all the information from everyone! Sorry for my slow response. All great points and I do have  another quick question regarding replacement woofers I’d like to ask

AUXINPUT—You are correct, I did some more research and contacted other owners, took me a while, but you are right. There was no stuffing from the manufacturer. GREAT INFO on how to modify the cabinet. I appreciate it.

ERIKSQUIRES—Excellent point about the heat of the woofers. I have owned all the infinity intermezzo speakers including the 1.2s subs. They almost ALL had problems from heat build up exactly as you describe.

KINESIS & GEOFF—I agree with your experience. And you are right it’s the old “everyone is doing it”

QUESTION—I need a replacement 12” woofer for this large volume enclosure. I know the T/S parameters of the old driver which is helpful. I have been shopping and see a huge range of prices from $40-$1000. Seems like a suitable replacement is $400+ if I were to go with a home audio driver.

What I was wondering is what about CAR stereo woofers? I see a ton of 12” car stereo woofers that are extremely well built (sometimes better than home audio), have good parameters, and are at a lower price. The only downside is that they are DUAL VOICE COILS, DVC. I know a DVC would have to be wired in series thus taking 2 ohm to 4ohm for example. Is there any downside to a car audio woofer? Any downside to merely connecting the 2 voice coils?

Thanks for your thoughts!

There could be several subwoofer drivers that may work well in this cabinet.  The most important T/S parameter to look at is VAS.  I would avoid car subwoofers because they are designed to operate in a smaller box than normal subs.  Your box is 4+ cubic feet (or about 120-130 liters).  So look for a subwoofer that has a VAS larger than 4 cu.ft or 130 liters.

The other part is the port tuning.  It's a 4.75" port and not that long.  Depending on the subwoofer, it could cause a slight peak just before the frequency response rolls off (probably in the 25-35hz area).  It really depends on how the driver rolls off the lower frequencies and how the port comes in to compensate for those rolled-off frequencies.  It may be difficult to get something exactly, but you could get a very good performer.  Madisound has Morel and Scan-Speak subs that are nice.  I wouldn't worry about trying to get the super expensive massive subs, like RE Audio or Stereo Integrity.  Those are for the nutsos.  JL Audio makes a very nice product, but watch for the VAS being too small.

Take out your current subwoofer and make sure of the exact diameter of the hole.  Subwoofer sizes can vary slightly, even though they are marketed at 12".

Madisound has dimension drawing on all drivers.  You could also check out Parts Express.