acoustical stuffing / sound dampening subwoofer cabinet REL BRITANNIA B1 subwoofer

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.

Depending on cabinet volume and tuning frequency, some drivers may want a port that is 25-35" long (based on 4-3/4 diameter).  That's what I really mean.  A shorter port means the tuning will be at a higher frequency, which could mean a bump/increase at something like 35hz where the port and the driver are working together.  This may not be really bad at all.  It's up to you, but the goal would normally be to engineer a flat response with a controlled roll-of.

Do you have a copy of Bass Box Pro?

https://www.parts-express.com/bassbox-6-pro-software-cd-rom--500-923

It might be good just to buy at $129.  Then try to measure/calculate the actual interior volume of your cabinet.  Then select a driver at random (say ScanSpeak 30W/4558T) and then play with the Fb port tuning frequency until you get a 4.75" port close to the 17-18" length.  Then do a frequency response graph to see how it looks.  I did a few, and some may have a very slight bump at about 40hz.