Integrated Bass Bins/Spacing

[derekbannatyne]

A few years ago, I built the Modula MT (bookshelf) design on this website using the Dayton RS180 and the Seas 27TDFC. Unfortunately, I've once again developed the itch to build something audio-related, and was thinking of simply re-designing the cabinet into a floor standing design and re-using the same speaker components.

I've decided on the cabinet design shown below - it has curved sides, tapering from 9.5" at the front to 5" in the back. Not taking into account displacement for speakers, bracing, etc., this leaves me with about 1.7 cubic feet to play around with - much more than the single RS180 needs. This got me thinking about integrating small (8") subwoofers into the bottom half of the speaker cabinet. I have one subwoofer that I had in my old car, an 8" Tang Band W8-740P, that would work perfectly in a smaller enclosure, and also has decent Xmax. The driver would be downward-firing (the PE calculator gave me about 2.8% sag), with a 2" port (also downward-firing) tuned to around 23Hz. I would power them using an external amplifier, and the crossover would be handled by my receiver.



However, in an attempt to keep the enclosure relatively slender, I have run into spacing problems for the subwoofer. As seen in the top-down view below, I only have about 1/8" between the inner cutout of the subwoofer and the side of the cabinet wall - will this cause any issues?



Thanks for any help!

[5th element]

Nice design btw

The only issues I can think of is that the MDF of the side walls will split if anything is screwed into it - at least as close to the edges as you've shown. However as the screws mounting the driver will have to pass through the base of the cabinet first, you'd need pretty long screws for that to occur. You won't be able to use T-nuts though.

[derekbannatyne]

Nice design btw

The only issues I can think of is that the MDF of the side walls will split if anything is screwed into it - at least as close to the edges as you've shown. However as the screws mounting the driver will have to pass through the base of the cabinet first, you'd need pretty long screws for that to occur. You won't be able to use T-nuts though.

Thanks!

Yeah, I was noticing that the woofer screws would definitely hit the very edge of the inner wall - I'll probably have to get creative to avoid that. Hopefully I'll have access to a CNC machine here at school, so it'll make things a little easier.

Other than the construction issues, would there be issues with backwaves/chuffing due to the woofer cone being so close to the inner walls?

[5th element]

Other than the construction issues, would there be issues with backwaves/chuffing due to the woofer cone being so close to the inner walls?

No, the only thing you'd need to watch out for are air leaks from the sub enclosure into the MTs and visa-versa. You don't want the sub pressurising the MTs mid/woofer - although I am sure you already know this.

[derekbannatyne]

I've decided against the bass bins, and have instead decided to build a small (relative to my 8 cubic foot one) subwoofer.

I've narrowed it down to two driver choices - either the 12" SVS Plus 12.3 driver or the Dayton RSS315-HF. This will primarily be used for music, and I'm thinking the Dayton will probably be more "musical"? However, I believe the SVS woofer has considerably more Xmax, which would be appreciated during the occasional movie. The enclosure would be 3-4 cubic feet, tuned to around 20hz and powered by a 240-300w amplifier.

Can anyone offer advice comparing these two woofers?

[derekbannatyne]

Nevermind, just found out the guy sold the SVS driver, going with the Dayton!

[DeathMonk]

You will be happy with the dayton. Its no slouch for movies, either

[derekbannatyne]

Just wanted to update this thread with my completed subwoofer! Ended up with the RSS315HF in a ~4.25 cubic foot enclosure tuned to 21Hz via two 3" flared ports, paired to a 240watt plate amplifier.

The box is finished in figured anigre veneer (clear coat is Crystalac Premium Gloss) for the sides and a piano black finish on top. Had heard how much work getting a piano black finish is, but never fully understood until I attempted it myself. Would definitely think twice about doing it next time.

Here's a few pictures (forgive the terrible cell phone pictures):







Certainly doesn't play as loud or low as the ported 15" Dayton DVC subwoofer next to it, but should be more than enough for my apartment (and my neighbors).