Compromise driver orientation?

[peace brainerd]

before anyone catches me on this one, this morning at breakfast a friend laughed and dinged my poor logic. The cabinet might have been made in 1980, the date of the book in it means nothing.

[revboden]

Originally Posted by peace brainerd

If I'm reading the correct spec for the 315-88 it's 7mm xmax. Then you don't think the 9mm of the Vifa 12 will be pose any real limitation for the needs I've described? If I could get some consensus on this I'll stick with this driver.

If the ViFa has the right specs for the box size... sure. looks like a nice driver.

[Bob Richards]

With that big cavity in front of the front mounted driver behind the door, you'd have significant "cavity effect" which is a resonant chamber in the lower 100's of HZ. That's no good. down firing is what I'd do. I'd also put in cross braces near but not at the center of the cabinet, from the middle of each side to the middle of the opposite side, and I'd glue and clamp them together where they cross. Glue the door shut and add wood around the crack on the inside if necessary. The internal volume may well be bigger than is optimal for the Peerless woofer. You should find out what internal volume makes it happy, and put in a solid shelf to adjust that right. With a closed box, the internal volume isn't nearly as critical as with other designs. I'd also glue foam rubber or some other acoustically absorbtive material tight to the inside walls of the cabinet, especially in any corners. With a sealed cabinet, you can force the acoustic output to be flat to 20HZ with active electronic EQ ahead of the power amp (make internal volume slightly smaller if you are going to do that, for a smoother tighter bass rolloff before EQ. Very worth it if you can handle the electronics. I am using the Peerless XLS 12 inch woofs and love them. They have a bigger Xmax (voice coil travel) than most 12 inch woofs that I've looked at. Very important if you ever want to take them down to 20HZ flat. What a great Oak cabinet!

[peace brainerd]

With a sealed cabinet, you can force the acoustic output to be flat to 20HZ with active electronic EQ ahead of the power amp (make internal volume slightly smaller if you are going to do that, for a smoother tighter bass rolloff before EQ. Very worth it if you can handle the electronics.

That was suggested elsewhere in the form of a Linkwitz Transform. I haven't been reading up on this in a few years. I'm pretty comfortable with basic electronics and repairing/replacing components on boards, including smd's. Is there an LT circuit available that I can integrate onto the board of my existing 100w sub plate amp? Actually I have two of the 100w plate amps so I can bridge/combine for more power if the LT circuit demands it.

A large part of the fun of DIY for me is maximum value for the dollar. Got a couple of plate amps at that NHT sale a while back. This woofer was marked down almost 2/3 (granted it was overpriced?) and the oak cabinet for 10 (granted stripping/refinishing will be work but that's enjoyment for me).

Returning, while I'm still able, the Vifa in exchage for the Peerless is looking more and more attractive. Equal to the Vifa musically, with sufficient extension for any future use should I wish to "go there" with it.

[peace brainerd]

Uh oh... just went back down that rabbit hole of "subwoofer equalization circuits" via google search and my brain is squirming. Back to basics for this project me thinks.
But I do see the problem posed by the likelihood of creating a resonant chamber there.

Maybe bottom firing may be the way to go. I could go rear firing, but that limits placement by disabling the option to place it against a wall.

[peace brainerd]

If it is in fact the case that the front cavity might be prone to resonance, how would this remedy fare?

Just a couple of oddly spaced baffles.

[adason]

how about making the baffle with woofer leaning, not paralel to the front
make the cavity V shape, that should cut the resonances
kinda like that sub already showen from the bottom

[peace brainerd]

Damn. I really want to keep this from looking like a big subwoofer in the living area. Rear and bottom firing are out. The box, unchanged dimensionally, has 4.2 cu ft of volume to work with before calculating for driver and bracing.

So here's the latest idea. Side firing RSS315HF-4 12" behind an art deco grille. Amp on bottom. Grilles on both sides so that it looks like plain ornament from a distance instead of a speaker grille.
art deco side firing 12.jpg

[johnr66]

Originally Posted by peace brainerd

Damn. I really want to keep this from looking like a big subwoofer in the living area. Rear and bottom firing are out. The box, unchanged dimensionally, has 4.2 cu ft of volume to work with before calculating for driver and bracing.

So here's the latest idea. Side firing RSS315HF-4 12" behind an art deco grille. Amp on bottom. Grilles on both sides so that it looks like plain ornament from a distance instead of a speaker grille.
art deco side firing 12.jpg

That too is a nice idea but the amp needs to be on a vertical side so natural convection will pass over the heatsink fins.

[tb46]

Hi pb,

I think your box would work just fine as in your Post #36. For the Linkwitz transform cirucit I'd recommend: Linkwitz Transform Subwoofer Equaliser.

Have you given any thought to using a 4th order bandpass (sealed back chamber with tuned front chamber)?

Regards,