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peace brainerd 19th September 2011 10:58 PM

Compromise driver orientation?
I'm committed to building a stealth sub posing as an endtable with books and a lamp on top... maybe a potted fern. False hinges and pull handle on the front "door". No visible speaker or grille. This means bottom firing or rear firing.

Plugging in the TS numbers at the PE calculation page for down-firing candidates my Viva 12in neo rates 6.7 percent. Barely above the 5 percent cutoff for comfort. That's due to it's 9mm xmax. How about rear firing? My take on many of the the threads here is that corner or wall loading is less than optimal for most accurate bass for a 100 percent music sub.

What about the above? A six inch wide slot in the front of the sub cabinet is formed by a false front. The rear compartment is sealed. Still floor coupled/loaded but to a much lesser extent. Those feet are already six inches tall, and the cone center is another eight to ten inches above those.

Any thoughts?

Ron E 19th September 2011 11:23 PM

This will work fine, you will probably get a little extra mass loading.

adason 19th September 2011 11:26 PM

why not just to have the woofer dowfireing like in many other subwoofers? simpler to construct...

peace brainerd 19th September 2011 11:35 PM

Might not have been clear enough on this. I'd rather be 100 percent "no worries" about horizontally mounting this driver since PE suggests that it's a little outside of the recommended zone for such orientation based on their formula, particularly since it's got only 9mm xmax. There's not a lot of room for droop there.

Still tempted to return this driver for the Peerless 12. Peerless 830500 12" XLS Subwoofer. This might be the deciding factor in the end.

peace brainerd 20th September 2011 12:03 AM

Hmmm, that Peerless measures approx the same percentage of sag/xmax as the Vifa.

Guess I'll do the hidden build with this one and call it good. Not much extra carpentry in there really just to put one extra baffle in place and just about the best physical protection for the woofer I might manage.

revboden 20th September 2011 01:03 AM

That'll work just fine

nice idea! :p

m R g S r 20th September 2011 02:15 AM

if its a music only sub, why do you need more xmax? Pro audio drivers have around that xmax and they are music only.....i don't think you need a sub that plays down to 18hz for music...unless your music calls for that i guess?
unless you are using this for HT as well...then 20hz is necessary

Arty 20th September 2011 10:54 AM

just simply turn it around, so the driver faces the wall.
depending on the room accustics and listener position it can be benefical anyways.
Less to worry about if you ask me :D

weltersys 20th September 2011 05:37 PM

The plenum seems a bit large, no need to have the exit area larger than the cone's SD.

peace brainerd 20th September 2011 10:38 PM


The plenum seems a bit large, no need to have the exit area larger than the cone's SD.
Thank you. That's exactly the kind of advice i was hoping for.
The Sd is 506.7 sq cm. I'll calculate that aperture within a margin over that for comfort and see how much smaller it makes it. That should help me reduce the depth of this sub as well since it started out as a very deep 21 inch file cabinet.

Found the cabinet at my favorite thrift, St. Vincent DePaul yesterday.
Ten dollars.

It's solid oak. Not one stitch of veneer (edges of all panels are visible). Office file of some sort. Antique, but not of any collectible value beyond what I want to use it for. Nice thing about this really old oak, especially if it's been well preserved over the years by coats of paint and varnish, is that the grain is gorgeous beyond most off the shelf stuff at the big box stores. Not easy to see in this shot, but it amazingly beautiful...

All that needs done is to disassemble, sand off the finish with a vac connected orbital sander, reduce the overall height by four inches, reassemble, slap on a coat of urethane, and this is what it looks like drawn to exact scale along with my present speakers..
It's 3/4 inch solid oak all around. What I'll probably do is build a sub out of 1/2 inch MDF to exact outer dimensions to fit within this cabinet's inner dimensions and glue it within. That solves my sealing, mass, and joint strength issues. Also plan to keep the front hinges and keyhole visible, and put some books and a lamp on top to disguise it better... more invisible bass!

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