416-8B Enclosure

[acre]

Hi again folks! I have a friend who just acquired a set of A-7-500's and he wants me to build him a set of domestic enclosures. I have Bass Box Pro and the T/S parameters but I was wondering if anyone has come up with an optimum enclosure design that has proven to be the best, who would also be willing to provide the dimensions. His usage is for home CD listening and extended low frequency is NOT needed because he has a very good PSB sub. Many thanks folks........Lee

[boltupright]

Yeah,,,+1 to what Jim said!!!

[GM]

Greets!

Not a bad plan at first glance, though at minimum I recommend damping the vent as required to get a better blend to the sub. The main problem I've found though with this type of (mis)match is that a typical consumer sub won't have enough efficiency or clean HF BW to XO high enough to blend with a HE system, much less with this high a horn's roll off BW.

That said, I'm not familar with PSB subs beyond browsing what little info is available at their site, so as always YMMV.

GM

[boltupright]

Yeah,,,you would need a pretty decent sub to keep up with the A-7 for best performance, you really can't beat the chest thumping mid-bass you would get from the A-7, but you need a decent size room to get the best of the horn.
JBL 1500 or the 2245 18" with at "least" 600 watts per driver should do quite nicely.

[Jim D]

If the owner does not need low bass, simply rework the A7-500s into furnature. The bass horn in them produces a more immediate, faster, and directed midrange/mid bass than can be gotten from a direct radiator. Spend your time with internal rebracing and exterior covering. Jim

[acre]

Thanks for the input folks! The room is 36 feet long by about 14 feet wide. The listening/sitting area is at one end and the A-7's are at the other. Quite a good arrangement. The idea of keeping the A-7 cabinet with extra bracing and better finish is the ultimate but the concern here is for the size of the footprint. Although this is a huge living room, it is also done in a high class Victorian decor so huge cabinets at one end would be a challenge. For those unfamiliar with PSB, they are a Canadian made sub. The one in question here is only a 12" ported cabinet but don't let size fool you. It responds beautifully with the A-7 configuration. PSB make there own drivers and the SubSonic-6 (the model in question) has a class A 400 watt amplifier. Very warm sound when run with the A-7 and even better if combined with smaller cabinets. Any further ideas for a smaller vented cabinet would be appreciated. Many thanks......Lee

[GM]

Greets!

Well, the components and average ear height when seated dictates the minimum overall cab dims unless a particular height is desired, so assuming these will be covered with grill cloth, depth = horn length + ~1" (25 mm), width = horn width + ~1.5" (38 mm), and height = ear height + 1/2 horn height + ~0.75" (19 mm) if there's no restriction.

Once you decide which vertical alignment you'll use (woofer/horn mtg. orientation), then you can do the plans to calc net Vb for sims to find an alignment that will work with the sub's fixed 80 Hz/2nd order XO.

GM

[steveviso]

Hi,
I've just designed and built an enclosure of about 100 litres for the 416-8z. Fill with insulation it should appear on about 130 Litres. It is a bass reflex, of course, with a Fs at about 25 Hz.
Dimension external are: 440 x 440 x 750 mm.
My goal was to have "small" dimension, I'm living in an Italian house (small), i don't have space of American houses (big) :-) .
The horn is mounted externally, on the top of the box.
I'm now designing and testing the crossover, so the system is not yet finished. But bass extension is very good. And it looks very good, WAF is OK!

You can view a photos on:
http://www.geocities.com/steveviso/a...VISO_4-8-5.JPG

Ciao.

[martyh45]

Howdy,
The optimum enclosure in this case is the one that mates best with your sub. I would look to use the same type of enclosure as the sub, I.E vented on the sub, vented on the 416. If the sub is vented, it would help to know the alignment type. The point is to try and match the group delay through the region where the sub and main speakers overlap. Even in the case where you are using a good xo with adjustable delay, the delay ?curves? of different enclosure alignments are quite variable. A large mismatch such as using a sealed top and a quasi-butterworth (QB3) sub can lead to considerable smearing in the 50~200 Hz region that robs you of the slam you have earned by choosing a high quality woofer like the 416-8B.
Good luck with your project,
M

[acre]

Thanks for the words Marty! Unfortunately, the sub in this case is of high quality and remarkable dynamic output but it only has a 0 or 180 degree phase shift switch, unlike my Paradigm Servo 15 which has an infinite control. I think my best bet is to try to limit the low end to about 80 Hz with a rapid drop off to this F3. (I know it's a waste of such a good driver!) Hopefully the low stuff will stick out while still achieving that nice Altec growl. Regards......Lee