Box for 2213H

[Hans]

Please give me some ideas about a proper box and vent for 2213H. The smaller box the better. I´m going to use it for PA. I need internal net volume and vent length and internal area. Also interested in tips about lining(?) (stuffing)??.

Hans K
Sweden

[GordonW]

Please give me some ideas about a proper box and vent for 2213H. The smaller box the better. I´m going to use it for PA. I need internal net volume and vent length and internal area. Also interested in tips about lining(?) (stuffing)??.

Hans K
Sweden

Minimum of about 2.5 cubic feet (~70 liters), with a 4" (100mm) diameter round port/vent, 10 5/8" (~27cm) long. This will give an Fb of about 35 Hz, and an f3 (low frequency rolloff point) of around 36 Hz.

Line the box with about 2" (50mm) thick fiberglass insulation, on all sides except the front panel. No other stuffing should be required.

If necessary to get the port length into the box without infringing on the rear wall, you can use a pipe elbow in the length. Just make sure that the TOTAL length, INCLUDING that through the centerline of the elbow, adds up to about 10 5/8", or 27cm.

Regards,
Gordon.

[Hans]

Thanks Gordon!

The L-100 and the monitor has a volume of around 44 liters!? Why do you recommend nearly twice as much?

Hans K

[GordonW]

The 123A (alnico) and 2213 (ceramic) actually want FAR more air volume than even 2.5 cubic feet, to behave optimally. In fact, the S70 Alpha (which used the 123A-1) was MUCH closer to optimum at about 6 cubic feet (170 liters, plus or minus), with a passive radiator- and went very close to 20 Hz on the bottom end. According to most box programs, 10 cubic feet (284 liters!) isn't out of line!

Those drivers are relatively high Q- IIRC, the specs for all the 123A/123A-1/123A-3/2212/2213 models are all in this approximate range:

Fs= ~25 Hz
Qts= ~.49
Vas = ~ 4.5 cubic feet (~128 liters), IIRC.

Run those numbers, you'll see... in a big box, they go LOW. But, in a box more along the size of 2.5 cubic feet (70 liters), they will handle more power, and will still give good bass "whomp". A good compromise for high-power application.

I currently have a pair of 123A-1 drivers in about this exact cabinet- 2.4 cubic feet (66 liters, plus or minus), tuned to about 30 Hz with a 4" diameter, 8" long port. They definitely do have prodigious output, and don't require a lot of power to do it! Not "hi-fi flat" exactly, but lots of bass slam. Just the ticket for DJ/small PA...

Regards,
Gordon.

[Zilch]

Illustrating that driver's capabilities in big boxes, Gordon's design for a TCB isobaric sub using 123A's is here:

http://audioheritage.org/vbulletin/s...t=3922&p=36262

Maybe build THAT instead!

I know, I know,

[Be neat if someone built it though....]

[Hans]

Thanks Zilch, very interesting! But, now it's PA we're talking about. Gordon, in this case size matters. I need a small box with a 2213 and some small mid-hi driver-horn. The bass will be taken care of ( if needed ) by a 15" sub. So please give me the data for a smaller box. And, of course, the power handling is of great importance.


Regards
Hans K