That old saw: A7 port size

**gearfreak** · February 27th, 2009, 07:40 PM

Thanks for the input GM!

**gearfreak** · March 23rd, 2009, 05:37 PM

Greetings all, and to the dead horse I rode in on and am now kicking. :-)

How critical is structural attachment of the wings to the cab itself?
e.g. is the goal structural attachment, or some maximum gap tolerance between the cab and the 'wing'?

Asked because:
I have other cabs that would well approximate the wing size.
Unless obvious folly, trying them out as such will be my next move.

cheers-

**SD-50** · March 23rd, 2009, 07:16 PM

Originally Posted by gearfreak

Greetings all, and to the dead horse I rode in on and am now kicking. :-)

How critical is structural attachment of the wings to the cab itself?
e.g. is the goal structural attachment, or some maximum gap tolerance between the cab and the 'wing'?

Asked because:
I have other cabs that would well approximate the wing size.
Unless obvious folly, trying them out as such will be my next move.

cheers-

I'm waiting for the paint to dry before I install 10in. wide wings on my A7s, also very interested on any mounting suggestions for the wings.
Cheers

**Panomaniac** · March 24th, 2009, 12:03 AM

Originally Posted by gearfreak

How critical is structural attachment of the wings to the cab itself?

On the pair I used to use (20 some odd years ago) the wings were not very well attached.
Just a few metal L brackets. Seems to work just fine and never caused a problem.

**altec-man** · April 24th, 2009, 04:17 AM

Originally Posted by Panomaniac

On the pair I used to use (20 some odd years ago) the wings were not very well attached.
Just a few metal L brackets. Seems to work just fine and never caused a problem.

Can you remember what the width was of the wings and area size of the port.

**altec-man** · April 24th, 2009, 04:23 AM

Originally Posted by GM

Greets!

Assuming this is the link, then the chart makes certain assumptions that may/may not be the best compromise for your app WRT electronics, room, etc. considerations, not to mention personal listening preferences.

Right, vent fine tuning should be done in the desired speaker position and with wings, if any are used since all these things affect the baffle step's LF corner frequency and typically the best compromise tuning is the one that adds reinforcement to extend the ~flat in-room response. Note that this can result in each channel being tuned to a different Fb.

GM

GM
I've noticed in posts regarding port size you mention that you tuned the 825 boxes lower than the 75 square inches, what port size area would you suggest when using the 416-8B, I've noticed that this has a higher VAS than the Ceramic versions.

GM · April 24th, 2009, 05:49 PM

FWIW, the factory wings were 10" wide (50" total width), but with today's much more extended LF BW capability, wider is always better if in a large room and well away from the rear wall/corners.

I much preferred tuning both the 416A and -8B to between ~ Fs - 32 Hz depending on the room they were in. Ditto my tower (aka MLTL) designs. Per Hasling AFAIK independently arrived at the same conclusion, posting extensively about it on the Sound Practices List (aka joelist): Hasling Audio Systems Denmark

Anyway, using a 5" i.d. pipe, experiment with it 1" - 4" long in 1" increments for low tunings in the ~25-30 Hz BW and dual 5" for ~32-37 Hz, etc. with more tubes. I recommend making a one piece vent baffle and locate the vent(s) down close to the bottom. You don't need to flush mount the tube(s), so leave enough exposed to be able to easily remove it and put some rope caulk or similar around to seal it. Of course the cab has to be sealed up tight for the duct vent(s) to work properly.

GM