How many stacked 816 cabs to get to 40Hz low freq??

[GM]

Greets!

A flown 816 horn has a calc'd F3 around 152 Hz, so the mouth area would have to be doubled 20*log10(152/40) = ~11.595x, or twelve cabs. A true 'tower of power'. I'm not sure how much the combined coupling will lower Fc so they all may have to be tuned lower than their ~62Hz to be solid to 40 Hz.

Unless you already have the cabs though, stacking 817s is the better solution due to the side vents, and add a center divider to each if the parallel wall standing waves are a problem.

GM

[rafaro]

Planning to use 816 cabs for low mids but was thinking if you stack enough of these you could also cover the low freqs and avoided equally bulky and less efficient direct radiator subwoof cabs. Question is how many cabs are needed to get into the forty Hz range??

Really the only real advantage of more compact flown speakers seems to be less size and weight. For example the 2x10" with central tweet horn and the unity. But using stacked 816s down to woofer freqs would negate this advantage at least to me. Any comments appreciated?

[Todd W. White]

You can also stack the Hanuschak-designed 816VI to do this - they don't have the parallel walls like the earlier models, but I agree - use the 817's, or, better yet, go with three or four 210's!

If you cut out the septum's, WOW - they would sound GREAT!

[rafaro]

Appreciate the response guys!

[Murray Keidge]

Hello, Stacking 817's works very well. I will quite often use 6 - 8 817's flown vertically for large arena or outdoor concerts. The 817's are all loaded with 515-8GHP's and are driven by Crown MA2400's.

The LF performance is very impressive with the 817's, however, if you still need real sub-bass then I run sub-woofers that have 2 x 3184's in each 24foot enclosure. It is normal to run eight dual 3184 sub-woofers per side to compliment the 817's.

The system is confiqued to run as follows:

28Hz - 56Hz.

[Murray Keidge]

Hello again, I somehow posted my reply before I had finished, so here it is.

28Hz - 56Hz. 3184 cabinets.
56Hz - 500Hz. 817 cabinets.
500Hz - 5600Hz. 1005/290 horns.
5600Hz - 16 000Hz. 1005/288 horns.

The system delivers the "classic" Altec sound to very large in and outdoor audiences. It has been used to cover 80 000 people for outdoor concerts and has also been used to cover audiences for airshows covering a frontage of 800metres.

The system is driven by Crown MA1200 and MA2400 amplifiers.

If you want to see more of this system have a look at www.cpcproductions.com and go to the Company heading and then Altec Lansing.

Please call if you need any more info on using multiple cabinets.

Murray.

[rafaro]

Murray:

Presently in third world country trying to set up sound for huge reflective indoor hall. Acoustics here are so poor with direct radiators that bands are literally unintelligible. Need very directed horn sound to reduce reflections so looking into the altec cabs etc. Thanks the advice...love your set ups!!!

[Todd W. White]

You are FAR better off fixing the room, rather than trying to compensate with the sound system - do the room FIRST, then design a system that will work well in it.

[rafaro]

Todd no economics to do the room . This is a HUGE room. About 60 foot high and bigger than a tennis court size. Limited budget allows a few highly directed cabs if at all. I am just doing a favor while visiting here.