80-800Hz Ideas on the right Altec solution

[Steve Mac]

Hi-Fidelity and power...those are the requirements. I've got the right sub-woofers and I'm loving the 511Bs. I think the next step is something like the 817a. Not sure if it gets down to 80Hz...I talked to Bill at Great Plains and I thought he said they started rolling at 100Hz...but they might need to be EQed. I want something I can crank but will not suffer my cravings for rock n roll... 80-800...I mean this is a pretty important area and I don't want a lousy PA sound...I want this to be right. What do you guys think? My area right now is 24x28 feet with 9 foot ceilings and I'm moving soon but I'll be looking for an area around this size. I want the guts right...ya know the horns and the cabs and over time upgrade but this is the next step.

On another note the Behringer DCX2496 sounds good. Good enough that I thinking I'm gonna bi-amp everthing. Henry engineering makes this digimax 2x6 digital box that will allow me to take s/pdif out of the studio and feed the digimax which then can distribute the digital properly via aes/ebu to multiple behringer boxes. Run mogami cables all over the studio...it just sounds slick doesn't it? The maggies...the duplexes...the big horns...all fed from a single s/pdif stereo.

[GM]

Greets!

Dual 515Bs in modded corner loaded 210 horns were fun and what it takes horn size wise to get to 80 Hz without a corner, but ultimately just by themselves works best overall, so the parallel walled 817 won't cut it either IMO. That said, no big cone driver is going to tonally match to a proper compression driver, especially when asked to go to 800 Hz, so you'll need at least four alum. loaded 288s on a large custom low gain horn/channel; and while you're at it, might as well load the 1" on the end Unity style for coincident summation and shuck the 511. It will be 5+ ft long with a ~4 ft square mouth, so might be too tight a fit unless the room's length is 28 ft. Get this layout dialed in though and I doubt you'll ever feel the need to upgrade.

GM

[Steve Mac]

Fascinating...thank you so much for responding!

Originally posted by GM:
Greets!

Dual 515Bs in modded corner loaded 210 horns were fun and what it takes horn size wise to get to 80 Hz without a corner, but ultimately just by themselves works best overall, so the parallel walled 817 won't cut it either IMO. That said, no big cone driver is going to tonally match to a proper compression driver, especially when asked to go to 800 Hz,

<font size="2" face="Verdana, Helvetica, sans-serif">How about 700? 600? 500?

...so you'll need at least four alum. loaded 288s on a large custom low gain horn/channel; and while you're at it, might as well load the 1" on the end Unity style for coincident summation and shuck the 511.

<font size="2" face="Verdana, Helvetica, sans-serif">talk about this some more...it sounds interesting...if you could

It will be 5+ ft long with a ~4 ft square mouth, so might be too tight a fit unless the room's length is 28 ft. Get this layout dialed in though and I doubt you'll ever feel the need to upgrade.
GM

<font size="2" face="Verdana, Helvetica, sans-serif">I don't mind big...I'll bust the wall out if I have to. What would something like this look like?
Sketches and jpegs anyone?

[GM]

Greets!

You're welcome!

With a 32" throat height, the 1st standing wave will occur at ~13,560"/2/32" = ~212 Hz, so the XO will have to be well below the horn's BW! If you mod it with a slope baffle like on the 825/828 the problem goes away, but you still can't get to 80 Hz ~flat without shelving all the horn gain away: http://www.lansingheritage.org/image...515g/page3.jpg

Truth be told, it was a 'tongue in cheek' response since you wanted an Altec solution and the cost of doing it this way would be so expensive/complex. It would be more cost effective to buy a pair of Steve's big RCA style midbass compression drivers in lieu of all the 288s or do it in the true Unity concept way of purpose built midbass BP units. If you have 'deep pockets', serious enough, and have test gear that actually measures acoustic phase and not just derive it, then I can come up with the basic dims for you to prototype/refine it through measurement and electronic EQ or you'll need a good passive XO optimizer that will allow you to load the actual measurements to work from, like LspCad. If you're serious and want it done right without all the extra work, then contracting the Unity's inventor, Tom Danley to do it is the way to go, assuming he's willing of course.

Done right, a Unity concept is no trivial pursuit and in retrospect, a single 1" CD on the end of such a large horn may roll off its HF response too much without going to an expo flare, which defeats some of the purpose of the Unity. Note that he designed these while at ServoDrive and now has his own business, so there's multiple models under two brands, but the same patented technology:

patent: http://patft.uspto.gov/netacgi/nph-P...anley-Thomas-J

A three way Unity, yours would be without the woofers and ideally with a square expansion: http://www.servodrive.com/SPL-td1.html

A new forum for DSL products: http://www.danleysoundlabs.com/forum/category-view.asp

He's posted extensively on the Unity over on the HE forum, so do a search for tomservo: http://64.154.92.195/scripts/etv.pl?forum=hug

Here's an ambitious DIY Unity concept thread for a car app with some good 'hands on' info, which also has pics of an original 300 Hz Unity in a HIFI app plus a scaled section rendering of it: http://www.audiogroupforum.com/csfor...ad.php?t=62789

There are other threads on various forums, but these should be informative enough.

GM

[Steve Mac]

Um, GM...uh...uh...okay I was stunned by what Danley and the rest of the engineers over at sound physics did with the spl-td1...the concept of multiple drivers in one horn like that is new to me. I've coarsed through multiple forums extracting info. Thanks, I punted my ambitions this evening. I have to hear one of these systems. Building one of these...it seems to me that it would make sense to forget the 511s if I were serious and go after the "point source". Any idea what a pair of spl-td1s are either new or used? What I wouldn't give for the dimensions of one of those boxes. Seriously thanks for the info...a real eye opener!

[BoydB]

I also desired 817A's but opted for 2 pair of 816A's, which allowed for an MTM arrangement. A stacked pair of 816A's are the same dimensions of the 817A. Neither the above would have the LF impact of either GM's suggestion of the 210, or as I did was to mount the Altec 815A (3/4's the size of the 210) in the wall and port the bass entering the room below the cabinet.

Boyd

pics of Altec 816A's in MTM arrangement
& 815A's mounted in the wall.
http://www.wmeckle.com/BOYD/Boyd.htm

[scott fitlin]

WOW, that MTM arangement looks outtasight! How does it sound? Amazing, Im sure!

I like what you did with the 815,s too, very creative, and looks factory finished, Bravo.

I have 817,s in my system, I also have four 816,s and two 815,s! I`m a big fan of the small, but punchy character of the 816.

My corner loaded 815,s have the most midbass punch out of the bunch!

What a wonderful job you`ve done with your Altec speakers!

[Steve Mac]

Back to topic...why couldn't I use a compression driver and a big horn for this project? Why would speakers be better? I have a pair of EVM12Ls I could sacrifice for this project or would be okay buying a pair of drivers but I need a big sound that's all "horn" and don't care about the size. I'm thinkin I've got the subs ...I've got the 511s...I just need to finsh this system and fill it out.

[GM]

Greets!

Like I said, you can, with either a single huge expensive driver or a number of smaller expensive drivers. Relatively wide BW cone drivers aren't designed to be compression horn loaded, sounding their best as dipoles or in large boxes. If you want to go traditional horn design, then mildly compression loaded dual 515Bs in radial ~90 x 40 expo horns will be a decent match to the 511s. Basically it would be a reshaped 210 horn section with a sealed rear chamber.

GM

[Steve Mac]

Originally posted by GM:
If you want to go traditional horn design, then mildly compression loaded dual 515Bs in radial ~90 x 40 expo horns will be a decent match to the 511s. Basically it would be a reshaped 210 horn section with a sealed rear chamber.
GM

<font size="2" face="Verdana, Helvetica, sans-serif">I think this is a good idea. I was thinking to get new speakers from Bill...I could restore some but I'd to see his business grow. If yer half into helping get me started I would be forever indebted...especially in understanding and documenting the technical elements. I'm in the process of moving...but I have time to draw up plans...commit them to nice architectural drawings...probably learn a great deal in the process...I've built many a sub-woofer but this is uncharted...albeit potentially intriguing and fun...journey into classic audio.

I'm listening to a beautiful CD track tonight... "Fare Thee Well Northumberland" off Ragpickers Dream by Mark Knopler. The lyrics are saying "roll on georgia boy"...and yer from Georgia, right?