Query on 299-9A

[ngccglp]

Hi,

Anybody know whether the 299-9A driver can be used with a 511B horn? Do I need a special adaptor?

Thanks

[bfish]

As you likely know, the 299 is a large format driver (1.4", 3 OR 4 bolt), and the 511B is a small format horn (1", 2 bolt). There is a small-to-large adapter, but it's meant to be used the other way=sf driver to lf horn. You could turn it around, and your 299/511 will bolt up, but you won't like the results. There was a 511 horn (A or C?),with a 1.4" throat, but they're VERY rare, I've never seen one, and have only seen 2 singles on eBay in 3-4 yrs. A 511B looks like it could be line-bored to 1.4" and you could weld on a 3-bolt flange, but I can't help but feel if the 511 horn was suitable for large format drivers, they'd have made a bunch of them set up that way......

The large format Mantaray horns are THE ticket for 299s, and the MRII594 is approx. the same dims as a 511, and is also 90x40, but is a superior performer, and doesn't 'ring'. They aren't as common on eBay as 511s, but don't usually cost a whole lot more. If interested in an MR horn, check with Todd, as Iconic may have new ones.

[hmole]

I was told it was an 811G with the 1.4" opening.
On the Lansing Heritage Site the library section has the listings for all the horns, go by date and pro gear, the manta ray horns start somewhere around 1980.
I think you want the medium format, I am going to try the mrII 5124. Todd White said he had one he wanted to part with.
The 299 start to drop off a bit before 500HZ as far as I can tell.

[Steve Burger]

Email Jim D. and he can give you some direction on how to shorten the 511b horn and make it into a 511e.

[bfish]

I had believed the 511E was the same casting as the 511B, with a modified throat and mtg flange, but after checking the dims on the cat page GM linked to, I stand corrected, as they're entirely different beasts;

511B - 23-1/2 x 10-5/8 x 11-1/2
511E - 25-3/8 x 16-3/8 x 17-3/4

So, if those dims are correct, there's no way to make a 511E from a B, but I'd be curious how a modified B would perform with a LF driver.

Was the 511E used on the first A5s, and if so, was that its' only OEM application?

[bfish]

Looks like at least part of the B dims on the '78 Pro cat page are a typo, perhaps the E is incorrect as well.

[GM]

Greets!

Never heard of an 811G, the only small format sectoral horn that's suitable for large format drivers AFAIK is the very rare 511E: http://www.lansingheritage.org/image...pro/page13.jpg

GM

[GM]

Greets!

Yeah, the 'B' dims are bogus and I don't have a clue what a 511 'A' is or what driver it would use. Unless someone has some definitive data, I'm going to assume that at least this portion of the catalog was put together either by someone unfamiliar with the subject matter, or considering the times, 'stoned out of his/her tree'.

I've only seen pics of the 511E, and not very informative ones at that, but from a design POV, the first section of a 511B is a vertical linear slot expansion to ~control the driver's HF BW's pattern (aka 'rubber throat'), then it 'necks' down to a radial expo expansion to get the rest of its BW's gain/dispersion. Increasing the throat area/shortening the initial expansion lowers this transition's corner frequency and raises Fc. The larger driver has more acoustic efficiency though, so can still be XO'd at 500 Hz.

Also, since the initial round to slot transition will be compromised, there will be reflections back to the driver's throat that will wreak havoc with whatever HF response it still has and I assume it will also affect the rest of the horn's response to some extent like it does when square or rectangular throat lens are used. Hopefully, Altec completely redesigned this section to smooth it all out.

I don't know what the 511E's primary app was (assuming there was one), but the A5 was part of the original 'A' series line-up http://www.voiceofthetheatre.com/ima...att1945.10.jpg with several different versions over the decades, so began well before the 511 series lens was introduced in the '50s.

Anyway, chopping up serviceable 511s seems like such a waste, but at least enough of them have survived that's it's not a great loss.

GM

[bfish]

"Unless someone has some definitive data, I'm going to assume that at least this portion of the catalog was put together either by someone unfamiliar with the subject matter, or considering the times, 'stoned out of his/her tree'"

LOL! Yeah, the Nixon days (shudder)........Hunter Thompson revisited.....Fear and Loathing in Anaheim.......multiple screw-ups on that page, they even called a 32B a sectoral....

I see no sense in chopping 511s either, especially since superior large-format alternatives are available and affordable.

[GM]

Greets!

Yeah, I view it as a keen insight into where Altec's 'head' was at by then.

I just remembered I must of had a 'quickie' audition of what had to have been 511Es in some big 288 horn dual woofer loaded floorstanders around this time. In retrospect, the cabs were big, but I don't remember them being big enough to house any of the big horns. They sounded pretty good overall as I recall, so it had to have been a fairly decent conversion if they were 511Es. Didn't get to see them though as they were waiting for a truck to pick them up and I was in a hurry to get my parts and 'boogie'.

Mostly, I recall the 'slam' of a pair of these strapped to palettes sitting on a concrete loading dock with Janis Joplin drowning out Piedmont Rd's rush hour traffic (one of Atlanta's major divided hwys.) ~1/4? mi away as I rode up

Hmm, maybe I need to keep an 'eye out' for a pair........

GM