Fiberglass multicells?

**scharron** · February 4th, 2011, 11:14 PM

Hi Guys,
was wondering if any company ever made a good copy of a 511 horn out of resin, plastic or fiberglass, specificly without the vanes? I have seen some stuff that looked very close to that shape and curve, but wondered if anyone did a good one that you could mount small format drivers ie 802s and such on. There has always been a lot of discussion here about curing horn ringing and also the better dispersion patterns at closer listening positions that this design seems to deliver.
just wondered if any of the sound guys here had seen such a thing. some of the old JBL stuff was very close.
thanks,
scott in nc

**SD-50** · February 4th, 2011, 11:58 PM

Adding to the question, any made from hardwood? Might be an interesting project for myself.
Cheers

**Old Guy** · February 5th, 2011, 07:43 AM

The 511 isn't a multicell. I call it a radial, it is without the dividers, which lead Altec to label it "sectoral"

But friends and I tooled up in the 70's and made fiberglass ones without the vanes.

As far as getting a set , probably hard. We only made a couple hundred sets, some 35 years ago.

There are lots of similar fiberglass horns...

**bfish** · February 5th, 2011, 12:43 PM

Originally Posted by Old Guy

... it is without the dividers, which lead Altec to label it "sectoral" ...

OT:

I't's been my impression that the term "sectoral" indicates the intended (theoretical) radiation pattern of the horn.

In theory, an omnidirectional source radiating into free space is analogous to an expanding sphere. Using a device such as a horn to concentrate the radiation directionally can produce a pattern that can be considered a "sector" of that sphere, hence "sectoral".

I know some types of RF horn antennas have been classified as "sectoral" for this reason (none of which utilize any fins or dividers). I've not seen any backup for this as Altec's intention, though it stands to reason enough for me to accept it...

**Altec Best** · February 5th, 2011, 01:36 PM

Originally Posted by scharron

Hi Guys,
was wondering if any company ever made a good copy of a 511 horn out of resin, plastic or fiberglass, specificly without the vanes? I have seen some stuff that looked very close to that shape and curve, but wondered if anyone did a good one that you could mount small format drivers ie 802s and such on. There has always been a lot of discussion here about curing horn ringing and also the better dispersion patterns at closer listening positions that this design seems to deliver.
just wondered if any of the sound guys here had seen such a thing. some of the old JBL stuff was very close.
thanks,
scott in nc

I think JBL's Bi-Radial horns is basically a 511 without the vanes.Forget the model # as I'm not a JBL guy !

**bfish** · February 5th, 2011, 01:46 PM

Originally Posted by Altec Best

I think JBL's Bi-Radial horns is basically a 511 without the vanes...

Not really;

Flat-Front Bi-Radial? Horns -- 2380 Series

Bi-radial horns have radial expansion in both axes. Altec sectorals are only radial in one axis, and if you factor in the preliminary vertical "neck-down", not really that.

Radial 'glass/plastic horns are pretty common though, by several manufacturers. EV's HR90 is ~pretty close.

**Altec Best** · February 5th, 2011, 05:57 PM

Thanks Bfish ! :2thumbsup:

**Old Guy** · February 5th, 2011, 10:16 PM

Out of curiousity started digging..McGraw-Hill's Scientific Dictionary sez:

(′sek?tə?rəl ′h?rn)

(electromagnetism) Horn with two opposite sides parallel and the two remaining sides which diverge.

Altec horns certainly don't fit that definition. Dunno.

Webster's comes up with...

Sec?tor`al
a. 1. Of or pertaining to a sector; as, a sectoral circle.

Whatever that means ...

But then...TheFreeDictionary sez

sec?tor (sktr, -t?r)
n.
1. Mathematics
a. The portion of a circle bounded by two radii and the included arc.

The mathematics A definition sounds likely to me. Which would be a radial horn.

We may never know why Altec referred to them that way. But then what's the fun of knowing everything?

**scharron** · February 10th, 2011, 07:27 PM

Hi Guys,
thanks for all the replies. good info here. just seems like there has been a lot of talk about vanes and trying to deaden the 511 and 811 horns and I was just curious if some one had taken it to another level and found and/or installed some other horns in their various altecs with any degree of sucess or satisfaction. not sure I would want to do it to my maggies but possibly in the home theater A7s. thanks again guys.
scott in nc