PA series horns - usable for Hi-fi?

[dhook17322]

From browsing catalogues, apparently there was an alternate series of horns which were used more for PA use. A current offering on ebay of a 1203 (2 x 6)multicell got my interest. Apparently a 511A is significantly larger than a 511B, and similar with model 31 and 32 horns. These models seem to be rare or not in demand much. Are they of value in hi-fi applications? They seem to go lower in crossover frequency.

[bowtie427ss]

My understanding of the modern (post 1950) Altec horns and drivers is this:

There are 2 basic formats/families, the small format 800/900 series drivers, and the large format 280/290 series. The 811 horn is small format exclusively. I believe the only difference between the 511A and 511B, is that the 511A does not have bolt holes drilled in the mounting flange from the factory. There is a rare bird out there, the 511E which has a 1.4 inch throat and 3 bolt pattern to accomodate the large format drivers. I also think the 511E is the only horn they made in cast aluminum to fit the large format drivers, but i'm not 100% sure of this.

Most of the large format multicell horns are useable down into the 300-500hz range. The 511, altho claimed to have a 500hz cutoff frequency, does not do well much below 800hz in my opinion, but i've not looked into this enough to see if the limitations are caused more by the horn or the small format drivers. I haven't had the pleasure of hearing a 288/511E combo yet. Due to the cost and limited availability, there isn't much large format inventory in my hi fi stable.

My guess would be that Altec didn't "purpose build" the horns and drivers, so much as they tried to offer consistent performance/fidelity over a very broad range of products to accomodate an even broader range of applications, from home audio systems to sound reinforcement in the largest of stadiums, with their mainstay being theater sound.

There are others on this board who can give you much more specific technical details, but in my opinion the large format horns offer a significant fidelity advantage in that they are relatively non resonant, whereas the cast 811's and 511's ring like cowbells.

[Old Guy]

The 300 cycle muticells were often used for PA use. They were also used for HF use, no problem either way.

The 511 A abd B are the same size AFAIK. The E is indeed rare, many advertised as E's on Ebay are butchered A models.

Altec made a number of cast horns for 1.4 drivers.

The original 311 (no suffix) is bigger than a 90 and I believe later became the 329- I am not sure of this but at least one other person shared the same thoughts with me. The 329 is also cast.

The 311 60 and 90 are cast.

Lastly the 31- it was mostly for PA use, many considered it low fi. I have never tried it just because so many looked down on it, so I can't say for sure how well it worked. It is cast.

Stay away generally from screw on drivers. And horns that have folds in them.

If yoy have to have a screw on driver get an adapter and use a regular small format. The design of most screw on drivers causes them to be higher distortion. Not the screw on design, just their construction.

Some of this is opinion, your mileage may vary.

[LICORNE]

Hi,

Concerning the 32 horn used in the A8 model VOTT.

This was a great speaker for small halls and venues.I would not under estimate it's capacities.
I had 6 A-8 for live sound " out of this world".

I used 4 with a mexican band MARIACHI.
They play mostly Mexican folk music on their
big guitars . They couldn't believe it themselves.

Combined with the 416 woofer inside the A8. You got yourself HI FI speakers.

http://www.mexconnect.com/mex_/guadalajara/marhis.html

....................................

[just me now]

regarding the screw on driver/horns...

have you ever had a chance to play with the ones pictured here...

http://www.audioheritage.org/vbullet...hlight=Frazier

I am curious about them...

[Old Guy]

At the risk of angering those posters there who love them- I think they are junk. The driver is an Atlas Sound. Or at least has been in every Frasier I've seen.

Atlas drivers at best rank as mediocre.

Virtually all high quality manufacturers locate the diaphragm behind the magnet. PA drivers including Atlas locate the diaphragm in front.

I'm not a speaker engineer and not claiming to be. But every paper I have read says that's the bad way to do it. Results in much higher distortion.

If somebody has them and is happy- fine. I wouldn't buy them except as a collectible. And wouldn't pay much. I could build something much better with little effort.

[Old Guy]

Originally posted by CONVERGENCE:
[QB]Hi,

Concerning the 32 horn used in the A8 model VOTT.

QB]

<font size="2" face="Verdana, Helvetica, sans-serif">Agreed the 32 is a good horn. I was addressing the 31.

[dhook17322]

The main reason I was curious about the PA series is the dimensions of the 511A from the 1975 catalogue:Horn and Throats (1975)
The catalogue lists the 511A as 18 1/2" high and 17 3/4" deep and 8 lbs. heavier than the 511B. It also lists the 511E as also of similar size, much wider and longer and 8 lbs. heavier than a 511B. The 1978 catalogue lists the same dimensions. Has anyone seen these?

[bowtie427ss]

I think some of those dimensions may be incorrect, if you look at the photo on the previous page of the '75 catalog there is clearly not 6 and 8 inches difference in heigth between the "B" horn and the "E" version. I have seen and owned 511's that had no holes drilled in the mounting flange, a local "altec expert" told me they were 511A's(that may have just been his opinion). I have not seen 511E in person. Since they were intended for a driver that weighs 30lbs, common sense tells me they were probably made from a thicker/heavier casting, certainly a different casting to accomodate the larger throat, maybe even a one piece casting like the early 811's. I would also expect the "E" version to have a bit larger front mounting flange to accomodate the intended driver weight. Judging by the illustrated mounting method for the 511A, it seems that a heavier/stronger casting would play a role there also.

I pretty much trust the opinions and information on this board far more than the printed catalogs.

I trust someone will post a very accurate explanation of the differences in the 3 horns.

As has been pointed out before, the engineers and technicians at Altec were generally working on more important projects than making catalogs and advertisements.

[altecjunky]

Im new to this forum and Im not as defined as most of you in are but, I own a pair of the 511b's and I also own a pair of the 511e's. Yes the 511e has that rubber like coating which the 511b has not. The thickness of the metals and such are exactly the same, the 511e is about 1.5 inches shorter(throat length) then the 511b. The diameter of the throat is larger(1.25 inches). All altec did was cut a 511b off and welded the driver flang back on where the throat was more then 1.25 inches! Simple as that!Thats why its slightly shorter then the b series horn. The dementions otherwise are the same. I have a pair of 291-16bs on my 511e's and I to wanted a little more high fq out of them so I played with many different cross overs and ended up keeping a pair of altec 1285-8b and in my opinion a match made in heaven. I have them crossed over at 500hz. I tryed the jbl slots on my system and tryed all kinds of different ways to make them work. In the end the best way to have the slots was to unhook them, they totally made my altec system not sound real, they reminded me of my wife screaming at me to turn it off!! My biggest break through was getting my sansui au7900. This amp has a loudness that not only boost the bass but the fq of 10k which seems to be the fq that this 511e's just sizzle. If want something to make your altecs talk pick up a au7900, on ebay you can get on for around $200.00. Its a by-amp at 75wpc but I just use it as a preamp. Sansui only put this high boost feature in a couple of there amps so pay attention to the model. I hope Ive helped! I want to rubber coat my 511b's has anyone tryed using that rubber guard stuff for cars? PLease help! Thanks