View Full Version : Altec 511 / 811B

07-31-2006, 08:07 PM
What is the difference between the Altec 511 / 811B sectoral horns?


07-31-2006, 08:15 PM
size matters :D

511 is larger. Other than rare E-suffix 511 units, all I've seen (811 and 511)
are two bolt 1" inlet horns. Check out the Library section here...


Steve Schell
07-31-2006, 09:36 PM
The two horn types are of very similar design; the main difference is that the 511 loads the driver to 500Hz., while the 811 loads the driver to only 800Hz. Both horns need a crossover points of these respective frequencies (or higher) to protect their drivers. The 811 was made earliest, and replaced the H-808 multicellular horn in Altec's lineup.

There are variations within type. The original 811 (1952) was a one piece casting and had mouth fins that bowed outward. It was soon replaced by the 811A, a two piece welded design. Later the A was replaced with a cost-reduced 811B, thinner and lighter in weight. As far as I know the first 511 was the 511A, later replaced by the lighter weight 511B.

Both designs are basically radial horns, though they have initial throat sections that create some on axis beaming of high frequencies. Many people feel that the 511 series sounds quite a bit better than the 811 series, even apart from its ability to load down to 500Hz. These are all cast aluminum horns, and benefit sonically from damping of their exteriors. A couple of ziplock bags of sand placed on top is a good start.

08-01-2006, 10:29 AM
Thanks for the info guys!