811 Fins

[robertbartsch]

Interesting flyier from Western Electric.

In the olden days, the Lansing companies ads touted design features such as edge-wound coils, machined top plates, alnico mags, cast not stamped frames, etc. and also used to discuss technologies adapted from Bell Labs and Western Electric.

Does anyone know if either Bell Labs or W.E. held the original patents for edge-wound coils, alnico motors and the like in these early designs? The histories of both Lansing companies that I have read recently don't cover these points.

[bfish]

Does anyone know if either Bell Labs or W.E. held the original patents for edge-wound coils, alnico motors and the like in these early designs? ...

Short answser, no, they didn't. Edgewound flat-wire coils were patented for rheostats several years before Wente's (Bell Labs) first use. Wente's patent was also preceded by another for loudspeaker voice coils.

AlNiCo is really a trade name for a permanent magnet material, so the patent(s) for it refer to the blend (ratio of aluminum/nickel/cobalt) and process (cast/sintered) rather than the trade name, but Bell still wasn't the first.

[RonSSS]

No, personally I don't recommend completely removing the vanes unless a super tweeter system is used, preferably horn loaded, though I've auditioned small piezos arrayed around the bell that worked quite well too.

GM

With the M19 xovers, the extreem hf is not an issue, even to my ears.

Ron

[RonSSS]

I would leave it. The reason is if Altec went through the trouble to put them in, there must be a reason. It is probably there as as a method of stiffening the horn.

Not!

[RonSSS]

So, I presume the sand and latex paint will work equally as well on the 511 horns. I understand the 511's ring worst than the 811's. I have not had the ringing condition on my 511's but, I would like to know of a remedy should ringing occur.
Thanks...

Sand and latex about, 7 coats make either dead like wood. I don't care how hard you screw it to the baffle, or cut the middle of the ribs and replace with RTV...they don't come close.

Ron

[Steve Schell]

Today I was measuring some drivers, a stock TAD 4002 and a JBL 2445J with 375/2440 diaphragm. I took measurements on both an AMPEX D-6970 cast aluminum 90 degree horn (equivalent to a JBL 2350) and an early Lansing H805 tar filled horn from 1936. One think that surprised me were the cumulative spectral decay (waterfall) plots, which in every case looked very clean and well behaved with the Lansing horn and really messy over a wide frequency range (slow ring down) with the undamped aluminum horn. These results are enough to make me take pains to damp any aluminum horns used in future projects as well as possible.

[Panomaniac]

..... clean and well behaved with the Lansing horn and really messy over a wide frequency range (slow ring down) with the undamped aluminum horn.

"Surprise, surprise, surprise!" Gomer Pyle, USMC.


Here is an old trick that can help, tho it might be redundant if you've already damped the whole horn. Get a pair of Ace bandages. The elastic type you wrap around a sprained ankle. Wrap them around the throats of the horns. Strangle 'em good. (511E got no throat). This helps. There is a lot of energy in that small space and when it rings, it comes right out the mouth.

Cheap, easy and completely reversible. Just looks goofy.

[sba2]

Steve?s measurement confirms the delayed ringing that I had noticed after tapping on my un-damped aluminum 511s. Since the vanes seemed like the biggest offenders, I decided to remove them. Clasping two of vanes firmly with one hand would stop most of the ringing?and I thought, these things have to go.

However, once gone, the horn still needed damping. I ended up using self-adhesive roof flashing, first wrapping all the sides behind the mounting plate, and when that wasn?t sufficient, the lips in front of the mounting plate. Afterward, I used a razor to make a bunch of crosscuts in the flashing, and then used a propane torch to warm up the flashing and make it comfortable on the horn.

The mounting plate only dampens the ringing about ?? on either side?so, whether it?s secured or not matters very little.

[All of this was a hard, loud, PITA, five-hour job, so I can?t really recommend it.]

I didn?t know about the extended HF black hole. When I get the system running again I?ll look into that.

"Surprise, surprise, surprise!" Gomer Pyle, USMC.

LOL

[RonSSS]

The sand and Latex paint works VERY well. It's a great summer day project.
Just be sure to mask the mounting surfaces so the horn will go back in it's orig location.
I'm telling you, I've done 3 sets, and the end result is dead like wood, hardwood!

Ron

[SOOTSHE]

The sand and Latex paint works VERY well. It's a great summer day project.
Just be sure to mask the mounting surfaces so the horn will go back in it's orig location.
I'm telling you, I've done 3 sets, and the end result is dead like wood, hardwood!

Ron

I can vouch for that! I've just finished mine & they are completely non resonant now. I applied 6 coats of paint with sand & then 2 more top coats of paint to seal all that sand in. Went through 1 1/2 litres of paint & I'm not sure how much sand, but I can tell you they are a LOT heavier now.

I'd estimate that the coating is almost 4-5mm thick!!

The photos give some idea of the thickness......I used a litre of white paint for the first 4 coats & then another 1/2 litre of black for the 5th & 6th coats, so you can see the first 4 white coats after I've peeled back the masking tape. I'll just tidy up the edges with some black later.

Just got to give them time to dry right out & I'll report on any differences in sound quality.