Making 511E horns from 511B horns

[BillWojo]

Ok, I know all about the factory Altec 511E horns (at least I think I do) where they cut the flange off and shortened it to fit larger flanges for the large format drivers. There is even a drawing some where that shows it needs to be shortened by 2.2" so the the horn interior is 1.4".
I already have a very nice set of 511B horns that I want to keep stock so I started looking and found a single 511B that was local for 75 bucks. Going to grab that this weekend.
Those of you that have played with the large format drivers on the 511E horn, can you tell me what to expect compared to the 511B with the smaller drivers.
I would be experimenting with 291-16K drivers with the symbiotik daiphragms.
I know I will be down in the higher frequency ranges but overall is it worth the time and trouble to build these?
I hate to cut up a good set of horns to do this but the chance of finding a set of 511E horns for cheap is slim to none.
I have the machining skills to pull this off and one of the fellows that hangs out at the race shop is an outstanding welder. I had a chip on the lip of one of my 511B horns, about 3/4" long and a 1/2 deep. He welded it up and blended it in to the stock contour so well that after painting it can't be seen. Needless to say, I was impressed.
So is this going to be a nice improvement or am I chasing a silly idea. I'm not even sure what Altec sold those horns for, seems the 311 horn would be a better match. They seem to go for stupid money though.

BillWojo

[Elitopus1]

I had a pair of 511e horns for about a month. I ended up flipping them because I didn't have any large format drivers at the time. They were factory horns with thick aquaplas coating. The welds on the flange were very sloppy. I was not impressed with the construction. It looked like they just cut a 511b and welded on a 3 bolt flange. I am sure anyone with even decent fabricating skills could do a better job.

Sorry I cant help out with the performance of them. I didn't have any large format drivers at the time and ended up selling them for 10x what I paid.

If you end up making some you could build some "Rodspeaker" clones

[GM]

I'm not even sure what Altec sold those horns for, seems the 311 horn would be a better match.

For a big bada$$ studio monitor to ostensibly replace the A7 series. Note its 700 Hz XO point: http://www.lansingheritage.org/html/altec/specs/pro-speakers/9848.htm

GM

[Elitopus1]

For a big bada$$ studio monitor to ostensibly replace the A7 series. Note its 700 Hz XO point: http://www.lansingheritage.org/html/altec/specs/pro-speakers/9848.htm

GM

So dual 411 woofers with a 288E driver on the 511e. Those look pretty cool! Are the 288E a ferrite or AlNiCo driver? I am not familiar with that model.

I was also wondering why they made the 511e. I bet there were not that many pairs made.

- - - Updated - - -

So in doing some quick research it looks like the 288e is basically a 288c with a different diaphragm.

[GM]

Correct, if it ain't broke.....:

https://web.archive.org/web/20070106173839/http://www.wmeckle.com/INTRO/LARGE/Altec.htm

https://web.archive.org/web/20070106071344/http://www.wmeckle.com/INTRO/SMALL/Altec.htm

http://alteclansingunofficial.nlenet.net/Diavc.html

GM

[BillWojo]

Those "Rodspeakers" look like they would be cool but I don't have room for anything like them.
My idea would be to place them on my AS101 cabinets and use them instead of the 811/902 combo. I just have no idea of what to expect and if it would be worth all the hassle of building these.
I'm hoping that the shims come in tomorrow so that I can install the diaphragms in the 291-16K's. I'll take them over to my friend Davids house and hook them up to his EV horns. These are huge 3' fiberglass monsters that apparently were designed by Don Keele just before he left EV and went to JBL. That should give me a good sense of what they sound like. He is more excited than I am over this, they will go on loan to him for awhile as he integrates them with his big JBL bass bins. It will be very interesting to see what he comes up with.

BillWojo

[BillWojo]

Just an update, those big drivers worked well on the HR9040 EV horns. Those things are bigger than I remembered, about 40" across the exit flange! I left the drivers with David to play and tweak to his hearts content.
So far I picked up one 511B horn to modify, I'll wait till I find a deal on another before I start cutting them. I looked on Ebay completed sales, these things are very rare (511E), what is the value of a completed set and is there a market for them? I know they won't be genuine Altec 511E's but I intend to make them every bit as good or better. Can someone tell me about aquaplast?
Thank you

BillWojo