Coelcanth it looks like there are small bumps that are on the casting I'm sure to line up the castings before they weld them...Am I seeing that right and are they in fact small bumps ? I marked them with small red circles can you confirm this ? Also does the other side have these bumps or just small indentations for the bumps to sit in ? Thanks for the info !
You are correct. There is a small aligning nodule on one side of the casting, and a corresponding void on the other edge.
From what I can see, the two halves of the horn were cast in the same mold and are identical - there are matching imperfections on both halves that idicate this is so, and the alignment features tend to suggest this too.
If you can follow the logic in the above text, it shows that the two identical castings marry together perfectly when one is tipped up and sat atop the other.
Today, we would design the horn on a CAD program, and cut it from billet with a CNC mill to create either our master for molding, or just each individual piece we were making. The crucial inside shape of the horn here must have been hand carved originally (unless someone has another idea how this was done) so it will be hugely interesting to measure the shape for side to side consistency etc.
The aluminium is fairly low grade, very powdery. There is a part of me that wants to have the horn recast in bronze, for fun, and for 'art'. I have grown to find it quite excellent - and am starting to develop an appreciation for the technical skill and creativity that went into the design and creation of it.
Let me say that my plan to even COPY the horn will be no mean feat..... imagine the hours spent making it work in the first place. RESPECT.
Last edited by Coelacanth; June 22nd, 2015 at 03:35 PM.
Fascinating thread! An employee of Altec Lansing in the mid 1950s told me a funny story years ago (which I may have previously told here). A foundry in the L.A. area had been casting 811 horns in great numbers, and also welding the halves together before delivering them to Altec for painting. Some bean counter did not like the expense of the welding operation, and said that Altec could do it cheaper in house. Soon large piles of half-811s were deposited all over the factory, dirt clods still clinging to the parts from the casting process, and the in house efforts at welding proved unsuccessful. Before long the foundry was once again given the task of welding and things returned to normal.
Coelacanth, the initial throat portion of the H811b appears to have been designed to narrow the directivity of the high frequencies to partially equalize the on axis resonse. This is not a great solution for the falling power response of a compression driver, as the on axis response and reverberant field will vary greatly in high frequency content, which our brains interpret as unnatural. I would be tempted to model a horn similar to the 811 where the major flare portion maintains itself back to the driver aperture. The horizontal axis should (as designed) maintain the driver's power response to the limits of the straight horn walls, the driver's falling power response being EQed in the crossover, resulting in a more natural listening result. Just a thought, anyway.
Hi Steve. Thanks very much for your input here.
Firstly, I found this tiny (about 5mm long) maker's mark stamped into the horn - "WD Co". This seems to attest to Altec having at least for a time, outsourced the casting work....
Re your technical observations and advice... I am not even close to having more than a very basic understanding of this stuff.. What I do have is curiosity and some skill with tools and equipment. If there is a better design, more suited to the GPA 902 driver I intend to use in this build, well, I am happy to build it. But someone would have to supply me with plans, because there is no way I could work it out myself at this point.
One of my plans however is to experiment with different horns once I have the 811 copies up and running (along with the rest of the system!), so I am happy to continue as planned with these.
I do appreciate the suggestions - and if you can point me to plans for any horn you deem more suitable, I will gladly take a hard look at them :-)
Check out the A300 radial horns in post #6 of this thread. There are also some comments on the 811 from Steve Schell in post #11.
I've been tossing around the idea of a wood horn for the 802 but, actually, I find very little wrong with the 811 for my listening habits. I have heard better horns that have a more dispersed presentation and a finer sound (large format drivers, to be exact) but the 802 is a damn fine driver and my 811's work all right for me. If there is a next iteration it may be a wood horn with the larger format drivers.
Where on the horn is this stamp ?Originally Posted by Coelacanth
Hi Steve. Thanks very much for your input here.
Firstly, I found this tiny (about 5mm long) maker's mark stamped into the horn - "WD Co". This seems to attest to Altec having at least for a time, outsourced the casting work....
Re your technical observations and advice... I am not even close to having more than a very basic understanding of this stuff.. What I do have is curiosity and some skill with tools and equipment. If there is a better design, more suited to the GPA 902 driver I intend to use in this build, well, I am happy to build it. But someone would have to supply me with plans, because there is no way I could work it out myself at this point.
One of my plans however is to experiment with different horns once I have the 811 copies up and running (along with the rest of the system!), so I am happy to continue as planned with these.
I do appreciate the suggestions - and if you can point me to plans for any horn you deem more suitable, I will gladly take a hard look at them :-)
Thank you gentlemen for helping whip the evil Klipsch virus from my traitorous soul!
Been there, done that, had the moments of glory and the hours of frustration......
Hello all.
Wow... its been a long time between drinks... but I have made it back. A great many things all happening at once really blindsided me and absolutely nothing has happened about this build...
Sadly I lost all of the information I had collated on this project when I switched jobs. I also had several seizures, which do strange things to my memory. So I am basically going to start fresh.
Despite some challenges, there have been some real positives too - one being I have moved into a much larger house, with a workshop. Another is the new work environment - filled with useful machinery - enourmous lathes and CNC mills etc. - some of which I operate.
Here is where I am at:
1) I want to build Altec 19's or an MLTL derivative. I will buy GPA drive units and import them..
2) I have the 811 horn which I can copy - or I can make better horns if someone can share a plan with me.
3) I had decided to use an upgraded XO network designed by Zilch. The XO was going to be used if I built replica 19's but I cannot recall if I was going to be able to use the same same design in MLTL cabinets.
I'm going back through posts and pms.. but if anyone can point me back to the road regarding the XO issue and a suitable wooden radial horn design for the GPA hf unit, I would be humbled and truly grateful.
I will get back on track with this and i will share here. Thank you all.
WOW.
after reading your post I would like to say. i'm sincerely glad to see you back.
everyone is still here. so it's a matter of reorienting and mapping new pathways.
Sonic Barbarian
Bookmarks