My 19 build begins in earnest - H811b arrives....
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    My 19 build begins in earnest - H811b arrives....

    My 19 build begins in earnest - H811b arrives....
    The 811 I ordered arrived the day before yesterday - all the way from the U S of A to little old New Zealand....



    It is in very good condition - but not for very much longer... Tonight I will split the horn into its two original castings and begin adding 'shape' to the outside of one of these castings, making it more 'copy-able' for my router-based wood copying machine.... I will hopefully end up with four 'sides' copied nearly exactly, which will then be stuck together to replicate the inside of an 811b, and look a little different on the outside.

    I will also make some moulds out of the halves while the horn is apart.

    My darling wife has been a bit against the idea of an audio project, but we sat last night and listened to the tiny speaker from my Samsung S5, pressed up to the throat of the 811 - ok, lets face it, it was pretty low-fi - but that horn magic was very real and present. Imagine what they can do with real drivers? I asked... Now she is eager to find out.....

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    My 19 build begins in earnest - H811b arrives....


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    Re: My 19 build begins in earnest - H811b arrives....

    Quote Originally Posted by Coelacanth View Post
    The 811 I ordered arrived the day before yesterday - all the way from the U S of A to little old New Zealand....



    It is in very good condition - but not for very much longer... Tonight I will split the horn into its two original castings and begin adding 'shape' to the outside of one of these castings, making it more 'copy-able' for my router-based wood copying machine.... I will hopefully end up with four 'sides' copied nearly exactly, which will then be stuck together to replicate the inside of an 811b, and look a little different on the outside.

    I will also make some moulds out of the halves while the horn is apart.

    My darling wife has been a bit against the idea of an audio project, but we sat last night and listened to the tiny speaker from my Samsung S5, pressed up to the throat of the 811 - ok, lets face it, it was pretty low-fi - but that horn magic was very real and present. Imagine what they can do with real drivers? I asked... Now she is eager to find out.....

    I give you an A+ for the ingenuity of getting the Mrs. hooked into your project... Hook,Line and Sinker !

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    Re: My 19 build begins in earnest - H811b arrives....

    So, is this the official DIY M19 speaker build and do you still plan to just basically replicate it or a MLTL instead per here?: Way OT.. an afternoon with some Klipsch's.....

    GM
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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    My 19 build begins in earnest - H811b arrives....


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    Re: My 19 build begins in earnest - H811b arrives....

    Before you get started take a look at this Yahoo Group by Martin King !

    Quarter Wavelength Loudspeaker Design

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    Re: My 19 build begins in earnest - H811b arrives....

    Hi GM, I am still open to the MLTL thing, in fact I would prefer to go that way. Just been waiting for your input.. not sure if you are getting my emails? Perhaps not. I will go the 19 duplicate route if the mltl option is beyond my ability to resolve.

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    Re: My 19 build begins in earnest - H811b arrives....

    Anyone ever seen an Altec 405.5a horn? Well, here you have it!



    Note the grey-green area forward of the throat, no doubt caused by rogue abrasive soundwaves - I believe the previous owner may have owned solid state amplifiers and been a Celine Dion fan.

    But seriously, I wonder what caused that? Its over the paint, rather than paint missing...

    The horn came apart very easily - all welds only superficial - barely penetrating the casting, so as soon as I ground back the bead, the two sides virtually sprang apart. The only notable exception to that was on the mounting flange, where the weld had to be hacksawed.

    The halves are entirely re-usable and undamaged other than light grinding marks - and I cannot see why I wont be able to weld them back together if needed.

    For now I have my 'mothers' to copy in timber. Will keep you posted, if on the off-chance y'all can forgive me for maiming a sacred Altec horn. Its for the greater good. The Greater Good.
    Last edited by Coelacanth; June 20th, 2015 at 06:29 AM.

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    Re: My 19 build begins in earnest - H811b arrives....

    I am going to enjoy this post! Keep the updates coming!

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    Re: My 19 build begins in earnest - H811b arrives....

    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 !


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    Re: My 19 build begins in earnest - H811b arrives....

    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.

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    Re: My 19 build begins in earnest - H811b arrives....


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    My 19 build begins in earnest - H811b arrives....
    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.

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