511A large format fake or real ?

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Will the horn tend to change shape in that area if the support is removed?

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Perhaps it returns to the original shape of the castings?

What we don't and will probably never know is whether steps were taken during the welding process to maintain strict dimensions.

other questions that cross my mind are if the support was intentionally oversized to create a structural load and possibly change the resonant frequency of the whole assembly? How was the pillar installed, was it welded to one casting before the two halves were welded together?

This is probably an easy thing to "over-analyze".

Removing the throat brace lowers some of the horn's mechanical stress and improves the HF response due to removing some of the 'slap echo' [AKA Dr. Geddes's 'HOMs'], so tapering the leading/trailing edge in theory wouldn't help enough to matter, but only one way to know for sure though.

The biggest changes in a 'last ditch' effort to get a little more prosound mileage out of them was to Aquaplas damp them and instead of welding the vanes, inserting hard rubber spacers to damp its bell modes, which dramatically changes the horn's overall tone more than just damping the bells, especially if the throat brace is removed also, so cutting them out and filling the void with liquid rubber or similar and mass loading the entire horn to damp it the same as a multicell?s thick tar coating is the 'hot ticket'.

Even with the flange holding its shape, don't be surprised if it 'pops' and slightly deforms as production tolerances were apparently pretty 'flexible'.

For the OCD afflicted among us, adding external ?fin? bracing along the horn?s axis to compensate for the lack of an internal brace and reshaping the conical-to-expo transition and smoothing/filling in the side welds, then seal up the entire internal area with a micro finished coating worthy of a 100 pt. show car to reduce drag to a minimum.

For the very few ?beyond salvage? types, replacing the cardboard spacer with a metal one and using wax paper gaskets, then align honing the driver to the horn?s throat yields about as much difference as all the other tweaks aimed at improving its HF overall performance.

I did all this on a pair and as good as they performed compared to stock, once I started experimenting with different mouth terminations on conical horns I quickly concluded it was a ?dead end?.

Mimiing the ?tulip? profiles of musical instrument horns, engine valves, etc., highlighted just how distorted the theoretically acoustically correct expo flare is, especially when truncated, so decided that it was worth trading some of its relatively compact size/efficiency for a more natural, ?relaxed?/?open? sound; though I had to accept the radial?s relatively slight added distortion over square and especially a round, horn?s increased vertical spacing, which caused way more time/phase distortion than I could tolerate at my listening distance.

Get far enough away for them to appear < ~1/4 WL apart at the XO?s ?12 dB point and they will sound like a single point source though.

Over time, I experimented my way into reducing this physical/acoustical gap, but never quite put it all together like Tom Danley did with his Unity concept and especially its Synergy ultra high performance upgrade, which for now is AFAIK THE horn alignment to have if a truly wide, accurate reproduction BW is the primary performance goal.

The downside to it though is that it masks nothing to my hearing, so one gets to hear all the good and bad in a recording and chosen HF driver, which with many of today?s recordings ?voiced? for vehicle, smart phone, etc. systems combined with compression drivers designed primarily for prosound apps where SPL output rules means mostly a horrible listening experience without significant digital EQ.

GM

So, if I just buy 16 old trumpets from the Pawn shop, cut the ends off, I also can have multi cells. Cool. :)

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Originally Posted by VolvoHeretic

So, if I just buy 16 old trumpets from the Pawn shop, cut the ends off, I also can have multi cells. Cool. :)

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With a bit odd flare rate, but yes.:cool:

Lets see, a tuba, a sax , and a trumpet could go three way...maybe a good Jazz speaker? We could prolly add Monster cables and get rich.

From a technical POV, I thought Rudy Bozak's ultimate truncated B-200XA 'multi-cell' as used in the Concert Grand was rather elegant and performed admirably for the day: http://www.hifilit.com/Bozak/blue-6.jpg http://www.hifilit.com/Bozak/1968-4.jpg

With the really tiny 'FR' drivers available today, a Jensen [32] cell is possible and relatively cheap compared to an original.

GM

Hum, that bozak looks alot like my proposed 12" earth globe Piezo array;

http://www.hostboard.com/forums/hbmc.../2011/06/3.jpg

Stay on target, red leader, you're almost there...

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Originally Posted by Alien_Shore

Stay on target, red leader, you're almost there...

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So I'm no the only one that immediately thought "Death Star" :-)

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Originally Posted by bowtie427ss

Perhaps it returns to the original shape of the castings?

What we don't and will probably never know is whether steps were taken during the welding process to maintain strict dimensions.

other questions that cross my mind are if the support was intentionally oversized to create a structural load and possibly change the resonant frequency of the whole assembly? How was the pillar installed, was it welded to one casting before the two halves were welded together?

This is probably an easy thing to "over-analyze".

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True. It's easy to file the leading and trailing edges tapered, so I'll give that a try. I doubt it will hurt anything, and it will make me feel better.

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Originally Posted by fpitas

True. It's easy to file the leading and trailing edges tapered, so I'll give that a try. I doubt it will hurt anything, and it will make me feel better.

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Avoid sharp edges. Air flows around a rounded- think teardrop- shape much better.