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Old 30th March 2007, 03:50 PM   #121
49 - for the 18th time - again!
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Mamboni -

In your drawing for the variovent you speck a 3/4 inch circular cutout of the speaker dome covered with 3 layers of felt. In post #38 you mention that the cutout for the vent is 1/2 inch. I'm at a bit of a loss - can you clear this up? Also - what are the diameters would you speck for the three layers of felt? Your drawing looks like 1 1/4 inch, 1 1/2 inch, 1 3/4 inch, diameters were used - would this be correct - or would these work?
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Old 30th March 2007, 05:07 PM   #122
49 - for the 18th time - again!
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Well - need to press on and get some things done - so jumping right in with the Mamboni mod's to the Pioneer 10 inch as specked in his drawings. BudP is a jumping up and down (in a good way) for me to finish my speakers and do some listening test.

I have to mod speaker #2 and prep it for the BudP's EnABL pattern, cut up another hunk of Sonotube and then carve up some MDF for the end caps and center brace. OH YEAH - WE'RE HAVING FUN NOW!!!

photo of 1st speaker with Mamboni magic!!

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Old 30th March 2007, 09:43 PM   #123
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Default Here's My Two Cents

Hey, Mr. Mamboni, here's a variant of the Mamboni Mod you might want to try:

Why not make the triangular felt strips different sizes? Specifically, I'd try 2 or 3 different sizes, ratioed in the Golden Section 1:1.618:2.618 ratios.

I'd also limit the biggest size triangles to no more than 3 or 5 pieces, and would avoid have the big ones in 4, 6, 8, or even numbers. This helps the cone avoid the symmetric breakup modes, while maintaining a degree of cone rigidity.
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Old 31st March 2007, 12:44 AM   #124
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Quote:
Originally posted by c2cthomas
Well - need to press on and get some things done - so jumping right in with the Mamboni mod's to the Pioneer 10 inch as specked in his drawings. BudP is a jumping up and down (in a good way) for me to finish my speakers and do some listening test.

I have to mod speaker #2 and prep it for the BudP's EnABL pattern, cut up another hunk of Sonotube and then carve up some MDF for the end caps and center brace. OH YEAH - WE'RE HAVING FUN NOW!!!

photo of 1st speaker with Mamboni magic!!

The size of the vent is not precise. I used 3/4 " dia. hole. The felt pieces, three in all, are large enough to cover the vent and have about 1/2" to 3/4" felt around the opeinig. So, the felt circles were about 1 3/4" inch diameter. The photo of the finished driver looks fantastic - very clean and uniform work.

Sure, different size triangles would spread the resononce modes more and could sound better - experimentation is good. I am anxious to hear yor impressions of the modified drivers with tweeter. Are you clear on the wiring?
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Old 31st March 2007, 01:13 AM   #125
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Hi Mamboni!

I used your 1.5 inch sized equilateral triangles and varied the size of the felt pieces used on the dome assembly @ 1.75, 1.50, and 1.25 inches.

I assumed the hook up was going straight to the woofer + to + and - to - , and then from the + side of the woofer through the cap and 4 ohm resistor in series to the + side of the tweeter. Correct?

I'm working on an "Olsen" variation of your theme but I am concerned with edge reflection so I'm going to include BudP's EnABL pattern as well. The attached example uses "Golden Section" ( Fibonacci) section triangles and I have those placed - will add EnABL after I post.

I believe that your triangles serve as a torsion mechanism that damps the major cone flexing with a variable degree of mechanical resistance vs. frequency and that BudP's EnABL will act as a "trap" on frequencies reflected from the speaker edge by setting up an mechanical interference on the cone surface. Should be interesting!!

Glad I purchased an extra speaker to mess around with!

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Old 31st March 2007, 02:00 AM   #126
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Default Re: OHM Acoustics "Walsh F" Speaker remakes

Quote:
Originally posted by microwalsh8504
Hello DIYers,


Another question is, has anyone tried to replicate there landmark speaker the Walsh F?



I was wondering if anyone was able to replicate this unusual design and make a speaker using the WALSH technology.

Thanks.

my first thought on seeing this-

my 14 inch full range speaker!

Quote:
Originally posted by GRollins



On the other hand, you might just decide that you like the sound of an ordinary driver upside-down, in which case you're done.

Grey
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Old 31st March 2007, 02:04 AM   #127
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Anyone think of using this pattern? It ought to be close to bulletproof, damping wild cone excursions well into the stratosphere!

Sorry. I forgot to take my medication.
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Old 31st March 2007, 02:28 AM   #128
49 - for the 18th time - again!
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tomtt

WOW! Damn - now I have another project to play around with to add to my wish list. Just go ahead and shoot me!

Thanks for the info - I love it - and this guy is way outside of the box!
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Old 31st March 2007, 11:54 PM   #129
49 - for the 18th time - again!
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Well - until I can get around to learning how to make my own paper for cones I'll guess I'll be working on the Mamboni Walsh 5 remakes.

Cut down some more SonoTube today. It's pretty slow going cutting this stuff up with those little plastic knives tho - and you go through a bunch of 'em!!

I'm making 3 speakers - two to keep and one as a "test-tube" to play with mod's on. Concerned with wall flex - but will address that at a later place and time. Might put one of those 14 inch babies inside an 18 inch tube and use some expandable foam between the walls to improve flex resistance and deaden things up a bit. Sounds a bit more practical than filling the base up with Jello pudding.

Anyone know where I can pick up one of those old quadraphonic units that were around in the 70's? Quad sound and an 8-track!

BudP would shoot me - most likely several times!
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Old 1st April 2007, 03:05 AM   #130
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Quote:
Originally posted by c2cthomas
Hi Mamboni!

I used your 1.5 inch sized equilateral triangles and varied the size of the felt pieces used on the dome assembly @ 1.75, 1.50, and 1.25 inches.

I assumed the hook up was going straight to the woofer + to + and - to - , and then from the + side of the woofer through the cap and 4 ohm resistor in series to the + side of the tweeter. Correct?

I'm working on an "Olsen" variation of your theme but I am concerned with edge reflection so I'm going to include BudP's EnABL pattern as well. The attached example uses "Golden Section" ( Fibonacci) section triangles and I have those placed - will add EnABL after I post.

I believe that your triangles serve as a torsion mechanism that damps the major cone flexing with a variable degree of mechanical resistance vs. frequency and that BudP's EnABL will act as a "trap" on frequencies reflected from the speaker edge by setting up an mechanical interference on the cone surface. Should be interesting!!

Glad I purchased an extra speaker to mess around with!


Yes, the woofer is wired straight from the amp. But, some suggestions:

I would wire the woofer (+) to the binding post (+) because although the woofer is firing down into the box and is actually 180 degrees out of phase vis-a-vis a forward firing woofer, the tweeter will be in correct phase.

I preferred the sound of the tweeter wired in what is opposite phase: woofer + terminal to tweeter (+) terminal. The woofer coil inductance is causing phase shift, and I believe that the tweeter wired in this opposite phase sounds better. So, you are correct as you stated + to +. But I wanted to point this out: that in reality the woofer and tweeter are being wired in opposite phase because the back of the woofer cone is the sound producer being mated with the tweeter. I hope this is clear.
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