Rings,Don't have to be Larry's,similar would be nice.

xfactor

The finished interior has a minimum thickness of 5/16", or ".3125" of just the structural epoxy covering the entire interior. A min. of three coatings were used on all surfaces. The carbon fiber itself is nearly 1/8" thick "before" being impregnated with the epoxy mix. It expands a bit at that point. In total I used well over "Six" gallons of the epoxy and hardener mix at the (1:2) ratio needed. That is quite "A LOT", to complete both speakers. And also, Nearly "3" commercial yards of the fabric. Which is actually, "trade" measured at (36" x 50-56") per yard. I use primarily a "stabilized" but never a, "Pre-preg" carbon or carbon/kevlar, fabric which is more expensive but much easier to work with". This "mod", must always be "Custom ordered".
They are now significantly heavier pieces than they were originally. Though I have not measured the difference yet.

xfactor

xfactor

And , this is "very unconventional" I know. But this works and is very cost effective as well
And it is the easiest way to affect damping and that "Faraday" effect field I talked about.
The copper tape has on both sides an "effective", "Conductive adhesive" and that helps to "bond" the pieces together, both mechanically and electrically.

xfactor

xfactor

The, "3M" adhesive, "two-sided" tape is for mounting approx. (26) pieces of (12" x 12") pieces. Of a 2" thick, "closed cell" acoustic foam panel/s.
That's (26) per, "each speaker" in their interiors.
Yeah, if you calculate the "Internal area" even including the bracing? That is going to give you a bit more than your calculated sum.
But, this works. And many are "floating", as in taking up some of the geometric free-standing space as needed.
Also, There are some, "Open" cell; panels as well used as fill. Which were needed to allow the transducers to "breath" during operation in their now sealed environs.
My math is never, "Fuzzy". But, "My math does include calculations a bit different than what you'll find anywhere else". But that is "my" choice as I find that the one's I felt the need to develop? They simply work much better than those classically taught.
"Never get stuck in a (Textbook)"!
I believe that this was, "Commercial consumer audio's" - possibly largest mistake.
Yeah, yeah yeah,....I'm opinionated. So shoot me.
But "listen", to my work first!

xfactor

And "that's"? Where I am currently at.

xfactor

I almost forgot. The footer assembly is nearly complete as well. And the transducers..
I decided to go initially
with a (1.125", O.D.), "Mag-Planar, Spiral Type" tweeter.
Currently these are not on the market.
"Yet".

xfactor

The, "middle" drivers are untouched but I played with the rings a bit. The "modded" drivers are in the rear.
But this all started because of these...They are some "Sad little fella's"!

xschop

So after all this, what will be your limiting factor of your goal now? Stamped steel driver baskets?

And why the copper tape faraday? Expecting an EMP? In an all-out apocalyptic scenario, I'd want my transducers still operational too.

I can vouch for the effectiveness of CF. I had a Hayabusa front fender vacuum-wrapped in a single layer of genuine CF and it substantially increased the plastic's stiffness. It stopped "dancing" at over 120mph.





Keep up the work and pics. I'm sure the plastic rings were for wave-guide purposes and "looks". They can surely be improved upon.

xfactor

"Polrbehr",
I would love both actually. "Pics and also any measurements you can make or have",
Thanks.
Ok, These particular rings are for the "model, "SDA-2B". Is that correct?
That's the one "SDA" model which I have "Currently in storage", that I have never had the time to set up and listen too. "Go figure".
So, just the "2", rings needed per speaker?
Do you use one for the "Passive Generator" also? Or anything on/with, that particular component.
I have to admit that my experience with "Passive Generators" is basically, "Nil".
Thanks again!

Gardenstater

Most impressive. What do they sound like now when you rap on them with your knuckle vs previously?

Any idea of what % reduction in interior cabinet volume?

Why the closed cell foam? Doesn't make a very good vibration dampening mat'l due to the low mass density and you need open cell foam for sound wave absorption.

I have to admit I don't really get the need for a faraday cage in this case. I mean maybe it might reduce EMI and RFI to some extent but that isn't much of a factor at speaker signal power levels.

Those waveguide anti diffraction rings are a good idea. Did you make them with a molding process or 3D printer? I feel they need to be stiff just like the interior rings, so as to apply even pressure to the thin stamped steel baskets (especially the rim) but you have to do it in a way that you do not harm the rubber surrounds.

What did you do to your "modded" drivers? Damping materials?

Gardenstater

PS: I just found your other thread on this project.

Gardenstater

This thread has pictures but no dimensions of the extensive fabrication Larry did at one time:

https://forum.polkaudio.com/discussion/comment/2186767/#Comment_2186767

xfactor

Hello "Gardenstater"...
Yeah, Many do not understand the, "Why" of actually most of what I do.
And no "single" part will yield necessarily a "large" difference. But when done in "concert"?
If placed behind say a "curtain? And then played something you know well? You would have a very hard time believing that those few things that I did would yield such a drastic change in quality. Especially since I have not even touched the crossover.
"I am waiting for the rest of the (snail-mailed) parts to begin that".
Making and adding the, "Heat Sink" which is located at the top of the radius once I re-installed the mid's seemed to help a good bit though.
There was a measured, (avg.), "+47 Degree F., (+-3 degree's)" difference in the shield around the magnets temp. That was compared to a normalized, "72 Degree F." ambient temp. Which I observed after these were driven at an estimated, "15-20%" of load to the voice coil for just one hour. And I found this on all (four) transducers used as mid's.
"Four mid's for the pair of speakers".
That meant a large change in gaseous density and more energy used for a lower mass of air moved.
"And if you were to plot that on a graph the curve would be quite sharp per the time alloted to test".
And of course some few distortions of the primary forward wave. As the top of the voice coil and cone etc. had such a variance in temp.
I would love to just swap out these mid's and woofers also. BUT, I am trying to keep the cost down. And they don't sound "horrible" to begin with..
But this is mainly for the benefit of my other thread meant for the upgrade
So the Heat sink helped nicely.
Hee hee,
And now, I'll quit talking about "what should" be relegated to that, "Other" thread!~
Honestly? I do not think I will have time to get to my pair of the "SDA-2B" for maybe (2-3) weeks. As I do have multiple projects happening at any one time.
And building an eight foot tall, two foot wide (Waveguide/Freq. roll-off),
Um- (assembly) that is, "true" and will stay that way for thirty-odd years+?
Hee hee, Is fun but very challenging too!~ "Aircraft, airfoil forms" were WAY EASIER...
But I will get to it. I'll need to in order to finish designing the rings.
But at this time I am leaning towards a "Corian core" with carbon fiber on the (O.D.) and rear face. Four rings per speaker. With threaded inserts "inset" into the inner ring to bring both together. This way there can be a, "Torque value" applied when mounting to assure a (Flat) installation. Regardless of any material or build irregularities in the enclosure itself. The original transducer mounting holes can be used for, "Location" and also mounting the inner ring onto the enclosure. But these are just my preliminary thoughts. Hence subject to, "And usually" changed.
See fella's!
I didn't "Over-think" that at all!
Ha ha ha ha..

xschop

Here's a better drawing of the rings to illustrate. They require simply cutting out the thinner, crumbly baffle step that has the stripped-out screw holes anyways. Once glued in, should triple baffle stiffness, if not more...

Gardenstater

OK gotcha. Less blockage of air flow from the basket openings that way too. What would be the thickness of the inner flange/gluing surface?

Many will be scared to attempt this mod though. In my case, my early 7B's aren't even rabbeted, so I would have to use a rabbeting bit followed by a top bearing trim bit. Certainly not out of the question.

Once the baffle has been stiffened, one could even experiment with decoupling schemes for the MW driver, if one was bold enough. I don't know what the results of that would be and it would involve oversized holes, much thicker cushiony gasket material, and hurricane nuts with springs between them and the inside surface of the ring.

xfactor

I have tried all of that, and more. The "basket shields" are usually about (.010-.015") thick.

xfactor

If you have a transducer with heat issues, (Purchase a different one)? (Modify the enclosure)?
But since this is a journey..

Heat issues, as the two Mid drivers did in each of the LSiA9's. Those baskets are made using a "mild steel" as shielding.
You can use either a "Forstner" bit of the diameter you wish. To remove the material needed for venting. Just be aware of the "length" of that particular "Forstner" bit's
centering blade. As you never want to cut into the very brittle "Ceramic" magnet powering your voice coil.
Or (preferably), If you have access to a decent vertical mill, "Like a (Bridgeport).
You can then use an endmill. The type made with the ability for "Down-cutting" in it's geometry. After, "plunge cutting" the initial hole you can then cut horizontally as needed, for a "Channeling Vent" which should be at or near the top of the baskets radius, for obvious reasons.
Attaching a heat sink, "properly" will also help to draw the excess heat away from the voice coil as well. Use a "two-sided, thermal tape" or epoxy, to attach the heat sink but take care to also utilize a quality "Thermal paste" or similar product, "Liquid Metal", to help move the heat along on any exit path you have devised. "Kapton" film tape can be used to good effect as well to keep heat channeled, for shielding and insulation as well from certain area's and components. Only, "$8 - $1000" per roll on, "Ebay, Amazon and etc."
Otherwise? If not well thought-out and/or with a shabby implementation. You may simply be increasing the thermal insulation around your voice coil. Which would be self-defeating.
Also, any metal removed must be caught and the debris not allowed to interfere with the transducers magnetic field or mechanical movement, Or else the device will not be able to work as designed. "Or improved upon".
Since I am working with a device I cannot just "dismantle" completely. And then modify it's parts safely and separately. "So that for one thing".
I could then use the standard, (flood coolant/lubricant) as I wish I could.
But, there are still a few ways to do this. "Air" is one. A moderately high pressure, focused stream of air. This stream is aimed at approx., (90), degrees, "roughly", across the tooling.
But also, a little "above" the cutting plane itself. And the cutting edge of the tooling as well. So that "hopefully", you never, "Push" the chips into the tooling, or inside the work piece.
"Like inside that basket"!
"This would be very bad"! But NOT the end of the world.
But you will probably curse as you stomp around for several minutes regardless..
I also use a few very powerful magnets. These are strategically placed and mounted, "very" securely but also in such a way that I may quickly adjust their placement and also "attitude of field polarity", "on the fly" as this always seems to be needed. And if well orchestrated?
This will cut way down on any clean-up time and effort as well!
Things such as this are actually, NOT very hard to do. They are just things that need some patience, some intelligent thought, "Both before, but also during the work itself". And a little commitment. And once complete? The results are not something you can actually show other people, "necessarily"..
Once all the work is done. There is not anything at all to see really. And doing just the "one" thing? Never yields massive improvements which can easily be measured and then confirmed by hearing it on the first track played.
But if you do, "many" of these things?
Either all at once, or do such things simply, "one by one" as you have spare moments. And you do these things maybe over a large amount of time.
As in over a few months or even, "Years"?
The feelings of personal satisfaction? They are indeed quite immense.
But the results you can achieve!
To some, "many actually" those results are an, "Intangible". And they will stay forever as, "Intangible".
Incredibly, they will never know or understand what they are missing.
But if you are reading this? Then you are like me, "At least a little bit".
And I am honestly telling you that the results can "forever", "floor" you.
Everyday, when I listen to either my rigs? Everyday I am floored. I do not know of any other "thing" in life that can do this, to this extent.
(Well ok, "Religion", but that's it).
Being an, "Audiophile"?
Man-o-man, but that is a difficult hobby to enter into if you were not one before ever hearing the word. The one hobby which utilizes our least used, yet "possibly" our most powerful sense. Out of the only, (5) that we know of. In all our existence.
Dude,.where did I leave my "waders"?
It's 'gettin too deep is here!

Clipdat

Your posts are very "entertaining"!

F1nut

Look at Drew being all polite and stuff.....

ken brydson

Words, so many words....

Clipdat

Don't you mean:

ken brydson wrote: »

"Words", so many "words"....

audioluvr

Maybe he means:

ken brydson wrote: »

"Worms!, so many worms"....

xschop

Bridgeport mill cutting fluids don't like -8 degree temps.

xfactor

That would depend on the cutting fluid you decide to use.
The stuff available at your local hardware store which they call "cutting fluid"?? Probably not.
Besides, I didn't know there was a company making a specific formulation that only works well in, "Bridgeport" Manual mills.
Where do, "You" purchase this concoction?
Ask for it by name? "Bridgeport Cutting Fluid".
Do they make one just for, "Makino" too??
My five axis mill is looking awfully dry.

xschop

Kool Rite normally, but I'm pretty sure the 2 mills have been getting the MUCH cheaper DIY concoction lately. The shop has been under lockdown for last couple weeks due to coldest temps and power outages here. Even if the coolant fluids survive those temps, this warm-blooded mammal goes nowhere near there lol.

You can do some upgrades with that 5-axis no doubt.

msg

I like the stream of consciousness conversational writing style. I don't understand a lot of what's presented, but I'm interested to see the final result and hear the listening impressions after such drastic design mods.

xschop

I got the revised design programmed in the CNC mill (it's 70 degrees in the shop ha).
Updated the geometry to move the inner radius away from woofer port edge. 1/4" thick cold-rolled steel for a nice flat profile. Integral 8-32 taps located exactly center to any of the classic MW's adjacent bolt holes, so they can be rotated and installed vertical or lateral.

EASY to install, just drill out the old wood screw holes 3/32 and they self-align.

I left the down-ward pointed lip for maximum baffle span.

I would suggest running a bead of glue between ring and inner baffle...

Listening to the 5Bs. Kick drums have tightened right up and haven't glued them in yet.

VR3

Looks great and dangerous.

Driver runs by day, bat star by night

xschop

These are intended for the Monoliths. From all the pics I've been sent and threads and replies on the forum, this should be the last weak spot of the front baffle.

What would you think is the best cost-to- benefit ratio solution of the large passive on 1.2TLs and SRS's?

From the bracing pics, it looks like the baffle should NOT flex as much as the MWs baffle areas, due to the large brace front to back. So simple hurricane nuts should suffice there.