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

xfactor

I do apologize for being very, very slow in my postings but certain of my projects have changed their projected time-lines for completion and are now "Expedited".
But just to ask.
Would it not be more beneficial to cut a "Slot" into the enclosure?
Maybe located on the rear, and near the, "Top or side" of the enclosure?
That slot being cut just large enough to slide the rings into the interior of the cabinet. And maybe that slot could be placed near a corner as well. So any medium used to "close the breach", could be secured on two "planes of force".
Instead of just "one" on the interior.
Then, After installing the rings, and any other required materials through that slot, "or transducer cut-out already existing". That slot could then be very easily sealed.
"This thought keeps nagging, in the back of my mind".
So I thought I would ask.
The "slot" could be easily cut with almost any radial type saw. "of a certain minimum size".
"After physically checking to make sure all wiring, fill and etc. are well out of the way" of course.
Any thoughts on this idea?
I think that the simple fact, that you could then gain the benefit of the, "Full Ring" being utilized here. Instead of a "Segmented" ring would be worth the :"scar" imposed upon the rear of the cabinets exterior. And it would make the "ring-set" much easier to install as well.

Gardenstater

Nice work Rob! Designed by Klingons? Bat'leth Rings heh heh (NERD alert but at least I had to look up spelling). What orientation do you believe will be best for the Monitor Series speakers like your 5B's and my 7B's? What about the early models where the drivers are not recessed into a rabbet? Epoxy the particle board and then rabbet?

Which orientation stiffens the baffle best but inhibits communication with the passive the least?

xschop

On any of the monitors or SDAs, the semi rings go on top and bottoms of MWs.
With billet or metal tweeter plates, all flex is gone as far as I can tell. A really dead-silent thud on the front cabinets now. So indeed kick drum frequencies are tight, the last weakest link to these monitors in my opinion.
LOW bass is just as tight and controlled at high volume. I'm happy.

Gardenstater

Did you try them orientated vertically? If so, not as good SQ wise?

xschop

Haven't tried vertical because on the sides, there is no cabinet flex being near the side boards that are 90 degrees to the baffle.

You're down for a set on this run as well.

xschop

xfactor wrote: »

I do apologize for being very, very slow in my postings but certain of my projects have changed their projected time-lines for completion and are now "Expedited".
But just to ask.
Would it not be more beneficial to cut a "Slot" into the enclosure?
Maybe located on the rear, and near the, "Top or side" of the enclosure?
That slot being cut just large enough to slide the rings into the interior of the cabinet. And maybe that slot could be placed near a corner as well. So any medium used to "close the breach", could be secured on two "planes of force".
Instead of just "one" on the interior.
Then, After installing the rings, and any other required materials through that slot, "or transducer cut-out already existing". That slot could then be very easily sealed.
"This thought keeps nagging, in the back of my mind".
So I thought I would ask.
The "slot" could be easily cut with almost any radial type saw. "of a certain minimum size".
"After physically checking to make sure all wiring, fill and etc. are well out of the way" of course.
Any thoughts on this idea?
I think that the simple fact, that you could then gain the benefit of the, "Full Ring" being utilized here. Instead of a "Segmented" ring would be worth the :"scar" imposed upon the rear of the cabinets exterior. And it would make the "ring-set" much easier to install as well.

These lock the MWs more solidly to baffle by using more 8-32 thread depth (better bolt torque) ,and they more than triple stiffness of baffle area between MWs and Tweeters.

I think it took me about 20 minutes to do both monitors after knocking out previous hurricane nuts.

JayCee

Here's a PSA of sorts. One negative consequence of rings and the ability to apply extreme screw torque....the screw head can/will bend the metal around the respective passthrough/mounting hole on the MW drivers. If not careful, it could blow through the hole and also compress the particle board. This happened on my first pair of SDA's (no longer have) and many other folks experienced, too.

Common practice is to use 1 or 2 washers between the screw head and MW rim. I still find the small washers can deform and mushroom in if using a heavy hand....and I have. Would be nice if there was something wider and more substantial (heavy duty) to distribute the load but not compromise the edge of the rubber surround.

invalid

JayCee wrote: »

Here's a PSA of sorts. One negative consequence of rings and the ability to apply extreme screw torque....the screw head can/will bend the metal around the respective passthrough/mounting hole on the MW drivers. If not careful, it could blow through the hole and also compress the particle board. This happened on my first pair of SDA's (no longer have) and many other folks experienced, too.

Common practice is to use 1 or 2 washers between the screw head and MW rim. I still find the small washers can deform and mushroom in if using a heavy hand....and I have. Would be nice if there was something wider and more substantial (heavy duty) to distribute the load but not compromise the edge of the rubber surround.

I would think that would happen much easier on the older sda's that they didn't build the cabinets out of mdf.

Gardenstater

My activities the other day of installing a new toilet in my house made me think about those toilet installation bolts with the rectangular (rounded at the ends though) flattened heads. Would need to install nuts on inside of cabinet though. Why not make some thin steel plate washers that are narrow but curved slightly? Problem then is not to damage the surround rubber. Then some large MW sized anti-reflection, anti-diffraction felt rings could be employed on top of it all.

JayCee

invalid wrote: »

I would think that would happen much easier on the older sda's that they didn't build the cabinets out of mdf.

True, but there is potential. I periodically check them and over time the screw needs a bit of reseating. My pair of 1.2tl's from '89. Kind of hard to see but the mushrooming is there. I'll add it can deform the MW flange hole, too. There's allot of pressure in a small space. Just shot this...


I've installed rings on 4 sets of SDA's, each gen, and it's worth noting for folks that don't know this.

Gardenstater

xfactor wrote: »

I do apologize for being very, very slow in my postings but certain of my projects have changed their projected time-lines for completion and are now "Expedited".
But just to ask.
Would it not be more beneficial to cut a "Slot" into the enclosure?
Maybe located on the rear, and near the, "Top or side" of the enclosure?
That slot being cut just large enough to slide the rings into the interior of the cabinet. And maybe that slot could be placed near a corner as well. So any medium used to "close the breach", could be secured on two "planes of force".
Instead of just "one" on the interior.
Then, After installing the rings, and any other required materials through that slot, "or transducer cut-out already existing". That slot could then be very easily sealed.
"This thought keeps nagging, in the back of my mind".
So I thought I would ask.
The "slot" could be easily cut with almost any radial type saw. "of a certain minimum size".
"After physically checking to make sure all wiring, fill and etc. are well out of the way" of course.
Any thoughts on this idea?
I think that the simple fact, that you could then gain the benefit of the, "Full Ring" being utilized here. Instead of a "Segmented" ring would be worth the :"scar" imposed upon the rear of the cabinets exterior. And it would make the "ring-set" much easier to install as well.

A full MW ring can be installed through the larger Passive Radiator cutouts of course. A full PR ring can be installed if thin enough steel, by bending just enough. If using epoxy, 2 or 3 thin steel rings could be laminated or just let the clamping force of the screws do it.

Thing is, full rings are large and difficult to ship, and wasteful of material to boot.

Nice job thinking outside (inside?) the box though

JayCee

Gardenstater wrote: »

Why not make some thin steel plate washers that are narrow but curved slightly? Problem then is not to damage the surround rubber.

Yes, or similar.

Gardenstater wrote: »

Then some large MW sized anti-reflection, anti-diffraction felt rings could be employed on top of it all.

Trey's making a set of MW felts for me...should help w/recommendations once I test them.

xschop

The primary benefit is to stiffen baffle via gluing the semi ring to the backside. The extra torque-abilty is secondary.

Another caveat is IF Polk had the middle braces dead-center on some of the monitors, then the rings clear no problem.

JayCee

Guessing more costly but staring at my MW array and thought, from a strictly max stiffening POV, a bar that runs the length of all MW's x 4. My drawing skills suck but here's a very rough sketch:

Quick measurement and something like a 1.5" bar with the internal round (MW side) milled to contour to the opening/curvature of the MW spokes.

xschop

It's the thin widths of mdf between vertical MWs that are the weak spots.

pitdogg2

The screw head can/will bend the metal around the respective passthrough/mounting hole on the MW drivers. If not careful, it could blow through the hole and also compress the particle board. This happened on my first pair of SDA's (no longer have) and many other folks experienced, too.

True stuff !!

xfactor

I actually developed a, "system" (If you will). Of what I call, "Interior damping braces". They give several benefits besides just the (Not so simple),(Think pre-loaded shock values with also post-loading as well) And it all may be, "TUNED" AS NEEDED.. So actually not so simple bracing". And they are fairly easily made. But I don't have any pics unfortunately..,. "That particular hard drive crashed wih out back-up". They are part of something I was thinking of petitioning for patent.
But ...I guess I'll just make one and post a new pic, along with a list of the parts needed".
"Those parts can be aquired from (True Value) hardware".
And I'll also post also a process list. So anyone here , may try them.
I would use,"6" of them plus a "Damping bar" I believe to brace the above "SRS" speakers. (Also "carbon fiber", but I know that is a bit too involved for some).

The large passive is another animal entirely.
I'll have to draw that particular device I have built and also used for you as well.
But the removal of the rear speaker, "plate" would be needed to install that device.
"I" wouldn't have a problem doing that, as I would also use it as an, "excuse" to add a better, more dense material "as" the rear plate.
But I do understand how some may, "Balk" at that thought!
Maybe a week to do this?
And just to put this out- The interior of a speakers enclosure "should" be designed in a way that follows "most" of the design concepts used in the modern, "Silencer".
"Yes", The one's used in firearms.
Study those a bit? And you'll realise some common faults in most modern speaker design.
The "Balancing of harmonic resonance" is part of that design structure. Also "Wave fraction" at a very high level. "Think; (Wake Fraction Coefficient)".
If you study those....

JayCee

xfactor wrote: »

I actually developed a, "system" (If you will). Of what I call, "Interior damping braces". They give several benefits besides just the (Not so simple),(Think pre-loaded shock values with also post-loading as well) And it all may be, "TUNED" AS NEEDED.. So actually not so simple bracing". And they are fairly easily made. But I don't have any pics unfortunately..,. "That particular hard drive crashed wih out back-up". They are part of something I was thinking of petitioning for patent.
But ...I guess I'll just make one and post a new pic, along with a list of the parts needed".
"Those parts can be aquired from (True Value) hardware".
And I'll also post also a process list. So anyone here , may try them.
I would use,"6" of them plus a "Damping bar" I believe to brace the above "SRS" speakers. (Also "carbon fiber", but I know that is a bit too involved for some).

Thanks for offering up a mock-up and directions. There's been some sidebar conversation re. bracing and, like you, I mentioned carbon fiber. I have no experience w/CF DIY. Do have a CF bike and it does wonders with long rides to reduce vibration/aggravation of carpal tunnel syndrome brought on w/a career using computer/mouse work.

Gardenstater

JayCee wrote: »

Guessing more costly but staring at my MW array and thought, from a strictly max stiffening POV, a bar that runs the length of all MW's x 4. My drawing skills suck but here's a very rough sketch:

Quick measurement and something like a 1.5" bar with the internal round (MW side) milled to contour to the opening/curvature of the MW spokes.

Could even tap them for the tweeter attachment screws. It's true that the baffle between the MWs is the weakest place but if you have a beam between two pivots, putting the pivots in closer to the center or making the beam much shorter is very effective for stiffening. Your bars could even be about 2" wide or whatever is needed for the tweeter attachments, making it really more like a beam of particle board/mdf that is fixed at each end and only 3-1/2" long. I would think that 1/8" steel or even 90mills would be just fine. Would have to make sure that a magnetic material, in this quantity, so close to tweeter magnets would not be a problem. Perhaps it could even be fabbed out of carbon fibre bar stock, with diamond or carbide mills, or even non mag stainless. Something to think about anyway.

https://www.mcmaster.com/fiber-bar-stock/

Edit - I just looked at the prices

JayCee

Gardenstater wrote: »

JayCee wrote: »

Guessing more costly but staring at my MW array and thought, from a strictly max stiffening POV, a bar that runs the length of all MW's x 4. My drawing skills suck but here's a very rough sketch:

Quick measurement and something like a 1.5" bar with the internal round (MW side) milled to contour to the opening/curvature of the MW spokes.

Could even tap them for the tweeter attachment screws. It's true that the baffle between the MWs is the weakest place but if you have a beam between two pivots, putting the pivots in closer to the center or making the beam much shorter is very effective for stiffening. Your bars could even be about 2" wide or whatever is needed for the tweeter attachments, making it really more like a beam of particle board/mdf that is fixed at each end and only 3-1/2" long. I would think that 1/8" steel or even 90mills would be just fine. Would have to make sure that a magnetic material, in this quantity, so close to tweeter magnets would not be a problem. Perhaps it could even be fabbed out of carbon fibre bar stock, with diamond or carbide mills, or even non mag stainless. Something to think about anyway.

https://www.mcmaster.com/fiber-bar-stock/

Edit - I just looked at the prices

Interesting on the art/science of mechanics. Thanks for the suggestions and link.

My nephew is going through engineering school right now. Will be fun to talk to him when he gets some experience. He's interning w/a very big window manufacturer this summer.

Your comment on magnetic field reminds me of something I was going to mention when I transferred over the domes to the new bezels. The magnets are frickin' strong. With the plates on they have a bit of interference when placed side-by-side.

As I transferred the domes in the assembly line approach I lined up the domeless magnets and just about knocked them off the workspace when I slide one close in-line. I was able to push the first in a line of four and get them all to move. Meant to measure it but didn't. I'd say it's a good 2-3" radius.

Edit...to add to your edit. Ouch!

xschop

Best pic I could get. There is still 3/4" between top of ring and bottom tweeter port hole. And 1/8" step in of inner ring radius to MW hole...

xschop

Just remembered, the new revision has the ends plenty far away from centerline of midwoofers where the cabinet braces are. So no chance of interference there unless a Polk worker was inebriated that day.

Got about 12ft of stock to do....

Gardenstater

JayCee wrote: »

invalid wrote: »

I would think that would happen much easier on the older sda's that they didn't build the cabinets out of mdf.

True, but there is potential. I periodically check them and over time the screw needs a bit of reseating. My pair of 1.2tl's from '89. Kind of hard to see but the mushrooming is there. I'll add it can deform the MW flange hole, too. There's allot of pressure in a small space. Just shot this...


I've installed rings on 4 sets of SDA's, each gen, and it's worth noting for folks that don't know this.

I'm going to try oversized finishing washers, filled with JB Weld with socket head flat head screws. I will file the epoxy flat on the bottom and also grind them into a rounded rectangle shape to fit in between that cutout in the surround and the basket flange.

Another option is to take a square nut and chuck it into my Taig Micro Lathe and countersink it for the screws. Then grind as needed for clearance at basket flange and surround cutout.

Great picture ^^

xschop

Yes, thats a good picture. The area could be beefed up. Besides a larger washer under bolt head, a tougher ring that still seals to cabinet would be an improvement.

pitdogg2

As you see he cut out the rubber. I can attest that if a washer just nuzzles up against the rubber it will start to crack and it will pull away.
One must be careful to not let them play too close.
He did a good job with that.

JayCee

Thanks, guys. A beefy rectangular washer that drops into the rubber notch would be perfect. Also, I prefer the Allen wrench heads much better than star bit. Avoids stripping the head and much safer around the driver...fewer accidental slips. I tend to get torque happy.

xfactor

HA HA HA,
I guess now you realize why I began doing the Carbon Fiber "Lay-ups" myself!
$172.37+ Shipping and tax for a (6" x 6" x 1) plate"??
Yeah, that had me calling a friend whom just happens to have a company here, "MD, Wash. D.C., VA. DE." that specializes in "BIG", Carbon Fiber installations. "As in hand laying-an entire, "four level" parking garage". (Every square inch of every structural surface in the space. Which is all of it...)
Especially since he is the one whom got me started with the epoxies about 25 years ago to begin with!
There is a learning curve as with everything worthwhile. But there are tons of video on "Youtube" showing just about every possible type of fabrication with Carbon Fiber and also most of the problems you can encounter. "Except" it seems for the three dimensional, complex modeling of compound shapes.
When asked? "They all seem to just go, "Shhhhh, It's a secret". And there do not seem "even now" to be any video's on that particular subject. My old friend hooked me up with his foremen who helped a lot. "All I had to do in payment was show him how to make the, "Epoxy grenades" they still remembered me for 25 years ago. "Chemically timed, with chemical ignition and a blast/frag, radius exceeding that of a coventional (HE) grenade by over 35%. And no plastique OR black powder involved".
Anyway.
From the "Get-Go" I have looked at it simply as another, "Dye-making" job. Just with that messy, "gooey" epoxy to deal with. But, I will say that I have made some very interesting things.
This pic is the bottom of a "Not so secret" compartment in that end table.


My point being, "If I can do it? Anyone can do it"
Hee hee, But you (will) make a bit of a mess a few times. But then, (everyone) does"!
You "can" use "El-cheapo epoxy" if you wish. Which costs about "$40" per one gallon, "Kit". And not the "System Three" at about four times the cost. But you will,
"Get what you pay for".
Also, I purchase most of my "Carbon Fiber fabric" from a company called, "Composite Envisions". in the midwest. I have been dealing with them for maybe five years with no problems. One square yard of their "Remnant" or "Seconds/Clearance" fabrics are about $10-$15 a piece. The "premium" fabrics which I use cost $55-$90 per yard, + about $15 a yard for the "stabilizing" treatment which makes it VERY easy to work with! (You also have to pay a set-up cost each time you order stabilized fabric plus the
$15 Per yard charge), but man-o-man.
NOT having the fabric just falling apart as you attempt to secure it to a form with the glue you layed in drying up already, "And with the headache getting worse by the second", and how did my elbows become o-so sticky!? (Crap, It's in my hair again?), WTF?>?)

Yes, It can be just like that!

Just pay the man the extra "thirty shekels" or so, and then go whisteling on about your merry way.
"Trust me on this".

Stabilized fabrics are easier to work with than even, "Pre-Preg".
Which you would "think" to be about the same.
But the 'Pre-Preg" has it's place too.

Then again, "A little bird just told me".
That (they), "stabilize" the fabrics by simply rolling it out flat on a clean surface. And then spraying it until evenly "wet" using a plethora of, "Aquanet" hairspray. The type that comes in cans.
(Available at your finer grocers, drug stores and other fine retail outlets everywhere).
And then just letting the fabric then, "Air dry, over-night".
"Composite Envisions" also sells another product for "DIY" stabilization but it is VERY expensive.
And I have "incidentally", found ways to overcome many, "Nearly all" of the problems that even "The one's they call", the industries "BEST" have given up trying to do...
I have been told that this is because "I" simply , "Never Give Up".
If you try this type of work and run into, "anything" that, "They" say simply cannot be done? "Like six sides at one time", Or, (360 degree's on all 3 axis) or less..
Please, Just ask.
And that is always-"free".
Unlike; "Dragonplate".

FDPLHP48T*ALL*TWL*2424
Quasi-isotropic Carbon Fiber Twill Prepreg Sheet ~ 1.5" x 24" x 24"
24" x 24" 1-1/2" Woven 0/90 and ±45 $4,100.00
ADD TO CART

xfactor

It would cost about, "$250" in materials to make that plate, "DIY" with the premium epoxy and fabric that I use. Maybe two hours of labor as well, "All prep"..
Slight difference in cost eh?.
And it could easily have much higher specs. "Temp, hardness, tensile strength etc.".
Simply by changing the process used a small bit.

Clipdat

"Cool"

xschop

I've seen some large passive radiators here that could use a new skin of CF overlay that won't delaminate.