New Project Kickin' A-- and Taking Names!

[toddalin]

This was part of another thread, but I figured that the build deserves it's own thread.

I am working on a new build that should kick butt over most systems, is maintenance free (i.e., no foams to ever replace or magnets to recharge), and uses no horns that can be peaky or honky, yet provides all the volume and dynamics you could want.

At this point I've assembled the components, and only lack for making new cabinets for the mid-range woofers (~0.75 cu ft).

The system starts with 2241H as the basis. These are mounted in custom made cabinets (to JBL specs) just under 7 cu ft and tuned to ~32-33 Hz. The cabinets are 24" x 21" x 30" deep. These were used in a church and are in absolutely perfect condition without a scratch on them. The cabinets look absolutely JBL, complete with JBL logos and handles that say 2241H, and even "tilt-back" wheels for easy moving. These will go out to ~250 Hz. They can be used horizontally or vertically (21" wide x 24" tall) to reduce edge diffraction with just 1-1/2" to either side of the woofers.

The mids are 2251Js and will be in their own smaller cabints that perch on the 2241s (ala Wilson and a bunch of other high end models). Use of the small cabinet will allow it to be positioned/aimed independant of the woofer and will not take volume from the woofers cabinet. Testing shows these are extremely smooth from ~200-2,500Hz.

From there the system will cross over to a set of modern Heil AMTs.

The system should be very dynamic.

 

[tyeeslayer]

Are they "Digital Ready"?

 

[toddalin]

Last weekend I cut the faces for the 2251Js and routed the corners round to reduce edge diffraction. These are actually fiberboard. The raised sides/top from the router will be taken down in final sanding.

Today I cut the top, bottom, and sides out of red oak and glued one together. I only have two big clamps so have to do one at a time. I wanted to do a 45 degree mitered edge, but a straight edge is easier so that's what I settled on. Also, the boards were 4 feet long, so I probably would have come up a hair short in the long run by the time I got the angles in there. I haven't had wood shop in over 50 years (7th grade), and we never got this far

I also did up acrylic stands in CAD for the Heils, but wanted to check the clearances before wasting a nice piece of acrylic on the laser cutter. A piece of scrap 1/4" ply shows that my calculations were right on and I can cut the acrylic with confidence. I did cut the acrylic feet.

Actually, the clear acrylic is very apropos because Heil's Trademark is "Sound as Clear as Light."

 

[toddalin]

I peered into the 2241H cabinets with a flashlight and I can see that they put NO INSULATION on the walls. I have the system set up so I can A/B the 2241H cabinet against the modified L200 cabinet, with the "AlNiCo 2235", (both using the 2420/long horn and 2405) and the 2241 cabinet sounds a bit hollow/boxy. I think the insulation should take care of this.

BION, the 2241H brings out the vocals so much better than the 2235. I attribute this (and always have) to the foam edge and heavy cone in the 2235. The 2235s give a "heavy chestiness" compared to the 2241s that just seems unnatural and like it shouldn't be there (and is not with the 2241s) and omits some of the lower midrange with singers like Joni Mitchell just on acoustic guitar or Wurlitzer electric piano.

Of course, I've complained of this since swapping out the 130As to the 2235s over 10 years ago. If I ever had the AlNiCo 2235s redone, I would have them leave out the mass ring (ala, 2234), and run a sub, which I do anyway.

 

[toddalin]

I ordered 12 rolls of denim insulation and a can of spray adhesive to to the woofer cabinets. Made from recycled jeans, this is not itchy like fiberglass and at 1.8" thick, should line the cabinets nicely without blocking any ports.

 

[toddalin]

I finshed making the sides, tops, and bottoms and sanded them out.

I need to sand the fronts to mate with the faces and will probably re-route the face curves to go to the edge rather than sand the cabinets back and sanding off the "lip" on the face. Had never used a table router before, and I hope I don't screw up the re-do. The backs will be inset.

 

[drbiggles]

Hey Toddalin,

It was your title that drew me into your thread, couldn't resist. Then what caused me to stop by and say something? The image of UltraTouch. I've got PTSD from that stuff. I realize that there are online references to people using this stuff to line the insides of their cabinets. I got my information from Bozak related posts. And that's why I spent approximately 170 bux on it, had it delivered. After completing my Bozak Symphony build, 7 cubic foot cabinets with dual 12" woofers, something wasn't right. I was missing a whole lot of lower bass notes, the presentation was flat and dull. It was member Retrovert that did some research on UltraTouch and found out that end users that use it for insulating their homes don't like it very much. It's not a good insulator. And as it turns out, it makes absolutely lousy acoustic batting for lining speaker cabinets. I did extensive A/B testing between UltraTouch and 100% 1" thick cotton upholstery batting. This testing spanned just over 30 days and between 3 different Bozak loudspeaker systems. The UltraTouch ruined them all, the difference was remarkable. And by that I mean, one speaker sounded like it should. While the other was dull, flat and didn't dig nearly low enough. What you're essentially doing is making your cabinet smaller, that's all. And brother, or sister, making a speaker cabinet smaller is progress in the opposite direction.

xo, Biggles

 

[toddalin]

Interesting,

And yet...

http://www.audiokarma.org/forums/in...-your-experiences.792945/page-2#post-10962865

Did you try a 1/2 thick layer (~1" thick) ? Is it easy to separate into layers?

 

[wiredbecker]

Just a friendly FYI--Zilch regularly ran that nasty old pink/yellow fiberglass R15-R21 in his speakers.

Zilch said:
"Fiberglass is the preferred loudspeaker damping material, according to those who have studied it and alternatives, Dickason, for example.

High density is preferred. I use R-15. R-21, if I want more fill, as in closed-box systems. Thinner is also available; HVAC guys use it, coated on one side for easy attachment to cabinets...."

This is what's inside the C36 Econowaves that I'm dialing in.

Love the stuff but it sure does make me itch when I even so much as look at it.

 

[Sandstrom]

Are they "Digital Ready"?

Unfortunately that would require a pile of money, an army of engineers and a whole busload of marketing people to reach that high water mark...

Awesome project by the way, look forward to the results, your wood work is looking great so far!

 

[drbiggles]

Interesting,

And yet...

http://www.audiokarma.org/forums/in...-your-experiences.792945/page-2#post-10962865

Did you try a 1/2 thick layer (~1" thick) ? Is it easy to separate into layers?

Thickness plays no part. It's a lousy insulator, it's too dense. The backwaves from the woofer hit it with a thud and go no further. I'm familiar with the references on the net regarding using ultratouch. That's what sucked me in, I bought into it too. Remember, simply due to the A/B testing, I tossed approximately $170.00 into the trash. Never again.

Biggles

 

[drbiggles]

Just a friendly FYI--Zilch regularly ran that nasty old pink/yellow fiberglass R15-R21 in his speakers.

Zilch said:
"Fiberglass is the preferred loudspeaker damping material, according to those who have studied it and alternatives, Dickason, for example.

High density is preferred. I use R-15. R-21, if I want more fill, as in closed-box systems. Thinner is also available; HVAC guys use it, coated on one side for easy attachment to cabinets...."

Agreed. That and the upholstery cotton batting, just depends on what type of system you're building. Infinite baffle prefers cotton. There is no substitute.

Biggles

 

[toddalin]

At least I should be able to put it in one cabinet then A/B it with the other before committing to glue it into place. Maybe I just blew $80.

Could send the unopened pack back.

 

[Retrovert]

As far as I know I am the first to debunk UltraTouch for speakers, certainly for Bozaks, but I am far from the last. He's a summary of what I've written hither and yon.

To begin, I must say that I welcome cotton or other natural fiber alternatives to fiberglass and rockwool, which I regard as unsafe. (Topic for another discussion.) But UltraTouch is unfortunately not the solution.

UltraTouch is a poor material for backwave absorption in a speaker for a simple reason: it has no loft. Fiber insulation in speakers works, greatly simplified, by absorbing or by restricting air movement. This means that the material used for this purpose must be airy, not dense, and not reflective on the surface. The fluffy nature of insulation and its ability to rebound after being compressed for shipment is commonly called "loft". Fiberglass, rockwool, and polyester fiber fill are all materials with a great deal of loft. When used in a cabinet the backwave can become lost in the fibers. Not so with UltraTouch; after opening it remains is a solid, dense mass with no loft and it presents a hard surface which is reflective to soundwaves instead of absorptive.

I'm sure your experience with the dense nature was identical. As Biggles noted, using a hard lining in a cabinet is equivalent to substantially reducing the interior volume of the cabinet, which greatly degrades bass response.

When Biggles used UltraTouch in his Bozaks he reported having exceedingly poor bass response. So much so that he was about to give up on his Bozaks. Yes, such a horrible outcome very nearly came to pass. Bozak Cult nearly lost one of its charter members. Yet this poor bass response from a Bozak was, in a word, impossible; Bozaks produce so much bass that the surplus was historically exported to bass-deficient nations as part of our foreign-aid package. So I convinced (pronounced "browbeat") Biggles into trying cotton upholstery batting. As he above documented, the bass came back to the point he was bringing down low-flying planes with it, and the US Geological Survey arrived at his house to investigate earthquake reports similar to Tesla's resonator.

Other Bozak owners who used UltraTouch had similar experiences with reduced and abysmal bass response. Once they made the change to cotton batting they all reported a dramatic improvement. Yes, this is anecdotal, but I think we have enough data to say it doesn't work in speakers.

Thicker cotton batting is available from upholstery supply stores and online distributors. It can likely be purchased from any furniture re-upholstering store which can order exactly what you want from a distributor which would not otherwise do business with you on a one-time basis. (I have found that the magic phrase "I will pay in cash and give you a deposit" works wonders on most small businesses.)

 

[drbiggles]

Hey toddalin,

I say, take nobody's word for it and A/B it for yourself. The internet is simply a guide, we need to make the final choice ourselves. Oh, and have fun with it!

Biggles

 

[mars_volta]

Ohm uses recycled denim. Its great stuff.

 

[toddalin]

It is from the central/Internet HD so I guess I can take it back to the local store unopened.

 

[Retrovert]

Ohm uses recycled denim. Its great stuff.

Which model? I saw nothing about UltraTouch in Ohm speakers when I searched for it or recycled denim insulation products.

I have explained the problems with UltraTouch, the product the OP was using. Biggles has related his poor experiences as well. If you are able to comment on this specific brand of product, that would be productive. Insofar as Ohm speakers do not appear to use UltraTouch this claim has no relevance to the discussion.

 

[Retrovert]

It is from the central/Internet HD so I guess I can take it back to the local store unopened.

If you repack the used material and complain about its lack of loft Home Depot will take it back, too. Just stuff it back in the package.

 

[toddalin]

I haven't even opened the shipping boxes, so will probably just return them untried.