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Multi-Way Conventional loudspeakers with crossovers

A Monster Construction Methods Shootout Thread
A Monster Construction Methods Shootout Thread
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Old 10th August 2020, 06:25 AM   #121
Baldin is offline Baldin  Denmark
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Quote:
Originally Posted by HeadShake View Post
It is open cell.
I found someone selling it for accoustics that had a graph:

Melamine Acoustic Foam | Open Cell Melamine Foam


"Melamine is a flexible, open cell foam made from melamine resin, a thermoset polymer. ... Its characteristic feature is its three-dimensional network structure consisting of slender and thus easily shaped webs and provides abrasiveness when the material is used as a cleaner."
Have seen these kind of foam blocks used in commercial speakers, where blocks are used as bracing between either sides or front-back panel. This serves 2 purposes; damping of wall resonances and sound absorption inside the box.

I would think, this together with MDF will be almost as good as it gets, and very easy to implement.
Another brand for this is BASF: Basotect, the melamine foam by BASF - Sound absorbing, lightweight, flame retardant and flexible - YouTube

Wondering if it is the same material you get in these "magic" sponges for almost nothing. You could glue them together to get the shape you wanted!
Lot Magic Sponge Eraser Melamine Foam Stain Dirt Mark Remover Cleaning Block | eBay

Last edited by Baldin; 10th August 2020 at 06:55 AM.
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Old 10th August 2020, 11:36 AM   #122
black300zx is offline black300zx  United States
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Quote:
Originally Posted by augerpro View Post
I'm ordering some tomorrow for testing. It would be great if we could find something as good as the denim, but without the shedding of fine fibers.
It seems like Denim is the best or at least 2nd best material without even considering it's lower cost. There are a lot of really smart people on here. I have to imagine that a cheap and effective way of controlling the fibers can be found. A couple ideas initially come to mind, but I've never worked with the denim insulation so perhaps these aren't feasible:
  1. Roll out the denim insulation, apply a light mist of spray adhesive to the face, and then apply a layer of speaker grill cloth to constrain the fibers
  2. Do the same as above, but instead using a thin layer of neoprene, butyl, or some other appropriate type of flexible rubber sheeting. Perhaps this might mimic the sound damping used on the firewall of my Z?
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Old 10th August 2020, 07:42 PM   #123
augerpro is offline augerpro  United States
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I've set up a gofundme for this project! Fundraiser: A Monster Box Construction Project
Any amount helps, especially since I'm currently unemployed, having switched jobs at a most inopportune time. The initial goal will cover my current costs, plus the next round using CLD techniques. Speaking of that, got some Nidacore coming: Nida-Core - Nida-Core H8PP Plain 1/4" #14-h8pp-07
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Old 10th August 2020, 08:22 PM   #124
Sixto is offline Sixto  United States
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Quote:
Originally Posted by HeadShake View Post
It is open cell.
I found someone selling it for accoustics ...

Melamine Acoustic Foam | Open Cell Melamine Foam
I called Acoustical Surfaces and talked to a sales rep. They will sell to individuals via credit card (online) did not ask about shipping since they are local to me. In-stock material is 2' x 4' sheets . Larger is possible, but requires a minimum order amount... I did not ask, since I do not need large quantities. I did ask what a price break would be for a large group buy, and he said about 5,000 s.f. which might be typical for a gymnasium or auditorium, but out of my range....

The flat board costs $6.69/s.f. for the 2" thick and $9.12/s.f. for the 3" thick material

The wedge board costs $5.36/s.f. for the 2" thick and $8.65/s.f. for the 3" thick material.

I was just happy to find a local source for this material.

Also glad to see the Go-Fund me was setup.

Six.
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Old 12th August 2020, 05:54 PM   #125
augerpro is offline augerpro  United States
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Harmonic distortion results up next. These are taken from the rear panel in the same manner as the first frequency response measurements.

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

The last two had holes routed for the dummy driver for lining/fill testing. I capped the hole with the respective material, but I'm not comfortable comparing these directly to the ones above.

Click the image to open in full size.
Click the image to open in full size.
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Old 12th August 2020, 06:21 PM   #126
wolf_teeth is offline wolf_teeth  United States
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Looks like the MDF did well for this round.
Wolf
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Old 12th August 2020, 07:55 PM   #127
augerpro is offline augerpro  United States
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Quote:
Originally Posted by 454Casull View Post
Is it possible to turn those CSDs into multi-plot charts where each line is corresponding to t = 0, 1.0, 2.0 ... milliseconds? It's not necessary to see all the granularity, especially if what we are trying to do is to identify damping (falloff) vs frequency vs time.
I don't believe I can set it up that way.
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Old 12th August 2020, 08:19 PM   #128
augerpro is offline augerpro  United States
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Materials I have on the way: 4/5" wool batting, 1/4" NidaCore, Resonix CLD squares. Still deciding on CLD adhesives.
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Old 12th August 2020, 08:50 PM   #129
augerpro is offline augerpro  United States
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How does Shore A rating factor into CLD adhesive?
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Old 12th August 2020, 09:06 PM   #130
454Casull is offline 454Casull  Canada
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Quote:
Originally Posted by augerpro View Post
I don't believe I can set it up that way.
Are you able/willing to share the text/csv data?
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