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A Study of DML's as a Full Range Speaker
A Study of DML's as a Full Range Speaker
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Old Today, 01:26 AM   #1641
Veleric is offline Veleric  United States
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Originally Posted by davelang View Post
I use the same technique to make double tops in that I put a measured (g/in^2) amount of epoxy on a third surface precisely quantified then set the Nomex in the spread out epoxy. This transfers a minimal amount of epoxy to the Nomex and should keep the contribution of the epoxy to the weight of the panel next to nothing.
I only tried nomex once before and didn't know this technique at that time. I used way too much glue (and wrong kind). I've since seen the technique you described but have not tried it yet. Lately I've been trying CF construction with fabric (not prepreg) which makes using nomex more challenging though not impossible. Something like balsa or foam works better than honeycomb when working with carbon fabric. I'm not sure where I'll end up yet.
Eric
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Old Today, 01:31 AM   #1642
davelang is offline davelang  United States
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A Study of DML's as a Full Range Speaker
Veleric

I was taught that technique by Alan Dunwell of Dunwell guitars outside of Boulder,Co. I felt his exact g/in^2 was too proprietary to share but the amount I gave should work. Alan is a great and very smart guy. Kudos to him.

I am not familiar with B /mu^3... B/ mass unit area^ ?
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Old Today, 01:38 AM   #1643
davelang is offline davelang  United States
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A Study of DML's as a Full Range Speaker
I wondered about using the lightest CF weave which is about .1 mm thick or possible random CF cloth and doing a manual setup with epoxy and maybe thicker 4-5 mm Nomex.

It could be laid up on a piece of plate glass with release agent and a vacuum bag. Probably many ways to skin the cat. The trick is keeping costs down so hobby types can play.

Have you tried plexiglass as a panel ? AER seems to have pulled it off. Not sure how thick their panel is.
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Old Today, 01:52 AM   #1644
gapmedia is online now gapmedia  Australia
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Originally Posted by davelang View Post
I am hoping this works as it would reduce the cost of a honeycomb panel by 7-800 dollars by not using CF
I spoke with this company Carbon Fiber Sheet | Carbon Fiber | Carbon Fiber Tube | Carbon Fiber Sheet | Carbon Fiber CNC Machining Parts | Dongguan Xiechuang Composite Material Co., Ltd. mid last year about carbon fibre skinned foamboard, not sure if they do honeycomb cores. They quoted a sample price of US$65 per piece for 2x 600mm x 500mm 2mm thick (0.5mm CF skins on 1mm foam core) plus US$45 for shipping. I don't know if they go larger, I know they go thicker. They also take Paypal from their proforma invoice. They also cut, and machine parts.

I didn't/haven't ordered yet due to the crappy Australian $. Wasn't exactly sure what I needed either. Might wait for you guys to experiment a little more
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Old Today, 01:57 AM   #1645
gapmedia is online now gapmedia  Australia
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Originally Posted by davelang View Post
gapmedia

I found the tunes you posted on Tidal today... awesome groups and great audiophile recordings.
I hear about a lot of great performers from these forums or other 'audiophile' sites.
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Old Today, 02:00 AM   #1646
davelang is offline davelang  United States
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A Study of DML's as a Full Range Speaker
I don’t know for sure but 2 mm seems really thin. That is thinner that what I am setting up. Might be worth 65 as an experiment. Do it and report back. I used the Nomex I had on hand and am trying a process to build the panels cheaply. Thin CF is cheap (15-20 bucks/ yard) Nomex can be had cheaply. Carbon fiber plate of any thickness is crazy expensive. Premade panels with Nomex or foam and CF are also very expensive.

The old NXT panels that I have( prior post ) have 2-3 mm thick panels for a 8x12 ish panel
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Old Today, 02:49 AM   #1647
gapmedia is online now gapmedia  Australia
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davelang, your guitar(s) look great, well done. Have you ever tried toneboard(?) as a panel material? Expensive, and not available in large sizes I imagine.

I see you appreciate Markaudio drivers as well.

Yes, I think 2mm was their idea, I was thinking of 5mm total thickness. Not sure if they offered thinner skins.

I'm sure you seen this youtube video, but if not the guy does some panel mode experiments around 17:20, in a similar fashion to your guitar mode tests, plus some panel damping as well.

YouTube

A Russian company(?) making some DML's for the audiophile market, I think.

YouTube

Last edited by gapmedia; Today at 02:55 AM.
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Old Today, 02:59 AM   #1648
davelang is offline davelang  United States
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A Study of DML's as a Full Range Speaker
Yes I have tried Tonewood as a panel. I tried a 5mm thick 20x20inch spruce board with a Dayton Thruster. It sounded weak. Formular 150 is better than my spruce tone wood and a lot less dense. Using wood has a romantic appeal but I think composites hold the most promise for all the reasons discussed in this thread. I didn’t want to risk good guitar wood by thinning it to try as a DML. That You tube video “Worlds Best Speakers” is the one that got me going on this. I didn’t believe it. I had no idea that a DML forum has been on diyaudio for so long.
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