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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 20th September 2019, 05:52 PM   #521
jerryo is offline jerryo  Isle of Man
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Blue asbestos actually. Only the best for me. ��
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Old 20th September 2019, 08:21 PM   #522
Veleric is offline Veleric  United States
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Where can I buy the 3M VHB adhesive tape to replace the exciter mounting tape on my Dayton DAEX32U-4 Ultras? I can only seem to find the stuff with foam on it, which I don't think is what I want.
Eric
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Old 21st September 2019, 09:50 AM   #523
drewan is offline drewan  United Kingdom
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Try double sided carpet tape.
The common ceiling tile here are with a fine stipple finish and about 1/2 in thick, seem to be made from compressd fibres a bit like a very coarse and light mdf, but are also very easily damaged and I would expect them to disintegrate quite quickly.
I do have a couple of piece of high density fibreboard about 7'x2'x1/4" I'm thinking of trying. I guess it would take three or four exciters to move them enough?
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Old 21st September 2019, 11:15 PM   #524
DMLBES is offline DMLBES
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Here is a tip. When using EQ there is a spike (in most exciters) in the 1-2khz as well as the 4-6khz range. Lowering these spikes in the high frequency range will bring out more bass in the panel and also lessen listening fatigue over prolong periods of time.

There is a limit to EQ though as it wont make a bad (design) sounding panel sound good. Ones panels need to sound pretty good to begin with as the EQ is only to fine tune the panels.
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Old 23rd September 2019, 02:08 PM   #525
Jerms is offline Jerms  United Kingdom
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Quote:
Originally Posted by drewan View Post
Try double sided carpet tape.
The common ceiling tile here are with a fine stipple finish and about 1/2 in thick, seem to be made from compressd fibres a bit like a very coarse and light mdf, but are also very easily damaged and I would expect them to disintegrate quite quickly.
I do have a couple of piece of high density fibreboard about 7'x2'x1/4" I'm thinking of trying. I guess it would take three or four exciters to move them enough?
Nope.... Just the one.
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Old 23rd September 2019, 07:27 PM   #526
Think is offline Think  Netherlands
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A Study of DML's as a Full Range Speaker
Quote:
Originally Posted by gapmedia View Post
These are working well for me.

I gather there is a lot of (audio) science working here that I don't fully understand as yet, and probably never will. I have tried to follow the Golden Ratio with the design, but I am not sure if it adds anything or not as these are the only DML's I've heard. You can change the frequency responce by adding blobs of bluetack around the diaphram and I am still experimenting with this, and other things.

At the moment they are in the guest bedroom to give some space between the speakers and rear wall. In my usual listening room, due to WAF, they had to be placed too close to the rear wall to work their 'magic'. I am not sure if the bed between them is adding or subtracting anything from their performance. I gather it is damping the sound though. Will try in another location soon.

How do they sound? I think their characteristics are summed up, better or as well as I could, in these two reviews, which might already be referenced here.

6moons audio reviews: Podium Sound Model 0.5

6moons audio reviews: Podium Sound Model 1
Click the image to open in full size.

These look beautiful!
Quote:
Originally Posted by gapmedia View Post
I stumbled across 4mm Twin Wall Polycarbonate glazing panels. I believe the same material is sold for greenhouses. Not sure if it's the best material, but it looked interesting. Seems to work. ........
Interesting choice as these panels are lighter then solid polycarbonate. But don't these panels flex a lot in in 1 direction? Vertically the way you used them.
And are the small tunnels not creating resonances/distortion? Or did you close them?

Panels need to be lightweight and stiff.
Inspired by surfboards and modern boats, I suspect that polystyreen sheets with super thin (model airplane) fibreglass cloth and epoxy will be great.

Other idea is polystyreen, (wrapping) paper and sprayglue.
And maybe you wife can decide on what kind of wrapping paper...... and maybe on some finish to match the living room.

//edit: Maybe it is an idea to print pictures or artwork on the paper, although that paper will be a bit heavier.

Last edited by Think; 23rd September 2019 at 07:43 PM.
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Old 24th September 2019, 02:49 AM   #527
gapmedia is offline gapmedia  Australia
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Hello Think,

Thanks for your kind words. (I can never work out how to use quotes)

Weighing some polycarbonate scrap material I have left over I estimate that the panels each weigh around 360g. It is very stiff in the vertical, and is quite hard to bend, let alone snap without scoring the face. It is certainly more flexible in the horizontal, but does not sag under its own weight if you hold it out flat.

I haven't closed/filled the tunnels, and have always thought, rightly or wrongly, that DML panels would be better if created from one solid lightweight material without laminating or internal hollows. I haven't done enough experimenting as yet to confirm any of this. The only other material I have 'played' with is 1.5mm bamboo laserply. It worked quite well in some small prototypes I made, but seemed too flexible in the panel size used here. Maybe lightweight poplar-ply might work well? I truly stumbled on this glazing polycarbonate while looking at other possible materials in a hardware store.

I would like to try carbon fibre, but unless you purchase direct from China it appears to be cost prohibitive. China also offers honeycomb carbon fibre board and polysyrene laminated board. Maybe in the future. I believe BurntCoil did some experiments with a small piece of Carbon Fibre sheet and was impressed with the sound. I would also like to try laminated polystyrene art board. The only thing I have found so far is that I believe the better the connection of exciter to diaphram, the better the result/sound. This means the few exciters I have to play with at the moment are all two part epoxied to their diaphrams, making them single use.

One thing I've read quite often, in articles discussing DML's, is that others who have tried multiple diaphram materials say that there is not much difference between the sound of 'suitable' diaphram materials.

My wife wasn't too concerned with the look of the panels, she's just not that happy with how far I want them off the back wall. Still experimenting with best placement for these particular panels.

Last edited by gapmedia; 24th September 2019 at 02:52 AM. Reason: To thank poster for kind words, which I forgot earlier.
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Old 25th September 2019, 02:39 AM   #528
perceval is offline perceval  Taiwan
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Just saw an ad.

Someone figured that if you put an exciter on a motorcycle helmet, it acts like pretty much the same.

Product is called Domio if you want to look it up.
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Old 28th September 2019, 01:33 AM   #529
geosand is offline geosand  United States
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Hey GapMedia, those are just stunning in looks! Theres just something about a clear panel design that screams beautiful. Great Job!


Can you tell us a bit more about how you constructed them? Are the front and back frame routed out from a single sheet? What material did you use. Can you explain more about how easy the panel media would be to replace...the method you used to join the front and back frames, etc...


And finally, in the "how does it sound dept.", what are the lows and highs like? Are they rolled off and need EQ or are they fairly extended? Maybe I missed it but what is the panel size itself? Are the corners rounded or are they left square and the frame itself is rounded for looks. I assume you are just using some type of foam/weather-seal material and basically squeeze the panel between the front and back frame?


Geo
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Old 29th September 2019, 04:47 PM   #530
jerryo is offline jerryo  Isle of Man
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Hey Veleric,
I found out that the ceiling tiles I am using are called ‘Armstrong Recyclable Dune Supreme’

Had a good listen last night with a parts of a CD called ‘They’ll have to kill us first’.

I am finding it increasingly baffling how these DML’s can sound so good, and how the sound is emitted around and into the room. I have mine hanging by cords running through holes in each corner of the same side of a tile and then hanging from a cable stretched across my shed about two feet from the wall. Lashed together you might say.
Try walking up to the tiles and between them and then around the back and see how the sound continues to fill the air around you. It is a remarkable effect, completely unlike conventional speakers.
They are very good at revealing special clues in recordings, ambient effects and acoustic spaces seem to be better resolved or emphasised. I have have found a similar effect with BMR’s! Is this due to the flatness of the emitting surface or something else.
Puts a big smile on my face.
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