A Study of DMLs as a Full Range Speaker

when i was recording the art panel around the room i noticed that when i changed hands the microphone came very close to the panel and sounded quite good.
so i decided to do another recording at about 12inches to see how it sounds.
but on listening to the recording i noticed the microphone was picking up the harsh sound produced within the coil area.
this is pretty much the same as the sound i mentioned in the aagas recordings, once you know it is there it is hard to ignore.
i already had some blu tack in the centre of the coil area,but this obviously was not enough.so in the second recording i applied a larger amount.
hopefully if you play the recordings quite loudly on headphones you will be able to hear the NOISE , mainly on vocals which can be quite painful sometimes ,but is always there if the coil area is ignored .
hopefully after listening to the two recordings a few more penny's will be dropping :D
blu tack is not my ideal way to reduce the problem but it is a quick fix.
the sound is still there in the second recording but it is considerably reduced .
steve
 

Attachments

  • Harsh Sound Noise! mp4.mp4
    2.7 MB
  • Improved 2 mp4.mp4
    2.8 MB
  • Thank You
Reactions: 1 user
Spedge,
When you talk about a noise, are you talking about the deep droning? If so, that is just the deep bass background on the recording. There is some heavy-duty bass on that recording. How does the panel sound with the subwoofer playing? If not the bass, what specifically did you do to lessen it? I am probably going to get the 16x20" canvas panels to start with before I make my own panels. I have some thin paneling-type luan with another type of wood 3-ply for the 4x6" panel. Should I use the water/glue mix on the canvas? I read that gesso is a type of acrylic paint, so maybe a slightly thinned coat of regular acrylic paint would work well instead. I was planning on a thin coat of polyurethane on the wood panel. What do think of those suggestions?
 
Last edited:
Jaxboy.
No the noise is produced mainly by her voice which tends to become a little shouty ? When she raises her voice.
It makes me wince and frown when it happens.
I'm wondering if your tinnitus is masking this a little?
Maybe I should have removed the original blue tack first ,I'll have a listen and see if it is worth another recording?
I see what you mean about playing this song over and over again ,it never gets tiring ,I've lost count of how many times I've listened to this recording.
Steve.
 
mexjerry,
Somehow I missed reading most of your post. I think maybe I got interrupted while reading it. You had a lot of valuable information in it that I missed the first reading. Thanks. From what you said, it seems that a polyester blend would be the best bet, and I could use a small heat gun to shrink it. I have two, a regular two-stage one, and one used to set and melt the ink used in stamping designs on projects. I think the smaller one would work better, as I could better control the heat. Thanks again for the info.
 
Spedge,
I cannot leave to check on something in the middle of writing a post without it disappearing. For the third time, I am writing you a post. I replayed your two recordings, and, I didn't hear the "shoutyness" you described. To my ear, the second recording seemed to have lost a tiny bit of nuances, like it was maybe a hair too bright. That's my ear, though. You're right; my tinnitus is so loud, it may be interfering with what I hear. Definitely don't change your panel based on anything I hear, or think I hear. I have trouble making out conversation in a noisy environment, for example. I went back over the last couple of pages, looking for a post I thought I sent you, but don't see it, so maybe it got lost, too. I had suggested that you listen to Gretchen Peters. If you like Jennifer Warnes, I'm pretty sure you will like her, too. I recommend as starter songs Jezebel, Jubilee, and Little World. She wrote all those, as well as many that others have recorded, like Independence Day, that blockbuster of Carrie Underwood. If I could only have one singer in my music list, it would probably be her.
 
Last edited:
Jaxboy.
I'm not an expert on paints,but looking on YouTube gesso is not water based,so I presume shrinkage would be minimal ?
Not forgetting,pva is a glue not a paint.
If coating ply or card I usually coat both sides at the same time(if possible).
As coating one side only with pva will make the ply or card bend in the direction of the pva!
Although when pretty dry you can coat the other side to pull it back again.
The good thing about pva is that when it has dried it is a fraction of the weight when wet, even more so if thinned.
On eps a 50x50 mix changes the weight of the panel very little but improves the sound considerably.
The free vibrating area of my canvas is about 11.5 inches x16.5 inches.
If you like the sound and performance of my panel ,I would suggest keeping as near to this as possible,as altering the size could change the performance,good or bad ?
Or maybe similar to the size of the patent? Which is fairly close to mine?
I'm not even sure if I coated the whole panel or left half an inch of so at the edges,as I did with the cascamite?
To be honest as I have had no problems with buzzing and such like with the standard frames of my panels,I do wonder if just stretching and then gluing the canvas directly to a square frame will be a problem? If glued well ,and then maybe a bead of something around the edges if needed?
It's down to you realy.
Steve.
 
jaxboy
I'm sure a heat gun would work, just not as controllable as an iron, if you do an internet search for "stits polyfiber" it should lead to a FAQ/instruction on calibrating an iron.


spedge
remind me again your set up, so many pages in this discussion, and the search function is not the best.
Think I'll look at the personlisation section and see if there is a method to have a custom signiture.
thanks
 
Jaxboy.
Thanks , I look forward to listening to gretchen Peters when I get time.
I used the notch filter on my daq and traced it to about 3k ,wich was similar to the aagas panel .
Maybe I'm ultra sensitive at this frequency?
Blue tack damps this area,but I'm afraid it damps everything so I don't use it if possible.
That's the problem with damping!!
I could describe the sound as having a bit of a sting to it,but I'm not sure that will help.
Steve
 
Spedge,
I went on youtube, trying to find out how to make my own gesso. Several videos on how to all said to use pva, water and acrylic or latex paint, plus baby powder (cornstarch) or powered chalk. Commercial gesso uses a different formula. Please rest assured that I was NOT doubting you. I found this formula only trying to be cheap and make my own. In all of them, the water/pva mix was about 1:1, and then a 1:1 with the acrylic paint, plus of that mixture about a 1:4 with the cornstarch for a tooth. So, for 1.25 cup of gesso, it would be 1/4 cup each of pva, water and baby powder, and a 1/2 cup of paint, your choice of color. The commercial gesso sites said the gesso should soak into the canvas. Since we just want to stiffen the panel without adding weight, I would think the water ratio should be closer to 2:1 with the pva, or even more, as the resulting gesso the diy sites made was thick enough to completely cover in 1, maybe 2 coats max with a solid color, and they didn't even mention about it soaking in. You can even use colors other than white, which is a definite bonus. I don't know if the cornstarch is necessary, since we only want to coat the canvas, not paint on top of it, and the corn starch thickens the gesso quite a bit. It looks like the cost to make your own is way less than $4 for a quart, as opposed to $6-22, depending on the brand, and you probably have most of the ingredients already at home. Also, the weave of the canvas they used was approximately the same as the ceconite used on light aircraft.
 
Jaxboy.
Feel free to experiment with different materials and paints or glues.
The gesso I believe is used as a filler and to add texture and will add weight and bulk and as such is not intended to shrink very much ,I believe?
Sort of opposite to what you want I think?
Paints such as vinyl silk can mellow the sound of a harsh sounding panel so should be used with care especially on eps.
Never glue the exciter on to a painted surface ,glue the exciter directly to the wood or eps ,I use pva and then paint around the coil area,not the coil !
I'm always looking for something better than pva, hence the cascamite ,but so far pva seems to work best (for me).
Steve.
 
Spedge,
The real gesso uses rabbit skin glue, but is otherwise the same (it seems) as the homemade gesso, so the pva is a replacement for the more expensive rabbit skin glue. Since the pva is thinned by water, I would think it would shrink the canvas, especially if you use heat to dry the gesso. Most canvases you buy for art already have gesso pre-applied, too, and are still light. Just me thinking out loud. I'm a neophyte to all of this. My younger brother is a renowned artist in Canada, but I wasn't home when he began his career, so I never saw what he did to prepare his canvases. By the way, he retired to a huge home on his own beach at age 50, so art can be rewarding in more ways than one! By the way, have you looked up the definition of catamite? Yuck!
 
Last edited:
New Transducer

Hello, The post #3128 of podium sound panels is just marketing BS. Sound waves are longitudinal and not transverse waves even from thin plates and strings such as guitar and pianos. The statement that "it is impossible to propagate longitudinal waves with a resonating panel loudspeaker." is completely false since sound is a longitudinal wave only it is never a transverse wave. Sound only occurs due to expansion and compression of the air or other gaseous medium. Here is a new example of my latest 100mm diameter transducer with a 5" sub woofer cross at 500Hz . Again there are no moving parts in this new design.
Cheers,
Steve
 

Attachments

  • Both Sides Now.mp4
    7.9 MB