pepe.
also if you missed my recordings on page 116 (yellow, duhast , to rich for my blood,)where i demonstrate how loud the panels can go, now you do not have to download them,they play from the site.
these (and all my other recordings) were recorded at disco levels(yes i know im old) so you have to crank the volume up on you headphones to get the full experience .
and also please use your headphones only.
you will not get the depth and size presentation in the room but within the limitations of my recording technique ,you should get some idea of how they sound, hopefully.
steve.
also if you missed my recordings on page 116 (yellow, duhast , to rich for my blood,)where i demonstrate how loud the panels can go, now you do not have to download them,they play from the site.
these (and all my other recordings) were recorded at disco levels(yes i know im old) so you have to crank the volume up on you headphones to get the full experience .
and also please use your headphones only.
you will not get the depth and size presentation in the room but within the limitations of my recording technique ,you should get some idea of how they sound, hopefully.
steve.
I'm OK with inefficiency- watts are cheap and easy. My main objective is an even, responsive, full range sound. Plexiglass is even and full range, but kind of dull... hoping a CF panel in the same size will cover the same spectrum but with more "life"
What about polycarbonate? Less expensive then CF and stiffer then plexiglass.
That does sound like an interesting and flexible system!
The dml could be very handy when one is moveing around indoors and the cone+dml can be used during seated listening.
Eric,
Thank you for the links. I am adding in the "history file" already posted a sheet with my bibliography about DML. As I didn't store all the links to documents, yours are welcome!
This week I was going in my doc about how pistonic loudspeaker works and I found the criteria E/rho^3 which is also D/mu^3 was proposed in 1958 by Harris as factor of merit for cone materials.
To follow
Christian
Pepe
You could have a look to the pdf file I posted #4211. It will give you a view about some realizations, the related posts.
Thank you for your answer Eric. You answer exactly to the questions I have. Don't worry about the units. With thread I am now used to convert.
On my side I have in stock balsa for next panels. It is 10cm (4" about) x 1m (3'?) x 1mm thick board. My intention was to make a sandwich with this balsa outside as skins and a core made of 3x5mm balsa rods radiating from the exciter axis and xps (or eps) for the space between the rods (clear enough without drawing?) so reaching 5mm total thickness. Another possibility which needs much much work (if feasible) is to make my own honeycomb. So before investing time, it is interesting to share this kind of ideas.
It is very encouraging to read your experience putting this balsa panel in the top of what you tested. Balsa is a kind of "obvious solution" to improve efficiency, not so obvious from stiffness point of view.
Christian
Pepe.
I was looking through some of those recordings from page 115 to 119 starting with some eps and working through my then collection including card with domes and chalk board.
I can always tell the eps panel as they sound so alive and the realism is amazing.
the idea of using the bandor unit was for recordings that can sound odd on dml panels.
usually ,I believe because they have been heavily mixed on normal cone speakers which don't show up the problem if you play them on normal speakers.
Having a choice of the cones and dml covers all variables in the recordings.
Steve.
I was looking through some of those recordings from page 115 to 119 starting with some eps and working through my then collection including card with domes and chalk board.
I can always tell the eps panel as they sound so alive and the realism is amazing.
the idea of using the bandor unit was for recordings that can sound odd on dml panels.
usually ,I believe because they have been heavily mixed on normal cone speakers which don't show up the problem if you play them on normal speakers.
Having a choice of the cones and dml covers all variables in the recordings.
Steve.
Oh, I see. Thank you. I didnt think of that recording/mixing variable. Makes sense and allso makes even more sense to have both options then.
I wonder if a plexiglass base with an EPS top layer can combine the low frequency response of the former with the "life" of the latter.
Has anyone played with corrugated plastic? I have a long shopping list for Home Depot tomorrow.
About the corrugated plastic, I seem to recall much earlier someone who had quite a bit of experience with DMLs saying that it did not give good results, but I don't remember who or the specifics. However, it is a cheap material, so you will not be out much money if you want to give it a try.
ok, I'll bite.
Tried corrugated cardboard, 3 ply, several coats of lacquer,brushed on, both sides. To me it sounds very good, but, without sealing the edges, it will warp, due to changing humidity levels.
My next attempt will be plastic corrugated panels, I have sampled a listen, on a size far larger than I will use, and it sounds comparable to card board corrugated.
Sorry, but I'm not getting into the "weeds" about testing, and posting some non-nonsensical, ******** that takes a mathematical genius to decipher, these sound good to me, not some machine telling me "what is correct"
Tried corrugated cardboard, 3 ply, several coats of lacquer,brushed on, both sides. To me it sounds very good, but, without sealing the edges, it will warp, due to changing humidity levels.
My next attempt will be plastic corrugated panels, I have sampled a listen, on a size far larger than I will use, and it sounds comparable to card board corrugated.
Sorry, but I'm not getting into the "weeds" about testing, and posting some non-nonsensical, ******** that takes a mathematical genius to decipher, these sound good to me, not some machine telling me "what is correct"
Mexjerry , jaxboy.
I did have a look at 1cm hollow polycarbonate sheeting but wasn't that keen on the sound.
But thought the 4mm might do better.
I looked into the prices but unless I bought in bulk it wasn't that cheep,so gave it a miss.
I think there was a YouTube video ?
I felt that the 1cm was too heavy ,maybe for my exciters .
I originally started off years back with I think it was 2mm corrugated cardboard which at the time sounded great.
Everyone else seemed to go for the thicker three of more plys
Some used to inject shellac into the flutes which made the cc bend out of shape.
This also made the panels even heavier.
It would be interesting to know what the 4mm polycarbonate sounded like ,but I'm not that keen on corrugations even if they are in the shape of honeycomb, like the podiums.
I think my 5mm xps with epoxy coating is probably a better option, for me anyway.
Steve.
I did have a look at 1cm hollow polycarbonate sheeting but wasn't that keen on the sound.
But thought the 4mm might do better.
I looked into the prices but unless I bought in bulk it wasn't that cheep,so gave it a miss.
I think there was a YouTube video ?
I felt that the 1cm was too heavy ,maybe for my exciters .
I originally started off years back with I think it was 2mm corrugated cardboard which at the time sounded great.
Everyone else seemed to go for the thicker three of more plys
Some used to inject shellac into the flutes which made the cc bend out of shape.
This also made the panels even heavier.
It would be interesting to know what the 4mm polycarbonate sounded like ,but I'm not that keen on corrugations even if they are in the shape of honeycomb, like the podiums.
I think my 5mm xps with epoxy coating is probably a better option, for me anyway.
Steve.
basically , I think you have hit the nail on the head.
When I bring in my TLS to cover the 300hz and down ,I use my ears, and without fail I always end up with an increased output in this area.
to my ears if the panel is equalized flat or a dip is left in this area ,the dml panel seems out of balance, I don't know why but the panel sounds to me , like It has more energy above this frequency ?
raising the response below about 300hz or so ,brings back the warmth and body to the panel sound.
This is the main reason I am not keen on equalizing a dml panel to have a very flat response, to my ears this sounds wrong.
to be honest I usually find That dml panels have a slightly sloping response(not always) similar to the room curve I have seen in papers , I usually just follow this line below the 300hz and with a little bit more boost depending on the panel.
I think this could be one of the main reasons that some find dml panels hollow sounding or lacking in warmth ?
Steve.
Relax Mexjerry,
We have all our own way of doing or understanding things. Mine for example is to keep in parallel realizations and measurements and math. It is not math that tell me what works or not but I think that we could find some elements that would help going faster to design that fits to our expectation by limiting the trial/error cycles. Just an example, for a given material, which area to reach the expected low frequency. By some aspects, DMLs remind me the loudspeakers in the 80s (or before?) when there was no calculations of enclosure. I think we all agree to say they sound pretty good and are promising. The different approaches we can have is a possibility to make them better together.
Your post was the opportunity to read what you posted before. Very interesting your experience with aircraft and the techniques you described in stretching fabric (#3131, 3136, 3153, 3159 page 157.
Christian
It is not a hollow panel. It’ a plain 3mm sheet.
Thanks Spedge, I will start my research on exciters. Allways good to know where to start.
@Spedg
My plan was to split the panel in half and get two 40cm wide x 120cm tall panels, 20 € a piece seems resonable to me.
Just have to decide what exciter to use now.
This one seems good?
Low inductance, is that something to look for in a semi fullrange exciter?
My plan was to split the panel in half and get two 40cm wide x 120cm tall panels, 20 € a piece seems resonable to me.
Just have to decide what exciter to use now.
This one seems good?
Dayton Audio DAEX25FHE-4
Low inductance, is that something to look for in a semi fullrange exciter?