Hello Steve,
I have chosen the conservative figures 300Hz to 10kHz to mention as even in this case DML can make wide range panels for home application. Wider range can be reach as you shown.
Christian
Christian the studio is fully booked, and we need time to set up properly the panels and do the measurements, but i will surely put them here for all.
Steve, thanks for the clarification, and i do consider the efforts to achieve that.
In thesis i´am not keen either but measurements are just a starting point that only make true sense in the realms of psychoacoustics. Christian, many thanks for your excellent post #13,816 .
Although the point is not "adding reverberation to enhance" but rather understand the unique panel dispersion which is common in DML sound in various (all?) materials (upon i think we all agree) with smooth or not response and beside our sound preferences and hear/skull/brain characteristics, i,e:
HvdZ, you are not alone, what strives me the most is that broad spread which, for me, is the heart of that special sound. The reverberation hypothesis did erase because the dipole pattern always sounded to me to have a kind of reverberation, a surgical one such as the ones sound engineers strive to achieve. So Steve, of course the evident ones go to the bin, but is not as we add but rather a intrinsic Dml sound propagation characteristic. Which leads to:
Precisely.
Objectively by measures? Maybe the day will be near with all the forum members efforts, but not in present days.
Objectively by listening agreement on that "special sound"? For sure, and my best response is that because of DML wave propagation the coupling to the rooms and brains at a ridiculous cost still put many conventional speakers in the bin.
Good auditions
Hi Steve,
I work in a medium sized "black box" theater (240 seats), with a large volume (18x12x10m) foyer with a lot of hard surfaces.
In the theatre space we compared the dml panels to our standard (expensive, high end) Meyer Sounds upq active PA. Sound wise (how nice it sounded) it faired quite well, albeit of course with a much lower possible SPL.
In the foyer I tried the DML panels for various things :
- background music, with one panel in the middle of the room, serving the whole space (with sub woofer) - that worked OK.
- "delay speaker" for use with small pa for speech and acoustic instruments - also OK
- infill speaker for small PA - OK-ish but needs high pass for usable levels
- small stand alone PA for mainly speech - Not good, very muddy from halfway the hall. Not what I had hoped for, with all the stories about the difuse sound projecting further and mixing with all the room reflections. High freq seems to fall off too fast.
- Using the "null"on the side of the DML to achieve high gain before feedback (like you would use a fig 8 mic) - more or less works but is of limited use because of the difficulty of projecting the sound far enough.
So in conclusion I think there's something special about the sound, and that could well be the ringing/chaotic nature of the panel that my brain reacts positively to. In recording I sometimes use adding random noise to make a clean recording sound better and more alive. I think that may be the case with the DML also.
In practice (like amplification for PA) they have shown limited use for me, but I keep dreaming of a difuse sound filling the room without hearing a distinct source.
Greetings, Hans
Hello Hans.
Can you show pictures and a description of the panels you have built.
Christian and I have been playing around with small PA type panels, and might have a few ideas for you to try.
From this short time of testing PA type panels, I believe I have come to the conclusion that I would design them differently from hifi type panels.
Feedback seemed pretty easy to remove if the right materials are used.
Maybe this should be under a small dml PA system forum.
🤔
Steve.
Can you show pictures and a description of the panels you have built.
Christian and I have been playing around with small PA type panels, and might have a few ideas for you to try.
From this short time of testing PA type panels, I believe I have come to the conclusion that I would design them differently from hifi type panels.
Feedback seemed pretty easy to remove if the right materials are used.
Maybe this should be under a small dml PA system forum.
🤔
Steve.
Hans,
I agree mostly with Christian's response above, and in particular the wide radiation pattern, though I think 100 Hz to 10kHz is possible. And the "sometimes difficulties" Christian refers to are really a big part of the appeal. What fun is it if it's easy?
Eric
Hans.
100hz to 10k is easily attainable for starters and probably a good choice for PA work.
If you are after large amounts of sound dbs then I would go for EPS as this is the loudest material I have come across so far, and as it happens is my favourite material to use.
Although maybe not ideal for PA work , I'm not sure.
Steve.
100hz to 10k is easily attainable for starters and probably a good choice for PA work.
If you are after large amounts of sound dbs then I would go for EPS as this is the loudest material I have come across so far, and as it happens is my favourite material to use.
Although maybe not ideal for PA work , I'm not sure.
Steve.
Hans, did you read the DML thread https://www.diyaudio.com/community/threads/dml-pa-systems.390363/ , particulary Leob experience?
Hope he joins this.
Thanks to bring here that context of application. My thoughts:
- the first paragraph and the tree first points are a win for DML;
- when i used panels in the context of a big school lounge room, as in our infill third point, i thought on the approach of a church sound install, i,é, several panels crossed from hi mid to hi, at low spl. Till now i just have two panels in the middle of the room with good effect on speech intelligibility (on separated amps to decrease sound pressure on musical program);
- with today`s state of the art dml use as stand alone PA is not an option for me (Leob tell us your developments);
- the ideia to overcome the sound projecting impairments is to create a panel "chain", we are discussing the wall of panels apprroach which seems to be be the cost efective way to difuse sound filling;
- on other hand, Leob cluster approach for high spl (4 per panel if i remember well) with several panels to create a "wall" seems perfect aside the budget (thet the school don`t have).
Precisely.
Tell us more.
It was the identification of studio recording techniques in DML sound reproduction who leads me to the reverberation hypothesis, although is just a begining of the disclosure.
Hans, let`s dream on.
Good auditions.
Steve, the answer is in what Hans said: "something special about the sound, and that could well be the ringing/chaotic nature of the panel" as "adding random noise to make a clean recording sound better".
I did try to explain that at beginner level in previous post #13,620, namelly with Warren Hurt perspective on voice recordings, but i will be clearer.
When some members analyze the measurements and PETTaLS plots they try, also, to correlate those with the listening experience and that objetive "inging/chaotic nature" seems, instantaneously, to have same studio recording characteristics.
Maybe his a defective way of thinking for same of you, but the river is not enterely the same for a children a fisherman and a biologist.
So for the ones interested to dig this path without been buried in the psychoacoustic hell of unverified things, help us light the DML special sound with the correlation to that ancient and well documented recording/mixing objectiveness (which is psychoacoustic) as a way to understand what he are hearing and enjoying.
Notions as reverberation, random noise, analogue dithering or, apparently different but not so, direct recordings in selected environments (ex, the old Decca classical sound engineers) are crucial to understand the measurments so we can develope DML`s according to space, needs and... tastes.
The point of those notions is that the auditory cortex likes, as the sound engineers put, the wrongness, randomness and all the garbage notions that polluted the aseptic measurements.
But, well, we are humans...
Good auditions
Good afternoon everybody. I wanted to conduct a study about subjective preferences, if you don't mind contributing your opinion, I think this would be very valuable for myself and people who want to hear from people who have been listening to these panels for years -
- What is the best-sounding panel you've ever heard? Your absolute favorite.
- Subjectively, what did it sound like to you? Smooth? Clear? Loud?
- Was it damped, framed, what material was it?
- What size was it?
- What exciters did you use, where did you place them, and how did you affix the exciter to the panel?
- How was the panel mounted? Just sitting on the ground, hanging from string, or hard mounted to a wall?
Christian, and for all with interest, hope this help:
- sory but i just have the book and didn`t find any full pdf:
https://link.springer.com/book/10.1007/978-1-4612-4738-8
- but this is a kind of book synthesis from one of the publishers:
https://www.researchgate.net/publication/247476067_Fundamentals_of_Directional_Hearing
- simple explanation:
https://www.edmprod.com/haas-effect/
-in pro sound view:
https://blogs.qsc.com/live-sound/what-is-haas-effect-and-how-to-take-advantage-of-it
- spatial sound:
http://sites.music.columbia.edu/cmc/courses/g6631/fall2012/page4/files/A 3D Sound Primer.pdf
Good auditions
I could wax lyrically about how wonderful these panels are, but I prefer to let others listen and make up their own minds.
This recording was being played as loud as I could stand in my room, they could have gone much louder, but then I wouldn't have been able to stay in the room.
I recommend listening using a good pair of headphones only, not speakers,
The sound is very clear and clean, the reverberation in the hall is produced so clearly and the whistling is so realistic.
I can literally hear everyone in the hall, I love this recording especially when playing on the EPS panels.
The realism is astounding, I am literally sitting in the hall listening to the performance.
The actual sound in the room is far better than this recording could ever reproduce, but it gives an idea of the sound I can hear in my room.
My youtube site shows other types of panels I have made over the years which are also very good, they get you to about 90% of the way to these EPS panels.
But lack the total realism I like.
Steve.
Hello Steve could you comment on how the different shapes of these two panels impact their sound please? thanks.
Yeah, Steve I was also wondering how using 40W exciters would affect the sound, particularly the HF on those kinds of panels, comparable size etc -
Also, what is the best way you've found to attach exciters? I have epoxy and double sided tape...
Also, what is the best way you've found to attach exciters? I have epoxy and double sided tape...
Trenth.
The smaller 25watt 25mm coils give a better hf performance up to 20k than the 30mm 40watt exciters .
I have not tried 40watt exciters, but that is what everyone says.
I just use neat pva on on the treated EPS surface.
It takes about 4 days for the pva to dry properly then the hf comes up to 20k, but only if you follow the instructions I have previously posted.
Epoxy would probably melt the eps.
I only use a 10watt exciter and a 10watt max digital amp, which is far too loud for me.
Steve.
The smaller 25watt 25mm coils give a better hf performance up to 20k than the 30mm 40watt exciters .
I have not tried 40watt exciters, but that is what everyone says.
I just use neat pva on on the treated EPS surface.
It takes about 4 days for the pva to dry properly then the hf comes up to 20k, but only if you follow the instructions I have previously posted.
Epoxy would probably melt the eps.
I only use a 10watt exciter and a 10watt max digital amp, which is far too loud for me.
Steve.
The two circular shapes with the exciter in the middle was my attempt at minimising the parallel sides 😀
I over did it a little and basically removed too much of the sides, so that the panel "sounds thinner" compared the the full width rectangle panel.
Apart from that they sound practically identical, I think 🤔
On a square or rectangular panel you will get 4 strong reflection points which can cause problems.
Best to try and minimise this.
Steve.
After a lot of screwing around I finally got my power amplfier working -- temporarily, at least (it has/had some sort of intermittent problem), So today I had the opportunity to listen to my one plywood DML. It's 1/4" `6mm birch plywood I bought at Lowes. I lightly varnished both sides so it won't pick up too much dirt from handling.
Here's a photo of it:
The panel is 22 inches wide by 24 inches high, and the driver (a 40 watt version) is mounted 9-1/2 inches from the bottom and left side. All 4 sides are attached to the frame using butyl double-sided tape. My decision to do that was based on some comments here which suggested that the panel's bass response would be better compared to ones that have less constraints on their perimeters.
My first listening impressions are that the panel places an amazing sense of space around the instruments -- even with just ONE running. In that respect I can't wait to hear what two of these things can do in that respect.
The other impression is that the mids are a bit "off", at least to my ears. Vocals sound recessed. I also found that the panel did exhibit a "sweet spot" where vocals in particular sounded the best The sweet spot is right in front of the panel.
I'm going to listen to the other panel before I mount it on a frame to see what that sounds like.
BTW, the lute-like object on the fireplace mantel isn't functional. It's a solid piece of wood. A bit of decorative art my dad made.
Here's a photo of it:
The panel is 22 inches wide by 24 inches high, and the driver (a 40 watt version) is mounted 9-1/2 inches from the bottom and left side. All 4 sides are attached to the frame using butyl double-sided tape. My decision to do that was based on some comments here which suggested that the panel's bass response would be better compared to ones that have less constraints on their perimeters.
My first listening impressions are that the panel places an amazing sense of space around the instruments -- even with just ONE running. In that respect I can't wait to hear what two of these things can do in that respect.
The other impression is that the mids are a bit "off", at least to my ears. Vocals sound recessed. I also found that the panel did exhibit a "sweet spot" where vocals in particular sounded the best The sweet spot is right in front of the panel.
I'm going to listen to the other panel before I mount it on a frame to see what that sounds like.
BTW, the lute-like object on the fireplace mantel isn't functional. It's a solid piece of wood. A bit of decorative art my dad made.
Mark,
In case you missed it, you don't really have to take anyone's word for it anymore. There is free modeling software called Pettals which allows you to test different mounting types and see for yourself. There is a thread about it here:
Pettals Thread
Anyone who frequents that thread, including the developer himself, will gladly help you with any questions you have about how to use it and interpret the results provided. It's still in development so perhaps not yet perfect, but still very useful for simulating different materials, aspect ratios, exciters, exciter locations, etc.
Eric
On the last point, see the latest post from JoskaNZ in the PA thread, combining a bass exciter with a smaller exciter for top end which would make a for a more cost-efficient high power plate. https://www.diyaudio.com/community/threads/dml-pa-systems.390363/post-7954377
While I think the Xcite performs very well, there are various models from manufacturers like Billionsound that could be used to make a similar design but keep the cost down further.
Regarding the DML sound for PA use, I had so much feedback from people on the panels, and at least for the kind of application I use them for, playing electronic music with a dancefloor setup with speakers in all corners, the benefits are very obvious.
1) Distortion remains very low even at extreme SPL. This means that you can have conversations even if volume is very high, don't get ringing ears and sensitive people does not feel they need earplugs.
2) Coverage is great and difference between right in front of speakers and middle of dancefloor seems smaller.
3) Transient response seems much clearer, resulting in excellent directivity, with a huge sweetspot and ability to hear stereo imaging even if positioned right in front on one stack.
4) Extremely punch low mid that is easy to cross over with subs.
5) A much more open natural sound making even good PA mid-tops sound boxy. Sound more like listening on a good hifi system or headphones than a PA.
6) Extremely cost efficient and light weight compared to regular speakers.
There are some issues as well of course:
1) So far I have not made a really reliable construction. There are quite different challenges than with a regular speaker, and a lot of trial and error. But at least I feel confident now that the exciters can hold up for PA use. I have pushed them very hard for long durations, and have a pair of plates in my studio now, and those exciters are still fine. But will plates and exciters last many years of intense use?
2) The dipolar response can be an issue, indoors because of increased reflections and outdoors because of sound pollution.
3) They do need DSP to adjust the response. I'm sure you can make something good enough by tweaking the design, but DML responds well to EQ and it is an easy way to improve the sound a lot even with a good design.
4) While they give good SPL per kg, they do need a bit of surface area, which makes them a bit more complicated to rig compared to regular mid tops.
5) When using EPS plates at least, dismounting exciters from the plater is not possible without ruining the plate, which makes them not very serviceable. Plates are cheap to replace, but it is a bit of work to pry off the exciters and clean them, and if an exciter fails it is not something you would fix in the field.