I would rather build fewer plates with more exciters to get higher power density, but if it is for sure fixed to using in that room and you want tall panels for style reasons, I think it should be possible to do with good results, especially if you are aiming for 200Hz.
Should not be an issue to fit 4 exciters per plate, but with that many plates it would be total overkill for that size room. I think one exciter per plate should be plenty.
Also, 4 plates would be easier to work with if you want to run all exciters on one column with one amp channel.
I apologize for the english translated by google, but i hope it is understandable.So here is some more details about the system and event I used them on.
First a little about the plates. They are graphite enhance EPS (GPS). I found the GPS to sound slightly tighter that the EPS of same density, but I think there is more variation between different EPS materials then between EPS and GPS. Link to the specific plates I use is in original post.
The corners are 3d printed and holds together the two frames that the GPS plates are clamped between, using some adhesive foam strips:
https://www.amazon.se/gp/product/B091HPDSH4/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
View attachment 1092076
The corners fit the wood bars for the frames very tightly, and plate pretty much holds together as it is, but they of course have screws to secure the frames.
The exciters are fixed with epoxy to the GPS plate in a configuration similar to what Tectonic use.
Here is a sketch for the template I used to fix the exciters, which I put in the middle of the plate:
View attachment 1092077
I attempted to make a support spine, and I tried a couple of variations, but got issues with distortion. The exciters should stay glued on without issue, but doing stress testing during a very hot day on my veranda and and instead of using a HPF, boosting bass a lot, the exciters also started distorting. Conditions was very extreme and I doubt I'll be able to replicate the issue unless I organize a party in a sauna without using any subs
But as a desperate quick fix I added some strings to hold up the exciters just very slightly, making the distortion disappear. I probably do some more experiments printing a holder to hold up the exciters, but also want some kind of back bracing anyway to protect exciters during transport. Although now the do stack very well, so is quite easy to transport safely.
I did various experiments with coating the plates with PVA glue, shellac and hide glue, and found that at least on the EPS plate I'm using, hide glue with a very thin layer of shellac gave best sound and sensitivity. You have to be very careful with the thickness though. I used a roller with 3 parts water to one part hide glue granules to apply one thin layer, and when that dried I rolled on a single layer of very thin shellac solution.
I decided it was simpler to build a roof over the speakers than try to make them protected against rain.
I made construction as simple as possible and could do it all myself without a proper workshop in a couple of weeks. While it doesn't look very finished and professional it worked really well, and I will try to tidy it up and optimize it as well as get my own subs so I have a complete system I can tune carefully.
The Sanway plate amps I use give 500w per channel in 8 ohm and 900w in 4 ohm. With 4 exciters in series-parallel on each plate, each plate is 4 ohm, and I'm running 2 plates per channel for 8 ohm. If I would run half that, one plate per channel instead of two, that would quadruple the power per exciter, which I think would be beneficial even if it is well over the spec of the exciters. Initially I was thinking to use active subs, hence wanted plate amps, but think I will go with passive subs and will get an amp rack to drive them instead so I have plenty of power to run all 16 plates along with amps powerful enough to drive some really power dense subs.
The event is a small private psy/goa festival over a couple of days in the forest in Sweden that we held for 10 years in a row now. Usually it is around 200 people and dancefloor is a little bit over 20x20m.
Here is a video showing a speaker stack during sound check:
https://drive.google.com/file/d/1kdh1yNhkZY9F1waNljSoVIBvRwwy2Uj0/view?usp=sharing
Here is a video of the dancefloor during the night:
https://drive.google.com/file/d/17_3u1bt28VpCXvznFyX0TkftK3jj4rHK/view?usp=sharing
Here is a video shot some 30-40m away from the dancefloor:
https://drive.google.com/file/d/1fxUo9T3XxfEODbqAU8kiqNXHstAyVmD4/view?usp=sharing
Thanks to leob for opening the PA specific forum we talked about in the main forum. As you may remember, I bought the panel from the Italian site in Nomex carbon, then I bought the exciters as you recommended DAEX30HESF-4
I now lack an adequate amplifier to drive only 4 of these exciters, this is because if it were to go well I would like to make it autonomous each plate.The plate amps are too large and would completely close the rear part of the speaker. solution for an amp suitable for 4 speakers?
Remember that the panel is about 50x40cm by 3.5mm thick.
At the moment not having the amp I just randomly tried with a small pc amp with only one exciter, around the edges to avoid spurious vibrations I used the same window material that you used with great results. The sound is nice but surely it must be both mechanically and electronically equalized, the very high part is present but slightly attenuated compared to the sound that can be heard by not resting the exciter anywhere, however it is good.The volume is very high really very high.At the moment the biggest problem in the sound but perhaps it depends on the fact that the piasta lacks a rigid frame is that at medium-low frequencies if solicited with very present voices it tends to vibrate in an uncontrolled way like a loudspeaker with a broken membrane. I hope I managed to make myself understood.
Overall, the sound is good if you get close to the very high frequencies, it is very present in correspondence with the exciter but immediately disappears in the periphery of the plate, if you move further away this effect is obviously not perceptible.
I would also like to buy panels like yours to try but the thickness I find it only 2cm and 3cm not 2.5, what do you say I take it bigger or smaller?
That's all for now but I follow the forum every day and maybe I would like to buy before other 4 exciters increase, in this regard I also saw a model EX30HESF2-4
besides cost more, do you have any information about it? I would like to be sure to try with the best in terms of power and quality, it would also be useful to know which exciters tectonic uses, I suspect they may not be on the market.
For now thanks to everyone and I hope that this forum becomes important for those who use professional systems.
Great, glad to hear the composite plate seems to be working out! Would be very interested to hear if you get a chance to compare sensitivity with EPS.
I think 2cm will be good thickness.
As for the amps, I was planning to build a frame where the plate amp would fit below the plates, but cancelled that plan due to lack of time and the distortion issues I mentioned when applying bracing. Now I'm going with an amp rack myself, but I think the only way to get a smaller amp is if you get chip amps and build them into your frame somehow.
Not sure what the EX30HESF2-4 offers really apart from the new mounting system. Same power rating and same inductance it seems like. Seems very unlikely to be worth the extra 50% cost.
i will buy the eps panel right away and let you know the difference with carbon.
You're right about new spekers cost too much in anticipation of a major purchase.
Sorry I didn't read that you had problems with the structure? with the frame?
In your opinion, what does the croaking I have on some medium-low frequency and high volume voices depend on? the plate too thin or the lack of support in the perimeter of the carbon plate? in practice it croaks and if I apply a signal generator it generates several harmonics in practice a distortion and the sine wave probably squares. I have no tools at the moment to evaluate but the distortion is audible
I had a couple of distortion problems. The one I referenced in previous post was when trying to add a spine to hold up the exciters. Probably a good idea to do that, but seems to be very delicate. This distortion was somewhat subtle though.
The second was when they where in the sun on a very hot day on my veranda, blasting music with heavy bass boost and no HPF. Seems like the temperature made the exciters sag, resulting in a very obvious square wave when playing a sine, and that could be fixed by holding them up with a string.
How have you fixed your exciters to the plate? Are exciters heating up?
I connected only 1 the amp is small it is used for the boxes of the pc, so it is little power, but yes the exciter was hot but a little bit.The exciter is put with its adhesive.
When you said that the exciter in the sun went down what exactly do you mean?
I wonder if one could gain more efficiency with larger panels. I still have some ordinary XPS, I think it is the dual textured skin version, 30 mm thick (I need to check, could be 20 or 40 as well). When the exciters arrive, I need to try for myself. I got some 0.8 mm glass laminate, 430 x 320 mm size from a friend for testing - either to use directly or to glue onto something.
I doubt you manage to heat them up enough with a small amp to make them sag and distort. I had to push them really hard in direct sunlight in a really hot room to get the issue. I'm surprised they get warm at all really, I had to use quite a lot of power at low frequencies to notice even the slightest temperature increase. Can your amp be clipping?
Larger panels will give you deeper response, but will not affect efficiency it seems...at least not looking at the 1m on axis sensitivity. But it will give a bit more DML property to the sound, so my guess is that it might spread a little bit further, but also prolongs the impulse response more, causing a less tight sound.
I haven't tried XPS myself. Seems like most prefer the sound of EPS, but with both there are many different qualities and of course it is worth trying whatever you can get you hands on.
i am a little skeptical about some of the claims made in the first post of this thread but the one that stands out to me is the violation of the 2piR law how is it possible that these devices defy a prime law of physics??
and without measurements is the efficiency really as good as claimed??
and without measurements is the efficiency really as good as claimed??
they would have to be acousticly large compared to the listening distance but no one is supplying even pictures, never mind measurements!
I would be as well
It doesn't really make sense to me either, and experiencing the system it does feel a bit like the laws of physics are being defied.But does line arrays also defy the laws of physics?
I guess you can see a DML speaker as a grid of tiny line array speakers. The wave of the plate means a frequency will be emitted from a multitude of points at the same time. The further away from the speaker you are the more of those waves will catch your ear at the same time.
Admittedly my physics knowledge is limited, and I recommend the thread in full range for discussions about the theory behind DML, where there are some users that actually know what they are talking about
But yes, those points are mostly observations based on how me and lots of visitors experienced the plates, not facts. There are some measurements that support some of them, and can try to take some more when I get to run the system outdoors next time.
I will do my best to supply measurements and such, but want to get an opportunity to do tests at high levels outdoors since I'm not happy with the measurements I have. But some measurements are posted the full range thread.
Any specific measurements you would like to see?
Same goes for pictures, let me know if it something specific you like to see.
Calibrated SPL with drive voltage and distance on axis. Distortion at varying drive level (can be done close mic with a dynamic mic). Some kind of polar measurements but I know these are very laborious.
Just some pictures of your panel so we know what we are talking about would be great.
Thanks!
Just some pictures of your panel so we know what we are talking about would be great.
Thanks!