More details:
Panels are 12" x 48" 5-ply poplar plywood, 0.23" thick.
Frame is 1" x 6" poplar, and includes a brace on the backside.
Panel is mounted to frame with 3M Extreme double sided mounting tape, 3/8" wide, around the entire perimeter (except about 1 inch from each corner)
Exciter is DAEX25VT-4 (one each panel).
Exciter is offset from the panel center by 1.25" across the width and 6" along the length. A piece of EPDM foam is placed between the exciter support and the back of the exciter.
Panels are 12" x 48" 5-ply poplar plywood, 0.23" thick.
Frame is 1" x 6" poplar, and includes a brace on the backside.
Panel is mounted to frame with 3M Extreme double sided mounting tape, 3/8" wide, around the entire perimeter (except about 1 inch from each corner)
Exciter is DAEX25VT-4 (one each panel).
Exciter is offset from the panel center by 1.25" across the width and 6" along the length. A piece of EPDM foam is placed between the exciter support and the back of the exciter.
And some measurements:
Here are the frequency responses. For each speaker individually, and with a sub added (purple)
And especially for Christian, here is the Spectrogram (wavelet), for the right speaker alone, which I think shows that the resonances are reasonably well controlled, but not completely eliminated.
Eric
Here are the frequency responses. For each speaker individually, and with a sub added (purple)
And especially for Christian, here is the Spectrogram (wavelet), for the right speaker alone, which I think shows that the resonances are reasonably well controlled, but not completely eliminated.
Eric
Great looking build Eric ! Thanks for posting all the info. Wondering what sub your using with them.
Thanks Pete
https://www.trcompositi.com/shop/lastre-su-misura/lastra-sandwich/
this is the site, it is in Italy where I live, you can choose both the thickness of the carbon and the nomex separately.Of course if you want you can contact them or if you have difficulty with the language I can do it for you https://www.trcompositi.com/shop/lastre-su-misura/lastra-sandwich/
Ok, that will hopefully be good plates. Very interested to hear what results you get!
Exciters seems quite easy to drive, and I'm using some cheap Chinese Sanway amps with built in DSP:
https://www.china-sanway.com/D2S-2CH-900W-DSP-Built-in-Amplifier-Module-Class-D-pd353583.html
They worked really well for when using as a PA system, but for home use the fans become a bit annoying. They are temperature controlled and start silent but even if amps are just idling, eventually they start ramping up.
Currently the plan is to replace them with a separate LSMS unit and regular amps since I'm leaning towards making some passive subs since it seems hard to find plate amps delivering enough power for running powerful woofers. This will also mean I can run the plates on a smaller but more quiet amp at home where I don't really need that much power.
hello sorry for the english translation.
The fan noise is not a problem, then I was looking for something to integrate directly into the speaker, my purpose is exclusively as a PA and to maximize the maximum number of exciters that make sense, from what I see tectonic uses 4 with the addition of a ribbon driver for highs. It seems to me that it also has a model without a dml only ribbon driver. a first phase. This if the preliminary tests go well, for this reason at this stage I would like to keep aligned with the tecnonic specifications.
I think the Tectonic plates with a ribbon tweeter is an older model. The current model is DML500 which covers full range without.
I also reasoned that since they should know DML for PA applications, Tectonic should be good to use as a guideline. I did get the materials to make carbon/nomex plates, but settled for EPS plates for now, at least until I have mastered vacuum bagging well enough to do the plates well without wasting a lot of expensive materials.
If you want plate amps with DSP on a budget, the Sanways must be hard to beat. Hypex is more expensive and doesn't have as powerful units. Powersoft and pascal only sells OEM. If going with a separate LSMS unit and rack amps there are a lot more options of course.
I would compare loudness of your carbon plates to a high density EPS. I suspect that 0.3mm skins are still a bit too thick to give optimal efficiency, and for a PA you really want that. I think that means polystyrene foam or custom made composites, but can very well be wrong.
i intend to follow tectonic guidelines for this i got the 50x40 panel with 03mm thick, when in youtube movies you see the tectonic seller showing the panel looks very close to what i expect i bought. which exciter and how many will you put in your project? do you think tectonic uses particular exciters not for sale?
Pete,
Thanks for your kind words. The sub is a Polk PSW10, about the cheapest sub you can get, I think. I bought a SVS 1000 Pro for the main living area, so the Polk was available for me to move downstairs to the lab.
Eric
pixel1,
Thanks. Those are specs of the nomex core, but what I am actually interested in is the properties of the finished panels, especially regarding their bending stiffness or weight per unit area. I can make some estimates of those based on the information you have already shared, but it would be interesting to see what the manufacturer might claim for these properties, for comparison.
Thanks,
Eric
Very nice realization Eric. They might sit in our living room with no difficulty (I am allowed to have some prototypes here if not yo ugly of course!)
Would you mind to communicate some basic characteristics as listed in the "history file", any information that might help to follow your example, some measurements, listening comments?
In the history file : membrane (dimension, material, thickness, coating...), exciter, exciter/membrane interface (VHB, epoxy, PVA...), exciter position, frame depth... and what is my current main question : suspension (what, where).
I didn't understand up to now that you had "only one-off proto". I hope you will enjoy the incredible unique imaging of this pair spending time with your favorite records. Here DML have been in daily use (running full range because no EQ neither no sub ready) for almost one year... even probably far to be perfect or at least at their best, I have difficulty to come back to most standard sound (I don't have "hi-end" loudspeaker and my 3 way which were performing not to bad died - mid suspension broken). My wife adopted them also. The speakers that are not here, only the sound stage. Really fun.
Thank you for your post.
Christian
PS : sorry Eric, I think I add a problem of refreshment; Forget for the questions you seems already having answered. Keep the congrats.
Thank you for the link Pixel1. No need for the language, the site is in French... ah, ah... and by the way, English also
Hi Eric
A very attractive build... Well done!
I like the contrast between the frame and panel, and the pale poplar looks great.
A couple of questions:
1/ The frame material is interesting.. We can't get poplar in frame sizes in Aust Was it pre-finished? ... Looks like it on your bench
2/ I'm interested to know if you tested the panels with and without the deep frames. I have found that such framing can have a noticeable tunneling effect on the sound which I assume is due to refection of the rear waves
3/ The exciter you chose is one I haven't tried... Looks quite good value. Have you used others, and if so, how does this one compare?
Cheers
Eucy
Thank you for the intention Eric. Very clean yes. It might be the job of an EQ to reduce the remaining peaks.
For the construction details :
- Is there a coating or a finishing layer on the ply? front and rear?
- How the exciter is linked to the panel? Original VHB?
Christian
So, to clarify, I have made mostly (not only) one off prototypes. You may recall the "revply" speakers were my first finished pair. Those are the speakers we have been using in the main living area for music and TV since late 2019.
And in the "lab" I often have had several similar prototypes to choose from to listen to DML in stereo. But I finally decided the DML lab needed a real speaker pair of its very own.
Eric