[Odal3]

I re-measured the 1/4" boards I have used, and realized that the store measured tolerances probably are not the tightest - one only measured 0.2 in, and the rest was just shy of 1/4". I actually wanted to buy thinner birch boards, but couldn't find any at the local store so I tried some thinner 1/8" oak boards instead. I have also tried some thicker panel sizes with no luck. I haven't tried any other materials, but am curious to hear if anyone has had success with other tone woods used for instruments. Here's an overview of some alternatives: http://www.guitarnation.com/articles/calkin.htm

Here are some pictures on my experimental project

Back


Close-up on exciters from the side
It's hard to tell from the pic, but there is some velco between the top exciter and the stand it leans against


Front
Note that it stands on two nails

[zygadr]

I re-measured the 1/4" boards I have used, and realized that the store measured tolerances probably are not the tightest - one only measured 0.2 in, and the rest was just shy of 1/4". I actually wanted to buy thinner birch boards, but couldn't find any at the local store so I tried some thinner 1/8" oak boards instead. I have also tried some thicker panel sizes with no luck. I haven't tried any other materials, but am curious to hear if anyone has had success with other tone woods used for instruments. Here's an overview of some alternatives: http://www.guitarnation.com/articles/calkin.htm

Here are some pictures on my experimental project

Back


Close-up on exciters from the side
It's hard to tell from the pic, but there is some velco between the top exciter and the stand it leans against


Front
Note that it stands on two nails

Hi Odal3.
Firstly, you MUST remove the excites from those stupid spider plastic casings as it seriously affects the performance of the exciters. The output and clarity will be noticeably superior as has been found on previous postings including my own original findings.

Now, you have discovered the obvious benefits and incredibly natural sound of thin laminated wood sheets and it's about time that we all started to focus on this material with the more ''grunty'' exciters and mounting methods/positions!!
Have you tried the ''MONACOR PLACEMENT'' of the exciters???

I myself have an irresistible urge to try 6-8 of the highest powered exciters in a vertical line configuration to enable the required output from thin, good quality plywood.
There is a dark horse sitting here somewhere..........I'm sure of it!!!!

[Odal3]

Thanks for the input! Yes, I know - the white shells got to go (which I believe was one of your general recommendations a long, long time ago on this thread.) I was eager to try them out when I first got them that I just put them on as is, but then I never found a good replacement tape in my local store so they got left on as it. But once I clean-up the panels and wiring, I will definitely follow your advice and use them without it.

I read about the Monacor placements after the fact, but haven't tried it yet (but will soon). It makes sense to adjust placements after where the acoustical resonance nodes and anti-nodes are located on the board. The Monacor placements as linked to in post 1755 seems to be a great starting point, but my guess is that there exact locations will be dependent on a lot of factors such as board thickness, material, how the board is held, etc. I only had 3 exciters at hand for each panel when I started so I used my ear in the same way as I would tune my guitar. What sounded best to me is not too different from the Monacor placement. The forth exciter was an afterthought when the next shipment came, and I'm not sure how much it really added. It will go back into the middle again.

[zygadr]

Sounds great Odal3!
Keep us posted!

[unnnot]

Hi guys !!! I was on vacation and built a few days NXT system using cardboard. I used the cardboard from the box of the TV. Panel size of approximately 800x600 mm. It is covered with five layers of acrylic lacquer on each side. Instead, I used exciter car speakers with a power of 40 watts. Speakers modified - glued paper tube. For the strength this tube is impregnated with glue. Tweeters are connected via capacitors. My feeling is the frequency range of cardboard panels 50 Hz - 10 kHz. Tweeters without capacitor - 500 Hz - 20 kHz or more. The sound is awesome for such a construction !!! P.S  see gallery.

[zygadr]

Hi unnnot!
Sorry...........your post is a bit confusing  ..............what kind of ''car exciters'' did you use????
Please post some pictures with explanation on this thread so that we can understand what path you have taken.

Thanks.! 

[Kludden]

Hi Zygard!
I think he mean something like this with an old speaker.


Regards
Kludden

[unnnot]

Hi Zygadr!
Sorry for the poor explanation, my English is not very good.
Look at pictures. If necessary, I will explain. Kludden almost right. I used a new (cheap) speaker with tweeter is removed. Exciters buy problem.
Regards unnnot.

[zygadr]

Very smart and innovative thinking unnnot!!!!  ...............................WELL DONE!!!!!

HOW DOES IT SOUND?

TELL US MORE ABOUT THE ''PAPER TUBE VOICE COIL''

[oldschoolVlad]

Just my 2 cents on plywood. It seems there is no need to try another wood type since birch itself has almost maximal possible internal damping. You can google “Experimental Investigations of Wood Damping and Elastic Modulus” pdf file.  Internal damping is important in terms of uncolored sound reproduction. If you want to make a ringing guitar, you have to use spruce soundboard to resonate as much as possible. But if you want to make a good audio speaker, you have to get less resonances as possible to get uncolored sound. That’s why most hi-end speakers has paper cones. By the way there are JVC wood cone speakers, and these are birch cones. That’s all the ''MOTHER OF TONE'' as Zygadr say 

Regards, Vlad

[unnnot]

Hi  Zygadr!
Cardboard  panels sound  have a uniform, does not emphasize a mid frequencies. High frequencies begin to fall down from about 10 kHz, but the sound comfortable. The fall down in high-frequency, I explain the lacquer is not rigidity of the surface of the cardboard panels. The panels are covered with five layers of acrylic lacquer on each side. When I started to listen to, it's been five days since I covered with lacquer. Lacquer is not yet sufficiently firm. By this I added tweeters. This two speakers from the TV 4 Ohm 3W. Speakers pasted on panels of HD expanded polistyrene. These panels are covered with acrylic lacquer over a year ago (lacquer has become solid). TV speakers are connected in series and in a 2.2 uF capacitor and is connected to the amplifier.
 Driver cardboard panel- chinese car speaker . Tweeter from it, I remove it. More construction speakers I did not break. This prevents buckling of the voice coil (it is attached in two places).  "Factory" NXT  exciter coil is mounted in one place !!!
      Paper tube made of paper to the printer 80 g / m 2. Strip of paper covered with cyanoacrylate glue and wound around a mandrel, CAUTION. After the glue stiffened tube glue around the voice coil. The tube diameter larger than the diameter of the voice coil. In tweeter NXT used tube from the syringe for injection 5ml. Sensitivity NXT panels allows voice room of 50m2 with a power amplifier 2 x 7 watts.
The sound this panels is very voluminous, detailed, very natural. With such a simple and inexpensive design is clear to me why not mass production. It can ruin a great business expensive acoustics.
P.S. I did not expect from these panels such a deep and clear bass !!!
Regards, unnnot.

[zygadr]

Sorry for not having responded to your great efforts on this thread guys.
I'm afraid that I am having difficulty dealing with some health issues and am finding it hard to be continually involved in the one and only great audio discovery ever.

I wish you all the best in your excellent input so far.................keep it up........... as it will benefit all in the end.

Regards,

Rob.

[oldschoolVlad]

Get well soon, Rob!
I do hope things go well with you!
We'll be waiting for your next posts here.

Regards,
Vlad

[zygadr]

Anyhow, giving cardboard the flick.....................too heavy, soaks up too much upper mids and treble, plus lowers efficiency. Let's get real guys...................this material is a compromise that takes away from the true technology of the DML.

Have just got hold of some STAX LAMBDA electrostatic  headphones that have changed my notion and opinion of the ''Mother of Tone'' rave that I have been pushing............. . The sound of ''Mylar'' DOES NOT deviate from the realistic tone of instruments and brings back a whole revision of what realism is all about..............I am shocked!. Yes, we are talking headphones against loudspeakers, but there is a serious point to be realised here.

These headphones have Mylar(plastic) diaphragms  that  are at the opposite end of ''The mother of Tone'' theory which probably applies more to musical instruments than sound reproducers................. 

I recall quite clearly that with VH polystyrene sheets, the sound had massive highs, mids and superior transparency.................there is no doubt of this, even though I refused to believe that it was a real phenomenon and that a paper based sheet HAD (?) to be better.
Well, the loss of high frequency detail and micro dynamics with soggy/heavy cardboard has changed my mind after spending some time with the electrostatic headphones which showed up how much detail has been lost with heavy sheets.

So, ..............where do we go from from here?...............I'm not sure......................but VH poly. will be given a second chance.............with and without coatings.................we shall see??????

You can accuse me of going around in circles................and maybe I am?................BUT SOMETHING HAS TO BE DONE TO IMPROVE ON THE LACK OF HIGH FREQUENCIES.
This is important and is holding back the DML from being ''HI-FI''.

Rob.

[oldschoolVlad]

Hi Rob,

about a week trying to simulate my next single СС panels. I've managed to get all of the CC mechanical parameters needed and successfully fed it to the NXT Designer. It seems the results are more than truthful - there is NO highs....  Just check out the pic:



The simulator's Help uncovers some interesting facts on that problem, will post it later...

[Squibby]

hello everyone.......just a quick update on my progress so far with 3.5mm birch triplex panels......they sound fantastic!







They sound particularly good with classical, acoustic music, vocals and drums. bass is certainly deep enough and highs are crystal clear. could they sound better? probably. do they sound good enough to replace my existing setup? absolutely.

If you'd like to see a video of them in action recorded on a smart phone (sound will not be that great from the recording, but you'll get an idea), i can upload a video to youtube.

Thanks to all on this thread, especially Rob (Zygadr).

[zygadr]

hello everyone.......just a quick update on my progress so far with 3.5mm birch triplex panels......they sound fantastic!







They sound particularly good with classical, acoustic music, vocals and drums. bass is certainly deep enough and highs are crystal clear. could they sound better? probably. do they sound good enough to replace my existing setup? absolutely.

If you'd like to see a video of them in action recorded on a smart phone (sound will not be that great from the recording, but you'll get an idea), i can upload a video to youtube.

Thanks to all on this thread, especially Rob (Zygadr).

Hi Rob,

about a week trying to simulate my next single СС panels. I've managed to get all of the CC mechanical parameters needed and successfully fed it to the NXT Designer. It seems the results are more than truthful - there is NO highs....  Just check out the pic:



The simulator's Help uncovers some interesting facts on that problem, will post it later...

Hey guys!

Yes, that response curve looks very much like an average 8 inch twin cone driver doesn't it???

Yes, (again) the sound of wood can indeed be sensational with incredible highs and mids and bass.

Perhaps if we are to go the plywood route, we may HAVE TO use the ''HIGH SHOVE'' exciters from P.E.??

[j gale]

Hi guys,   All these posts about plywood got me thinking again. I've tried quite a few thin panels but kept going back to cardboard treated with shellac mostly because I thought it sounded more natural. To quote Squibby re: his birch panels"they sound fantastic" tempted me, but         oldschoolVllads post #1929 got me thinking about my experience. I realized that most of the panels I tried were a veneer of what ever wood with a mahogany centre. A local company carries baltic birch (5'x5') 1/8 or 3mm. Cost about $15 dollars Canadian. All 3 layers are birch and no voids according to the dealer. Cut in half 30"x60" matches the size of my cardboard panels. I replaced one cardboard with the birch and listened comparing. The birch is cleaner. Now the birch has replaced the cardboard-- ---better sound and I think better on top as well. My wife immediately noticed and commented on the improvement. I believe oldschoolVlad's comments about the self damping properties of birch is the reason. To me the birch is a big step forward.

[zygadr]

Hi j gale, and all !

I too retrieved my 2.7mm thick, high grade ply (don't think it's Birch) and THIS TIME ( ) used the Monacor placement calculations for the exciters as opposed to the vertical, evenly spaced straight line down the middle placement used previously.

Well, the sound is far, far superior to what I recall from using thin ply in the past. The highs and mids are much more prominent as well as being a bit more dynamic which is an unusual surprise. The bass too is full and blends in well with the other frequencies.

I will now look around for Birch or something similar. Here in Australia we have a large variety of plywood types so it will be an interesting quest!!.

This has me quite excited as we have suddenly rediscovered just how good wood and exciters can sound. Potentially we have a huge breakthrough IMHO.

Rob.

[oldschoolVlad]

Hi guys,

Glad to hear from you that my comments on birch plywood were useful. Ok, let’s go forward. I would like to note that those JVC birch cones are made from Karelian birch veneer. Just Google, it looks beautiful and I guess JVC guys chose it for its perfect sound performance. Maybe we should go that way? But Karelian birch plywood is an exotic one. I think to get some veneer plies and glue them with the shellac would be the solution. Especially if we want to get a perfect DML panel which has isotropic structure in all directions and therefore has more even output performance. Typical plywood has odd plies number (3,5,7…) so it has more wood fibers in X direction than in Y direction, so X-axis stiffness prevails. The simulation of such a non-isotropic panel gives more “toothy” performance graph. Handmade plywood with even plies number will have equal stiffness in all directions and therefore more even output performance. The fact is that I have some successful experience in DML simulation which helps me to estimate the influence of various parameters on output performance. I’ll post here my experience later (+ pics and graphs).
Now the main thing – CC or plywood…In a nutshell, there are some crucial parameters I have to note. The base is the panel’s core stiffness. It's crucial for highs transfer. The stiffer is the core - the better. Plywood is tens times stiffer than CC so we have more highs. That's it. From another hand, plywood has lower self damping, less even output performance and power efficiency than CC. But it’s handy, and highs are so clear…
So it’s up to you, guys, which way to go. Meanwhile, Tectonic, Amina and Podium guys have chosen honeycomb core for their panels. More stiffer and lighter than plywood, available on market. Not so handy, but if we want Hi-Fi, maybe it’s time to go Hi-Tech?..

Vlad