[zygadr]

the company i linked also has laminated end-grain balsa wood, which is even cheaper - i wonder how that would sound...

and the carbon fiber would be my first choice, but that's quite expensive - a 48x48 1/4" thick honeycomb panel is $370.  but the balsa wood isn't too bad, at $99 each for two 24x48 1/4" thick panels.  all this (and the other prices i quoted are for 1-ply carbon fiber or fiberglass; additional plies are more expensive.  not sure you would want more, tho, if using for speakers.

doug s.

Balsa wood has been a possible contendor for some time now.I believe that it may be possible and cheaper still if a large sheet be made from long, thin planks that are readily available. They can be re-cut truly so that the edges can be glued together as a jigsaw puzzle like configuration - end to end, top to top etc.

There are various grades of Balsa also so it doesn't just stop there. I think there is Balsa plywood as well?

[zygadr]

Remember the GOEBEL loudspeaker that used bending waves?

Check out the following link - especially the second papragraph...............BALSA WOOD?!

http://www.goebel-highend.de/pdf/goebel_sixmoons_highend2012.pdf

[jackman]

Have you guys seen these?

http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-387

[zygadr]

Have you guys seen these?

http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-387

Yes, I have been wondering about these and similar units available - ROLEN STAR AUDIO, VIDSONIX PHANTOM 4.25, VISATON BS 76.
Here is a picture of the Visaton :



Here is the Rolen Star :





The question is...............are these as good as NXT type exciters that can provide true high fidelity sound?

Has anyone heard these type of transducers?....................are they any good?

[zygadr]

Last night I grabbed a 4 foot x 3 foot, 3mm thick peice of plywood and stuck two exciters to it.

First impression was a decrease in output/sensitivity and some slight buzzing on various frequencies.This time round though there was a lot less self panel noise and buzzing since I last gave wood a shot. Strange that this should be the case..........possibly the placement position of the exciters or a better quality plywood may be the critical factor here?

BUT........................THE SOUND!!!..............crystal clear, very, very natural tone.....far superior to VHEPS.

If the higher power/high shove exciters can do what they promise to do, there is a massive potential in using thin wood sheet as a panel material.
This is without doubt the best I have heard yet

[Abelma]

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[Abelma]

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[zygadr]

Thanks Abelma
I listened to the wood panels again last night and am absolutely positive that it superior to Gatorfoam,foam board, cardboard (treated and untreated), EPS (standard and VH grade), Corflute.
The difference is in the ''tone'' of musical instruments and the ability to transmit very sweet and plentiful highs as well as bass

I will try your suggestion on edge dampening............sounds sensible to me.
Going back to the Goebel speakers, the company's panel has multiple diagonal cuts around the edges that have been filled with a silastic sealant. This is most likely to prevent edge resonances and there is mention of this in some reviews on the net. I may try this to see what happens............plywood is cheap so if I stuff it up.............who cares.....I'll buy some more!
http://www.goebel-highend.de/en/company/research.html

Thank you for letting us know about the ''other'' audio transducers. Luckily I did not waste time and money on these!

I can't wait to try the high power/high BL HiWave exciters. As they have an adhesive  outside support structure, they will probably not need a rear spine which will simplify construction.

[zygadr]

My suspicions were correct. See page 3 for details on the membrane/panel material and the silicone filled cuts to tame resonances 

http://www.goebel-highend.de/pdf/goebel_image_hifi.pdf

[hblester3]

  The talk about balsa got me thinking about my model airplanes, we could build a frame of balsa sticks then sheet it with balsa sheets, light and strong or check with full size aircraft suppliers for lite ply plywood. The wood would be heavier then eps but if suspended and high shove exciters attached to a back spine. In other word copy the podium frame and replace the honeycomb panel with lite ply.

[zygadr]

hblester3, welcome to this thread!.
I agree with your suggestion on Balsa wood.This is exactly what Goebel are using(with some special treatment though). I would probably go the light plywood route here. How large are the peices?
Are they expensive?

[hblester3]

Ziggy should have said it is Hubert, from aircraft suppliers lite ply not bad price wise and can be 4' x 8' sheets. Should be able to find local or semi local to avoid shipping cost.

LITE-PLY 4X8 1/8" 3MM   02-00115   $36.50      
LITE-PLY 4X8 1/4" 6MM   02-00116   $56.50

The beautiful, pliable answer to shaped and curved construction problems. Lite Ply ® is distinguished by its even grain, virtually snow white appearance and unusual resilience. It is a true "white wood, " poplar and finishes uniformly, whether stained or painted.

Supplied for over 50 years, Lite Ply ® has proven to be an excellent wood for industries where weight is a concern. Lite Ply ® has been proven to be a cost effective alternative to other light weight panels.

http://www.aircraftspruce.com/categories/building_materials/bm/menus/wp/plywood.html

Hubert

[zygadr]

Hey thanks Hubert!
This will be a great alternative to standard plywood.

This thread is now motoring along with some new ideas : better panel material, better exciters!!

[zygadr]

Bought another sheet of plywood yesterday at the hardware store so that I could run the system in stereo.
This time I purchased 4mm Marine ply AA grade as the 3 mm  standard stuff was not available.

On listening, the slight extra weight of the marine ply was just detectable as a little bit less efficient, but the rigidity and quality of the sheet was obviously better. The other choice at the store was 2.7mm BC grade(Premium)but I was not too impressed with the way it looked. Even though it was meant to be premium grade it looked shabby and nearly every peice I picked up was severly warped so I gave it a miss.

First impression of the marine ply is a reduction in self panel noise and buzzing. I don't know if this is due to the superior bonding of the layers in the ply or the fact that it is more dense than the cheaper, lighter stuff?

I will listen in more depth tonight, but it seems that ultra light panel materials have some serious shortcomings and are not what they are cranked up to be.I believe that it is all a balancing act to obtain the best sound with the compromises that need to be taken.

[zygadr]

Well, IMHO, wood is without doubt the ultimate DIY panel material available to us.
Yes, the heavier the sheet, the more volume/power required from your amplifier, but the benefits outweigh the disadvantages by a huge margin.

It's quite an experience to hear a symphony orchestra in full flight in your listening room. The whole room is energised with a realistic replica of the venue it was recorded in.The tiniest of details can be heard at the listening position without having to clamp your head in a vice like conventional box speakers. Each instrument's tonality is so accurate it is a delight to listen to.
The orchestra spread itself high and wide...........very omnidirectional like as it would in real life.

Jazz is equally impressive. Piano is sensational, drums are jaw dropping as are the cymbals. Double bass sounds like a real double bass - a ''stringed instrument'' being bowed or plucked. The resonance of the wooden body easily discerned.
I have never heard the reedy, breathy saxaphone so convincing..........what a joy!

This is with two 4 foot X 3 foot thin ply panels with two standard el-cheapo exciters.
What will happen when the high power, high quality exciters are deployed?.............I believe that standard plywood will be all that is required. No need for any specialised light forms of ply I suspect.............we shall see!

[j gale]

Hi  I bought a 5'x5' sheet of 3mm baltic birch to give wood another try. Hoping it will be superior to the 3mm stuff I tried before. It should be because they claim there are no voids in the core. It certainly looks well made.  Looking at the exciters I have a feeling that the HIAX32C20-8 might not sound as good as the HIAX25C10-8/HS even though it is more powerful fs is 400 vs 200 for the smaller unit. Maybe a driver suited for driving 1/4" glass and signage applications is not the one we want. Thoughts? 

[zygadr]

Good point. I did not notice the fs difference between the two.
I would suppose that if it was designed to drive glass windows, there would be no high expectation to obtain much bass?
Even though the BL is very high, this may not mean much in practice where the application is for DML's?

[zygadr]

There is another exciter that may be of interest:

http://www.parts-express.com/pe/showdetl.cfm?partnumber=297-224

http://www.parts-express.com/pedocs/specs/297-224-hiwave-hiax32c30-4b-specifications.pdf

[doug s.]

if it were me, i'd be looking for the lowest fs possible.  (as long as it still was rated to 20khz.)  if it weren't as powerful, i'd simply add more...

doug s.

[bjohng]

On the basis that no musical instruments are square/rectangular has anyone tried any modified shapes, e.g 4' high, 24" at lower edge and 20" at top?