[zygadr]

Finished mounting the exciters last night : 4 per panel (4 foot X 3 foot, 2.7mm thick). Each exciter was bolted on to the panel, with the exciters spaced evenly down the vertical centre of the plywood.

Results?...................CRAP!!!!!

The sound was dull and no more louder than using 2 el-cheapo exciters per panel. As a matter of fact the el-cheapo's sound ten times better!!!

What has gone wrong?........I think I know.
By bolting these heavier than usual excters to an already heavy panel material(compared to what we have been using in the past), the panel/exciter weight combination has caused the sound to suffer...........significantly.There was an obvious solidity to the sound from the higher power handling of the new exciters, but the highs and mids had taken a big hit for the worst.

Really, the panel should be ''free floating'' with the exciter backs rigidly mounted to a support structure or spine. However with plywood being so heavy, the voice coils will no doubt buckle and be damaged if this is attempted.

I'm afraid that plywood can only be used with light weight exciters, and probably no more than two. This does not improve on what we have had in the past. Two exciters can only be used with little power and achieve low to medium volume levels at best.The whole point of this revised panel exercise is to enable higher sound pressure levels without burning out or overloading the previously used low power exciters.

I believe the new exciters from Dayton are very good ones but can not be mounted simply to the back of a panel that is free standing or leaning up against something. Their weight contributes to the panel's weight and stuffs everything up.

As much as I regret to say this, but the reality is that I will need to mount the Daytons on a spine and go back to VH EPS.
It will be a compromise as I liked the sound of wood, but a light weight material will be far superior to a heavy one which has too many issues.... as I have found.

The Dayton exciters will be adhered to the EPS this time with VHB (very high bond)3M double sided adhesive tape for obvious reasons. Bolting them on is not possible as the EPS is too soft.

[j gale]

I haven't had success with wood because of the weight. I am very pleased with the sound of shellac treated cardboard. It remains light and the shellac takes away the sonic quality that identifies it as cardboard. To me it sounds natural. I can't get past the plastic sound of EPS and so recommend cardboard (treated). With patience and a dollar store plastic bottle with a small nozzle type lid the treatment is not hard to do. I found that using it sparingly in treating the internal flutes was the way to go. Let it dry then repeat until satisfied. My panels are 30 inches wide five feet tall. They are mounted on a spruce frame. (Spruce reputed to sound good--cheap here) The panels stand on a cross piece about 8" above floor (for looks) making contact with 2 pieces of self adhesive felt about 3/4 " square and 2 self adhesive about 1/2 "square pieces of foam weather strip near the top of the frame hold the panel, so essentially it's free. At present I have 4 of the new dayton exciters 1 foot apart attached to a spine ( magnet sized hole about 3/8" deep and a little silicone to hold them)and attached to the panel with 3M hi bond tape. Panel stands on 2 points so no pressure on exciters. The other panel has 4 of the HIAX 32C20-I self supporting so no spine. This is just to compare and I prefer the dayton. It seems to have more top end extension and sounds better to me. Probably because the HIAX32C20-8 is designed for glass and similar. One useful tweak to the panel was the addition of a border of self adhesive felt triangles 2"x 2 1/4" Sheets are 9"x12"so sized to reduce waste. leaving about 1/2" in from edge. I believe this reduces noise by preventing sound from reflecting back from the edge toward the middle. I did both sides of panel and really like the result.

[zygadr]

Thanks for your input j gale.
I will try the cardboard again before settling on EPS which is not really where I want to go. How thick is your cardboard........single or double ply?

Can you post some pics of your cardboard panels with the spine arrangement?............this would be great to see!

[j gale]

Just single ply.  Will post some pics soon.

[zygadr]

Thanks j gale..............the pics will help!

Discovered something interesting over the weekend. The Dayton/Visaton style exciters with their square mounting plates are a trap for the unsuspecting panel builder (I am no exception).
If you use thin plywood and bolt the exciters to the wood, you may experience a less than ideal contact between the exciter and the panel.
I have found that using double sided tape is far superior to bolting! The mids and highs and general transparency has returned simply by using tape as the mounting method.
I don't know why, but I presume that there may be some minor warping of the plastic mounting plate when nuts and bolts are tightly screwed at the far corners of the plate. It's just a theory, but the differences are very obvious.

[zygadr]

UPDATE :
Have just picked up a 12 inch X 8 inch sample of ''RE-BOARD'' which is 10mm thick and has a complex arangement of vertically orientated paper flutes (honeycomb like......sort of) sandwiched between two cardboard facers.

It feels incredbly light and extremely strong/stiff.
Will place an exciter up against it tonight to see f it is a possible contendor for a panel material. 

[scorpion]

I think somebody tested earlier in the thread. It is made over here in Sweden.
There is nowadays also a 5  mm thick board: http://storaenso.reboard.se/userfiles/5mm%20Product%20Info%202012.pdf 

/Erling

[zygadr]

Hi Erling!

The test results last night was totally unexpected............the RE-BOARD worked extremely well!! .
The mids and highs came through without a problem and the efficiency/SPL was very good for such a small piece of board.
As an example, I had the left channel as a 4X3 plywood panel with two exciters and the right hand channel was a single exciter on the RE-BOARD. The sound stage seemed to favour the RE-board which actually sounded louder!

I am confident that this material will be the one we will stay with.
 All the others have severe limitations and colorations that can not be put up with anymore as far as I am concerned.

I am not sure however if the 5mm board is imported in to Australia......will have to enquire.

[zygadr]

YES!!!..............5mm RE-board IS available in Australia.

[j gale]

S
Some pic s. Spine is flush with frame edge leaving panel standing off about 1/2 "

[zygadr]

Hey nice work j gale!

[zygadr]

UPDATE!!!

5MM  8' x 4' sheet of RE-BOARD has been ordered. Expected delivery time : 10 days max.

Sheet will be cut in half and cut down, allowing  2X :    2 foot X 5.5 foot pieces to be used as panels.

Experimentation will be required to find the correct method to cut this stuff ............at the supplier, an attempt was made to cut a sample piece with a very sharp hobby knife without success .
Looks like a very fine bladed jigsaw may be the shot?

[zygadr]

A word of caution on the Dayton square exciters!.

I have had four (two from each wooden panel) fail on me. By fail I mean that they did not burn out or anything like that, but for some reason (maybe because the plywood is flexible and I normally lay them flat on their faces when not in use)the contacts have become faulty. 
If you place a continuity/multi meter on the terminals, they indicate no continuity (dead?), however, if you press the multimeter probes down on the terminals forcibly, you get continuity..........for a while, then nothing.

I would consider this a design fault due to the voice coil wires running in small straight insulated channels under the plate of the exciter motor. Something is not right in that department.

Anyhow, I have purchased 4 replacements from my local electronics store (same thing but round mounting plates.

Still waiting for the Re-board to arrive.
In the mean time, a 3M rep. has dropped off three two inch wide sample rolls of 9473 VHB double sided tape.....free!......good onya 3M!

[zygadr]

Still no show for the sheet of 5mm Re-board 
After contacting the company 3 times in the past as to an ETA, there is no sign of it. I am beginning to wonder if they have taken my order seriously?........besides, who cares about some dude that wants only one sheet of the less popular thin stuff and lives accross the other side of the country?

Well, they have until the end of this week............after that, they can shove it!

In the mean time, I have a single exciter mounted on a 3mm sheet of single cushion/layer corrugated cardboard that is approximately 2foot X 1.5 foot. The exciter has been positioned according to the Monacor document that indicates the X/Y positioning ratio on any size sheet of panel material.
The sound is not what I remember from using 7mm twin cushion CC in the first trials  .There are plenty of highs and the frequency spectrum seems very uniform and well balanced. Music sounds VERY natural and quite loud for such a small set of panels.

The good news is that after trying many suppliers, I have finally found one local one that sells very large sheets of single cushion 4mm CC. They have no problem selling only one and can cut to size.

So, this may be my next and last NXT panel adventure. Seems strange that one of the early panel materials may be the one that will stay as the winner of so many other types tried and tested?..............such is life................

[b2m]

Hey Zygadr,

just wanted to pop in to thank you for your continued work on the matter, I read most of the thread although there seem to be a lot of posts missing at the beginning. I ordered four of the square Dayton Audio DAEX58FP yesterday and will try them on some re-board or similar stuff (thankfully, a colleague of mine was doing art manufactured of different carton types and has quite a grasp on the matter). Do you happen to have the link to the monacor paper at hand? A quick google didn't get me any results, so I'd be much obliged if you can help me out.

Best regards from germany
b2m

[zygadr]

You're welcome b2m.
Here is the document:             http://www.monacor.de/de/FLE/EX1.pdf

The positioning diagram is at the bottom of each page in various languages.
Ignore the Monacor exciter - the Daytons are far superior.

[tino84]

zygadr, yesterday I tried my NXT from P.E on plastic housing of my LCD (an LG w2361v to give an idea...)

better give it a try 

[zygadr]

No thanks.

[emailtooaj]

Hello Everyone,
It's been long time since I've been active here. Good to see the spirit still going!!!
I wanted to post a few pics of my build from the el'cheapo exciters from PE.











So as you can see I'm using EPS for the panel material. My frame is simply 1x3 with a 1x3 support spline. I have the exciters and speaker wires recessed into the spline. I plan to "clean up" my prototype and make it more presentable by wrapping speaker grill cloth from the front to around the back and stopping at the spline. I like this design the best as you can either mount the whole speaker to the wall, or you can easily convert it to free standing with a floor base design. At the moment I have it suspended to the ceiling with rubber tie down straps...lol
You can't see in these pics, but I have some closed cell rubber strips that I cut from a sheet. I basically have the panels tensioned at the center top and center bottom. This effectively makes the panel free floating and relieves any stress to the exciters. I've never had any exciter, or voice coil drop by using this design. Plus the rubber is flexible enough and light enough to not impede the EPS's sound characteristics.

Some may ask why one side of the frame is cut off....well, it was a full square frame originally! But after the first minute of listening I realized by blocking the edges of the EPS the frame was killing a lot of the ambience of the panel. I just sounded like crap. To experiment, I cut off one of the sides and the speaker panel came back to life.
I've learned you CAN NOT block the edges of the panel!! If you block the edges you will not get the 170 degree sound field that these speakers are capable of.

As for the mounting of the exciters to the EPS panels, I've used G/Flex epoxy by West Marine. This stuff is great!!! It will not melt the EPS and it will accurately transfer the sound from exciter to panel!!!
I know a lot of people still use the 3M foam tape, which they've had great success with, but I feel is only good for testing purposes only. I don't see it as a permanent fix or solution. Plus I would venture to say the 3M foam tape impedes the overall sound. By using foam it will dampen the energy transfer from the exciter to panel.
I feel you must have a solid bond, but slightly flexible, between the two. I have found that G/flex epoxy provides this and have had great success with it!!

I noticed this thread is talking a lot about using 5mm wood for the panel material. I think that is a very viable idea.
I would imagine that that material would provide a warmer, non-harsh sound. Characteristics that most EPS is noted for.
If anyone hasn't already done it... what about laminating the wood panel with a thin EPS board? I would think that the EPS board would not only help make the wood more rigid, but also help amplify the woods overall tone and sound. The best bonding material to sandwich the wood and EPS would be epoxy...of course 
Has anyone tried this already?

Anyways. Its good to see everyone still at it. I wish I had more time to get back to this project. I find the wood panel an intriguing idea!!

Zygadr...Glad to see you're still active in this arena!
And yes, I'm still working on my driver design(if you remember from a year or so ago..lol). I have an even better idea and path than the one I originally shared with you.
I've been slowly gather materials to make a prototype. I believe it will be a good success if I can pull it off!!!
Only time will tell..hehe

Hope to get back more often!

Peace

[j gale]

Glad to see you back. It's always good to hear tips from others. I have been OK with the 3M tape but will look for the G/flex to see if I can hear a difference. I've tried all of the EPS available here and the extruded stuff and gator board and several 3mm and 4mm ply woods. To my ears shellaced cardboard sounds natural. There  seems to be resistance to the idea that cardboard is good. Perhaps it seems too easy or too cheap. The shellac changes it's character. Untreated the fact that it is cardboard is noticeable. The various woods sounded OK but not as good as the cardboard. Biggest complaint with wood--too heavy. Can't get enough volume even with the most powerful exciters. Those cheapo exciters sound very good. The biggest advantage of the daytons and more expensive Hi waves seems to be higher power handling and perhaps durability, but in my opinion don't sound better. (haven't done a direct comparison though) If you look back a few posts pics of mine show the triangles used to treat (damp) the edges. That made a significant improvement. I think that it  prevents sound from  reflecting back and so lowers noise.  Comparing with and  without there was a big difference when putting ear close to panel.