[bobloblob]

panomaniac-

For POL's posts on his set-up, go to his posts #'s 1126 &1128 on page 57 of this thread

[panomaniac]

Thanks Bob!  I thought I had been following this thread, but seem to have missed a lot.

Interesting setup POL.  BTW, you're Francophone?

[pol_bct]

Thanks Bob!  I thought I had been following this thread, but seem to have missed a lot.

Interesting setup POL.  BTW, you're Francophone?

YES, but I thought I was well hidden in Indian Ocean

 

POL

[panomaniac]

Ha!  There are a few Francophone islands in that ocean - but I won't tell.  Rien, je ne dis rien....

[zygadr]

Well, I'm still watching you guys and have mixed feelings on where this has all gone over such a long period of time

To those who have experimented with different materials and ideas, that's fine.

It's sad that VH GRADE EPS is so hard to find or get hold of around the world. That is a big surprise to me !!! 

It IS AND HAS BEEN the only material that can reproduce high frequencies and high output.........END OF STORY.

The honeycomb panels available here in Australia are NO GOOD.
They are coated with a too heavy timber or fiberglass skins which reduces SPL dramatically

If you are using some ''green''???? foam panels, I doubt that this is optimal, but I could be wrong?

For those who are fed up with looking for the right kind of EPS, then I suggest going back to the thinnest double layer corrugated cardboard you can get and treat it with a rock hard drying lacquer as j gale has.
However, it is VERY important to remember :

1. GO LARGE.................don't piss around with 2 foot square panels for God's sake!!!!!
2. Use the 3M tape I recommended ages ago to adhere the exciters to the panel material.........that tape you CAN get
3. You don't need any spines with the standard exciters...........they sound better without by being freely mounted.

 

[irishpatrick33]

So what's the verdict? Are people finding affordable VH 10mm EPS in the USA?

I don't hold much better prospects for finding the appropriate corrugated cardboard either. Seems like the combination of finding it and lacquering it, might be an even more painful expedition.

[zygadr]

Corrugated cardboard in approximately 6 mm thickness cut to a size of 6 foot by 2 foot should be easy to find.
Most packaging suppliers will have this stuff...............it is nothing special.

Lacquering the interior corrugations may not be worth the effort over all, but at least do the front and rear sides.
The difference is noticeable.

As a thought, ''SUPER GLUE'' or similar can be purchased in large bottles and squirted down through the corrugations at both ends (top and bottom) of the C.C................as far as it will go before hardening.
I have heard that this has been done by some and is of course an epoxy hardener as well as a glue.
Haven't tried it myself, but it may be worth a try??

The sound of EPS is very different to C.C.
EPS has a very clear and bright sound where the C.C has a warmer and probably more natural tone but at the expense of clarity.

The choice is yours depending on what is available.

Remember....................the exciters need a lightweight material that is able to ''TRANSMIT'' the sound vibrations from the rear to the front of the panel WITHOUT ''MUFFLING'' the highs

[pol_bct]

zygadr  & others

> Lacquering the interior corrugations may not be worth the effort over all, but at least do the front and rear sides. The difference is noticeable.

this is an interesting question, should we harden both sides or only one, and which one preferably? and WHY?

POL

[irishpatrick33]

What kind of lacquer? How many coats?

[zygadr]

The lacquer was discussed and used a while back, so you will have to go back on some old posts by j gale if I recall correctly.

Any quick drying solvent floor finish that dries hard can be used or perhaps first experimented with.

I had some success with SHELLAC flakes mixed with Methylated Spirits (a strong ratio that a high concentration of flakes to spirit).

BOTH sides need to be done.................and watch out for warping when it dries

If you can get hold of a coarse needle ended syringe, the Shellac mixture can be squirted down the top of the corrugation openings with the panel held vertical.
You will need to do a bit at a time and be careful that the bottom of the panel does not become saturated and soggy.

[bobloblob]

You might find Wood Hardener (a Minwax product) even better than lacquer or shellac, which tend to sit on the surface more than penetrate, though they do penetrate a little.  Wood Hardener is made to penetrate into rotted wood fibers and harden them, which it does very well.  I've used it for its specified purpose, but not yet on cardboard.  I think it might be worth it to try on a scrap piece and see what you think of it.  If you do, make sure you have lots of ventilation, and apply it rather heavily so there is enough to penetrate.  It should penetrate into the fibers and harden them, and you can also then apply a finish over that if you choose.

Something I would be concerned about is not having an even penetration of any finish used for this purpose.  If it is only sitting on the surface, or penetrates unevenly, I think it might dampen more than transmit sound, somewhat like constrained layer damping.  Something to think about.  Worth experimenting with, though, if just to see.  I would not commit any large panels to the project (or buy a large amount of Wood Hardener) without trying it on scrap first.

It would be nice to find a decent alternative to the VH grade EPS Zygadr uses, which is not that easy to source in small quantities.  So far Zygadr has established the gold standard for panel material.

[zygadr]

Well said bobloblob.

As much as I hate to say it, the VH Grade EPS is truly the material that we had all been searching for.

It was discovered by testing samples of various panel materials and the ''scratch test'' made famous by forum member sedge.

If you try panel materials from now on, remember this scratch test : hold one side firmly up to one ear and rub the surface of the opposite side of the panel material.
If the rubbing sound is dull with little high frequencies or crispy sounds passing through with low output, you have a BAD  panel material.

when the VH EPS was scratched, I nearly hit the roof................that's how big a difference there was.

Panel rigidity made no difference in this case..................strange

[irishpatrick33]

Alright, I am going with the 6mm corrugated cardboard. Double wall?

Also, what are people doing to mount these things? I previously suspended some panels within a wood frame using rubber bands... but I worry that CC will not be able to take the constant tension over a long period of time--possibly tearing apart where I make a hole to string it up.

[zygadr]

Try ''PROPER'' (not the Chinese knock offs) cloth tape. You can tell that you have the right tape by the canvas look pattern it has printing through.

Tape all edges around the perimeter of the panel and stretch while sticking down on to a frame or opening in the panel that will give you  approximately 1/2 inch clearance between panel and frame.

This will damp any unwanted resonances at the edges of the panel.Only one side of the panel needs doing.
Rounding off the panel corners is not required.

[irishpatrick33]

Try ''PROPER'' (not the Chinese knock offs) cloth tape. You can tell that you have the right tape by the canvas look pattern it has printing through.

Tape all edges around the perimeter of the panel and stretch while sticking down on to a frame or opening in the panel that will give you  approximately 1/2 inch clearance between panel and frame.

This will damp any unwanted resonances at the edges of the panel.Only one side of the panel needs doing.
Rounding off the panel corners is not required.

I have no idea what this means. Are you securing the panel to the wood frame with this cloth tape?

[zygadr]

I have no idea what this means. Are you securing the panel to the wood frame with this cloth tape?

Yes.

[tommus]

Hi folks, I've been lurking at this thread for a little while, absorbing information and collecting materials for my panel speaker project...

The final piece of the puzzle for me is getting the high density EPS sheets.  I finally found a manufacturer willing to deal with me, and I will hopefully be getting 3/8" thick, 4x8 foot, 2lb. density EPS sheets in a few weeks.  They will sell me 12 of these sheets for their minimum order of $75.00.  I need to wait until they get a larger order for the 2 lb. stuff, since they will be cutting it to size for me from a huge block.  I will pick the material up myself in Allentown, PA since I am not going to pay an arm and a leg to have a shipping company destroy these panels.

The manufacturer is Insulation Corp. of America. <www.insulationcorp.com>  I found the company at <http://www.epsmolders.org/2.html>  You can search for manufacturers in your area and start inquiring... 

Another option (anywhere in the world) is to try surfboard manufacturers. They use high-density EPS to make the cores of the surfboards.  I talked to one guy in California who could cut me 2x6 pieces of 2 or 3 lb. EPS, but the price plus shipping to the east coast was a non-starter.

At the moment, it looks like I am going to start with a single panel, 4x8 feet, with 8 exciters (I have the white "sonic impact" ones...) in the manner of Pol-bct's "ambiosonic" set-up.  I'll use silicon caulk to attach the panel to a wooden frame and maybe give the panel a thin damping coat on the back with diluted PVA glue a la Sedge.  I'm going to drive this thing with the Dayton DTA-100A 50-watt T-amp. 

It looks like the latest refinement is to omit the wooden back brace to support the exciters, and just stick them on with 3M double sided tape.  Is this correct?  Can the 3/8" EPS support the weight of multiple voice coils?  Is the back brace detrimental to the sound?

I want to hang this panel from a 45-degree sloped ceiling in my living room, and one potential problem is that gravity may not be kind to the silicon attachments... any thoughts?  Also, I have some rubberized cyanoacrylate glue (Gorilla brand) to attach the exciters to the panel... has anyone used it?

So I'm not really bringing anything new to the table, but combining a lot of the ideas you guys have come up with.  If anyone has any comments or suggestions about my plan, I'd love to hear them.

If anyone in the northeast US wants to split the EPS order with me, either at the factory in PA, or somewhere in NY (I live in the Hudson Valley 1 hr. south of Albany), let me know. 

Many thanks to the people (Zygadr especially) who have put so much hard work into bringing this idea as far along as it is. Hopefully I'll soon be able to give you some good news about my panels and contribute something to the discussion.  Cheers!

[irishpatrick33]

Try ''PROPER'' (not the Chinese knock offs) cloth tape. You can tell that you have the right tape by the canvas look pattern it has printing through.

Sorry to bother again. I am not sure I know what kind or brand of tape you are speaking of. Could you provide a link, brand name, or something? Is it gaffer tape?

BTW, that's actually a pretty cool idea. It was a pain to suspend a panel in the wood frame using rubber bands. Your solution is much simpler... and adds dampening to boot. Thanks

[usp1]

It looks like the latest refinement is to omit the wooden back brace to support the exciters, and just stick them on with 3M double sided tape.  Is this correct?  Can the 3/8" EPS support the weight of multiple voice coils?  Is the back brace detrimental to the sound?

It has been some time since I played with these panels, but the 3M F9473PC tape zygadr originally recommended does not seem to be a long term solution. At least with cardboard, and gatorboard the exciters fall off after a month or so. I don't know how they will hold up with EPS.

[zygadr]

Gaffer tape is the tape I'm referring to.
There are two types though : one is a plastic type and the other has a definate visible ''weave'' in it like cloth or canvas. This second type is what you want.

The tape I recommended was what NXT had advised they use on the exciter feet.
I too have had some fall off.
The trick is to ensure that the foot of the exciter and panel is roughened a little with sand paper and then cleaned with alcohol.
The other important thing to do is use a wooden spatula or something similar and press down hard around the circumference of the exciter foot after it has been attached to the panel.
Do this in small steps all the way around and watch out for the voice coil wires!

However, the use of glue is quite acceptable providing it does not react with the panel material or exciter foot.

If you are going to use glue, make sure that it dries ''HARD''!..................any softish or mushy drying glue will kill the coupling and the much needed resonances required to transmit from the exciter to panel...............this is CRITICAL !