[oldschoolVlad]

Rob, I know you don't like braceless exciters much, but take a look one more time at DAEX25SHF-4. It's very promising. Yep, it needs a frame, but it's as powerfull as thruster (same BL, 4Ohm too) and has lighter and narrower voice coil for perfect highs. It can be a stop point finally...

[jeffac]

Is the use of multiple exciters a serious compromise towards sound quality?!
Rob.

I think you already know the answer, its a pretty reasonable deduction that 1 appropriately-positioned exciter should win on almost all SQ counts except SPL, assuming all other panel design aspects have also been made as ideal as practical. There is definitely an interaction at the horizontal mid-line between vertically spaced exciters that is considerably louder and more distorted on VH-EPS panels, and that for lack of a better description, sounds sour compared to close listening to other panel positions. Luckily once summed with the rest of the panel it doesn't seem to detract 'too much'. Better this sourness not be there though, and minimizing deleterious interactions is obviously one of the primary reasons for the Monacor, Dayton and oldschoolVlad exciter placement solutions.

Go one.. go hard Rob.. keen to hear about what you learn..

cheers.. jeffac

[zygadr]

Thanks gentlemen for your encouragement and positive feedback - much appreciated.

I will attempt to summarise where we are at in this present moment in time:

1. VH EPS is as jeffac stated '' it's got to be very close to an ideal panel material''. We are at the final stages of fine tuning and experimentation  ..............pretty confident about that 
2. VH EPS is very light and can also be rigid depending on size to thickness ratio.........simple.
3. VH EPS is very cost effective and is available in large sizes that can be cut to any dimensions you require.
4. We no longer have a problem with high frequency drop off...............not in my case here at home at least 
5. The new ''thruster exciter'' from P.E. might be a game changer...............let me be the one to try this first!!
6. We have, thanks to sedge, a proven coating that works well as far as we can tell, and costs next to nothing to purchase and apply......'onya sedge!(''onya''............slang in Australian for - good on you).
7. From what I hear in my listening room, the sound of a DML is so far superior to other, very expensive, panel like loudspeakers, that I am truly shocked!!! . I have owned magneplanar, electrostatic speakers in many forms in the past, and am certain that DML's have a sound that cannot be matched and is truly unforgettable once you have heard it!!

Rob.

[zygadr]

THRUSTER EXCITERS HAVE BEEN ORDERED......................WOOOOOOOOH OOOOOOO!!!!!! (I hope  )

[sedge]

Zegadr
Can you tell us if you have a softish surface as jeffec has or is it hard , the panels I have used have been cut with a hot wire I would think , hence the hard surface ,It is the hard surface that gives the eps its plasticy ,self noise sound .
Coating the back of the panel should only help damp the self noise ,not change the tonality .
Steve

[zygadr]

Steve, the surface I have can only be described as slightly "rough".... ........I would not call it smooth by any means, nor would I call it noticeably rough.
I have seen the smooth surface you mention and it is only found on the very poor quality basic EPS in cheap packing materials.
We must not forget that "VH" grade EPS  is Totally different to standard EPS - no matter how it is cut............even the block, very thick VH stuff is slightly rough on the exterior surfaces.
Once again, the " VH " grade is a millennium ahead of normal poly foam board used to pack cheap crap from China!  High quality VH grade has far smaller, more compact beads than the standard stuff and sounds totally different.
Now here's something else to think about!...... My placement of the exciters on the remaining two scrap preices of VH poly is very approximate to the Monacor position of exciter number 1 !
I just took a rough guess without any form of measurement and have ended up with the best sound ever!........go figure!??????

[sedge]

Zygadr
Sorry ,you miss understood what I was saying ,I was not talking about roughness but hardness,the vh eps that I have was cut with a hot blade I think , which melts the surface and forms a hard plastic skin .
I think effec says his panels were cut in a different way ? As he says his panels have a soft surface , obviously this makes a big difference to the sound,so maybe we need to know how it will be cut before buying and save a lot of work softening the surface(removing the hard plastic skin).
Hope I have made myself clearer.
Steve.

[sedge]

Zygadr
What size test panels are you using ?

[j gale]

Hi, All I can say is listen to Sedge! whichever poly styrene panel you are using EPS or extruded sand the surface off on both sides and the edges too. You will be left with a surface that has a velvety feel, but more important the plastic sound will be gone. I tried it with both EPS and the extruded closed cell stuff and the result was the same. best result so far was a coat of 2parts PVA to one part water 1 coat on both sides, nothing on the edges. Used my sander with 100 grit (coarse) and it took ony minutes. The surface skin has to go if you want natural sound. I think a lot more experimenting with coatings needs to be done. that's OK since the panels are so cheap.    Jim

[OB_Newbie]

Wow fellas... sounds like a lot of progress has been made!  I read the last few pages but didn't see anything on what is considered the best exciter placement.  Rob still with 1 exciter?  Jeff with the old vertical line of exciters?

Whats the good word guys?

Thanks,
Rich

[zygadr]

Guys, I have run my hand and fingers across the surface of the panels. They are not silky smooth as I have mentioned before..............they have a slightly rough feel - this is all I can say. I have never come across VH grade poly that has a smooth or ''soft'' surface..............this makes me seriously suspicious that we are  talking about two different grades of materials !!!

My panels are of medium size sedge. Once again, how THICK are your panels?

I will say once again that something very significant has happened to the sound of these VH EPS panels at a time that I was ready to ditch them for good.
Remember, I am using only ONE exciter per panel (10mm thick) and have never heard a greater sound to date. You can accuse me of exaggerating if you like, but I am well aware of what is happening here regarding sound quality.

[OB_Newbie]

Thanks for the confirmation Rob.  Monacor placement is out?

Also, 1 more question.  What options to mount to panel?  Jeffac's panel with car carpet and velcro is easy.  What are others doing? 

Would it be asking too much to see pictures of you panel constructions?  A picture... a thousand words... blah, blah blah.  Just looking at Jeffac's  pics clarified his build approach in seconds!  Thanks Jeff!   

Many thanks!
Rich

[sedge]

J Gale
Thanks for the feedback, glad you like the panel modification .as you have said it works with all poly panel types I have tried so far.
Zygadr
I use many thicknesses from 3mm for my smallest panels 12inch by 10inch to 25mm for my 7 ft by 2.5ft,the sound of all the panel sizes is very similar but the presentation is different .
Steve

[sedge]

By presentation I mean the smaller panels have more space and depth to the sound especially in a small room ,more of a point source I think, with the larger panels you get a larger scale and room shaking dynamics drum solos can be so realistic, It is more a wall of sound or like having a giant pair of headphones.the smaller panels come very close to the larger panels dynamics but have a more delicate sound probably because of the lightness of the panel.
I could live with all of these panels but which will be my finale voice, I haven't a clue.
Steve

[Odal3]

So I'm hoping someone could help point me in the right direction for the panel material. Is it EPS or XPS that you are are using? In regards to the harder VH grade, how do I find it in the US. Does it also have a diff name? I only get AUS references when using google. I would really appreciate if someone could post a link so I know that I'm looking at the right thing.

[Odal3]

+1 to more build pictures. A picture only thread of final builds would be great since there are so many nice designs that gets buried and forgotten

[sedge]

Oral3
What size panel are you thinking of making ?
Steve

[Odal3]

Nothing too big at first. Was thinking a 3 x 4 ft as my plywood panels so I can do a direct comparison. What size to you recommend for best sound that fits into a normal living room?

[sedge]

Are you running them full range or crossing over to a LF driver, if so what frequency?
Steve

[Odal3]

I have been using one of the peerless bucket subs with good result. Plan is to put one bucket sub behind each panel and run them in stereo.  My current plate amp doesn't have specified numbers on the crossover dial so maybe 70 -100hz ??

Tried running my current boards without a sub but missed the low end. Boards probably need to be much larger size to get decent bass.

Will try to get hold of a mic so I can figure out what really is going on.