[osssyvan]

What is consensus on surface roughness etc?

I think rougheded surface or even dimpled would help for the random nature of things versus smooth.

Also has anyone tried holes in panel to drop the weight? As it is not piston movement I hope it could still work. You lose surface area but would that effect LF?
-ossi

[Odal3]

Cool - so how do you like the pucks? If you have some time, I'd be interested to hear how they would sound on some thicker birch plywood and low pass it perhaps around 100 - 150Hz. My guess is that the plywood needs to be thicker since it will over-vibrate the board if it's too flexible/floppy.

[Odal3]

Hole cutting can definitely be used for tuning but it makes it more advaned and if not computerized model would require some trial and error. Every change on the panel surface will change the bending wave in one way or another.

There is a commercial DML panel which had a laser cut holes in it. Can't remember the name right now.

[osssyvan]

Cool - so how do you like the pucks? If you have some time, I'd be interested to hear how they would sound on some thicker birch plywood and low pass it perhaps around 100 - 150Hz. My guess is that the plywood needs to be thicker since it will over-vibrate the board if it's too flexible/floppy.

Just got them yesterday evening. Haven't had the chance to try yet.

I'll try today or tomorrow but I am limited in thicker ply. I think i have somethinh like 5mm thick. I might have some glulam.

-Ossi

[sedge]

Ossi
The pucks supposedly have a usable fr of 20 to 80hz ,I probably would have gone for the hdn-8 at 50watts and a usable fr to 15k ,at about 15dollars ,not a bad price,this would also drive a 5mm thickness panel very well I , would think.
Dayton hdn-8 units are expensive in the UK ,about 26 pounds sterling at least,so will not be testing this I'm afraid.

Looking at 3.6mm ply in the diy store the other day ,i noticed they were all warped ,my 6ft ply  panel was straight when I bought it years ago, until I put it in the loft! So spine mounting my exciters to the panel probably wouldn't be a good idea ,unless anyone knows a way to stop thin ply from warping over time.
Steve

[sedge]

As for the 3.6mm ply frequency response ,early tests show it has a strong output from 25hz to 20k ,but as OB_newbie has quite rightly pointed out,even though the frequencies are there ,there still seems to be something missing,I noticed the same thing with the first prototype of the podium I heard when they were first shown at an audio show,don't know if they fixed this?
I am now being hampered by the onset of a cold,so listening tests are going to be a problem
Steve

[sedge]

Ossi
As for roughness and holes ,I have used panels with very rough surface but can't say that it mad much difference,my dog stamped a great big hole in one of my panels and it still played well!

On the other hand I thought I'd be clever(lazy)and use a rough sandpaper to sand my eps panel,it felt very fluffy , and soaked up a lot of glue ,but didn't go totally hard,still felt softish ,does not sound as I wanted it to.
Has anyone compared the sound of the 1inch eps and the 1inch xps ,do they sound the same ? I only ask as some of the comments of xps sound are not good,I wonder if the self noise is different,harsher in some way,the 5mm thickness xps panels I use ,after sanding and coating is quite dead sounding,but on the thicker 1inch panels this may not be the case,any feedback on this would be great.
Thanks.
Steve

[osssyvan]

Steve,

I've noticed the same that something is missing with the ply stuff. They are good but not quite there. Try them for a movie though. They are great.

I got 20mm finnfoam xps. They have their own sound aswell. I think sanding the skin helped. They had bit of a metallic tint to them.

If material sound signature is to be checked, does anyone know what material the small BMR units are? That could worth trying.

I did not like the look of the screw mount on hdn-8. Also as i wanted to try those dedicated shakers to see if they are different from fr stuff.

Haven't tried the puck yet. I was making the frames for my panels. They are massive! Colored them with white lacquer.

I think before christmas I don't have time for extensive testing but for some for some small tests I should have. I shoulb ablo test some bigger panels during christmas aswell.

-ossi

[OB_Newbie]

Ossi
As for roughness and holes ,I have used panels with very rough surface but can't say that it mad much difference,my dog stamped a great big hole in one of my panels and it still played well!

On the other hand I thought I'd be clever(lazy)and use a rough sandpaper to sand my eps panel,it felt very fluffy , and soaked up a lot of glue ,but didn't go totally hard,still felt softish ,does not sound as I wanted it to.
Has anyone compared the sound of the 1inch eps and the 1inch xps ,do they sound the same ? I only ask as some of the comments of xps sound are not good,I wonder if the self noise is different,harsher in some way,the 5mm thickness xps panels I use ,after sanding and coating is quite dead sounding,but on the thicker 1inch panels this may not be the case,any feedback on this would be great.
Thanks.
Steve

Hey Steve, I have not found any quality EPS so I can't compare directly to XPS either.  I lost my first Thruster on my ply panels last night and after looking for my other set of Thrusters I found them on an old set of XPS panels that I had stashed out of sight.  I was really digging the ply and thought that I might be going in that direction but after listen to just  a few songs I can say that the treated XPS sound more clean, detailed and more natural with better rhythm... more effortless.  I was not happy with XPS after going from the KEFs to the panels and but going back to them after the thin ply panels I can very clearly say where my preference is now... that was unequalized. 

Always choices and preferences that lead us in different directions.  I have a few sets of the DAEX30HESF-4 in my basket to go on some 1/8" ply panels but may be trying some different XPS panels instead now... double some treated 1/2" or layer a number of foam core boards after heavy PVA treatment... gez, I cannot see how a thicker, heavier ply panel could provide more detail over a thinner panel?!?

I have some cardboard that I treated last night.  Also have some old shellacked cardboard that will be put into service soon too.  They are almost 2 years old now and have really cured hard.  So will be trying these soon as well.

So much fun!

[OB_Newbie]

Oh common' fellas... I throw out some comments about the deliciousness of XPS panels and I get crickets?!?!   Nothing comes back?!?!

You guys are better than this.  Big grin.

[OB_Newbie]

Cool - so how do you like the pucks? If you have some time, I'd be interested to hear how they would sound on some thicker birch plywood and low pass it perhaps around 100 - 150Hz. My guess is that the plywood needs to be thicker since it will over-vibrate the board if it's too flexible/floppy.

Hey Odal,
I got a pair of the AuraSound AST-2B-4 shakers a few weeks ago to try a bass panel or combine the shakers on a larger panel and integrate it with a smaller panel (of potentially higher quality material) to handle 150Hz to 20KHz.

In some old posts, CLS commented that the shakers provided the best drum reproduction that he had heard (and he has some really nice OB subs) but his approach was to combine them all on a single panel which lead to other nasties to deal with.  Hopefully by splitting the shaker from the full-range exciter panel we will reduce some of the issues CLS had and can troubleshoot issues on the 2 different panels which are focused on delivering more specific performances (one bass, one upper bass to the highest frequencies). 

As I spend more time listening to the flat panel + sub combo I am getting more comfortable that a 2 way panel might be possible.  While the integration might be possible, I am still weary of DML bass... is it really better than what can be had by a traditional woofer in an Open Baffle U or H frame?!?!?   I really doubt it, and the The Eminence Alpha-15A is about $65.  But want to give it a try anyway... for fun if for nothing else!

Anyway... the AuraSound is still $5 bucks off and at $39+ is a great deal.  They are heavy and built like TANKS!! 

[Gary.M]

If material sound signature is to be checked, does anyone know what material the small BMR units are? That could worth trying.

-ossi

I have a Hiwave/Techtonic BMR here HIBM65C20F-4. Depressing the "cone" a little and looking from behind shows there is a layer that is either currugated, or more likely honeycomed paper / kevlar (its a brownish colour) making up the "cone"

[Odal3]

Sorry for keep you waiting. 

  I lost my first Thruster on my ply panels last night

So what do you do when you loose them? Only asking so I can try to avoid it, and perhaps we as a group can come up with ways to mod the exciters to be more durable.

I was really digging the ply and thought that I might be going in that direction

... finally!!....

  but after listen to just  a few song

...O no....that was quick. 

treated XPS sound more clean, detailed and more natural with better rhythm... more effortless. 

Here's my experience: clean - check, detailed - check, not as natueral as the ply imo but still very good, but that's just my ears in my room. I really want to like the XPS, especially since they play louder and are lighter, but I can't get them to my liking.  I can't fully get rid of the veiled sound. Might be user-error on my part - but I tried small and large panels, different thicknesses, different glue types and layers of glue, different exciters - doesn't matter what I do - it sounds good with the exception of the veiled sound. HELP!

I really want to try the EPS but never found a good source - stuck on the XPS. But the gator foam board shows some promise - will try to get hold of a bigger sample.

I actually really like that the we all like different things, have different perspectives and bring different ideas to the table. It really adds to the fun! Thank you all for sharing all your great ideas! And yes - I try many of the ideas I read here in one form or another - many are very good. I also believe the our different room set-up and electronics and not to say the type of music is preferred makes a HUGE impact on preferred panel.

The DAEX30HESF-4 brings more detail and HF than the thrusters. I can easily hear a difference. Before you glue them all up on the XPS, you should just try one with removable tape or something quickly. There is just one thing with it - it sometimes sounds a bit of metalic ringing - Not exactly sure what it since I don't hear it all the time.

gez, I cannot see how a thicker, heavier ply panel could provide more detail over a thinner panel?!?

I think we use the panels a bit differently. I play them full-range or around 100HZ while I think you cross them higher and can then use smaller panels. In order to get good and clean bass, it's my experience that they need to be as rigid as possible so they will not become 'floppy' - this is especially true when cranking them up while crossing them at 120hz or lower. I can play 1/8" at low volumes or cross them really high - but I agree, the bass doesn't sound good when playing louder. The 1/4 is perhaps too thick and something slightly smaller is what I found is better (after some hard work with the sander). Even on the thicker panels, it doesn't get much of the slam that you will get from a sub, but I have to say as an old electric bass player, that the bass from the panels is very clean and detailed. 

The more and more I experiment, the more I'm convinced of the multi-panel approach that takes the best from each material option and panel sizes.

[Odal3]

Hey Odal,
I got a pair of the AuraSound AST-2B-4 shakers a few weeks ago to try a bass panel or combine the shakers on a larger panel and integrate it with a smaller panel (of potentially higher quality material) to handle 150Hz to 20KHz.

Please keep us posted - I'm really curious. THose look powerful - you should make an IB panel sub!!

As I spend more time listening to the flat panel + sub combo I am getting more comfortable that a 2 way panel might be possible.  While the integration might be possible, I am still weary of DML bass... is it really better than what can be had by a traditional woofer in an Open Baffle U or H frame?!?!?   I really doubt it, and the The Eminence Alpha-15A is about $65.  But want to give it a try anyway... for fun if for nothing else!

I think we are heading the same direction. 

[OB_Newbie]

Sorry for keep you waiting. 
So what do you do when you loose them? Only asking so I can try to avoid it, and perhaps we as a group can come up with ways to mod the exciters to be more durable.
 ... finally!!.... ...O no....that was quick. 
 

People use LOL freely but I *REALLY* laughed out loud Odal!!

As for the failure on the Thruster... this was a strange one.  I was listening to the panels just as background music with everyone else in the house busy with other things so I didn't want to interrupt.  It was so low that I had a hard time telling at first but it sounded like it was cutting out... no buzz or anything.  Once it cut out a few times and I then knew for sure that something was going on so I got up to the panel and yup...no sound.  Because it didn't buzz before failing... like others that have failed... I thought it was my amp or CD player.  So I turned everything off, switch the speaker wires at the amp., powered on but still only sound out of the right panel.  The left panel was dead.  In an attempt to switch the panel as I was really surprised it was the panel, I gave it a shake a few times and could hear a rattling sound in the exciter... not uncommon.  All others started to buzz before failing... no this one.  I listen at low levels so never over powered them... usually listen at levels with peaks in the mid 70's dB range... if I really crank them... I might get peaks in the mid 80's.

The Ultras's use a pretty thin, unbraided leads to the speaker tabs.  I wonder if the Thrusters use the same thin leads?!?  I am ordering the DAEX30HESF-4's ... they have braided tinsel leads that look more sturdy.  Hmmmm... thats (not so) funny... I hear the same metalic sound on the DAEX25FHE-4... that is a good way to explain the sound.  It also seems to transfer more energy to the panel and took more damping of the panel to reduce some of that coloration.  But it is still there somewhat... just reduced.  After reading your post I wonder if it is the metal case or tabs that are ringing!?!?  I thought it was the venting as the exciter seems louder compared to the Ultra or Thruster when you listen close to the exciter but want to try coating the metal case with something to damp it and see if we can't reduced some of that that metallic sound!?!?  Certainly can't hurt...     

[Odal3]

Coating the back - that's a great idea! Just not sure with what??


Saw this review on PE for the TT25-16 puck 4 packs: "Great value fun little transducers to do diy audio projects. I just for fun screwed all four into a pair of headphones. It shakes my head so much i can't read my screen. I assume it is unsafe to do this a lot and i take no responsibility for any damages caused if you do the same."

Yepp - that's proof enough for me that it's working   

[sedge]

Sorry for not answering anyone at the moment ,as I am in the middle of a stinking cold.
Odal3
But one thing I will say is that the problem of the veiled sound  was minimized greatly by the thinning of the panel in front of the exciter area ,for me this is not an option,for good sound ,it must be done,for some reason it has been ignored,this could be that I did not make the point clearly enough,I was going to follow this up with another mod to stop the noise from this area too,but lack of good quality 25mm eps panels has stopped me.
They must both be implemented to produce the best sound
Steve

[OB_Newbie]

Here's my experience: clean - check, detailed - check, not as natueral as the ply imo but still very good, but that's just my ears in my room. I really want to like the XPS, especially since they play louder and are lighter, but I can't get them to my liking.  I can't fully get rid of the veiled sound. Might be user-error on my part - but I tried small and large panels, different thicknesses, different glue types and layers of glue, different exciters - doesn't matter what I do - it sounds good with the exception of the veiled sound. HELP!

I really want to try the EPS but never found a good source - stuck on the XPS. But the gator foam board shows some promise - will try to get hold of a bigger sample.

I actually really like that the we all like different things, have different perspectives and bring different ideas to the table. It really adds to the fun! Thank you all for sharing all your great ideas! And yes - I try many of the ideas I read here in one form or another - many are very good. I also believe the our different room set-up and electronics and not to say the type of music is preferred makes a HUGE impact on preferred panel.

The DAEX30HESF-4 brings more detail and HF than the thrusters. I can easily hear a difference. Before you glue them all up on the XPS, you should just try one with removable tape or something quickly. There is just one thing with it - it sometimes sounds a bit of metalic ringing - Not exactly sure what it since I don't hear it all the time.
 I think we use the panels a bit differently. I play them full-range or around 100HZ while I think you cross them higher and can then use smaller panels. In order to get good and clean bass, it's my experience that they need to be as rigid as possible so they will not become 'floppy' - this is especially true when cranking them up while crossing them at 120hz or lower. I can play 1/8" at low volumes or cross them really high - but I agree, the bass doesn't sound good when playing louder. The 1/4 is perhaps too thick and something slightly smaller is what I found is better (after some hard work with the sander). Even on the thicker panels, it doesn't get much of the slam that you will get from a sub, but I have to say as an old electric bass player, that the bass from the panels is very clean and detailed. 

The more and more I experiment, the more I'm convinced of the multi-panel approach that takes the best from each material option and panel sizes.

I definitely agree that it is absolutely cool the we all like different things and have different perspectives.  We all pick out different things that we like about this or prefer over that... and I want to listen to them all and I do enjoy aspects of each type of panel I try.

It is also hard to describe how something sounds and then comparing different panel material and how they differ... especially for those folks who may be reading and have yet to build a pair of these magic panels.   

So for those listening in, this is my very humble attempt to get the differences better spelled out and hopefully more solidified on this forum. [venturing out on a limb here fellas, be kind  )  To be accurate, all of the panel materials that we have been listening to have some coloration, signature or characteristic to its sound.  But here are my personal impressions of 1" XPS (treated both side with 2 coats of PVS+water in a 1:1 mixture with corners and edges rounded over) and 1/8" untreated ply... both 24" x 30" in size.

XPS:
* As Odal describes the material as veiled, but for me personally I hear them as more alive, detailed and differences in the recorded material seems to come across more clearly.  The panels sound different based on the recording itself.  This was my rational behind placing the label "natural" on them (more on this later).
* The coloration that I hear most on XPS is a vibrational signature.  I heard this very clearly when I switched from my Q500's to the XPS panels... was not happy with the panels for some time knowing this.  The coloration however is a warm sound that may slightly round off sharp details... yet the panels sound fast and detailed overall due to the fact that XPS is VERY light and ridgid (more ridged than ply).  And I think I've said this before on this forum, there is a tad sense of hollowness(best that I can describe it) to this same coloration.  Hit a XPS panel with your knuckles... the sound that it makes is not unsimilar to the "hallow" coloration that I hear when listening to these panels. 

1/8" ply.  NOTE: These are thinner than what others may be using so the comparison and comments reflect only 1/8" vs. XPS.
* To my ears, ply sounds smoother and believe they measure much smoother overall than XPS.  Smoother in the low and mid- freq. range but are also rolled off up top slightly.  However due to the power response of these panels they do not sound as rolled-off as the freq. response might suggest.  They are pleasant to listen to and have less detail than XPS which may very likely lead to their smooth, mellow, easy to listen to sound.  Not as efficient as XPS but this thin ply DML panel with the Thruster exciter is easily still more sensitive than most typical home speakers pulled out into the room.  Bass may also be more extended but am planning to post measurements tonight.   
* The coloration I hear most on ply is one of omission really as it seems to impart the same tone to the music.  This quality might also give it it's smooth, mellow character.  The panels are heavier and not able to respond as quickly and the more damped panel may dominate the sound waves, deadening the nodes more so than the very lightweight XPS panels?!?  Again here, I think it it safe to say that each material has its own sound.  Wrap a ply panel... take the sides in your hands and move the panel quickly to you and away quickly and repeatedly listening to it as it flexes... it makes a sound not totally unsimilar to what I hear when I listen to ply.

------------------------------------------

Really like both panel materials and they both sound very good to me.  I like certain aspects of both and could be happy with either and may even switch as to which one I like more.  Someone reading these posts might hear the word "coloration" in reference to these panels and get the wrong impression.  This should not be the case.  Me personally, I have yet to hook up my brand new KEFs for well over a month and now wonder if I should have purchased them in the first place.   

Whether these listening observations are described and interpreted accurately I am not sure, but want to put it out there to help form some general consensus to the sound of panel our materials.  I know we don't all hear the same things, enjoy or not enjoy certain aspects of the materials... all of which lead to different preferences but do hope that as we listen we can all start to hear the same colorations and hopefully we can put better descriptions beside each material, the good, the bad and other considerations for those who want to build their first set of panels.

My measurement system has not been functioning correctly for many months now but broke down and got a MiniDSP + UMIK-1 for Christmas so I hope to begin to take more measurements to get more of the technical merits of each material documented better.       

AND... if this wasn't the longest post in history already...
I was thinking that it would be fun (and valuable) to have a DML Magic Panel-A-Thon ? Extravaganza where we can listen to different panels and configurations.  Imagine the numbers would be fairly low since these panels are not mainstream (YET!!!).  I'm sure Steve, once he gets over his cold, would love to fly over to meet us all in person.   

Over and out...

[Odal3]

Can you imagine the customs and security  officers trying to understand why Steve is trying to bring on board a bunch load of large, fragile and  weird looking things that all have a suspicious magnets sitting in the middle. 

[OB_Newbie]

Well this is exactly WHY I am suggesting such a crazy thing... I REALLY want to see how that one might go down.