[sedge]

Exspec
This is a pic of the sort of panel I mean,I have not yet permanently filled in the bottom part of the panel yet.
This is basically my idea for the pro panel site ,but it is a pretty good all round speaker,there are still a lot more improvements I can think of but have so little time and too many panels.

This is another panel for home use ,50 per cent free edged panel 50per cent rigid ,I did this with an eps panel years ago which gave the same frequency response ,if I remember rightly.


This is another very rigid hard panel but lightweight  ,I tried to make the panel frame heavier with plaster,but it eventually cracked and fell off

This is the response of the 50 50 panel and the hard light panel ,using peak hold and playing Jean Michel Jared aero ,I've used this CD as it is very powerful sounding with thunder and other sound effects,very dynamic,this gives you an idea of the power response,this was playing very loud so used the steep 50hz roll off,the 10watt exciters still became to warm for my liking so would probably roll off to a sub at 100hz or more.

You do gain a few db when rigidly mounting the panel and is more capable of handling the power without buzzing and rattling.
If there are any questions please don't hesitate to ask.
Steve

[sedge]

There is also plenty of low end slam with these panels, at no time playing music on these panels did I think I needed to turn on my TLS sub s to give more oomph.
Plays full bodied double bass no problem.
Steve

[Odal3]

Nice. Are the panels glued to the frame? How does the sound compare to the panels with no frame?

[sedge]

Odal3
The thicker panel frames are glued and screwed for solid mounting,this act's as a reflector ,increasing the output between the exciter and the frame,spreading the sound across the panel.
The thinner 50 50 panel was just glued.
These are very much an nxt type panel and works very well with ply and other hard types of material,it is robust and has good power handling.
The panel is smallish but has a big sound,similar to the podiums.
As they stand they would give most speakers of today a good run for the money,actually these were dead cheap to make ,so there would be no contest.
I did write a lot more but lost it all again
So am afraid you got the short version.
Must go.
Steve

[osssyvan]

I guess my measurements are correct then. It is hard to realize how little the dips and jumps actually show.

Sedge, Can you re-cap for a tired dummy?

Rigid panel is 2ftx3ftx3mm with what measurement?

I think my panel with aluminium frame had better LF than without. Can't test as the delicate things broke . I am going to re-use the aluminium profiles and make myself some wall mountable frames with them. I already have some nice looking cloth that I was going to use with the big frames but ended up noticing that they were just that. Too big.

I think I will do a experiment on the foam panels. Has anyone tested how much making the panels narrower affects? I think visually and space wise tall but skinny panel would be easier to pull of.

-Ossi

[sedge]

Ossi
The thin eps panel at the back in font of the door was about a foot taller ,and I used to jam it in between the floor and ceiling,it was good sounding but sounded thin does not go as low as a wider panel,so use a higher xo as if a smaller panel,but it will be able handle more db as the larger panels do.

The eps panel to the right with a great big chunk out of it was my 50 50 panel from years back.
I presume when you say what measurement,you are talking about exciter position?
The 50 50 panel is partsexpress and the thick frame is monacor.
Have not a clue which is best ,too many variables,but they sound very similar to me.
Oh yes just remembered ,if you use the partsexpress position on the 2x3ft panel you end up with two sides the same distance from the exciter,unless I got it wrong that is?
Mounting a free floating panel in a solid frame will Rob the panel of it's light and delicate sound,so be warned.
Steve

[sedge]

Ossi
The dip in response between 8k and 11k you remarked on is probably caused by cancellations in the small area within the foot ring of the exciter,i have mentioned this problem in previous posts,tectonic called this the tin can effect ,but this does not really describe what is happening in this area,it can produce some pretty nasty sounds caused by peaks and troughs .
Can you use your measurement program to measure pink noise in real-time so as to see the panel output change while you alter the panel,this is always interesting to watch and very helpful.
Steve

[sedge]

I must point out that this is still in the early days of testing for this panel,I still have not permanently fixed the lower end of the frame yet,am looking at other types of panels as well ,so things tend to move slowly.
Still have not got my head round the fact that these panels have no trouble going low,within reason that is,always thought that a 2ft panel would roll off smoothly below about 200hz or so, especially if hanging in mid air ,as my panels do:scratch:
As for the hf ,am still not happy with the sound,even though the measurements say it's present, it still sounds dull, you could always add a tweeter of course,as tectonic do for their pro speaker.
I have a suspicion that it is to do with the depth perception,the echo and ambiance is there but it does not flow up and and away as if you are in a real hall ,so I think it's to do with spacial perception.
This is why I feel that nxt type panels are good for pro work,they produce a good clear up front sound of the instruments ,the ambiance and depth is produced by the hall itself.
The free floating eps panel does not suffer from this depth problem as it has a very strong primary source radiating from the exciter area.
The primary source will be swamped if the panel is pushed heavily into( nxt ) dml mode,which is of course what I am doing although the added db  is helpful.
A free floating sheet of ply is already more dml than a free floating eps panel,if you curbed the output from the centre of the eps exciter area or increased the output of the panel area by clamping in a frame you will end up with a eps panel that sounds more like the ply panel .

I do have a few ideas that might,if lucky, sort this problem but we will have to wait and see,when I can get round to it that is!
This is me just thinking out loud ,hoping this makes sense .
Steve
Steve

[OB_Newbie]

Hey Sedge!
Trying to get caught up here.     To summarize a few things: 

1. Rigidly mounting the panel to a frame results in more low frequency output?  Makes sense to me as the overall weight of the panel now includes the wood frame.  Follow-up... you are saying that the output (sensitivity) is also higher across the entire freq. response?  Or just the LF?  Very interesting.  Not sure what to make of it... a bit of horn loading but hard to imagine that it adds more dB's than what the extra weight of the frame should take away?? (the exciter will attempt to excite the panel and frame... if you get my line of thinking).  Or, I have to wonder if the energy from the exciter is unable to exit the panel cleanly...reflected back into the panel as additional output?!?... possibly this extra output smears the HF output and causing it to sound more dull?     

2. Also for a rigidly mounted panel to a wood frame... the high frequencies measure as if there is HF output but its dull.  The sound very similar to the Visaton exciter with the large plastic mounting plate.  It measured flatter than any exciter I have every used but it sounded awful... no magic in the panel at all.  Dull and lacking in detail and vocals (IIRC) had a chesty sound to it.  Just one instance where the measurements said "YES" but the ears said "NO!!!!".

3. If we take a free floating panel and place it into a frame, it looses it's "light and delicate sound"?  I remember one of the posters on this forum that cut off 1 side of his wood frame.  Hard to believe this knowing that there is a thin null (no output straight off the panels edges however you are at least the second poster to point out that some of the magic is gone.  Hmmm... I've been dragging my feet on the wood framed panel as I sort out the sound of my different panel material (think I found a decent quality EPS panel that I'm going to pick up tonight if the weather cooperates)

On another note... I had to put the panels away for the last week but once I can get them out, I'll take some multiple measurements using pink noise and sum the many measurements into a single response and see how different it is than a single sweep.  Interesting stuff.

Would also like to place a cardboard frame around a panel and see what that does to measurements.  Does it horn load?  If the cardboard is 8 inches wide, will it provide even more output than a 2 inch frame??  Very curious.       

[OB_Newbie]

Forgot to ask about the 50/50 panels.  How did they sound compared to the fully framed panel?  Still a loss of panel "magic"???

[OB_Newbie]

I have been listening to my old panels over the last few weeks and also trying a few other materials I've tried in the past.  I have learned more about exciters, panel materials, etc. and want to given a few another try.

While I tried a quick and cheap cardboard tri-fold panel from Dollar Tree, I treated the panel with a heavy dose of PVA+water in an attempt to soak the flutes as I had done with the shellac treated panels.  They measured smooth but didn't sound very good.  Sounded tiny and the exciter didn't seem seem to excite the entire panel... notably more output from the portion of the panel where the exciter is mounted.  As a result, they are not as transparent as ply or XPS.  I still have some nice shellac treated panels but this experience has me less excited so moving on for a period to try others.

Next up is cheap EPS... 

I'm not able to find high quality EPS local so I thought I would experiment with the low cost EPS from Menard's.  They didn't have any 1" so went with the 3/4" which is probably closer to 5/8".  I had tried the same low cost EPS that came in pre-cut 12" x 48" panels when I first stared with these panels.  They sounded thin and didn't seem to transfer energy through the entire panel... significant panel self noise.   This stuff is low grade... its hard to get a clean cut and the expanded foam pellets fall off when cutting or sanding the edges.  I wasn't very hopeful given this and past experimenting so I wanted to try a quick test to be sure they sounded reasonable enough before I spend more time on a serious build with them.  I had some smaller cut offs and prepared 15.5" X 21" panels sanding as more smoothly than the first panels, 2 coats of PVA:water on the back and 1 on the front.  Given what I know about the using the DAEX25FHE-4 Framed High Efficiency transferring more energy/noise to XPS panels, I thought that the Ultra exciter would be the best choice as it is quieter than the other exciters I've used on XPS with its compliant, soft floating motor design.

Results from the test...
Its early and I like to wait a bit to be sure but am excited about how these cheap little panels sound.  I few early observations:
* Less of that "hollow" coloration I hear with XPS.  XPS is more dense and imparts a slight coloration.  Some of this might be due to the thinker 1" XPS that I have used a majority of time. 
* These more detailed and clear than the XPS panels... even more clear than my smallest 10x14.5 panels.
* More panel self noise. Even at moderate levels I am clearly hearing panel noise.  The powerful, high power Ultra absolutely dominates the small and uber light EPS panel.  the high power exciters would well on XPS but this cheap EPS is much lighter and less damped than XPS.  Larger, thicker EPS panels should help with this aspect.  I will put another PVA:water coat on the front of the panel.  Should damp more and help to stiffen the panel further.  Mounting to a rigid frame ought to help too like Sedge's latest pro panels (sorry Steve, the reason why I was playing 50,000 questions in my latest posts about your framed panels & 50/50 panels).
* just clear sounding...some slight sizzle on some source material, but once the panels are better damped, I REALLY hope this aspect is completely eliminated.  Its minimal, exciter break-in and panel curing more may do entirely remove this aspect.  Less coloration than either XPS or Ply as this point.  More "rings" like a bell... this stuff is light and less dense yet hard... even under damped.  Interesting.  Have to wonder what a lightly more damped, higher quality EPS will sound.
* Listening with the inexpensive Dayton 8" sub.  DML bass is not smooth.  The added punch from a small, quality sub really helps these panels.  Broken record... OB would be better but in a pinch these Dayton subs are fantastic for the money and lower output scenarios.  They have very similar extension as my KEF's, are just as clean, and actually have less boxy resonances as the MUCH more expensive Q500's.  Anyone listening in, I can wholeheartedly recommend this sub.

A few measurements:

[Odal3]

Nice. I have previously tried and given up on the cheap eps after I had white fluff all over my basement. Your results are encouraging. Is the measurement without sub?

I have the 10" dayton sub and like it too. Just be careful with over driving the plate amp. It burned up and ruined some RCA interconnects for me once.

[OB_Newbie]

Nice. I have previously tried and given up on the cheap ESP after I had white fluff all over my basement. Your results are encouraging. Is the measurement without sub?

I have the 10" dayton sub and like it too. Just be careful with over driving the plate amp. It burned up and ruined some RCA interconnects for me once.

Hey Odal!
Yeah, I thought the original low quality EPS panels I tried were not good in any way and ditched them pretty quickly, but then again, I didn't treat them like I do my panels now.  There are some damping issues to resolve yet but they are really promising in my opinion.  I wanted to confirm some of my thoughts on EPS's firm foam cells, lower density and lighter weight compared to XPS.  The plan was to order some high grade EPS from a company in Michigan (free shipping with $75 orders) if these offered any promise....they do sound really good AFTER EQ despite the damping isses...I hear good things.  It sounds thin and tinny without EQ (you can imagine looking at the freq. response), but once EQing out the huge hump from 200-1000Hz, they are clean sounding and with less coloration than all of the other materials I've tried. I'm shocked honestly!!

Sedge was right about EPS... I thought a higher grade would be very close in density and stiffness of XPS but after these very modest panels, I am really kinda excited. 

I didn't mention in the previous post, this EPS panel saturates around 90-92dB... much earlier than XPS.  It doesn't take much power and the Ultra really manhandles it so a low powered exciter would do just fine.  I have a few of the Dayton Audio DAEX19SL-4 Slimline Coin Type 19mm Exciters (4W 4 Ohm) that I want to try for a smaller, wall hung panel.  With these EPS panels being so flippin' light, I think they will work fine. I want to finally put together a set of panels that I can use for HT... pretty stoked.  If we didn't have company coming I'd be working on them right now... arg. 

These are measurements with no EQ or sub... raw panel.  They go low(if you flatten the mid-range hump), but saturate INCREDIBLY early without high passing them.  So while they can go really low for such a small panel, their output is seriously limited.  I'm sure a larger panel would be fine. 

Yeah... the Dayton's are surprisingly good for the money... wasn't expecting much for $99 but exceeded expectations ... output is not mind blowing as you point out but very reasonable for a 8" sub!! 

[sedge]

Sorry OB I have been away on holiday,now I'm back I have got a stinking headache.
When I can think again I will try to explain how I think the panels produce sound,as we need to get this clear .

Steve

[OB_Newbie]

Sorry to hear your not feeling well Steve. Take it easy and get to feeling better... these panels can wait.   

I'm building a set of fully framed panels just to try them out with the cheap EPS... it's a cheap build and will be interesting to hear the results either way.

[sedge]

OB newbie
I think I'm going to have to do this in sections.
Let's start with the basics, they tend to show two pictures of the way the sound propagates across the panel,the first one shows the waves of sound flowing away from the exciter area as if you had thrown a stone into a pond,and waves flow outwards,this is the primary source that tectonic talk about ,this is the panel in direct radiating mode just like any other ordinary cone speaker, this is an essential part of the panel sound and care should be taken to make sure that the sound coming from the exciter area is clean and undistorted as possible,that means dealing with the distortions within the exciter foot area!

The second picture is usually of the panel in dml mode ,showing all the resonances and standing waves on the panel surface, this is when the sound waves have been reflected from the edge of the panel or an obstruction on the panel surface or a frame clamped to the outer surface.

The output db of these two modes will be charged in relation to each other ,depending on the panel material ,stiffness ,damping or clamping .

You cannot have one without the other for a dml panel,but getting the combination of the two in the right proportions is very important.

I will leave this as the first section and hopefully will follow up with more if nobody objects.
Your thoughts are welcomed.
Steve

[OB_Newbie]

Hi Steve,
Yes... lets do this is sections.  Much to think over and work our way through.   

I'm curious about the sound of your framed and clamped panels.  To this point, I believe we have both enjoyed panels most when they are free to move with little suspension.  For me it has been based on sound quality, if I use my hands to damp each side of the panel (or even place a hand towel across the top of a panel) some detail and "air" go awy.  Not that the sound was bad, but given this very short and subjective test, I have had a hard time moving away from as free suspension as possible knowing that dome of the delicacy and air is reduced.  No free lunch here either, this free mounting comes at an expense of smoother low frequency response.  The measurements I've seen of larger, clamped panels have smoother and more extended low frequencies.  Several white papers state this as well and should not be a huge surprise either that we both augment our panels (TL, OB, or traditional subs) to improve the systems low frequency response.  As is so often the case... one's preferences can take them in either direction and it seems everyone enjoys the magic panels whether freely or solidly suspended so certainly neither approach is "wrong".
 
My fear... without powerful tools to measure and understand exactly how these panels are operating and generating output, it could be difficult to really get solid, technical conclusions.  I am just as happy to use traditional measurements (frequency, distortion, waterfall plots, etc.) and most importantly... our ears... to help us understand these panels and drive us to the best sounding panels.

Getting back to the sound quality, are you able summarize what you are hearing in these different panels?  How do the solidly mounted panels sound compared to our freely mounted panels?  I will find out soon myself but believe it would be very helpful if we could begin to explain the sound quality differences.  It is *hard* to explain how something sounds I know but think we would be helping others out of we could explain the differences more clearly so others can understand what might work best for them and what their particular preferences are.

Last thing... 
Can't remember if I posted here or over at Parts Express, but I wonder if we should establish a common, easy and quick to build reference panel with a widely available exciter.  This will be a panel that we can all compare against different panel designs.  We have difficulty explaining differences because we have no reference to compare to.

Curious what others on this forum think about this idea? 

[sedge]

OB_NEWBIE
Yes I too am a great fan of the free floating light weight panel,I have not heard anything that sounds as good.
They are also the easiest and cheapest to build,but as you say ,for them to sound their best you really need to have LF driver's to underpin the sound in the low end,which of course means another amp and an electronic xo ,which starts to get expensive,you could use a passive xo but this would be a bit hit or miss,and not very flexible.
The reason I like the framed ply panel is that it is pretty much a stand alone speaker that does most things right ,no great need for a sub ,so in the end is the cheapest option.
You could do as tectonic do and add a tweeter,I'd probably use a piezo unit and blend it in with a L pad ,no xo.
I do think there might be a way to get the ply panel to more closely match the sound of the ffp ,but without a tweeter ,this is a future project.
I can't yet say which of the ply framed or half framed panels I prefer,as,I have not finished adjusting them yet ,at the moment I'm getting good performances from both.
If someone was starting out ,and wanted to test the water's with a dml panel ,I would recommend trying the framed ply panel first,they would be very surprised at it's performance.
Steve

[Crazyprepper]

Sedge and OB_NEWBIE

What xo point have you been using with the light weight freefloating panels, mated with stereo woofers or single mono woofer? And what size, thicknes where the panels? What exciter where used, single or multiple?

[OB_Newbie]

That is a lot of info...   

Quick response:
* I typically cross anywhere between 75 and 125Hz depending on the panel size.  Lightweight panel materials like EPS can have more noise and high passing a little higher helps reduce these noises. 
* Have both a mono sub and stereo OB bass bins.  However I have been using a single Dayton 8" most recently for convenience and the fact that I don't need high output nor extension to 20Hz. 
* Steve has at least one DML panel while I have many (big grin).  Mostly 3/4 to 1" XPS panels, but also cardboard, 1/8" birch ply and more recently... low quality 3/4" EPS. 
* Sizes vary from 12" x 14.5" to x 24" x 30".
* all of my panels are single exciter but am in the process of building a dual panel array but still 1 exciter per panel.  I've never made a multiple exciter panel.  Odal has however.
* I've used a bunch of different exciters but mainly the Dayton Ultra (great on poly panels), Thruster and DAEX25FHE-4 Framed High Efficiency on ply.  There are others that I tried but didn't like nearly as much as these 3.  I have not listened to the DAEX30HESF-4 High Efficiency Steered Flux Exciter yet but have a bunch of them ready.  Odal has used them and likes them so I bought a bunch when they were on sale recently.  These exciters are cheap and fun to experiment with so I keep a number on hand...

Hope this helps!