DIY Flat Panel Speaker Love

[rmeinke]

Re: DIY Flat Panel Speaker Love

Hey mrmky and welcome to the Flat Panel Love thread!!!

I have read almost the entire thread, if I missed it I apologize, but is there any reason not to try shapes other than square/rectangular? I'm definitely a beginner, but it seems that if you are rounding the edges, and eliminating the corners because they are areas of high energy/distortion, why not explore different shapes of panels?

I from reading I've done and what we see from commercial DML speakers, there appears to be little to gain from shapes that deviate largely from a rectangle for a single panel to exciter configuration. If multiple panels per side, I would consider changing the dimensions so the panels have the typical DML peaks and troughs at different frequencies so after combining multiple panels, there may be a smoother overall combined response.

I'll be ordering some exciters from PE in the next day or two, this sounds like a really fun project and a great way to get some hands on without having to invest $$$$$.

It seems that the thrusters and the ultras are the two most popular drivers, could anyone make some recommendations on where to start with exciter options? I'll be using an avr to power them, I'm not sure if running a 4 ohm load is a good idea? Should I be looking for 8 ohm exciters to be safe?

I have not had the best luck with the Ultra exciter from a reliability standpoint so hard to recommend that for testing purposes. maybe once you have a design together that you like, I might be tempted to try the Ultra on XPS/EPS.

Otherwise, I really like the "Dayton Audio DAEX25FHE-4 Framed High Efficiency 25mm Exciter" for testing. Its nice sounding and measures the smoothest of the exciters I have. the smaller mounting ring/voice coil also produces more extended high frequencies. Can't go wrong with this one.

Mounting them seems to be an unresolved issue as well. I have read about duct tape, which would not fly anywhere except in the garage with the lady of the house. And seen pics of foam sandwiched between the panels and a frame, which is better visually but still not great with WAF. What about a band of fishing line/string/rope/strap encircling the panel with tie offs to a frame that enclosed the edges without touching the panels. Perhaps with ~1/4" clearance except for the tie off points?

Another thought I had was shaping the panel like a bowl. With a thick enough piece of foam you could remove material to shape it like a shallow cone. If you used a mounting method like mentioned above in a round shape you could use tension in the rope and mounting points to play with dampening at different points.

Suspending with fishing line would be fine but someone used thin wire and that vibrated like a guitar sting. You would have less with fishing line but might still be audible. Foam is easier to work with as a light suspension material and you won't have to deal with that problem.

Please don't hesitate to shoot down any 'silly' ideas, it won't hurt my feelings and if someone knows it will be a waste of time I would rather know before I have wasted it.

I'm not sure about the bowl shape. Not sure how the DML nodes that form on the panel would be impacted. It would be more rigid and seems like the "bowl" might more severely impact the generation of the nodes. Now what I can't say is if it helps or hurts. I tend to think it may lean to hurts more than helps but this is completely speculative. Only way to know is to try.

But I'd start out making a simple panel to enjoy and get accustomed to the DML panel presentation.

I have several panels of 2'x4'x1" that I am going to start shaping into various sizes and shapes while I wait for my parts to be delivered. Really looking forward to another speaker project, especially one that doesn't set me back financially the way my last one did. I love my 'Johnny Sub', but my wife isn't quite as enthusiastic lol. Why aren't most women impressed when you build speakers that can shake pictures off the walls?!.

Its a mystery ma man... women *should* be more impressed but we just don't get the speaker "love" we deserve!! Tell her that you are helping with house chores and the shaking is actually, in fact, a light dusting activity.

One last question, is there a good way to take the exciters off and reapplying them to different panels? Or do I need to just order several pairs of them if I want to play with different panels?

I take mine off with a knife... wedging and a slight twisting between the panel and mounting plate usually pops off the exciter without to much damage. I remount with a higher quality Elmer's (Pro Advance max something!?) glue. Can remount again by sanding off the Elmer's.

Personally, I like to keep panels around to compare against later so I've been buying more exciters to keep them mounted to working panels.

The DAEX25FHE-4 is cheap so I'll be using that more and more for testing purposes. So much easier...

[Tin Ear]

Re: DIY Flat Panel Speaker Love

rmeinke - Actually, yes . . . Profoundly Deaf is approaching Total Deafness, as it is 91+ DB Loss. Been that way from my get-go in 1960, but it could be worse, aye?

I've gleaned quite a bit from your posts here and elsewhere, and look forward to more, perhaps returning the favor, given time.

Kornbread - Like others who have shared their trials and tribulations on PE and elsewhere, your journey down this particular path has been informative. I dug the first question ;) & in theoretical answer to your second query;

I believe the combination of full-range transducer and flat panel is the same as a log slit drum, whereby trebles are enhanced by solid thickness and narrow slit, bass by solid thinness and long slit, and midrange represented at solid points between.

In a sense it's as if light sound is best generated through thick material and dark sound through thin. And like a wavelength, a short slit and a long slit reproduce respective tones.

At least at this juncture I certainly wouldn't slit a panel, but I do think that gradient "steps" could purposefully cut off at given frequencies. To my way of thinking, that is why one sees a "stepped" flare from Vandersteen's Wall Speakers, to enhance certain high frequencies.

However, there are lots of frequencies overall, and that would be far more laborious than simply tapering a panel from thick to thin.

If a panel were tapered, it seems that if a pipe stethoscope were put to good, measurable use, a golden-eared one could pick up what tones are being generated at x distances from the source.

Then, based upon those findings, one could create a hybrid if "steps" were tapered at 1/3 octave intervals.

[rmeinke]

Re: DIY Flat Panel Speaker Love

Ah Tin Ear, sorry about that brother... thought you were laying down some sick, stylistic verbiage... my apologies sir!

[Tin Ear]

DIY Flat Panel Speaker Love

No sweat. Learn something new every day & lots of times by accident.

- PVA Glue & Water applied to sanded EPS panel, then heated is applying thermoplastic to thermoplastic.

For the sake of simplicity, I'll refer to the sanded EPS surface as being "primered".

Acrylic is one of many thermoplastics, and has been used in as-is form, but I've not seen if it used in "primered" form. This would result in a frosted appearance.

Along those lines, it seems that glass ("primered") frosted at edges would be superior to it's transparent, untreated cousin.

Perhaps even clean or frosted glass with titanium-based solar-blocking film (akin to PVA Glue+Water cured film) would be superior to both as-is.

The thing is by going one step further, one can combine more than what has been used thus far, and accidentally create a more coherent copolymer surface.

One of these days, I'll cut more than brain farts, some of which are real stinkers.

[Fshow]

Re: DIY Flat Panel Speaker Love

Hey FShow! So, do you have an idea why it might be smoother now? So you sanded the back around the edges of the panel and only lightly sanded the entire front yes?

Hi Rich

I think I might have to take back my comment about needing less equalization, I think I was fooling myself. I also found out some more about the distortion I reported, turns out my reference speakers do the same thing, at higher sound levels I get multiple peaks from a fundamental freq.

Also added a piezo tweeter. For now I just have it wired with a series resistor and a hunk of cloth pushed in the throat to minimize harshness. Definitely sounds richer.
The image below is unequalized, and with the tweeter.


Sounds very good, the bass I had before is back now and even a bit better.

Fred

[Tin Ear]

DIY Flat Panel Speaker Love

Oh, that looks tasty! It's been a continuous eye-opener to see your many steps forward, as well, Fred.

How did you utilize the piezo, and was it a CTS/Motorola derivative like one of PE's GRS offerings such as PZ1188?

[Fshow]

Re: DIY Flat Panel Speaker Love

Oh, that looks tasty! It's been a continuous eye-opener to see your many steps forward, as well, Fred.

How did you utilize the piezo, and was it a CTS/Motorola derivative like one of PE's GRS offerings such as PZ1188?

Hi Tin Ear

It's a cheap knock off horn 2" X 5", 3.5 kHz at 92 db/w. I have tried them for years but never liked them because they were always harsh. I researched the web and people claim they can be tamed, by various methods, we will see.

Fred

[Kornbread]

Re: DIY Flat Panel Speaker Love

rmeinke - Actually, yes . . . Profoundly Deaf is approaching Total Deafness, as it is 91+ DB Loss. Been that way from my get-go in 1960, but it could be worse, aye?

I've gleaned quite a bit from your posts here and elsewhere, and look forward to more, perhaps returning the favor, given time.

Kornbread - Like others who have shared their trials and tribulations on PE and elsewhere, your journey down this particular path has been informative. I dug the first question ;) & in theoretical answer to your second query;

I believe the combination of full-range transducer and flat panel is the same as a log slit drum, whereby trebles are enhanced by solid thickness and narrow slit, bass by solid thinness and long slit, and midrange represented at solid points between.

In a sense it's as if light sound is best generated through thick material and dark sound through thin. And like a wavelength, a short slit and a long slit reproduce respective tones.

At least at this juncture I certainly wouldn't slit a panel, but I do think that gradient "steps" could purposefully cut off at given frequencies. To my way of thinking, that is why one sees a "stepped" flare from Vandersteen's Wall Speakers, to enhance certain high frequencies.

However, there are lots of frequencies overall, and that would be far more laborious than simply tapering a panel from thick to thin.

If a panel were tapered, it seems that if a pipe stethoscope were put to good, measurable use, a golden-eared one could pick up what tones are being generated at x distances from the source.

Then, based upon those findings, one could create a hybrid if "steps" were tapered at 1/3 octave intervals.

TinEar; Thinking out loud, if we had a functioning copy of the NXT design software we could model the panel and possibly decide where to make our 'tune cuts' or our 'sound bridges' to the frame. This might also free us up to use more than one exciter per panel as it seems they like to fight each other otherwise. Another thing to consider, how accurate would the design software would be across different panel materials.

Using your logic, what do you think of 1/8" Lexan or Mylar as a panel material?

[Tin Ear]

Re: DIY Flat Panel Speaker Love

Without software, I'm thinking that absent means (ears) to use Pipe Stethoscope or the like - visually, Oobleck would be particularly handy, if not messy on areas with Deep Bass, and Flubber or Hydrophobic Silica on other areas to let those Soft Wares ;) determine where the action is.

Lexan & Mylar. Have a small stash of the hard stuff and a large roll of paper-backed thin stuff I'm saving for right time, place, space, reason. WAF in an upstairs 2 BR Apt. With Son home on extended LOA. What can ya do, aye?

In the meantime . . .

http://www.engineeringtoolbox.com/sound-speed-solids-d_713.html

[Tin Ear]

DIY Flat Panel Speaker Love

Need moar Kornbread recipes!

Duh ~ Knew I'd seen mention somewhere, perhaps you've seen same several times over . . .

PIEZO NXT Type Panel thread at DIYA in Planars & Exotics subforum. Granted, posts were from 2009, but see posts #474 and beyond.
-

Absent Software, summaries of Modeling may suffice.

Scroll to Plates - these PDFs have Physics and Layman's terms - inked by peeps with mad skillz.

http://www.randteam.de/RDTeam/Publications.html

[Tin Ear]

DIY Flat Panel Speaker Love

Perhaps you've been there & done that - I don't recall seeing this data

http://www.westpak.com/images/pdf/12_cushion_vibration_testing_sine_v_random.pdf

This study was done to facilitate transport of EPS panels, as they would otherwise be quite noisy without skins, and load/strapping limits must be observed.

That's all well and good, but graphs are provided which may assist in our endeavors to find that sweet spot of matching mounting pressure of exciter to panel to make it hertz.

- be it with or without spine -

While I do realize stiff spines have fallen out of favor over the years, after much semi-imitation was done of forbears who put their products on the market - there are also ways of attaching half-spines or, if full, bungee spines - something akin to a bow, but to help visualize control of force, perhaps a crossbow is a better example of attaining, maintaining and sustaining a draw weight.

A half-spine could be utilized with rear of exciter attached to something like a steel ruler. As we all know, those rulers can be springy, and slappy, without being sloppy. If need be, a hybrid of steel ruler & non-resonant "bungee" to make a full spine.

Disclaimers; Though inspired by the make it hurt Mantis Shrimp Documentary on NatGeo, let alone you fellers, I still don't know anything.

[Unbiasedsound]

Re: DIY Flat Panel Speaker Love

Since I was not satisfied with the sound of my panels in stereo mode I decided to make a center channel speaker using 1/2 inch EPS being 1ft.X2ft. I am using 2 exciters in my center channel with them on a frame holding the exciters in place.

Although the center channel speaker is still not on par with my bertagnis I can get away with it because the Bertagni speakers help carry the center channel. In fact the center channel actually compliments and enhances the Bertagni speakers used as mains/fronts. Whats also good with the center channel is that most receivers come with there own built in center channel eq. so I can adjust the center channel seperately from the main speakers eq. I have always been impressed by how the center channel can be used to enhance the mains and with similar exciter technology characteristics they seem to blend well together. Now I just need to match the rear surround speakers.

My next step is too build some very small surround panels but the (DAEX30HESF) exciters I currently have seems a bit too powerful for some small panels. I was thinking of buying some of the DAEX25FHE for my surround panels but not sure of it yet.

I also look forward to DE Focht Setting up surround system as I have tinkered many a nights to try to further perfect my 5 channel music listening pleasure.

[rmeinke]

Re: DIY Flat Panel Speaker Love

Since I was not satisfied with the sound of my panels in stereo mode I decided to make a center channel speaker using 1/2 inch EPS being 1ft.X2ft. I am using 2 exciters in my center channel with them on a frame holding the exciters in place.

Although the center channel speaker is still not on par with my bertagnis I can get away with it because the Bertagni speakers help carry the center channel. In fact the center channel actually compliments and enhances the Bertagni speakers used as mains/fronts. Whats also good with the center channel is that most receivers come with there own built in center channel eq. so I can adjust the center channel seperately from the main speakers eq. I have always been impressed by how the center channel can be used to enhance the mains and with similar exciter technology characteristics they seem to blend well together. Now I just need to match the rear surround speakers.

My next step is too build some very small surround panels but the (DAEX30HESF) exciters I currently have seems a bit too powerful for some small panels. I was thinking of buying some of the DAEX25FHE for my surround panels but not sure of it yet.

I also look forward to DE Focht Setting up surround system as I have tinkered many a nights to try to further perfect my 5 channel music listening pleasure.

Sounds like your making some progress UBS... good stuff man!!

You are headed in the right direction with exciter options. With my XPS panels, even a single DAEX25FHE added more panel noise than the Ultra or Thruster... slightly over driving even the 24"x24" panels. To me, it seems that 2 DAEX30HESF exciters on 1/2" EPS would be way to much for your center channel. With my smaller 3/4 EPS panels I am getting significant panel noise even at lowish/moderate levels with a single Ultra. I can't help but think that your center panel would easily become saturated and have unwanted panel noise as well?! Not meant as a negative comment, but just an observation and curious as to what you are hearing or what might be different between your center and my free mounted panels. Possibly a solidly mounting the panel to the frame is reducing the noise? Either way... 2 DAEX30HESF are muy powerful for such a small panel and will most certainly saturate the panel far to easily.

Is it possible to try a single DAEX30HESF for the center? Most receivers should be able to drive a 4 ohm load.

For small EPS rear panels, I would consider something even less powerful like the Dayton Audio DAEX25 Sound Exciter Pair (for 8 ohm) or the Dayton Audio DAEX19CT-4 Coin Type 19mm Vented Exciter (4 ohm). I am still taken back by how light my 3/4" EPS panels are. I have some 24"x64" EPS panels prepared and when I had them leaned up against the wall and even walking pass them, the slight turbulence caused them to pull way from the wall and fall to the floor. Uber, UBER light stuff... doesn't take much of an exciter for good output before the panel saturates.

[Unbiasedsound]

Re: DIY Flat Panel Speaker Love

Up date.....I did the foam tape in the back wrong, it should be exactly like how I did the front like a sandwich frame holding the EPS. By doing this it increased the BASS significantly compared to what it was before. My 1ftX2ft 1/2inch panel has bass, for a brief moment I had to re check to see if the sub was off. lol

I also put baking parchment paper on the front using it as a skin and it does sound a little better but still not up to my satisfaction.

[Unbiasedsound]

Re: DIY Flat Panel Speaker Love

Mildperil on the other forum said that the DEAX25TP had the cleanest clarity with more high frequency extension then the Ultras. I might just have to try the DEAX25TP out for myself as soon as I can muster up some extra cash I will be buying some. Hopefully that will solve some of my high frequency clarity/extension problems.