DIY Flat Panel Speaker Love

[Gary.M]

Re: DIY Flat Panel Speaker Love

Respectfully, "All" science begins with empiric endeavours, from cave men up to current times. Basic concept first, number crunching later. Certainly we would be foolish not to learn from the discovery of others.
The very reason for my quote from Ralph Waldo Emerson. I've always felt that we should learn the rules, then learn how to break them. This is why we don't build cars the way the Model T was made, we found better ways of doing it.

By all means use the NXT patent, measure and listen. But keep an open mind that their science is a set of parameters and there's always room to expand parameters to include new techniques.

Jack

Agree completely on the empirical basis for science.

I have the most open mind on this. It's an exploration.

[captainjack115]

Re: DIY Flat Panel Speaker Love

Okay, I may be a bit cynical on the Podium approach. I find that large panels have more resonances than smaller panels and its hard to totally free a DML panel of resonances so those pads likely help control resonances across such a large, rigid panel that the Podiums use. :o

I think after all is said and done, panels of various sizes, construction techniques and material choice will all have a common denominator.
I've tried a lot of different ways of making a DML, some of them followed NXT and many other designs in between.
Having access to an RTA and adjusting things to read flat isn't always what the ear hears. In my experience it's hard to make a DML sound neutral, all designs seem to have their own unique "Signature" Not necessarily a bad thing, just different.
Surely there's a lot more complexity at work here than meets the eye, err ear.

Jack

[captainjack115]

Re: DIY Flat Panel Speaker Love

[QUOTE=captainjack115;2091235]Hey Guys

I guess I'm just about the only one on here using corrugated plastic. My latest tinkering involves an 18"x24" panel that's been curved. No I wasn't trying for wide dispersion, we all know that's not a problem with DML's. Mounting the exciter on that sized board let things kind of floppy, especially on low frequencies. Last night while counting sheep, I thought about how I could make the panel more ridged, putting a curve in it seemed like it might work. Today I tried it and it does work, pretty well at that! I used packing tape to pull the sides in. I went from 18" to 17'. I'm guessing, but it looks like a 30 degree curve. Bass is flat to 50 hz and 4 db down at 40 hz. High frequencies on my preamp are set to roll of at 50hz, so this is pretty good.

I failed to mention that I've been playing a stereo pair into the mid 90's db,, the exciters feel a little warm so I haven't played them louder.

How about you guys, how loud are you playing the XPS panels?

Jack

[rmeinke]

Re: DIY Flat Panel Speaker Love

Hey Rich,
In direct comparison, the bigger panels are louder and of course go lower. The EQ was a lot different as resonance was shifted in various areas. Quieter music never seemed to be that much of a problem for me with either size panel, there "is" noise though. Noise can be heard with the bigger panels on sine waves, but not noticeable on music, at least not to my old ears. I'm pretty sure that all or most of the noise is coming from those 3 strips of tape running around the back of the panels. They're being excited by the outer edges of the panels and sitting there like a couple of big wide banjo strings.
I really just used the tape to confirm my thoughts on finding a way of firming up the panel. It does just that and it's really a usable technique in my case, bass seems quite remarkable. Despite their smaller size I can honestly say that bass response is better and more listenable than my MMG's. The mids are good,not as neutral as the MMG's, but very listenable Let's put the brakes on right here for just a moment. These ugly things would have to be improved upon a whole lot just to shine the shoes of the MMG's. The Maggies are smoother, more neutral and far more dynamic. That being said, DML panels are a fun pastime for me and I want to see just how far they can be taken. There's still plenty of cool factor to enjoy.

The magic is the draw for me, they may not have complete neutrality or punch, but they really are very listenable.

I can't say for sure about using 2 exciters, highs will be effected, but I don't know about the magic that is DML. I can't see making really large panels in the near future because I have pretty small room that's already crowded. For several years now, I've considered building a set of John L. Murphy's corner line arrays. These things have a very small footprint and would fit very nicely in the corners of my small crowded room. As far as comparison to XPS, I'll have to make a set, and you'll have to make a set of corrugated plastic......... That's a pact!

Jack

Thanks for the report back Jack... good to hear that the bass is improved with tensioning the panels as we had hoped for. Good stuff man.

I feel the same about these panels... technically they have a ways to go. The KEF Q500s are very nice speakers but is something about these panels that keep me listening to them. I really want to try other more expensive and exotic materials.

But also want to loop back and try treated cardboard. I have some shellacked cardboard panels that seemed to have really stiffened up with age. But I also will indeed try the corrugated plastic. What specific plastic panels do you use? I've seen a thicker, softer and more flexible panel but have also seen sign panels more recently that are made of a thinner, harder plastic that seems more rigid and brittle but treated might make a really nice panel too?!

Been out of state since Friday but want to visit some stores this week to see what I can find.

Where do you get your panels and how thick are they?

[Kornbread]

Re: DIY Flat Panel Speaker Love

Had to take a work break, repeated the response graph at 1 meter.

Yes, it is very much different than the first test. My best guess is somewhere along the way the built in lap-top microphone took precedence over the calibrated Dayton um.

Holding the Dayton mic about 3" from the panel and sweeping slowly from side to side, and top to bottom the response does very much change. The region from roughly 5k and up is much stronger directly in front of the exciter, there are many dips and peaks over most of the panel but only that area was close in treble to the rest of the spectrum. The treble is considerable shelved down everywhere else.

Bass was strongest near the exciter and/or the middle of the panel. My thinking was it would be strongest further away from the exciter nearing the furthest ends of the panel, it wasn't. Wonder if this might change after the edges are freed up?

Not much output in the corners although there was still considerable output near the edges at the sides and tops.

The lack of output in the corners makes me think cutting the panel free from the frame everywhere else and leaving a small tang holding in each corner may be the correct thing to do. We shall see.

Remember rmeinke, it may very well sound its best suspended in free air but I'm taking this a step at a time and trying to measure as I go. I'm thinking this base line data will help others and show some proof of what's happening.

[Gary.M]

Re: DIY Flat Panel Speaker Love

The post from "wires" in the link below suggests that the corners are places of high activity if unrestrained. Perhaps its possible to guess at where to suspend from the image he posted...

http://www.audiocircle.com/index.php?topic=70541.msg1248765;topicseen#msg1248765

[Kornbread]

Re: DIY Flat Panel Speaker Love

I was questioning where to leave the 'tabs' to hold the panel; in the corners which would seam to be a more solid and logical choice from my measurements, or leave the 'tabs' somewhere along the the sides not near a corner. As you allude to, as the panels are free'd up to vibrate the corners may become an active region.

Where did you find the nxt software design-ware?

[Gary.M]

Re: DIY Flat Panel Speaker Love

I was questioning where to leave the 'tabs' to hold the panel; in the corners which would seam to be a more solid and logical choice from my measurements, or leave the 'tabs' somewhere along the the sides not near a corner. As you allude to, as the panels are free'd up to vibrate the corners may become an active region.

Where did you find the nxt software design-ware?

That wasn't my post, it was just one I noted as a reference for my experiments. It would be nice to have access to it, but no-one seems to know where it went when NXT disappeared.

[captainjack115]

Re: DIY Flat Panel Speaker Love

Where do you get your panels and how thick are they?

I bought these from Amazon, 5 sheets 18x24 for somewhere around $16.00, they're 4 mm thick.

I had a thought to make a very solid frame from 2x4's. 17"wide, 25" long. The idea is to bend the 18" coroplast into the 17" width. I know what you're thinking, exact opposite of a soft pliable suspension.
I also want to hold the rear of the exciter in a good solid spline. The edges of the 18" sides could be lightly cushioned against the sides of the 2x4's to quiet buzzing. There would be need for another bit of framing on the opposite side of the panel edges to hold them in place.

Currently my Wife has other ideas for my limited woodworking skills around the house, extra shelving and whatnot before the holidays. If I attempt my project first................Well, it's too ghastly to think about!
Funny, I always thought I'd have all the time in the world after retirement.

Jack

[rmeinke]

Re: DIY Flat Panel Speaker Love

Had to take a work break, repeated the response graph at 1 meter.

Yes, it is very much different than the first test. My best guess is somewhere along the way the built in lap-top microphone took precedence over the calibrated Dayton um.

Holding the Dayton mic about 3" from the panel and sweeping slowly from side to side, and top to bottom the response does very much change. The region from roughly 5k and up is much stronger directly in front of the exciter, there are many dips and peaks over most of the panel but only that area was close in treble to the rest of the spectrum. The treble is considerable shelved down everywhere else.

Bass was strongest near the exciter and/or the middle of the panel. My thinking was it would be strongest further away from the exciter nearing the furthest ends of the panel, it wasn't. Wonder if this might change after the edges are freed up?

Not much output in the corners although there was still considerable output near the edges at the sides and tops.

The lack of output in the corners makes me think cutting the panel free from the frame everywhere else and leaving a small tang holding in each corner may be the correct thing to do. We shall see.

Remember rmeinke, it may very well sound its best suspended in free air but I'm taking this a step at a time and trying to measure as I go. I'm thinking this base line data will help others and show some proof of what's happening.

[ATTACH=CONFIG]61741[/ATTACH]

[ATTACH=CONFIG]61742[/ATTACH]

[ATTACH=CONFIG]61743[/ATTACH]

Hey Kornbread... yeah no worries man. These measurements look more normal for a DML panel... the low frequency output a bit more and the high frequencies slightly less but all in the ball park and reasonable. The bass still has the DML peak and dip which I had thought a solid mounting might smooth out more but can say it is not as extreme compared to a freely mounted panel but then again... this is as big a panel (width wise for sure) as I've seen built.

Keep the measurements coming as I have not seen solid mounted panels like yours. If you are going to move slowly and measure through the tweaking process are you going to first try to reduce the high level of panel noise you are currently getting? These specific measurements are not as useful if you are measuring a panel that doesn't sound good, has high amounts of panel noise and is generally unlistenable?!? Be curious to hear what the panels sound like solidly mounted with the panel noise suppressed! How much of the frequency response above is contributed by the panel noise would be interesting...

[rmeinke]

Re: DIY Flat Panel Speaker Love

I bought these from Amazon, 5 sheets 18x24 for somewhere around $16.00, they're 4 mm thick.

I had a thought to make a very solid frame from 2x4's. 17"wide, 25" long. The idea is to bend the 18" coroplast into the 17" width. I know what you're thinking, exact opposite of a soft pliable suspension.
I also want to hold the rear of the exciter in a good solid spline. The edges of the 18" sides could be lightly cushioned against the sides of the 2x4's to quiet buzzing. There would be need for another bit of framing on the opposite side of the panel edges to hold them in place.

Currently my Wife has other ideas for my limited woodworking skills around the house, extra shelving and whatnot before the holidays. If I attempt my project first................Well, it's too ghastly to think about!
Funny, I always thought I'd have all the time in the world after retirement.

Jack

Haaa... I almost purchased those same panels off Amazon but wanted to see what you used first so we are listening to the same panel material.

The tensioned panels will need to ride against something... soft, lightweight foam along the frame seems like a good solution... that won't be terribly heavy suspension and might be needed.... and it would be simple to add or remove the suspension as you go. First try with minimal foam and add as needed to suppress panel noise. Solid approach... especially if you are going to spline mount the exciter. While I have not used spline mounting, it just appears to me that Fred choose solid mounting to get rid of the bass rattles and added panel noise due to the spline. All based on others posts and a small number of my own observation with damping so very curious to see what you find. Its such a balancing act... a tensioned panel may take more energy or NEED more energy to dominate the stiffer panel?!?

From a sound quality perspective... did the panel sound better through the mid range as well compared to your other panels or is that not a direct comparison in your opinion??

[captainjack115]

Re: DIY Flat Panel Speaker Love

Haaa... I almost purchased those same panels off Amazon but wanted to see what you used first so we are listening to the same panel material.


The tensioned panels will need to ride against something... soft, lightweight foam along the frame seems like a good solution... that won't be terribly heavy suspension and might be needed.... and it would be simple to add or remove the suspension as you go. First try with minimal foam and add as needed to suppress panel noise. Solid approach... especially if you are going to spline mount the exciter. While I have not used spline mounting, it just appears to me that Fred choose solid mounting to get rid of the bass rattles and added panel noise due to the spline. All based on others posts and a small number of my own observation with damping so very curious to see what you find. Its such a balancing act... a tensioned panel may take more energy or NEED more energy to dominate the stiffer panel?!?

From a sound quality perspective... did the panel sound better through the mid range as well compared to your other panels or is that not a direct comparison in your opinion??

How about that? Great minds and all that! I like the black finish for aesthetic reasons there's just something richer looking compared to white. Also black is black because of carbon, I don't know if it's sonically different from any other color or not.

I was trying to write in words the picture I have in my head of how these things would go together. In my mind I see the panel bowed toward the front with it's side edges to the back edges of the 2x4 frames.
The edges would be stopped from going further by a thinner frame at a right angle from the 2x4. The damped edges of the panels would be pinched in place on the front side with something like quarter round moulding. Something that would fit flush against the inside of the 2x4, maybe held in place with silicone. As for damping..........I don't know? Maybe felt, something soft to take up a possible buzz, but not too compliant to make things lossy again. I'm kind of spit balling here. Maybe using 2x4's is overkill, but I'm thinking I don't want the whole frame modulated by the panel. I'm thinking brute mass here. Plus the fact that bending the Coroplast even one inch narrower has a surprising amount of tension to it. We're bending the fluted sections in a perpendicular direction instead of side by side.

As for the spline, I've never used one before but I think with a curved panel it may be what's needed. I think a little dab of silicone on the back of the exciter against the spline is all that's needed.

My best take on mid range is that the two panels have similar characteristics, or "Signature" as I think of it. I like the mid range, it has good presence without being an intrusion on the rest of the music.
So yes, I think it's safe to make a direct comparison. This of course is based on using the Berhringer 2496.

Jack

[Unbiasedsound]

Re: DIY Flat Panel Speaker Love

Haaa. bass traps and yoga mats?!? Where has our life gone???

Glad to hear you're tweaking away and making better sounds from your Bertagni Unbiasedsound! I am very interested in hearing a pair and may just have to pick up a pair on the bay if I can find one within a reasonable driving distance.

Are you considering building even a simple set of DML's??? A 24'x32' XPS panel with the Ultras would probably be a good place to start that will get you close to what you are listening to today. If you like the Bertagni's sound I think you will really enjoy building a set yourself...

My life is lost in hi-fi on a poor mans budget lol.....yes I am still debating which exciters to buy as I want the best sounding exciter but I also want it to be reliable and not have it fail within a couple of days like some of the ultras. Has anyone tried the daex30hesf-4? How is its sound compared to the ultra and is it durable? Or what exciter is second best to the ultras but more reliable/durable?

I just bought a Marantz equalizer on CL and OMG my Bertagni's sound awesome, I am totally convinced on flat panel sound. Brought the mids down to match the treble and it sounds so smooth and sweet lol.

[Gary.M]

Re: DIY Flat Panel Speaker Love

My life is lost in hi-fi on a poor mans budget lol.....yes I am still debating which exciters to buy as I want the best sounding exciter but I also want it to be reliable and not have it fail within a couple of days like some of the ultras. Has anyone tried the daex30hesf-4? How is its sound compared to the ultra and is it durable? Or what exciter is second best to the ultras but more reliable/durable?

I just bought a Marantz equalizer on CL and OMG my Bertagni's sound awesome, I am totally convinced on flat panel sound. Brought the mids down to match the treble and it sounds so smooth and sweet lol.

I have half a dozen of the DAEX32Q-4 exciters here. They're a little cheaper than the one you mention but physically the same size and perhaps more robustly built. Holding one and looking at it and comparing the cross section of this vs the image of the daex30hesf-4 on Parts Express website I would bet on the DAEX32Q. HOWEVER.... I have yet to build my panels and do any testing, so its just speculation at present.

[rmeinke]

Re: DIY Flat Panel Speaker Love

I have half a dozen of the DAEX32Q-4 exciters here. They're a little cheaper than the one you mention but physically the same size and perhaps more robustly built. Holding one and looking at it and comparing the cross section of this vs the image of the daex30hesf-4 on Parts Express website I would bet on the DAEX32Q. HOWEVER.... I have yet to build my panels and do any testing, so its just speculation at present.

Hey guys,
A quick exciter update here. I have been listening to the DAEX32Q-4 for a few weeks now and there are some good aspects to it - First, it is heavy and appears to be really well built and robust. It sounds smooth but on the standard 2'x2' project panels with rounded corners and edges broken/partially rounded there is a cupped hands coloration and more sibilance on voices that makes the panel sound tinny or hollow through the mid range. I EQed the panel in many different ways hoping to improve the sound quality and while you can make it sound better with EQ (more upper bass to mid-range) its not the best in flat panel sound quality but I did adjust somewhat to it but when I go back to the Ultras its a happy return. I'm not giving up on this exciter yet and will be moving to a larger 24"x32.5" panel with larger rounded corners and fully rounded edges in hopes that its the exciter/panel combination.

I have not listened to the DAEX30HESF-4 so can not comment however the impressions over at AC with it mounted to a 1/4" ply panel is good. How it performs on XPS I'm not sure. It does seem similar to the Dayton Audio DAEX25FHE-4 Framed High Efficiency 25mm Exciter (which, after going back and listening to again, can be made to sound better than my version 1 with just a little more panel damping) is a pretty good sounding exciter and especially so at the price so this one is the next one on the list to purchase.

If I had to make a choice today (it could not be the Ultra or Thruster) and you didn't mind spending more, I'd go with the DAEX32Q-4 then the DAEX25FHE-4 and maybe the DAEX32Q all on 1" XPS. But as I said, don't count the DAEX32Q just yet... need to try it on a larger XPS panel before I can be say with more certainty.

One more thing, PE is typically excellent replacing exciters as long as they were not abused. They do stand behind their products.