DIY Flat Panel Speaker Love

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I have been following this thread along with many other articles and sites about NXT and DML speaker technology. I also happen to live about 10 minutes from Parts Express's warehouse which is a big bonus. It seems that panel material is everything and after trying numerous materials discussed here and on other sites, and thanks to some friends at Wright Patt, I have been able to find a material 3mm thick, but lighter and much stiffer than gatorboard, xps, or basic foam core. With this I have been able to make speakers as small as 11x14 but that still provide good volume, and this panel material has the high frequency response that the foam core boards did not have. Even though they do sound pretty good for full range speakers, (especially considering the material cost for each is about $20.00 including the frame), they don't sound like the $1200.00 Boston Acoustics towers sitting next to them in the pic, but with a subwoofer they sound great as full range speakers, and as the rear channels of a home theater system they have real wife appeal.

[Bubba Boy Sam]

I have been following this thread along with many other articles and sites about NXT and DML speaker technology. I also happen to live about 10 minutes from Parts Express's warehouse which is a big bonus. It seems that panel material is everything and after trying numerous materials discussed here and on other sites, and thanks to some friends at Wright Patt, I have been able to find a material 3mm thick, but lighter and much stiffer than gatorboard, xps, or basic foam core. With this I have been able to make speakers as small as 11x14 but that still provide good volume, and this panel material has the high frequency response that the foam core boards did not have. Even though they do sound pretty good for full range speakers, (especially considering the material cost for each is about $20.00 including the frame), they don't sound like the $1200.00 Boston Acoustics towers sitting next to them in the pic, but with a subwoofer they sound great as full range speakers, and as the rear channels of a home theater system they have real wife appeal.

Gorgeous. Are those prints? Photographs? Glued on, and how?

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Yes, they are prints glued directly to the panels using Scotch Photo Mount.

[jp7189]

Hey everybody!

Read Rich's upbeat article on DMLs in a recent PE magazine, and spent the last few weeks working my way through this thread. It's like I've been on a fast forward ride through the last few years with you all.

I especially love the art vs. science undercurrent that's represented here, and totally dig both sides of it. I love the points Rich makes about experiencing the sound, and I totally feel Kornbread's scientific measurement approach. Personally, I'm more tone deaf than golden eared, which is great 'cause everything sounds good to me, and which is bad cause.. ya know.

Hate to admit it, but another IT guy here, and being such, am a data driven dude. I'm already leaning towards the think, build, and measure.. rinse and repeat methodology. To that end, I picked up a UMM6 mic and have been trying to figure out REW.. any pointers to getting usual, repeatable measurements would be much appreciated.

I have to say I've had tons of ideas while reading through this thread.. "I've got an idea" was usually followed by someone trying just what I was thinking... sometimes with good results and sometimes with bad.. but always I learned a lot. I could totally feel the disappointment in some of the posts, and to that I would say that it's all been a real inspiration to me! ..and thank you for sharing.

[jp7189]

thanks to some friends at Wright Patt, I have been able to find a material 3mm thick, but lighter and much stiffer than gatorboard, xps, or basic foam core.

So... I'm dying to know.. what is the material.. is it commercially available??? Have you heard a direct comparison to 2x2 XPS project panels (which in my mind is the baseline)?

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So... I'm dying to know.. what is the material.. is it commercially available??? Have you heard a direct comparison to 2x2 XPS project panels (which in my mind is the baseline)?

I don't know what it is actually called or if it is commercially available. It is costly, at least in comparison to xps or foam core. I figure it is costing me about $7.00 a panel. As far as comparisons are concerned, I have tried xps from Lowes, gatorboard, and foam core and all of those have seemed very deficient in the high end response. I believe this is caused by the soft foam core itself not transmitting highs very well as hard surfaces like glass do a much better job in the high end but are poor for volume or bass response. This panel material is much stiffer and harder than foam based panels but much lighter than most hard surfaces. Basically it appears to be the best of both worlds. I just ordered a UMM6 mic and analyzer software and I hope to have actual measurements to post tomorrow or Wednesday. Preliminary tests with an analyzer app on my iphone show very flat frequency response all the way to 20k. I built low pass filters into the speaker frames to roll off the base below 300hz as these are designed to be used as surround sound speakers or with a subwoofer for best full range sound.

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I'm also using 3M VHB foam based tape to mount the panels to the frame. This seems to insulate them fairly well from the frame surface.

[Unbiasedsound]

I don't know what it is actually called or if it is commercially available. It is costly, at least in comparison to xps or foam core. I figure it is costing me about $7.00 a panel. As far as comparisons are concerned, I have tried xps from Lowes, gatorboard, and foam core and all of those have seemed very deficient in the high end response. I believe this is caused by the soft foam core itself not transmitting highs very well as hard surfaces like glass do a much better job in the high end but are poor for volume or bass response. This panel material is much stiffer and harder than foam based panels but much lighter than most hard surfaces. Basically it appears to be the best of both worlds. I just ordered a UMM6 mic and analyzer software and I hope to have actual measurements to post tomorrow or Wednesday. Preliminary tests with an analyzer app on my iphone show very flat frequency response all the way to 20k. I built low pass filters into the speaker frames to roll off the base below 300hz as these are designed to be used as surround sound speakers or with a subwoofer for best full range sound.

I have heard on another forum that certain exciters have higher frequency responses then other exciters, could you tell me which exciters you are using? Thanks.

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I have heard on another forum that certain exciters have higher frequency responses then other exciters, could you tell me which exciters you are using? Thanks.

For the ones pictured I used the DAEX25CT-4 as they are very low profile. For greater power handling, I use the DAEX25FHE-4 and a deeper frame.

[Unbiasedsound]

For the ones pictured I used the DAEX25CT-4 as they are very low profile. For greater power handling, I use the DAEX25FHE-4 and a deeper frame.

Ah ok thanks, that could be it.....From the info I gathered from Mildperil, Odal3 and Rich is that the smaller 25mm vc exciters and under seems to produce higher frequencies then the 30mm and up exciters. I am thinking about purchasing some of these>DAEX25VT-4 25mm exciters.

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Ah ok thanks, that could be it.....From the info I gathered from Mildperil, Odal3 and Rich is that the smaller 25mm vc exciters and under seems to produce higher frequencies then the 30mm and up exciters. I am thinking about purchasing some of these>DAEX25VT-4 25mm exciters.

The FHE Has slightly higher rated power handling and is less expensive which is why I went with them over the VT.

[Uncle Bob]

Has anyone tried a coating like "DuraTex" instead of the white glue? That would provide the "skin" as well as the finish. This may have been covered in the prior 50 pages and due to skimming the past, I may have missed it.

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Testing mic did not come in today but I took these tests with an iphone app today. Certainly not professional but they do show a fairly flat response all the way down to 125hz which I think is not bad for a small panel of just 11" x 14". The high frequency response is what I thought was much improved from other panel materials I have tried and the response is good even 90 degrees off axis.

[jp7189]

Testing mic did not come in today but I took these tests with an iphone app today. Certainly not professional but they do show a fairly flat response all the way down to 125hz which I think is not bad for a small panel of just 11" x 14". The high frequency response is what I thought was much improved from other panel materials I have tried and the response is good even 90 degrees off axis.

Wow that does look smooth. You've done some really great work there!

I tried messing around with REW 5.1, and I'm getting a lumpy mess.. even with 1/6 octave smoothing. It could be the panels; it could be the room which is narrow and doesn't have anything soft in it.. or is could be the way I'm trying to measure. I have the UMM6 and calibration file loaded in to REW, SPL test is around -40db .. there are a lot of parameters that I'm uncertain of and left default. Below is a pic of the 'RTA' screen following a measurement.

I started out with two 20x28.25x1 pink XPS panels, rounded edges, rounded corners, sanded skin, two coats of white glue/water on each side and using a single DAEX32U-4 Ultra placed 2/5 from top and side. It's hanging from duct tape off the edge of a shelf about 20" from the back wall. It sounds ~ok~, but the vocals are shouty and the bass has a pretty narrow sweet spot

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All the foam based panels I tried gave me that same high frequency roll off that I see in your RTA.