DIY Flat Panel Speaker Love

[rmeinke]

Re: DIY Flat Panel Speaker Love

Comparing the freq. resp. of the DAEX58FP to the better sounding DAEX25FHE-4 you can see that the DAEX58FP does have more extended bass response which may be responsible for some of its boomy|sluggish performance???

DAEX58FP - 1. close miced' 2. from the listening position


DAEX25FHE-4 - 1. close miced' 2. from the listening position


note : Ignore the output levels as they did not receive the same signal level.

Look at the differences between the 2 DAEX25FHE-4 responses. There doesn't seem to bee as much difference between the 2 measurements. Then compare the DAEX58FP measurements... the close miced' freq. res. shows noticeably more bass output?

I wonder if the increase in bass response is panel "noise"? That may explain boomy, fuzziness when listening to the DAEX58FP... wouldn't rule that out.

Unfortunately I have already tore down the crappy sounding DAEX58FP's off the panels so no more troubleshooting and comparing can be done. :(

Curious what would happen if I EQed the new panel response to match the DAEX58FP's???

[laserpaddy]

Re: DIY Flat Panel Speaker Love

http://techtalk.parts-express.com/sh...ucer-surrounds

Sweet...

[donradick]

Re: DIY Flat Panel Speaker Love

Thanks for the tips rmeinke -

I work pretty slow, I've got 1 coat on one panel, and I'm putting a 2nd coat on the other panel.
Probably be next weekend before they make noise.

I somehow suspected that they wouldn't sound the best when hung on a wall, which is sort
of the natural place for a panel like that.

[rmeinke]

Re: DIY Flat Panel Speaker Love

I hear you on the general pace... I normally like to take my time as well!

Considering the wall mount... it may be that the DAEX58FP exciter you have will work *better* on the wall than in free space given it's more robust bass output (see RTA measurements above)!?!?

That may have been a design decision with that particular exciter?!? Have to wonder...

Good luck Don!

[laserpaddy]

Re: DIY Flat Panel Speaker Love

Is it possible that on the larger panel the previous material processes performed are not scalable? Also wouldn't a larger panel on the same material processes actually yield a less rigid panel? Therefore muddy waters flow...I would expect that each material process combination would have a "sweet" range of frequency ...I have some smallish ones on order since many on PE are out of stock...can't wait...got a lm3886 gain clone almost finished...might be interesting...thanks for all the info and links!!!!

[rmeinke]

Re: DIY Flat Panel Speaker Love

Is it possible that on the larger panel the previous material processes performed are not scalable? Also wouldn't a larger panel on the same material processes actually yield a less rigid panel? Therefore muddy waters flow...I would expect that each material process combination would have a "sweet" range of frequency ...I have some smallish ones on order since many on PE are out of stock...can't wait...got a lm3886 gain clone almost finished...might be interesting...thanks for all the info and links!!!!

I'm not sure if I follow about not being scalable. But by and large, the panel material is the same and generally the larger panels increase the radiating area and allows more low freq. output. High freq. output is roughly the same.

[rmeinke]

Re: DIY Flat Panel Speaker Love

Wanted to point out that the RTA measurements above are not accurate in the low freq. range. I posted them to show the differences between the 2 exciters on the same panel.

Overall, the low frequency output is quite good and probably plays flat to 65-80Hz in my estimation. These measurements are taken with my iPhone 5 with the Dayton Audio iMM-6 Calibrated Measurement Microphone and experience the same problems when measuring low frequencies with my open baffle bass bins so assumed that it was due to the bipolar response of the OBs and these panels.

Now I'm curious to understand why this is and will look into this tonight. Does anyone else have any ideas?

[laserpaddy]

Re: DIY Flat Panel Speaker Love

I'm not sure if I follow about not being scalable. But by and large, the panel material is the same and generally the larger panels increase the radiating area and allows more low freq. output. High freq. output is roughly the same.

By being "scale-able" I was referring to the manufacturing process on a small scale (small parts, singular batches) the sample of 1 or 2 made initially sometime will not carry the original design intent to a physically larger part or multiple batches. Although a larger surface area usually increases the low frequency output- you must remember that rigidity was the key and even though material "X" had the rigidity requirement at size "Y" just by increasing the physical size inherently decreases the overall rigidity not by material since it is the same but by size alone.

Possibly the material is fine at the larger sized panel but the surface coating might not work the same on the smaller scale..or visa versa.

I have some of these on order I plan to use a carbon fiber panel sandwich- fiberglass etc...wood...making it flat on some and using multi layered 3d material approach to see frequency responses on the combinations; maybe a more dense and BASS happy material at the points closer to the edges since the waves flowing through the materials will be longer at the edges. at the interior a good conducting epoxy resin to mount it and etc... I dont think size and 1 material is the key, at least at our income level..

these are just off the top of my head thoughts as this thread has made my curiosity factor go off the scale

[laserpaddy]

Re: DIY Flat Panel Speaker Love

Wanted to point out that the RTA measurements above are not accurate in the low freq. range. I posted them to show the differences between the 2 exciters on the same panel.

Overall, the low frequency output is quite good and probably plays flat to 65-80Hz in my estimation. These measurements are taken with my iPhone 5 with the Dayton Audio iMM-6 Calibrated Measurement Microphone and experience the same problems when measuring low frequencies with my open baffle bass bins so assumed that it was due to the bipolar response of the OBs and these panels.

Now I'm curious to understand why this is and will look into this tonight. Does anyone else have any ideas?

Is it possible that you are getting Constructive interference? I have seen similar instances in lasers; just like you have frequency cancellation being De-cronstructive interference the same is with Lasers

[laserpaddy]

Re: DIY Flat Panel Speaker Love

google search for acoustical properties of a carbon fiber sandwich panel. Mosst of these are for vibrational mechanical structure strength, BUT they all deal with wave propagation through material..

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=acoustical%20properties%20of%20carbon%20fiber%20sandwich%20panels

Heres an abstract

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1313386

[rmeinke]

Re: DIY Flat Panel Speaker Love

By being "scale-able" I was referring to the manufacturing process on a small scale (small parts, singular batches) the sample of 1 or 2 made initially sometime will not carry the original design intent to a physically larger part or multiple batches. Although a larger surface area usually increases the low frequency output- you must remember that rigidity was the key and even though material "X" had the rigidity requirement at size "Y" just by increasing the physical size inherently decreases the overall rigidity not by material since it is the same but by size alone.

Possibly the material is fine at the larger sized panel but the surface coating might not work the same on the smaller scale..or visa versa.

I have some of these on order I plan to use a carbon fiber panel sandwich- fiberglass etc...wood...making it flat on some and using multi layered 3d material approach to see frequency responses on the combinations; maybe a more dense and BASS happy material at the points closer to the edges since the waves flowing through the materials will be longer at the edges. at the interior a good conducting epoxy resin to mount it and etc... I dont think size and 1 material is the key, at least at our income level..

these are just off the top of my head thoughts as this thread has made my curiosity factor go off the scale

No, I don't think its an issue with scalability of the panel material across different implementations. Head over to AudioCircles Open Baffle section "Re: NXT.......rubbish??....THINK AGAIN!" thread and read what others have done and what has worked to date. KEF has used XPS for their DML panels and to date EPS and XPS have a good balance of characteristics and yielded the best overall results for the DIY crowd.

The "issue" above that I am troubleshooting are the RTA measurements. The panels themselves really do sound wonderful, jazz, acoustic and especially with live recordings. I estimate that I am getting solid response down to 60-65Hz... no problems with the performance of the panel. *Very satisfying* with the music I listen to.

Sensitivity is also very good and not typical of large flat panels of any type. Interesting panel technology for sure...

Good luck with your build and report back!

[laserpaddy]

Re: DIY Flat Panel Speaker Love

Thanks , I misunderstood probably read the posts too darn quick in my attempt to be helpful...I will read slower next time...hope you get it figured out...
My build will take some time as I have several projects at once which makes life happier..

[rmeinke]

Re: DIY Flat Panel Speaker Love

No problem man! More projects are always better!!

[rhubarb9999]

Re: DIY Flat Panel Speaker Love

Summary for those that want to 'jump in' ..

From what I can gather from this thread and others, the current 'best practice' is ...

Buy these

http://www.parts-express.com/dayton-...4-ohm--295-235

and some of this

http://www.homedepot.com/p/Owens-Cor...68WD/100320355

Coat the pink stuff with a mix of water and wood glue.

Mount the exciter 2/5 down and over.

Questions ....

Is this current standard?

Panel size?

Do the panels need to be 'sanded'?

Best way to support the panels?

[rmeinke]

Re: DIY Flat Panel Speaker Love

Hey rhubarb!

Summary for those that want to 'jump in' ..

From what I can gather from this thread and others, the current 'best practice' is ...

Buy these

http://www.parts-express.com/dayton-...4-ohm--295-235

and some of this

http://www.homedepot.com/p/Owens-Cor...68WD/100320355

Coat the pink stuff with a mix of water and wood glue.

Mount the exciter 2/5 down and over.

I've heard good things about that exciter but have not tried it yet. But I'd guess it should have very good performance.

Questions ....

Is this current standard?

No and Yes. No real standard but seems to be fairly popular. Good overall performance. For me the jury is still out on the bass quality of a DML panel. In a single 4'x8' sheet you could get 2 - 2' x 4' and 2-3 smaller panels (16" x 4'). Try them. If you have a sub maybe start with the smaller panel and see how you like the sound of the panels.

Panel size?

See above

Do the panels need to be 'sanded'?

Yes, sanding the "skin" off and replacing with a better skin is the trick. I used the cheap 1:1 wood glue and water as do most others. But shellac is said to sound good too. The glue|water is kinds nice as you can put nice thin and even coats and can add more if you still hear panel "self-noise". Water cleanup and quick drying with a hair dryer are also real plus for me. I have not played enough to determine what mixes and nbr of coats is best. More experimentation and listening is needed but 2 coats appears the best to me at this time.

Best way to support the panels?

I'm still listening propped against a chair. Can't stop listening. Suspending it with fishing line or thin nylon string just at the top of the panel is fine. I might also put one at the bottom with little/no resistance... just to steady the panel.

I have also thought that opposing rubber bands at the top and bottom would also be interesting.

Some use Velcro strips but to me that seems like it might damp the panel; if even a little. We want it to be as free to move as possible. Improves bass response.

Good luck with the build. Remember to give the panels a good week to breaking and cure. Was a pretty big improvement on my small 2' x 2' test panels!!