DIY Flat Panel Speaker Love

[Unbiasedsound]

I'm wondering if it is the lighter weight exciters that give higher frequency response, rather than the voicecoil diameter. Less mass to accelerate at higher frequencies?

I am not exactly sure what actually makes the smaller exciters have a higher frequency response but it could be a combination of many factors instead of just one......Another factor could be that this is a different "BRAND", of exciter that is why I am going to purchase more tectonic exciters to see if that could be one of the factors. I already have a dayton 19mm exciter so I want to purchase a tectonic 19mm exciter to see how they compare to each other. Plus I am going to buy that pre made mid/high crossover on clearance for $2.00 ea and use those as my surround sound speakers using the 2 watt 13mm tectonic exciter, since the high is crossed over at 5k it should be safe enough to handle my receivers 100 watts of power without blowing hopefully. lol

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I have been using both the DAEX25FH and DAEX25CT, and in my research, the panel material and exciter placement has far more effect on high frequency response than which exciter you use. With a lot of trial and error, I have come up with these picture frame speakers using the said exciters and some panels acquired from friends at Wright Patt AFB. These particular ones are intended for rear channels in a home theater system and I have installed inline 200hz high pass filters to increase power handling and keep the frames from rattling against the wall. They also sound great as full range speakers augmented by an amplified subwoofer.

[Gary.M]

James, that's a very low resolution response measurement there, and with a device of questionable accuracy. I agree though based on what I'm seeing, that the material is a factor. I am assuming that we are all using the recommended location for exciter placement.

I have been using both the DAEX25FH and DAEX25CT, and in my research, the panel material and exciter placement has far more effect on high frequency response than which exciter you use. With a lot of trial and error, I have come up with these picture frame speakers using the said exciters and some panels acquired from friends at Wright Patt AFB. These particular ones are intended for rear channels in a home theater system and I have installed inline 200hz high pass filters to increase power handling and keep the frames from rattling against the wall. They also sound great as full range speakers augmented by an amplified subwoofer.

[rmeinke]

I don't agree with the suspension argument. The suspension is necessary to support things, but when the coil is activated the force is in the magnetic circuit both pushing and pulling. The panel energy is created by the force excerted by the magnetic circuit acting against the mass of the exciter. The suspension will interfere as it will offer some resonance in the system but it does not excert any force..

Hi Gary,
I think you took the terminology "exerting force" a little too literally.

This discussion is a bit academic in nature, mind you, but if we would take an infinitely compliant suspension and placed that between the voice coil and the motor, the motor would simply oscillate around the coil and transfer no energy or exert any force upon the voice coil. The suspension, as a component, does indeed play a part; resting between the magnetic circuit and the voice coil and how compliant or less compliant it is certainly impact the performance of an exciter.

Traditional dynamic drivers despite, there robust motors and magnet systems, do not work well in DML constructions. Exciters have much firmer suspensions and shorter throw than a traditional driver.

In respect to the Ultra exciter and taking the discussion from academic to real world implementation; I can say that I didn't derive my conclusions based above on theory or studying its technical specifications. Instead, I listened to it on different materials and evaluated the results. On lightweight materials like XPS, it transferred less noise to the panel and required less suspension. On ply, it sounded very polite and lacked detail compared to the Thruster or DAEX25FHE-4 exciters. Despite the Thruster and Ultra's larger motors (and high BL specs), the DAEX25FHE-4 transferred more energy (and noise) to lightweight panel materials. Inspect the suspension on the DAEX25FHE-4; its very stiff and not smooth over its range of motion (if you can even call it that). now do the same with the Thruster or Ultra... the voice coil moves smoothly through its range. In doing this, you will see that the Ultra moves more easily and smoothest and you can see the motor and flexible rubber "suspension" (for lack of a better term) move freely. This is likely the reason for its super low 160Hz Fs spec.

How much a more compliant suspension impacts exciter performance I don't know man.... I can only use the data points that I mention above and have stated all along that it perform best on light-weight panel materials and less well on heavier panels material like ply or over damped materials like cardboard. Do still like it very much on EPS/XPS however.

Good to see all the Flat Panel posts!!! Life and work has been crazy but really looking forward to playing more with the panels...

[rmeinke]

I recently purchased some new exciters DAEX25 which was on sale and the DAEX19 and the tectonics which was on clearance. Out of all the exciters the small tectonics surprised me the most with its high frequency extension most likely due to there smaller 13mm voice coil, like Rich and many others have mentioned....This is he high frequency sound I have been looking for....The only down fall is that the tectonics can only handle 2 watts and sound out put of course its not as high due to it being very small.....it would probably work well with a crossover...however it did handle my Yamaha 100 watt receiver even at -20db with my receiver crossover set at 80hz as I dont play/listen to my music louder then -20db.....I will be purchasing other Tectonic exciters in the near future to try it out since I was so pleased with these small ones and at clearance price its a steal......These tectonic exciters high frequency clarity sounds almost like my Bertagni speakers, too bad they didnt make a 13mm exciter that could handle at least 10 watts or more.

Hey UBS!! glad to hear you are digging the smaller exciters! I would cross them very high and the 2 watt power handling will not be an issue. Crossing them high will also reduce the interference/cancellation from having multiple exciters on the same panel. 2 birds with 1 stone my friend. You'll have to play with different XO points and just season to taste.

Getting a handle on how high frequencies are generated by a DML will help clear up the suggestion and possible solutions you can try.

To comment on the impact of exciters with smaller voice coils (I posted this over at AC in the DML mother thread last year)...
The link below is a good video discussing how HF are generated by the panel and exciter. Basically, when the wave length is the same or smaller than the diameter of the exciter's voice coil, the panel/exciter creates an oil can resonance/effect and increases output in that region. The smaller the coil, the higher in frequency the resonance is pushed and generally the better the HF extension is.

This is not unlike a traditional dome tweeter where off axis response begins to decrease as the wave length becomes smaller than the diameter of the dome. In the case of a DML, when the wave length becomes smaller than the diameter of the voice coil the panel begins to operate like a direct radiator and no longer operates purely in a DML mode. Can't remember the posters name over at AC, but said poster had the DML Design Studio software and you could clearly see this effect as he changed the exciter's VC diameter.

Compliments of Technonic.

https://www.youtube.com/watch?v=GJiyndZaX_4

But as suggested, the material density, thickness, damping also impacts the HF performance. Thinner, lighter, less damped materials should have the better HF response.

Remembering back to the EPS measurements I posted earlier this year, you will see the narrow, but fairly deep, dip between approx. 11KHz and 16KHz. This wasn't the Ultra exciter or EPS as a panel material, in general, but likely due to the extremely uneven, rough and inconsistent surface of the low quality EPS. I didn't have time but I wanted to remove the exciter, sand the panel surface smooth and in a concave shape. I would do the same on the front of the panel as well. This would likely smooth out the response. Didn't have the chance to comment on that but thought this was a good time to revisit that particular measurement.

[rmeinke]

James, that's a very low resolution response measurement there, and with a device of questionable accuracy. I agree though based on what I'm seeing, that the material is a factor. I am assuming that we are all using the recommended location for exciter placement.

Yeah, these are REALLY low-res measurements (full octave). You will be surprised how ragged a DML looks with 1/24 octave measurements. But despite their ragged and uneven response, DML's still sound very musical and not unbalanced as it measures. I use ample EQ mind you, but even in the buff (wubba wubba) they still sound quite good!

I am also sure that if we listened to a traditional dynamic speaker with a similar response it would not be as enjoyable. DML's radiation pattern must have a large impact on that as well as the fact that nodes of different frequencies are randomized across the panel's surface.

Anyway... gotta run gentlemen. Hope to post again soon.

[rmeinke]

I recently purchased some new exciters DAEX25 which was on sale and the DAEX19 and the tectonics which was on clearance. Out of all the exciters the small tectonics surprised me the most with its high frequency extension most likely due to there smaller 13mm voice coil, like Rich and many others have mentioned....This is he high frequency sound I have been looking for....The only down fall is that the tectonics can only handle 2 watts and sound out put of course its not as high due to it being very small.....it would probably work well with a crossover...however it did handle my Yamaha 100 watt receiver even at -20db with my receiver crossover set at 80hz as I dont play/listen to my music louder then -20db.....I will be purchasing other Tectonic exciters in the near future to try it out since I was so pleased with these small ones and at clearance price its a steal......These tectonic exciters high frequency clarity sounds almost like my Bertagni speakers, too bad they didnt make a 13mm exciter that could handle at least 10 watts or more.

Ahhh, forgot to mention as well... you could mount multiple smaller exciters on the panel if crossed high enough. I purchased a bunch of the 13mm, 16ohm exciters a few years ago to do just that but have never used or tested them in that way but now I think I just might given your positive response. :-)

Thanks for the report out on those small exciters UBS!

[Gary.M]

I'm still not convinced. You have confused "motor". The voice coil and magnet assembly together are the motor, but the voice coil does the work. The magnetic field is what links them and the force is exerted through the magnetic field, not through the suspension.

Lets do a little thought experiment.

Take an exciter with a zero mass magnet assembly. (or at least close to) mounted to a DML panel.

Apply a voltage step to the voice coil, say 0V to 1V. Current will flow in the voice coil and generate a force, lets say the polarity is such that the magnet assembly moves away from the panel. It will move until the suspension restrains and prevents further movement.

The movement though has involved (almost) no mass, therefore (almost) no energy. The panel will not be moved.

The exciter can be fed a sinewave likewise and will oscillate, but because of the lack of mass will not exert any force on the panel.

Now consider the other extreme. Consider an exciter with a very high mass magnet assembly. Apply the same step. The exciter voice coil will move, pushing against both panel and exciter magnet masses. As the exciter magnet mass is so high it will move almost not at all, instead the panel will move away from it.

So there is an interaction based on the relative masses of the exciter magnet assembly and panel. The suspension will have a damping effect and will restrain maximum amplitude.

UnbiasedSound had noted that he thought the smaller exciters were better at high frequencies, perhaps there is a balance between small and agile vs large and sluggish? The Ultra is a large exciter with a lossy construction and large voice coil.

So far my finding is that the bamboo ply, with its higher mass and density, seems to allow high frequency to propagate much better than the lossy materials such as the doped cardboard. And a smaller exciter provides the most hf extension.

The Podium speakers use fixed and supported drivers (= to an exciter with very high mass magnet as it will not be moved by the voicecoil) attached to a very rigid panel. I think that material most likely also propagates high frequencies extremely well. Also as the exciter is restrained by the mounting it could be designed, or chosen, to have a smaller voicecoil and appropriate magnetic circuit parameters to work well at high frequencies while applying quite some force. Perhaps a stripped down tweeter mounted like this might work well?

Hi Gary,
I think you took the terminology "exerting force" a little too literally.

This discussion is a bit academic in nature, mind you, but if we would take an infinitely compliant suspension and placed that between the voice coil and the motor, the motor would simply oscillate around the coil and transfer no energy or exert any force upon the voice coil. The suspension, as a component, does indeed play a part; resting between the magnetic circuit and the voice coil and how compliant or less compliant it is certainly impact the performance of an exciter.

Traditional dynamic drivers despite, there robust motors and magnet systems, do not work well in DML constructions. Exciters have much firmer suspensions and shorter throw than a traditional driver.

In respect to the Ultra exciter and taking the discussion from academic to real world implementation; I can say that I didn't derive my conclusions based above on theory or studying its technical specifications. Instead, I listened to it on different materials and evaluated the results. On lightweight materials like XPS, it transferred less noise to the panel and required less suspension. On ply, it sounded very polite and lacked detail compared to the Thruster or DAEX25FHE-4 exciters. Despite the Thruster and Ultra's larger motors (and high BL specs), the DAEX25FHE-4 transferred more energy (and noise) to lightweight panel materials. Inspect the suspension on the DAEX25FHE-4; its very stiff and not smooth over its range of motion (if you can even call it that). now do the same with the Thruster or Ultra... the voice coil moves smoothly through its range. In doing this, you will see that the Ultra moves more easily and smoothest and you can see the motor and flexible rubber "suspension" (for lack of a better term) move freely. This is likely the reason for its super low 160Hz Fs spec.

How much a more compliant suspension impacts exciter performance I don't know man.... I can only use the data points that I mention above and have stated all along that it perform best on light-weight panel materials and less well on heavier panels material like ply or over damped materials like cardboard. Do still like it very much on EPS/XPS however.

Good to see all the Flat Panel posts!!! Life and work has been crazy but really looking forward to playing more with the panels...

[Unbiasedsound]

UnbiasedSound had noted that he thought the smaller exciters were better at high frequencies, perhaps there is a balance between small and agile vs large and sluggish? The Ultra is a large exciter with a lossy construction and large voice coil.

As you know I am not really knowledgeable with all that technical stuff but here is my take on the exciters I have owned......The Dayton DAEX30HESF-4 is the best exciter I have tried so far in terms of all around accuracy as its not sluggish at all even beating out the DAEX25FHE-4 in accuracy which is my second pick for best overall exciter.....These two exciters I mention have the most bass output/excursion.out of any exciter I have tried so far and are the ones with mounting holes/screws to mount them down. I believe these exciters utilized the the mounting holes because of there great excursions while the ones with less excursions do not need to be mounted because of less travel hence why the smaller less bass/excursion exciters do not come with mounting holes . The other exciter I believe to have a lot of bass/excursion is the DAEX25SHF-4 as it also has mounting holes to mount them. The DAEX25TP and VT are not as accurate and have way less bass and sound out put then the two exciters mentioned before but it does have a slightly higher frequency response. The DAEX19QLP has even less bass and sound output then the 25TP/VT with similar high frequencies. The 13 millimeter 16ohm tectonic exciter has the best high frequency sound so far but with almost no bass at all and very low sound output, all this probably due to the whole exciter being the same size as a actual quarter. LOL.....I will be trying the 19mm tectonic exciter in the near future to see how it compares with the dayton daex19mm exciter.

[Unbiasedsound]

Ahhh, forgot to mention as well... you could mount multiple smaller exciters on the panel if crossed high enough. I purchased a bunch of the 13mm, 16ohm exciters a few years ago to do just that but have never used or tested them in that way but now I think I just might given your positive response. :-)

Thanks for the report out on those small exciters UBS!

Those are the exact tectonic exciters I have the 13mm 16ohm ones in which I run 2 in parallel to make 8ohms..I really dig the tectonic 13mm exciters as tweeters.......What I think makes these exciters have a high frequency response is the small voice coil size since they are the same size as a quarter or a 1 inch dome tweeter. Why do I think that? Because these exciters LACK the midrange due to being so small and shines in the high frequency department and sounds very much like a tweeter. With all the other exciters I have used they tend to shine in the midrange especially in the larger voice coil exciters. The smaller the coil , less midrange so the highs are more pronounced.

[Gary.M]

Data points. I weighed and measured some of the exciters that I have here.

Dayton Audio DAEX32U-4 weight 138 grams voicecoil diameter 32mm - Poor hf response on 3mm bamboo ply. - 4 Ohms 40 watts
Dayton DAEX25HE-4 weight 97 grams voicecoil diameter 25.4mm (1 inch) - Good hf response on 3mm bamboo ply - 4 Ohms 24 watts
Tectonic Elements TEAX25C10-8/HS weight 85 grams voicecoil diameter 25.4mm (1 inch) - Very good hf response on 3mm bamboo ply - 8 Ohms 10 watts
Dayton Audio DAEX25VT-4 weight 78 grams voicecoil diameter 25.4mm (1 inch) - yet to test but it looks a good contender (build quality not great though) - 4 Ohms 20 watts

This adds to the suggestion that a lighter weight exciter on a dense material will produce the best hf response.

What I'm looking for as mentioned is a flat response from about 250Hz to 20kHz with no need for equalisation. I seem to have that, and next is to assemble a pair in temporary frames so that I can listen to them.

[Gary.M]

Tectonic Elements exciters and data sheets:

http://www.tectonicelements.com/audio-exciters/

[Unbiasedsound]

Data points. I weighed and measured some of the exciters that I have here.

Dayton Audio DAEX32U-4 weight 138 grams voicecoil diameter 32mm - Poor hf response on 3mm bamboo ply. - 4 Ohms 40 watts
Dayton DAEX25HE-4 weight 97 grams voicecoil diameter 25.4mm (1 inch) - Good hf response on 3mm bamboo ply - 4 Ohms 24 watts
Tectonic Elements TEAX25C10-8/HS weight 85 grams voicecoil diameter 25.4mm (1 inch) - Very good hf response on 3mm bamboo ply - 8 Ohms 10 watts
Dayton Audio DAEX25VT-4 weight 78 grams voicecoil diameter 25.4mm (1 inch) - yet to test but it looks a good contender (build quality not great though) - 4 Ohms 20 watts

This adds to the suggestion that a lighter weight exciter on a dense material will produce the best hf response.

What I'm looking for as mentioned is a flat response from about 250Hz to 20kHz with no need for equalisation. I seem to have that, and next is to assemble a pair in temporary frames so that I can listen to them.

It could also be the brand as even the Tectonic TEAX25C10-8 seems to have the best HF response out of the dayton brands youve tried......the same goes for me as the tectonic exciters that Ive tried have the best hf response.

Thanks for the review of the exciters.....Now I am considering buying the Tectonic TEAX25C10-8/SP

[Gary.M]

It could also be the brand as even the Tectonic TEAX25C10-8 seems to have the best HF response out of the dayton brands youve tried......the same goes for me as the tectonic exciters that Ive tried have the best hf response.

Thanks for the review of the exciters.....Now I am considering buying the Tectonic TEAX25C10-8/SP

I suspect that the /SP is the same as the /HS internally. Elsewhere in discussions people have found removing the plastic housing to be an advantage. I'll be interested to see how you get on.

[Unbiasedsound]

I suspect that the /SP is the same as the /HS internally. Elsewhere in discussions people have found removing the plastic housing to be an advantage. I'll be interested to see how you get on.

Although I am not exactly sure I think they are the same its just that the frog one has the plastic casing with the 4 legs around it while the HS does not. The reason I think that the exciters sound better with the plastic legs removed is because the exciter is suppose to move and flex the material its on but the extra legs holds the material so it does not flex as much. I just simply cut off the legs with a strong scissors.