From that video, I understood the possibility of a placement at 35/50% which is the one used in the Xcite exciter specifications. After some tests with it, I would say I am not convince. It might be not bad from modes point of view but in the tests I did, I was in the situation 3 distances on 4 from the exciter to the edges where almost equal leading to a dip in the medium (short circuit with the back in my opinion).
I have made some panels in the "Zenker setup" (you can see the specs in the datasheet of the exciters) although slightly modified.
Note that this setup is measured/used with a clamped surround. When you use foam tape the Pettals software calculates a different (more uneven) response.
Foam panel 80x40 cm, exciter at 40% (length) and 50% (width). The 40% is chosen after Pettals software predicted slightly flatter response. The edges are clamped to the frame, but I have made some "tone relief" grooves around the panel, acting as a kind of softer surround. I use a lot of highfreq boost eq, and no PVA coating.
This gives a nice sounding panel. I think my aversion to foam (plastiky sounding) was because of the coating. Without coating you lose a lot of high end of course, but digital eq's are easy to get.
Note that this setup is measured/used with a clamped surround. When you use foam tape the Pettals software calculates a different (more uneven) response.
Foam panel 80x40 cm, exciter at 40% (length) and 50% (width). The 40% is chosen after Pettals software predicted slightly flatter response. The edges are clamped to the frame, but I have made some "tone relief" grooves around the panel, acting as a kind of softer surround. I use a lot of highfreq boost eq, and no PVA coating.
This gives a nice sounding panel. I think my aversion to foam (plastiky sounding) was because of the coating. Without coating you lose a lot of high end of course, but digital eq's are easy to get.
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Why are DML enthusiasts & aficionados so reluctant to incorporate a tweeter in their build/design ???
I think it is because that loses the wonderful integration and coherence in the sound from the panel system - also, the directivity is different, less broad.
In the end it matters and I can see why a whole panel is preferred rather and XOed system.
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In the end it matters and I can see why a whole panel is preferred rather and XOed system.
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Do you mean a tweeter-exciter or just a regular cone tweeter?
In the case of crossover using multiple exciter types, the panels that work well for low frequencies usually don't work well for high frequencies, and aren't well matched to the high-frequency exciters. For example, with a panel that's designed for low end, you might get 85 dB sensitivity with the low frequency exciter, but only 70 dB sensitivity with the high-frequency exciter (since the panel is too heavy). Because the low-end exciters can usually handle 20-40 W and the high-end little ones can only handle 1-5W, you're SOL trying to get a flat response. So, then, the smaller tweeter exciters will also need a matching panel for the crossover to function properly, which kinda defeats the purpose of a single-panel system.
Is that really true though? I was thinking that would be the case, but now I'm not so sure. I was thinking making a 2-way design with separate plate and exciter for treble, but could not think of a better material than EPS for either mid or treble. Big exciters will have less treble, but it seems to me that if splitting into a 2-way DML, there might not be that much point in using different plate materials.
My impression is that hard materials that have relatively much treble, like polycarbonate, rather is lacking in mids than actually being sensitive in the treble range.
Do you consider the "treble range" to go past 10Khz up to 20Khz ? Accurate low distortion output in this range requires very low moving mass.
Early Bose speakers used a full-range driver and FORCED high frequencies out of a driver that wasn't designed for it - using active EQ .
This led to high frequency distortion and poor audiophile opinion. [ it is simple fact that a 'super tweeter' can greatly improve a DML ]
PS.
A very common response to this is > "My ears can't hear frequencies like that, so it doesn't matter". In fact, this is more the reason to use a tweeter.
You can even use 2x tweeters to provide both front and rear output.
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Haven't seen any indication with DML that treble will distort if mass of plate is too high, and some relatively heavy materials does make good sounding treble. Distortion in the treble range is low according to my measurements of my plates. And people have told me countless times how the treble is very clean compared to regular PA systems.
Comparing to some old regular speaker forced to do full range is really irrelevant. It is a well known fact that traditional speakers cannot handle more than about 3 octaves well. But now we are taking DML, and you have to use DML designs as an example if you want to explain what you think are shortcomings of DML.
I actually like the performance of DML speakers, and is not seeking to replace the low mid and treble with regular speakers. Seems like you either just don't like the sound of DML, or have problems with your design leading to trying to replace as much as possible with regular elements.
Comparing to some old regular speaker forced to do full range is really irrelevant. It is a well known fact that traditional speakers cannot handle more than about 3 octaves well. But now we are taking DML, and you have to use DML designs as an example if you want to explain what you think are shortcomings of DML.
I actually like the performance of DML speakers, and is not seeking to replace the low mid and treble with regular speakers. Seems like you either just don't like the sound of DML, or have problems with your design leading to trying to replace as much as possible with regular elements.