I really like the sound of DML for low mid, and set the xover around the same region where my plates start to drop of naturally, which is around 100Hz. But depending on the plates, sub used, etc, I think 90-120Hz is reasonable. Higher than that and you are above sub region and below that DML tends to struggle, and doesn't offer same advantages.
I rushed to the shop to extract the other thruster and set up the second panel.
As anticipated after last night, the pair sound better than any pair of panels or pair of conventional speakers I own (going by very recent memory). Outstanding highs in addition to huge bass and soundstage. But....
Compared to any complete system of speakers -- my panels + dml tweeters + sub; something ain't right with them. I can't do a direct comparison but I'm certain they don't, in their present state, have the ability to sound better than my present setup. So, that meant I had no qualms cutting them to the 14" Eric recommends and get ready to proceed with the frame build.
A big problem was integrating them with my subs. It's not the seamless job integrating any of my XPS panels has been. My sub amps are the Daytons with 180 degree phase knob and that didn't fix. The other issue is they sound very bright -- like I say, better than any pair of anything I own on by themselves, but I think the mids aren't right.
However --
- Eric recommends 14" and that might balance out the FR, plus the frame; I'm wondering if unlike the XPS where the frame helps produce lows, the frame is needed to control the lows. I mean, these things must have at least 1/2 mm of excursion.
- The panel on the left isn't baltic birch (HD also has sanded plywood). I had my doubts but was in denial, however, after cutting it, there is no way. It's mislabeled as 3/4 birch, and I corrected them on the 3/4 part at the register, but didn't occur to me more could be wrong.
- the exciters are applied with double-sided tape not directly attached.
- the thrusters are the interchangeable version, which on XPS, don't have the rich mids that the regular thrusters do.
anyway, def. a fun and overall mind-blowing test that was trivial to set up.
As anticipated after last night, the pair sound better than any pair of panels or pair of conventional speakers I own (going by very recent memory). Outstanding highs in addition to huge bass and soundstage. But....
Compared to any complete system of speakers -- my panels + dml tweeters + sub; something ain't right with them. I can't do a direct comparison but I'm certain they don't, in their present state, have the ability to sound better than my present setup. So, that meant I had no qualms cutting them to the 14" Eric recommends and get ready to proceed with the frame build.
A big problem was integrating them with my subs. It's not the seamless job integrating any of my XPS panels has been. My sub amps are the Daytons with 180 degree phase knob and that didn't fix. The other issue is they sound very bright -- like I say, better than any pair of anything I own on by themselves, but I think the mids aren't right.
However --
- Eric recommends 14" and that might balance out the FR, plus the frame; I'm wondering if unlike the XPS where the frame helps produce lows, the frame is needed to control the lows. I mean, these things must have at least 1/2 mm of excursion.
- The panel on the left isn't baltic birch (HD also has sanded plywood). I had my doubts but was in denial, however, after cutting it, there is no way. It's mislabeled as 3/4 birch, and I corrected them on the 3/4 part at the register, but didn't occur to me more could be wrong.
- the exciters are applied with double-sided tape not directly attached.
- the thrusters are the interchangeable version, which on XPS, don't have the rich mids that the regular thrusters do.
anyway, def. a fun and overall mind-blowing test that was trivial to set up.
There are multiway speakers around that take their built in sub well over that range. They can be used effectively until beaming and cone break up ect gets significant.
The reason for damping is that the spectrogram of an undamped panel will look something like this:
Now I'm not saying that the spectrograms of your panels look like this. Just that if you have a truly undamped panel, it will indeed look like this.
And what I mean by "look like this" is that at particular frequencies the spectrogram will show ringing long after the signal that created them has stopped. The ringing frequencies are shown by the vertical lines in the spectrogram. In this particular panel, the strongest of these happens to be at around 260 Hz, but there are others near 150 Hz, 560 hz, and about 1.2 kHz, among others.
This ringing happens not because this panel has "problems", but rather because it is simply the nature of an undamped vibrating panel to do so. For such an undamped panel, once excited, it will tend to continue vibrating at those frequencies. Some of those frequencies will be better at radiating sound than others, so those will be likely to stand out in the spectrogram. In this particular plate, the mode corresponding to the ringing at 260 Hz is this one (below) which happens to be one of those that is particularly good at radiating sound.
That said, one thing that I've observed is that when ringing occurs, it is worse at lower frequencies than it is at high frequencies. I usually don't see it much in spectrograms above 500 or 1000 Hz (the example panel is a bit of an exception). Is it because modal density (natural frequencies per octave) increases rapidly with frequency? Is it because at higher frequencies the panel's internal damping is more effective? Or does the viscous resistance of the air against which the panel is pushing provide more effective damping at high frequency? All of the above? Other? I'm not sure. But regardless, panels seem to act as if they are naturally better damped at high frequencies than low. So one thing that might really work, is simply use a high pass filter to avoid driving the panel at the worst of the ringing frequencies.
Another solution is to have damping. Damping doesn't eliminate standing waves (modes). In theory I suppose it could, but in practice it's really hard. Damping just spreads out the resonance frequencies so they don't happen at such well defined frequencies, but instead are spread out over a range of frequencies. Damping could be at the perimeter, or in the panel, or distributed along the panel. It could be damping you added on purpose, or just happened to be in the panel, or even be added inadvertently. But regardless of it's nature, damping is the most reliable way to eliminate ringing in a panel, if you would like to use it in the lower frequency range, where ringing is most likely to happen.
Eric
Glad your having fun!
I have a couple of uncut 2x4 panels, and some Thrusters I've never really used. Maybe I'll have to try them out.
You make a good point that you can learn lots of things with these DMLs using experiments that really are pretty trivial to set up. Building frames is a little more work, but still nothing like the effort it normally takes to build a cabinet for a cone speaker.
My best advice to anyone getting into this is to experiment for yourself and have fun.
Eric
I found it necessary to add selective damping strips and area pads to my solid Cedar panels, particularly for vocals. For the area pads, I used very thin self adhesive felt, and for the strips, I used closed cell foam. These panels have minimal support, so this is the only damping applied. All done by trial and error listening, and finger tip tracing of active areas at certain frequencies
Eucy
Steve, How is your current state of the art panel configured? I know you do all kinds of experimenting with canvas, card stock, etc. - but if I wanted to build and hear what you consider your best effort - exactly what would I build? Thanks, Bruce.
IT ONLY JUST OCCURED TO ME >
There many, many numerous reports of how DML's sound great but don't necessarily measure well.
The fast attack but slower decay is exactly analogous to Reverb, and a fundamental property of the panel/plate.
In recording, short time reverb is used to enhance sounds, and also create a 'space'.
This can explain how DML's may not be technically accurate, yet sound truly great !
The following info. of "Plate Reverb" is surely something to think about
https://www.vintagedigital.com.au/emt-140-plate-reverb/
There many, many numerous reports of how DML's sound great but don't necessarily measure well.
The fast attack but slower decay is exactly analogous to Reverb, and a fundamental property of the panel/plate.
In recording, short time reverb is used to enhance sounds, and also create a 'space'.
This can explain how DML's may not be technically accurate, yet sound truly great !
The following info. of "Plate Reverb" is surely something to think about
https://www.vintagedigital.com.au/emt-140-plate-reverb/
Thank you Eric. Yes, we all would like small panels that go lower than 100Hz. I just wanted an indication of the size limits of the plywoods. Using a high aspect ratio (3:1 or 4:1) with a 12” wide panel brings me back to the size of the Tall Blondes.
I really appreciate your experiments, measurements, findings, and contributions on this thread.
In some ways that is correct. There are basically two types of effects, those that introduce delays, and those that directly modify the waveform.IT ONLY JUST OCCURED TO ME >
There many, many numerous reports of how DML's sound great but don't necessarily measure well.
The fast attack but slower decay is exactly analogous to Reverb, and a fundamental property of the panel/plate.
In recording, short time reverb is used to enhance sounds, and also create a 'space'.
This can explain how DML's may not be technically accurate, yet sound truly great !
The following info. of "Plate Reverb" is surely something to think about
https://www.vintagedigital.com.au/emt-140-plate-reverb/
In the first group you have delay effects obviously, but also reverb, chorus, phaser and flanger. Also EQ in a sense, which is a frequency specific delay.
In the second group you have compressor, expander, distortion, saturation and waveshaping.
Since the plate will emit the same frequency from multiple points you will hear multiple versions of the same signal with a slight delay, which is in essence what most delay based effects will be doing, just with different number of copies with different timing.
I would say a good plate have more of a chorus effect, which is a few copies of the signals with slightly different delay. Reverb is a burst with lots of delays.
I don't think slapping an effect on your master is a good idea though. That should be done during production or mastering if it benefits a track.
But of course DML is not an effect you can add to the signal. Adding a reverb to the mix will not be a substitute. DML is an effect that has to be created in physical space, and works in a way that our hearing and even shape of our ears are constructed to handle.
Perhaps using some psychoacoustic modelling listened to on headphones could recreate the sound of DML, but in general, unlike your regular chorus or reverb, DML effect can result in a sound that no producer or mastering engineer can achieve.
@Leob
Yes, I am aware of the full gamut of Studio FX and understand their differences >
I was trying to keep things short & simple.
My main point was that compared to the electrical input signal, the sonic output of a DML
IS adding an effect (of sorts) to the signal. The pure physics of it can't be denied.
Yes, I am aware of the full gamut of Studio FX and understand their differences >
I was trying to keep things short & simple.
My main point was that compared to the electrical input signal, the sonic output of a DML
IS adding an effect (of sorts) to the signal. The pure physics of it can't be denied.
Eric.
Can you describe to me , a way of physically damping those resonances in your spectrogram, in a way that does not affect all of the other frequencies on the panel?
I personally prefer as little damping as possible but sometimes it is necessary on certain materials.
I usually use a few weights or mounting points, shapes, to sort out these problems, or throw them in the bin, if they are that bad.
A good panel material should have a clean clear sound with no discernable ringing.
Did you read the white papers by Mapp and Azima ?
Were they of any help to you?
Steve.
As can be seen in the first picture on the left, I used an angled length of wood to help break up the standing wave on this ply panel.
The second picture shows how I reduced the standing wave on a long narrow panel.
I have posted pictures somewhere on this forum of this panel.
It showed the panel clamped at the bottom, but with an angled brace clamped in a sturdy vice.
You could also cut or brace the top, or both .
I felt that clamping the bottom of the tall thin panel gave a good sound and a sturdy base for supporting the panel.
So solved two problems for the price of one👍
Steve.
The second picture shows how I reduced the standing wave on a long narrow panel.
I have posted pictures somewhere on this forum of this panel.
It showed the panel clamped at the bottom, but with an angled brace clamped in a sturdy vice.
You could also cut or brace the top, or both .
I felt that clamping the bottom of the tall thin panel gave a good sound and a sturdy base for supporting the panel.
So solved two problems for the price of one👍
Steve.
Attachments
Hello Bruce.
EPS,( NOT XPS) has been my favourite for many many years .
But it needs a lot of delicate care and attention to get it sounding its best.
The same can be said for the other panels, as far as I am concerned, they are all good sounding panels and will not disappoint.
Especially as they are usually cheap or free.
There is only one, that I know of , that sounds good straight from the get go, all you have to do is slap an exciter on it.
There is possibly a way to improve this panel ,I believe.
This sample was sent to me by JohnnoG, but it is very expensive and probably hard to get hold of.
I will have to pm John to see how he is getting on, but I know he is very busy.
It probably depends on how you intend to use them in your environment ?
Steve.
Steve - My environment is 14’ x 18’ x 8’ carpeted, acoustical tile ceiling. I want all genres of music to sound right, but the most challenging source example is Sheffield’s Drum and Track Record, Jim Keltner at live levels. I want listening to that to put a smile on my friend’s face! I have high density EPS and a wire cutter to make any thickness. I am not limited by panel size. Will your preferred 10-watt exciter be enough? I have an electronic crossover/equalizer, infinite baffle sub and lots of power. I need dimensions, PVA or epoxy, suspension method, etc. I’ve read and valued so much of your expertise, here and at AC, but I still don’t know what you’d specifically recommend for my needs. Thanks, Bruce.
Not an audio 'clip', but still general info. >
EPS vs XPS
https://www.google.com/search?q=wha...ate=ive&vld=cid:87a33537,vid:sX-vym8qMbg,st:0
EPS vs XPS
https://www.google.com/search?q=wha...ate=ive&vld=cid:87a33537,vid:sX-vym8qMbg,st:0
Due to my lack of talent for working with double-sided tape, here's my 14" birch with frame.
I ripped 1/4" strips of XPS, which I have plenty of, and glued to the inside of each one of those long boards, and then sandwich the edges of the plywood between the xps, tightening with bolts. I need to get more bolts, there's enough to do the basic job, but, it's a delicate balance to constrain the board enough not to buzz but without killing its relatively epic bass (for dml). The board might look straight but definitely isn't when trying to sandwich it, and so I think at least 4 bolts on each side, and then gradually tighten -- however, might not matter much because at the end of the day, crossing over at the trusty 100hz and letting the sub do its thing may sound the best anyway.
I did a long left-channel comparison with one my xps panels connected in series to my dml tweeter, both powered by the same version of amp and can easily toggle either off and on. More impressive than the bass is the highs, the articulation is off the charts; it might be too much. It also has more depth than my xps. The bad -- cold and bright. Lacking in mids. If I had to do a final build tonight, Id rip 10" off one xps panel and mount it to the front of the birch. Together they sound very good.
Coming from PE in a few days is a test mic. Today my -fhe-4 exciters came. So tomorrow I can try with the same exciter Eric uses. If I can figure out REW, I guess I can see exactly what frequencies are missing and go from there.
I ripped 1/4" strips of XPS, which I have plenty of, and glued to the inside of each one of those long boards, and then sandwich the edges of the plywood between the xps, tightening with bolts. I need to get more bolts, there's enough to do the basic job, but, it's a delicate balance to constrain the board enough not to buzz but without killing its relatively epic bass (for dml). The board might look straight but definitely isn't when trying to sandwich it, and so I think at least 4 bolts on each side, and then gradually tighten -- however, might not matter much because at the end of the day, crossing over at the trusty 100hz and letting the sub do its thing may sound the best anyway.
I did a long left-channel comparison with one my xps panels connected in series to my dml tweeter, both powered by the same version of amp and can easily toggle either off and on. More impressive than the bass is the highs, the articulation is off the charts; it might be too much. It also has more depth than my xps. The bad -- cold and bright. Lacking in mids. If I had to do a final build tonight, Id rip 10" off one xps panel and mount it to the front of the birch. Together they sound very good.
Coming from PE in a few days is a test mic. Today my -fhe-4 exciters came. So tomorrow I can try with the same exciter Eric uses. If I can figure out REW, I guess I can see exactly what frequencies are missing and go from there.