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.
//
In the end it matters and I can see why a whole panel is preferred rather and XOed system.
//
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.
It truly is the case that 'my design' retains the DML frequency response from 300Hz to 10Khz. That is hardly "replacing as much as possible".
I think I should quietly leave the Thread and keep my opinions to myself with a final comment being >
It could be an interesting 'angle' for the Thread to investigate more, the design of very small DML tweeters using light weight materials 🙂
That is great if you are happy with the results doing that. What I'm trying to get at is why?
The only reason for not using DML for low mid as I understood was that you lack exciter power? And for the top octave that you get distortion with DML?
Since I neither have issues with lack of power or distortion in treble, I just fail to get the point of using regular speaker elements when DML is more than capable of covering the full range above 100Hz. It is.not a criticism of what you are doing, but genuine curiosity as to why you would do it.
The only reason for not using DML for low mid as I understood was that you lack exciter power? And for the top octave that you get distortion with DML?
Since I neither have issues with lack of power or distortion in treble, I just fail to get the point of using regular speaker elements when DML is more than capable of covering the full range above 100Hz. It is.not a criticism of what you are doing, but genuine curiosity as to why you would do it.
Hello audio>x.
This is a video of one of my smaller panels.
Although you can use it as a tweeter up to about 20k, the frequency does go down to about 400hz ( if I remember correctly).
With the correct type of exciter and the correct type of panel materials a full frequency response down to the 100hz area is possible from dml panels.
I have used domes and cones on the central coil area which act the same as tweeters with success, if that helps.
Steve.
audio>x.
This is a frequency plot of my proplex panel without eq.
It shows a plus and minus of about 3db from just below 100hz up to 20k.
I have not used eq on any of my panels so far, as I have found it unnecessary.
I have made many different types of panel with the same sort of success with frequency response and sound performance.
XPS, has its problems with hf performance, and needs a hard coating such as epoxy to increase the hf output, and not pva, which only makes the problem worse for XPS.
I blame parts express for this mixup.
Steve.
This is a frequency plot of my proplex panel without eq.
It shows a plus and minus of about 3db from just below 100hz up to 20k.
I have not used eq on any of my panels so far, as I have found it unnecessary.
I have made many different types of panel with the same sort of success with frequency response and sound performance.
XPS, has its problems with hf performance, and needs a hard coating such as epoxy to increase the hf output, and not pva, which only makes the problem worse for XPS.
I blame parts express for this mixup.
Steve.
Attachments
Funny, I was just thinking about playing around with the idea of separate exciters for "lows" and "highs" on a single panel, and with a crossover to switch between them. And despite Dave's somewhat discouraging comments I'm still thinking about playing with the idea.
But the thing is, I have always been a "full ranger" and have no experience with active crossovers, and have none of the hardware to do it. Say I wanted to put together a cheap setup that would allow me to run separate channels for high's and low's, with an active crossover, and also the possibility to add an active subwoofer. Can anyone recommend some specific components to make a simple, inexpensive "starter" system for playing around? Suggestions?
Eric
But the thing is, I have always been a "full ranger" and have no experience with active crossovers, and have none of the hardware to do it. Say I wanted to put together a cheap setup that would allow me to run separate channels for high's and low's, with an active crossover, and also the possibility to add an active subwoofer. Can anyone recommend some specific components to make a simple, inexpensive "starter" system for playing around? Suggestions?
Eric
For evaluation purposes I'd suggest supplementing your current power amplifier collection with one or two class-D amps, if you don't already have what's needed. They're inexpensive and small. I got a 20-watt stereo version as a backup when I was repairing my main amp and it was OK for driving the panels. As I type this I see that Parts Express has a Lepai 2x40W + 1x68W on sale for $29.98 which would be good for driving a pair of woofers and a sub.
I currently don't have the gear for implementing active crossovers -- DSP or analog -- so can't offer much insight there.
I found out that you can buy Thomann gear in the USA. This device is very user friendly and good quality, a 4 in 4 out matrix/eq/crossover/delay :
https://www.thomannmusic.com/the_t.racks_dsp_4x4_mini.htm
Editing is via simple, practical software. USB cable connected to a windows (!) computer.
There's also a version with 4x 50W amp built in, but it runs on 250V, so that's unpractical.
I use, and like the T-racks a lot.
The wondom/berry bak amps are quite OK, based on a TI 3116 chip. I have a few 2x50 watt amps, powered with an old laptop power supply (19V).
https://nl.aliexpress.com/item/1005008534880065.html?spm=a2g0o.detail.pcDetailBottomMoreThisSeller.4.490doWn8oWn8WC&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.291025.0&scm_id=1007.13339.291025.0&scm-url=1007.13339.291025.0&pvid=f04ed310-3153-46ee-a451-ca73d4df22cd&_t=gps-id😛cDetailBottomMoreThisSeller,scm-url:1007.13339.291025.0,pvid:f04ed310-3153-46ee-a451-ca73d4df22cd,tpp_buckets:668#2846#8107#1934&pdp_ext_f={"order":"2","eval":"1","sceneId":"3339"}&pdp_npi=4@dis!EUR!27.15!25.79!!!216.16!205.33!@210385a817487154665683641ee752!12000045601760323!rec!NL!4792145678!XZ&utparam-url=scene😛cDetailBottomMoreThisSeller|query_from:
Cheers, Hans
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I hadn't seen the T-racks Dsp, was going to suggest the Wondom DSP 2x4 dsp. Comes setup as a crossover with adjustment via knobs but has all the normal dsp features programable with Sigmastudio, it's not as intuitive and easy as MiniDsp software but not that hard.
Mark,
Thanks, I am definitely considering a pair of class D amps as an option. I actually even have a Lepai that I use when I want to do outdoor testing. It's a lot easier to take outside than my Sherwood receiver. And I just noticed that my Lepai (which I got from a friend for free) has 4 channels. For a second I was excited until I realized it still has only two input channels, so I still need a second amp.
Eric
Hans,
That does look interesting. So the t-tracks 4x4 and 2 class D 2 channel amps as a system?
Or what about this? t.racks 4x4 mini DSP Amp Would this cover the whole package, i.e crossover plus amps?
Anybody familiar with this? Rolls Sx45 Crossover
Would the presumably more versatile t-tacks options be better?
Thanks,
Eric
JoskaNZ,
Oh that looks interesting too. Even cheaper than the t-racks, right? But I'm wondering how exactly to interpret this:
The BDSP2.4U features a 4-channel output with a pre-loaded 2-way digital crossover program, delivering 2-channel mid-high and 2-channel bass, making it ideal for 4.0 and 2.1 audio systems.
Does "mid high" and "bass" terminology mean the crossover point has to be within a particular limited range?
Eric