Very nice results Andre!
I did the indoor event this weekend, and worked out really good. We set up the plates next to the regular tops so we could compare them. The subs was two dual 18" per corner, and I would have liked a bit more power to match them and had to push the amps as hard as possible in the end.
They where a lot brighter than the regular tops. I was not familiar with the brand and forgot the name now (was three letters starting with "D" and from Germany). Looked professional and well built, but they didn't sound that great with quite dull treble and distorted mids.
In my tests and for the outdoor event earlier I have been targeting a 6dB slope to get a a balanced sound, but since that was so much brighter then the regular tops there was a concern that it would be too bright and last minute I put a high shelf around 1k reducing 4dB.
For my studio and home listening use though, I find that -6dB is too much, and a -3 target seems better.
Still want to try out the PC disc technique since your overall FR does seem really good, and I can always EQ down the treble to get a good curve for PA use.
I did the indoor event this weekend, and worked out really good. We set up the plates next to the regular tops so we could compare them. The subs was two dual 18" per corner, and I would have liked a bit more power to match them and had to push the amps as hard as possible in the end.
They where a lot brighter than the regular tops. I was not familiar with the brand and forgot the name now (was three letters starting with "D" and from Germany). Looked professional and well built, but they didn't sound that great with quite dull treble and distorted mids.
In my tests and for the outdoor event earlier I have been targeting a 6dB slope to get a a balanced sound, but since that was so much brighter then the regular tops there was a concern that it would be too bright and last minute I put a high shelf around 1k reducing 4dB.
For my studio and home listening use though, I find that -6dB is too much, and a -3 target seems better.
Still want to try out the PC disc technique since your overall FR does seem really good, and I can always EQ down the treble to get a good curve for PA use.
Thanks Leob,
I don't think it's strictly necessary to use polycarb. I suspect that anything stiff and lightweight will do, even the same material as the panel itself. The only reason I used polycarb was because it was there.
A CD-sized disc will be ideal if a little oversized, but that only means the 'boost' effect might come in at a slightly lower frequency.
Let us know the results when you try it!
The only problem is that if you want to have the same Boost effect at mids, then the ring that corresponds to mid frequencies would be larger than the panel itself.
I did try larger concentric ring around the high-boost ring, but the results were disappointing because they inhibited the whole panel resonating properly at bass frequencies.
A lot more work and experimentation needs to be done on this.
Other things to consider...
1. Those very nice responses I got were from polystyrene/paper sandwiches. Such panels will obviously never work in an industrial (PA/Band) environment, and will get damaged quickly without very careful handling. I need to investigate other materials and laminates that will survive rough handling.
2. Yes of course I can apply stainless steel protective grilles, but the weight advantage will be nullified—I want a 2kW system that I can carry under one arm, with my bass guitar in the other.
3. The panel dimensions need attention; I need to look at multiples of Poisson ratios in order to activate panel modes more evenly.
4. I'm not happy with the distortion measurements. I suspect this is because the exciters themselves are buzzing (I found that the VC had come adrift from the spider in one of them, and one of the feet had cracked in the other.) I want to use different drivers in my next iteration.
There's still a lot of work to be done. But I'm optimistically hopeful about this project.
1. Those very nice responses I got were from polystyrene/paper sandwiches. Such panels will obviously never work in an industrial (PA/Band) environment, and will get damaged quickly without very careful handling. I need to investigate other materials and laminates that will survive rough handling.
2. Yes of course I can apply stainless steel protective grilles, but the weight advantage will be nullified—I want a 2kW system that I can carry under one arm, with my bass guitar in the other.
3. The panel dimensions need attention; I need to look at multiples of Poisson ratios in order to activate panel modes more evenly.
4. I'm not happy with the distortion measurements. I suspect this is because the exciters themselves are buzzing (I found that the VC had come adrift from the spider in one of them, and one of the feet had cracked in the other.) I want to use different drivers in my next iteration.
There's still a lot of work to be done. But I'm optimistically hopeful about this project.
Mostly to show how the setup looked. I didn't expect that anyone would think they can judge the sound of a PA recorded on a mobile phone.
I would say though that the overall sound was not fantastic. The acoustics was far from ideal, with mostly lots of reflective concrete everywhere. It was a big improvement on the existing tops I found, but still left a bit to be desired.
you know the sound of your panels, according to your experience the sound was not good due to your panels or the interaction of the environment? what do you think is missing to be satisfied with your panels?
Being better in difficult acoustics is often touted as one of the main strengths of DML, and I definitely think that is the case. But lots of hard reflective surfaces will still cause a mess.
I do think the sound will be better with more careful tuning of the panels response before EQ, and that my amps are a bit underpowered and could be better quality. The other tops was running on Linea Research amps costing perhaps 15-20 times as much as the Sanways I use.
And I need to make them a bit more solid with some protection and cable management.
Yes, of course, I am aware and in line with what you say, at this point, however, I ask you a question, as opposed to traditional systems where there are infinite solutions that are good and less good but they are many, in our case professional use is only present the tectonic, if it goes well (never heard of in my life) why not exactly replicate the tectonic with carbon and honeycomb? exactly the same size? maybe the difference could be in the exciters maybe they don't sell normally? If tectonic has stopped at that project and surely they will have had the money to experiment we could assume that perhaps it is the best that can be expected. Then if one wants to experiment on their own it is right but since you have a point of reference at least start from that.
That is pretty much what I have been doing. I have started experimenting with making laminates to see how that fares compared to EPS, but it is a lot more complicated and costly and EPS is very efficient and good sounding so seemed good enough as a first step to try out if it is a worthwhile idea. And Tectonic has other considerations. They are making touring grade equipment that they are charging a premium for, and EPS might be a hard sell for them even if it would perform as well.
Of course Tectonic has some good engineers working for them, have their own simulation software, exciters that they don't have on the market, and has put a lot of research into their panels, so it will be hard to improve on that. For me this is about being able to make something that is at least comparable for less than 1/20th of the cost, and I'm happy that I feel I achieved that, but will keep tweaking them both to make them even better sounding and more sturdy. Maybe by using nomex/carbon composites eventually. Exciters are the main cost anyway, my current frame and plates are cheap to replace or modify.
I'm not sure that carbon/nomex honeycomb is that much better than other solutions to justify the expense. I think we can get pretty much similar performance at less cost by using additional exciters to make up the difference in SPL. That is, IF max SPL and sensitivity are the main dividing factors.
Having said that, FR for live PA applications does need certain boosts in the vocal bands, and also a more "active" (?) high end than hi fi or studio monitors.
Does DML FR over distance (say 50m) also suffer drop-off in the higher frequencies like horns do?
I meant a separate larger 'disc' with it's own exiter.
Also, could you not make your own exiters from PA drivers? Seems like an easy task. That way you get the properties you actually need.
When using them outdoors at the festival, the sound at 50m was definitely a lot brighter than with the systems we used previous years. However that can probably be explained by the dipole pattern, which certainly gives the impression of more treble at most positions, and especially outside the dancefloor, and not sure how big the difference is on axis at distance.
Since we want one coil responsible for everything from 100Hz to 20kHz, we cannot simply increase the size of the coil to get the power handling we want, because then inductance increases and top end starts to roll off. I did get a pair of more powerful 50w into 8 ohm drivers initially, but found that they lacked HF reproduction. So if using PA drivers you couldn't modify say a 12" driver to get a high power exciter to cover the full range, but will get something similar to the many different bass thrusters available.
I also bought some bigger exciters and they had the same problem, a lot of bass that does not render on the dml and a few high frequencies. it is useless to have an exciter with a more complete range at the expense of high frequencies and above all medium frequencies which make the particular sound of the dml. In summary, if a panel must be transported easily unlike traditional systems, in my opinion it is not possible to go below certain frequencies From my point of view the characteristic for professional use that must maintain is the weight and the volumes, obviously the quality must be good to replace a normal system.