Toddincabo.
I don't see why the wood foam should not sound good for all types of music ?
Although I do try not to get my hopes up, as some materials just don't sound good no matter what you not to them.
He also told me to look up a 0.9 watt digital amp chip that he reckons sounds awesome, that he blows up by continually over driving them 😱😂
He is a one off, I hope.
Steve.
I don't see why the wood foam should not sound good for all types of music ?
Although I do try not to get my hopes up, as some materials just don't sound good no matter what you not to them.
He also told me to look up a 0.9 watt digital amp chip that he reckons sounds awesome, that he blows up by continually over driving them 😱😂
He is a one off, I hope.
Steve.
Thanks Steve. Had no time to sort out the cable management, but could be fixed with some tape so there was no strain from the cables on the exciters 🙂
Seems like it is enough with the weight of the exciters to make them sag under extreme temps.
Didn't do much this time to tweak the panels together with the basses, but the 24dB filter at 90Hz I had configured worked really well. With the natural slope in bass of the panels and the softer and higher filter of the subs they blended nicely. But for next time I for sure want to be able to more carefully tune subs and panels.
Harmonics Steve...DMLs work by vibration...vibrations beget harmonics
Called by pistonic people harmonic distortion
Guitarists on the other hand love harmonics as it makes the instrument lively ( or so I believe)...
Eucy
Thanks! I made a parameterized template for positioning exciters in Fusion 360, but not sure how to show that so it makes sense. Here is a screenshot from fusion, but is is very hard to read:
Didn't spend a lot of time tweaking it to find an optimal configuration though, but also didn't notice that big differences when trying slightly different positions.
For the suspension I added small 2cm strips close to the corners:
Again, didn't have much time to really tweak the position and length of the strips, but was happy with the results like this.
Modifying suspension seems to have the greatest effect on the FR, and I think that if I really spent time optimizing that as well as exciter position and plate dimensions I could probably reduce the EQ needed a lot. Now I need to do 10dB cuts in the low mid to get a flat response, which is double compared to Tectonics recommended EQ curve for the DML500.
Still have to dig out those response graphs and will make another post with more info then.
These articles are a bit like Irish Stew...you know there has to be some meat in there somewhere but you just can't find it!!
Basically useless in practical terms until they take the next step and verify the results with physical models..in real panels
The real issue is finding the best balance between frequency range and evenness of response
Personally, I'd rather try and extend the response and try to find solutions to dips and peaks in the lower freq bands.
We know that random pattern stiffening can exacerbate wobbles in frequency response low down, but targeted corrective measures are worth pursuing to the bloody end.
Hello Steve
It sounds like a second harmonic distortion. I observed from some measurements this kind of things. I don't remember if I have posted about it..
With a FR made with REW it is easy to see as REW extracts automatically the distortion.
It might be an other property of DML to generate H2 distortion which is said to be pleasant.
Which level do you observe on the harmonic?
Christian
Thanks Leob
I have also the experience that the suspension modify a lot the FR which makes sense when we think that the suspension controls how the waves are reflected at the edges in a frequency dependent way.
We see from Tectonics documentation their panels have some material on 50% to 60% of the edges.
It is currently a question for me how to go on on that. Some finish elements analysis allows to deal with the panel dimensions (see Veleric work)... but for the suspension how to limit the test/error processus?
Christian
The main issue is that DMLs harmonise harmonics. They still sound great though 👍😁
Yes, my initial tests was with similar suspension where everything except the corners was clamped. Maybe that is good for a 3.6mm thick nomex/carbon plate, maybe their suspension is a lot less rigid, but the 25mm EPS seems to need a lot less clamping with the foam I used.
It is reasonably easy to modify the clamping, and I hope just moving them around will result in changes in FR that makes some sense. Will be a slow process though, with a lot of trial and error. But I see no alternative than making small moves and recording the results, other than making a simulation.
They do sound really good and loud as they are, and I'm not sure if spending a lot of time fine tuning of the plates would actually result in that much of a difference in practice.
I can probably get a little bit better sound and higher SPL with a few days of testing and adjusting. But it will take a lot of time to make them perfect. As we say in programming, last 10% of the work takes 90% of the time.
As Christian said, what you are seeing is evidence of harmonic distortion. Harmonic distortion is not somehow "inherent" in a DML. It really just means you are driving something a little too hard. Do your test tones again, and try adjusting the volume down. You will find that at some sufficiently low volume, the higher frequency peaks will disappear. That is, if you play a 100 Hz tone, and turn the volume down enough, the peak at 200 Hz will eventually disappear.
The peak at 200 Hz (for a 100 Hz tone) is a sign of clipping/distortion of the pure sine wave somewhere in the chain between when the signal is generated by the amp and the signal detected by the mic.
Eric
+ @spedge @Eucyblues99
Hello,
The distortion comes from the non linearity of the material when it transform the force from the exciter in speed (displacement). More power in, more displacement, more distorsion. I have no explanation for the predominance of H2 which suppose the effects of the non linearity are not symmetric when pushing or pulling.
You can go back to post #4656 where I posted the results of a spectral contamination test. This test doesn't focus on H2 distortion but shows the distortion. The principle is several sinus are sent in the DML, none of them are in harmonic relation. In other words, they are not multiple in frequencies. So if some Hn distortion appears, it creates a level out of the frequencies of the other signals, adding so "grass" above the noise floor or making the spectrum around one frequency not very thin.
When I did that, I found that all the materials are not equivalent. Some creates more "grass".
Difficult to make a ranking by eyes but it seems from the samples I had from the lower distortion to the higher
- plywood
- acrylic
- canvas, cardboard
- EPS
- XPS 9mm
Didn't say it wouldn't , just figured being all organic it would excel with wood and wind instruments.
Good to know Eric...I'm sure I've read more than one tech article which specifically criticises DML for just that reason..
No good Eric..Steve is a THUNDERSTORM man 😁😃
Eucy
Jumping slightly off topic, but I'm wanting to make some translucent panels out of frosted acrylic/perspex. For aesthetic reasons. Can anybody suggest thickness and dimensions to try?
Notice bracing being used for the exciter. Why is this? Are they not designed to be self supporting?
Notice bracing being used for the exciter. Why is this? Are they not designed to be self supporting?
Leob.
I noticed this product on line, I believe it is similar to what you are using.
It is in a size I have used before and am interested in using again.
for 7 panels it is only about £22 but for 8 it works out at about £48 both with delivery?
If you think this is the same as your eps panels ,I might give them a call and confirm the prices .
Steve.
https://ewistore.co.uk/shop/external-wall-insulation/eps-insulation-1-board-0-72m2/
I noticed this product on line, I believe it is similar to what you are using.
It is in a size I have used before and am interested in using again.
for 7 panels it is only about £22 but for 8 it works out at about £48 both with delivery?
If you think this is the same as your eps panels ,I might give them a call and confirm the prices .
Steve.
https://ewistore.co.uk/shop/external-wall-insulation/eps-insulation-1-board-0-72m2/
Eric.
I did as you said and lowered the volume and watched the higher tone reduce with the lower tone until the higher tone disappeared below my screen ?
By then I could hardly hear the lower tone.
But obviously the higher tone is still there, it has just moved off screen.
My question is what happens when we play music much louder than this with similar sounds or tones ? Will the higher tone still be there ?
Or is it something we just have to live with.
Steve.
I did as you said and lowered the volume and watched the higher tone reduce with the lower tone until the higher tone disappeared below my screen ?
By then I could hardly hear the lower tone.
But obviously the higher tone is still there, it has just moved off screen.
My question is what happens when we play music much louder than this with similar sounds or tones ? Will the higher tone still be there ?
Or is it something we just have to live with.
Steve.
Thank you eucy, harmonics, that was the word I was trying to remember, I was having a senior moment😲 I new the word this morning 😀
all instruments have them and I suppose panels are no different ?
Steve.