Thanks. I see that in different threads. Could you detail the chain a bit more with settings? From the audio player to the DAC. I had a look to the record you propose and I haven't understood if a native 5.1 format is proposed? Is there a 2 channels to 5.1 expension in your system?
@Veleric
Hello Eric
Here are 2 pictures of my implementation of the impedance measurement circuit.
Short explanations :
- chassis female jack on the left = to be connected to a headphone output (one channel used) = PC or soundcard outputs in the schematics above
- black and red bananas = speaker connections (+ = red, black = ground)
- male jack with shielded cable = connection to line in = PC or soundcard inputs in the schematic above
- Rsense = 100Ohms
- All the ground are connected together
That YouTube recording is not coming through as true 5.1, it's 2 channel. I can put my Sony on "Music" which mixes a 2 channel into 5.1 but that is not true 5.1, it's a representation.
Try Pink Floyd - The Wall - Movie if you want to hear some true 5.1 kick *** music.
Next project:
This is a 2.4metre panel, 280Wrms. There will be four of them for an installation.
There are nine drivers per panel, 5 x 25HFE-4's and 4 x Thrusters. The DML membrane itself is 5mm Foam-X which is a lightweight polyurethane-foam-core board (around 500g/sqm). The front surface is made to be printed on.
Since the panels will be mounted flat onto the walls, I've had to make them 60mm deep, which is a bit deeper than I would like, so there are randomly-perforated acoustic damping panels, two of them, behind the membrane, and two layers of underfelt or mineral wool, depending which offers the best noise absorption coefficient in this design.
This is a 2.4metre panel, 280Wrms. There will be four of them for an installation.
There are nine drivers per panel, 5 x 25HFE-4's and 4 x Thrusters. The DML membrane itself is 5mm Foam-X which is a lightweight polyurethane-foam-core board (around 500g/sqm). The front surface is made to be printed on.
Since the panels will be mounted flat onto the walls, I've had to make them 60mm deep, which is a bit deeper than I would like, so there are randomly-perforated acoustic damping panels, two of them, behind the membrane, and two layers of underfelt or mineral wool, depending which offers the best noise absorption coefficient in this design.
Hi Andre
What is "Thruster"?
Then I can't understand where to put the Exciter from the design drawing?
Have you done a simple test of this design first?
If you have tested it first, can you post the curve for reference?
Thank you very much~
The Thruster is the DAEX32EP-4.
That's just a concept drawing. I have not done the design yet except to nail down the electrical configuration of the drivers.
Once I get all of the drivers then I can start playing with their positioning and get a frequency response curve.
That's just a concept drawing. I have not done the design yet except to nail down the electrical configuration of the drivers.
Once I get all of the drivers then I can start playing with their positioning and get a frequency response curve.
It's interesting that in your applications you're basically forced to snuff out the rear waves and I'm wondering what effect that approach has on the front waves and the overall output response.
Also, have you considered trying to boost the bass output by using the rear baffle as an air spring rather than just absorbing the rear waves
It's great to see that you're having success in getting these units out into the public space
Eucy
Hello Eucy,
I remember a patent around that (I can try to find it later if you want) showing
- a hump in the medium
- the benefit of having a closed rear volume to "smooth" the modes
Nah, not yet, Christian, I'm still in pre-production. The work I've been doing so far is very specific, and bespoke designs are the only solutions.
If I can get a music chain store to stock the panels, then I might have to go the high volume route. But for now I can get by by doing customized solutions for difficult problems.
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Indeed! I believe the design of the rear baffle allows one to both boost and cut certain frequencies. Cut being achieved by using perforations that are tuned to specific frequencies, and boost achieved by the air spring effect using tuned cavities, as you mentioned. I did read somewhere that the air spring effect was also used to dampen certain modes, but I have not spent enough time exploring this yet. So far I have only used the rear baffles as broadband dampers, with plenty damping material, to control the rear dispersion. I think a lot can be done to flatten the response IF the rear wave is not needed.
Yes, it is difficult to absorb the bass on the rear side. If the panels are not mounted against a wall, then there is very little attenuation on the bass, both front and rear, even with a baffle.
But if the panels are mounted flush against a wall, then the bass roll-off is not acceptable. I think this has to do with panel material being too stiff and operating in full pistonic mode at too-high frequency (approx 150hz) which requires phase-based damping from at least 1/4wl upwards.
So I need to experiment with floppy panels for the bass end so that there's at least some bending-mode activity happening in the 100hz region. The theory being that bending waves have out-of-phase components by default. Therefore, the cavity behind the panel, when vibrating in the (1,2) mode, and higher, will be zero loaded.
Watch this space.
But if the panels are mounted flush against a wall, then the bass roll-off is not acceptable. I think this has to do with panel material being too stiff and operating in full pistonic mode at too-high frequency (approx 150hz) which requires phase-based damping from at least 1/4wl upwards.
So I need to experiment with floppy panels for the bass end so that there's at least some bending-mode activity happening in the 100hz region. The theory being that bending waves have out-of-phase components by default. Therefore, the cavity behind the panel, when vibrating in the (1,2) mode, and higher, will be zero loaded.
Watch this space.
https://rachel-shirley.blogspot.com/2013/01/artstores-exhibit-different-types-of.html
https://en.wikipedia.org/wiki/Canvas
https://www.claessenscanvas.com/en/products/types-of-canvas
https://www.jacksonsart.com/blog/2018/09/13/choosing-the-right-canvas-for-your-painting/
@jaxboy
@spedge
@homeswinghome
@pelanj
@BurntCoil
I would like to ask players who have experience in using canvas
I want to test canvas
But I found that there are many specifications of canvas
Even if it is used on the oil painting frame, there are many kinds
May I ask which kind of SPL is higher for DML?
What is the SPL (dB/1w/1m) you are currently using?
What is the most suitable thickness?
https://en.wikipedia.org/wiki/Canvas
https://www.claessenscanvas.com/en/products/types-of-canvas
https://www.jacksonsart.com/blog/2018/09/13/choosing-the-right-canvas-for-your-painting/
@jaxboy
@spedge
@homeswinghome
@pelanj
@BurntCoil
I would like to ask players who have experience in using canvas
I want to test canvas
But I found that there are many specifications of canvas
Even if it is used on the oil painting frame, there are many kinds
May I ask which kind of SPL is higher for DML?
What is the SPL (dB/1w/1m) you are currently using?
What is the most suitable thickness?
Hello Xsuper
I didn't go so deep in the "specifications" of canvas. I just went to the DIY craft store near to me and buy something among the what was available. I guess it is a kind of canvas suitable for oil and for acrylic (not specific). It is linen (not cotton) in my case. I remember that because it is a difference with the examples I had (Spedge, Jaxboy I think). The second difference is the pad is made of balsa not light plywood.
If it is not too, in 2 weeks from now I can search for the paper describing the canvas I bought. It should be somewhere in my workshop...