Which is the question of the benefit or not of a more or less orthotropic material...
The common plywood is with a cross grain structure. A in line grain structure may need a specific sourcing with the according cost. Without an idea of the benefit, it could explain nobody tested it.
If one truly wants to test an "in-line" structure, there is no reason it needs to be plywood. Guitar soundboard material could be used.
Eric
The veneer panel I made with the grain running in the same direction worked quite well, although it would have been nice to have it made in a larger size to see if it could work better?
It was about 17.5 cm x 34cm with an overall thickness of about 1mm I believe.
I just happened to have this material in a drawer for some reason ?
Steve.
It was about 17.5 cm x 34cm with an overall thickness of about 1mm I believe.
I just happened to have this material in a drawer for some reason ?
Steve.
Koskiflex is the product from Makerstock with an 'In Line' Grain, the increased flexion properties are clearly evident.
https://makerstock.com/products/birch-plywood-flexible
https://makerstock.com/products/birch-plywood-flexible
My take on this remains as discussed ages ago with Eric.... They are fundamentally different... With the main ply direction transversely arranged, the transverse stiffness dominates the panel and compromises low frequency performance. Imo, if using anisotropic material in a rectangular panel, the 'grain' must be vertically aligned. Although I have at times thought about using a slight angular bias off vertical, but haven't tried it.
Eucy
When an individual goes to the extent of producing their own Panel using the Plywood Structure for the Panels Design, there are options on how the Tiers can be laid upon each other.
These same options can also leas to researching stiffness for a Panel and where the optimisation for Dimension vs Flexion is to be found.
As a suggestion, not all Tiers need to be full panel dimension, a Tier within the Sandwich could be strips only of a selected Width and are the only Cross Grain used in the Tiers, as an example a 25% - 75% surface area of the main Panel Dimension could be a Cross Grain area, with different %'s of coverage to be used to create different flexions across panels being produced?
These same options can also leas to researching stiffness for a Panel and where the optimisation for Dimension vs Flexion is to be found.
As a suggestion, not all Tiers need to be full panel dimension, a Tier within the Sandwich could be strips only of a selected Width and are the only Cross Grain used in the Tiers, as an example a 25% - 75% surface area of the main Panel Dimension could be a Cross Grain area, with different %'s of coverage to be used to create different flexions across panels being produced?
This can also be achieved by laying strips of yellow trace paper on panels... You'll have to search it out on this forum
Eucy
When Panel Flexion being Optimised is a requirement for creating Sound that is improved.
It certainly makes sense to try out methods that create a Structure for a Pabmnel where there is differences in resistance on a Panels freedom to flex.
From reading reports/descriptions of experiences had, it seems Panel Weight/Panel Flexion are selected by an individual as a preference.
Maybe all individuals building these Panels will not settle on a One Weight/One Stiffness of Panel only solution. There will be a range of designs that are Wed to.
It certainly makes sense to try out methods that create a Structure for a Pabmnel where there is differences in resistance on a Panels freedom to flex.
From reading reports/descriptions of experiences had, it seems Panel Weight/Panel Flexion are selected by an individual as a preference.
Maybe all individuals building these Panels will not settle on a One Weight/One Stiffness of Panel only solution. There will be a range of designs that are Wed to.
Hi,
I've been following this thread on and off for some time now. I finaly have the time to build my own DML panels now and would like to start with somthing "proven" to be good. What quality is the EPS panels you use, I think I refere to density. There are S ratings for EPS panels like S80 and S150, lower numbers mean less density, contains more air. What S rating should I aim for? I will use 15" woofers open baffle and wish to cross over around 300hz to the DML panels.
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@Pepe Availability of different qualities of EPS is quite limited unless buying in bulk. I order from here, and had great success with their graphite enhanced 25 kg/m³ plates: https://www.dekokopf.com/neopor-styroporplatten-3er-set-50x33x2-5cm.html
I would not x-over at 300Hz for a couple of reasons. First of all I really like the sound of the plates from 120Hz upwards, and secondly it is hard for a sub to cover that high, and I don't want to have separate sub and kick with extra x-overs. And crossing around 100-150Hz usually works well...I guess since that is a region where the plate goes from wave to piston, and sound goes from directional to omnidirectional anyway.
I really like the Xcite XT32, which was a noticeable improvement in sound quality compared to the Daytons I used before.
I would not x-over at 300Hz for a couple of reasons. First of all I really like the sound of the plates from 120Hz upwards, and secondly it is hard for a sub to cover that high, and I don't want to have separate sub and kick with extra x-overs. And crossing around 100-150Hz usually works well...I guess since that is a region where the plate goes from wave to piston, and sound goes from directional to omnidirectional anyway.
I really like the Xcite XT32, which was a noticeable improvement in sound quality compared to the Daytons I used before.
@Leob My xo point where based on an assumption that the DML panels would benifit from being reveild of the low end and allso because I listen to music with stong impulses in the sub to 200~300 hz region. I will have to play around with xo point and will probably get an active xo to make it simple(r) (minidsp or similar).
I will use two stereo amps to drive this set up. No sub amp at this point.
I think we have quite good shops around here, rc hobby and art shops carry som different types of EPS etc...
Thanks for the reply, appriciate all the help and food for thoughts I can get to avoid as many DML noob pit falls as possible.
I will use two stereo amps to drive this set up. No sub amp at this point.
I think we have quite good shops around here, rc hobby and art shops carry som different types of EPS etc...
Thanks for the reply, appriciate all the help and food for thoughts I can get to avoid as many DML noob pit falls as possible.
DML is not great at producing a strong punchy sub, but for mid they are great IMO, and you don't need a big plate or lots of power to go down to 120Hz. I mostly play electronic music where a strong low mid is needed, and a good DML can deliver that really well.
Of course it depends on a few factors as well as taste, but I would definitely try using a lower x-over.
Of course it depends on a few factors as well as taste, but I would definitely try using a lower x-over.
Well if I could get away with crossing over that low (120 hz) I might just use a mono sub amp for the woofers. I might start there since it would simplify my system quite a bit.
Pepe,
I think Leob's suggestion for the Xcite XT32 is a fine choice. My own preference is the for the 25 mm variety, they do the highs a little better and don't compromise too much (IMO) on max power.
I like all of these:
Xcite XT25
DAEX25FHE-4
DAEX25VT-4
I don't doubt that the quality of the XCite units is better, but I have not had much problems with either of the two Dayton's above.
Eric
Well if the xcites are of higher quality I’ll just buy the 25mm and 32mm and try and see wich I like the most since they are so cheap. I can hardly hear anytning above 13000hz so I might prefere the 32mm.
I know people often use weatherstrip foam as edge damping but has anyone tried a stretchy fabric surround? I imagine it would need the exciter to be supported.
My thinking is the piston action in the low frequency range would be less restrained. I guess it may need some edge damping or else it could be like a free plate and ring.
My thinking is the piston action in the low frequency range would be less restrained. I guess it may need some edge damping or else it could be like a free plate and ring.
Not tested but for me it makes sense as there are several indications to let the plate as free as possible. It seems to be a cousin of the canvas panel.
Hello pepe.
Here is a guide to eps densities and grades.
This is a very expensive way to buy eps because of quantity and postage.
https://www.custompac.co.uk/polystyrene-cut-to-size
Personally, for home use I would keep the grade down to 70 grade 14kg/m3 or below .
About 10mm seems to work well for the size of panel in my video you posted.
Diy stores do sell 1inch 70grade eps very cheaply in the UK, which I have used for my larger panels.
I do run my panels down to about 100hz or so depending on the panel, but I always run the low frequencies up to about 300hz to combat the room suck outs that can occur in this area.
The panels will sound very week and lacking if you have a 10db dip in the response before the subs can take over.
A good thing to do is probably (if you have a flexible XO) XO at 300hz , then while listening to music or a frequency response plot , I lower the panel response slowly down to about 100hz and see how it sounds.
There will be a point where the output from the panel will make very little difference to the sound , this is where i would probably roll off the panel response , as long as the roll off is not too low.
This should give the panels a more full bodied realistic sound.
The hf in the exciter area should reach 20k (as long as the exciter is capable) and above if the measures I have shown are used, although these measures are mainly used to improve the sound of the panel, and not to increase the hf, but it is a bonus effect 😉
Steve.