Hi Spedge - Thanks for the testing comment
your density is 423g/m3 - perhaps a bit heavy for poplar - maybe a pine species - most packing materials in Aus are radiata pine so probably your local variety
Eucy
With this figures, it seems it is poplar plywood. The poplar by itself is given for 390kg/m², some additional glue (250g/m² for a 3 layer???). This fits the usual "white" color of such crate wood.
As you are testing different panel shapes (from 1 to 4 strips), could you check if the efficiency is modified by the shape ratio. It was pointed recently that high shape ratio might have better efficiency (in their range of use of course)?
How is your perception of stiffness along and across the grain of the surface layer?
If you want a new proposal for further test : what about having the grain something like 30 to 40° of the direction of the long side ? The piano soundboard are made like that with the grain not in the main direction of the piano.
Christian
Sorry, I didn't see you post before replying... At least in France, pine is less common in non structural plywood. Pine plywood has a white color with more brown/yellow wood vein. Poplar is almost fully creamy white.
Hi Spedge - Thinking about your pic, it struck me that given the extent the plywood versus the canvas, that you have perhaps inadvertently created a fabric suspended plywood dml panel rather than a plywood reinforced fabric panel
Hi Christian - Yes - I also wondered about the colour - it does look uniformly pale like poplar. Poplar is softer and more open grained than pine - that should be a giveaway. It's Interesting how timber usage varies between countries.
In USA poplar almost always has a greenish tint and some greyish streaks
Christian and eucy.
One side of the ply seems whiter than the other side, I've turned the strips around to match the colours.
The darker side has a more brownish tinge with brown streaks.
This panel material is quite springy , not sure if this is the reason for its good sound and maybe efficiency ?
I have run out of strips and panels .
So I now have a large panel made of strips, a small panel and an art panel using the same ply.
Plus 3 core strips with no outer ply.
When looking for vegetable crates , all I seem to find is the repro stuff for storage boxes.
So I have come to a bit of a dead end.
Steve.
One side of the ply seems whiter than the other side, I've turned the strips around to match the colours.
The darker side has a more brownish tinge with brown streaks.
This panel material is quite springy , not sure if this is the reason for its good sound and maybe efficiency ?
I have run out of strips and panels .
So I now have a large panel made of strips, a small panel and an art panel using the same ply.
Plus 3 core strips with no outer ply.
When looking for vegetable crates , all I seem to find is the repro stuff for storage boxes.
So I have come to a bit of a dead end.
Steve.
https://endurancelasers.com/density-of-various-kinds-of-wood-and-plywood/
I presume all of these are high quality plys ?
It is very confusing if you have no idea of what you are looking for.
Steve.
I presume all of these are high quality plys ?
It is very confusing if you have no idea of what you are looking for.
Steve.
Hi Spedge - I recommend this site for lots of good info on tone wood species - always a good place to start. Under 'Species List' you'll find species details in alphabetical order
http://tonewooddatasource.weebly.com
Eucy
+ @spedge
Thank you for those links. Always interesting to have the wood density and some aspect references.
I like the home page of the "tonewooddatasource".
Christian
Here was the same exciter used for the EPS and naked canvas panel ?
in the shown frequency response, EPS was showing little drop in high frequencies where as the canvas was showing smooth flat even level of high frequencies till the end.. so does the high frequencies is not entirely controlled/contributed by exciter itself?
what factors decide the high frequencies extension .. on many frequency responses in this thread we have a roll off from around 10k, and only very few times seeing even response till 20KHz..
Hi Steve,
is it the final/best version so far, for the full range canvas panel ..
i think the earlier recommended full range canvas panel was like 16 x 12 inch canvas, with 6 x 4 inch thin plywood at the center of the canvas , 50% diluted PVA or acrylic coating on the canvas and ply , and then exciter attached in the center of the plywood..
Could you please provide details of the final version .. what is the size of the plywood to be used and what thickness, and other details .. do we need to use 16 x 12 inch canvas or need little bigger for better full range frequency response ..
Also does more bass comes from "larger naked canvas area and smaller plywood area" , or "lesser the naked canvas and larger plywood area" gives more bass and full range sound ??
Is the DAEX25FHE most recommended exciter to use.. finally found it at https://www.soundimports.eu/en/dayton-audio-daex25fhe-4.html
with around $20 shipping to my place.
But the cost of this exciter (excluding shipping charges) is less than DAEX25Q which is available locally here.
with around $20 shipping to my place.
But the cost of this exciter (excluding shipping charges) is less than DAEX25Q which is available locally here.
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Why am I now envisaging a packing crate guitar with lots of jagged edges and nail holes
??Attachments
Sarathssca.
the exciters I use can reach 20k easily, depending on material used obviously.
Even my low grade EPS coated in pva reaches 20k.
the lowest grade without pva coating struggles to reach 8k.
I've never had trouble with hf with ply, usually ply has a strong hump in response between 10k to 20k with my exciters.
The very low grade crate ply seems to be the exception ,and gives a flat response between 10k and 20k ?
when I put a dome on my exciter to see what sort of response I would get it I used it as a tweeter , it had a response from about 2k to 20k , if I remember correctly .
Steve.
The canvas panel is still an on going project.
The idea was to eventually add a larger 2mm ply panel to the canvas with a few alterations, for a better response.
But I was not expecting the response from the crate ply !!
This already exceeds my expectations of what I was hoping to achieve.
To be honest , I was leaning more towards an all canvas panel with roll of at about 200hz for best sound.
The larger ply panel does prevent a lot of canvas flapping and buzzing , as pointed out the design so far is more like a ply panel with a canvas surround mounting.
I have made it quite clear that I have problems with the sound of hard rigid ply panels and use methods to reduce this problem , but without damping.
So you can imagine my surprise when I attached the crate ply ,and wondered what the hell was going on !
I thought I had flicked a switch or done something wrong in the setup, which has happened before.
To your questions, the art panel I use is 42cm by 30cm ,this is just as close as I could get to the patent size, but I am sure other sizes should work too.
to be honest I'm not really interested in using any panels below about 100hz , it just doesn't make sense to me anyway, as I prefer the high output from me TLS .
In my last recordings the panel on the right was my art panel , this was the only panel that was reaching 40hz ,the ply strip panel was only going down to about 60hz max.
The art panel plays the double bass very well.
The ply panel on the art panel is about 11inches by 7inches ,this was the largest size I had ,if you want to use larger sizes you can try ?
I'm not sure of the response I would have had if I had used ordinary ply with a few of my alterations ?
As I have said it is an on going experiment , but not a priority for me, as I don't really need the low end that much.
I hope this answers some of your questions.
Steve.