A third of the density? When I look up poplar plywood I find 400 kg/m3. The data sheet I linked to has density as 0.5 g/cm3 = 500 kg/m3. But still a contender I think. Have you found a lighter version?
More on material densities (all in KG/M3):
Birch Plywood: 700
Poplar Plywood: 520
PVC Foam Board: 210
XPS: from 25 to 45
Gatorfoam: 30
Very high grade EPS: 30
Low grade EPS: 11
By my arithmetic, 3mm thick PVC foam board has just over twice the mass of the same size very high grade EPS. Either of the plywoods in 3mm thickness will be at least 8 times heavier than the VHG EPS for a given size.
Lightweight canvas art panels are 280g/m3, so 40x30cm is around 34g.
Other materials for a 40x30cm panel come in at:
3mm birch ply: 252g
3mm PVC foamboard: 76g
10mm VHG EPS: 36g
10mm Gatorfoam: 36g
5mm Gatorfoam: 18g
There's a whole range of posts from p57 on different materials. At the end of the day, it's what sounds best that matters. High density EPS seems to get very good comments overall. I'm wondering if it's the lack of paper or other surface coating.
My plan when I return from a short trip away is to compare:
1. Free floating VHG EPS
2. VHG EPS attached to a frame BIF style (actually neoprene rubber in my case)
3. My own panel suspension system where the panel is attached to an oversized frame via neoprene rubber. (Think of a conventional cone speaker where the paper or other materlal cone is attached to the frame either with rubber or foam). A gap of around 1cm between the panel and the frame seems to work well.
Birch Plywood: 700
Poplar Plywood: 520
PVC Foam Board: 210
XPS: from 25 to 45
Gatorfoam: 30
Very high grade EPS: 30
Low grade EPS: 11
By my arithmetic, 3mm thick PVC foam board has just over twice the mass of the same size very high grade EPS. Either of the plywoods in 3mm thickness will be at least 8 times heavier than the VHG EPS for a given size.
Lightweight canvas art panels are 280g/m3, so 40x30cm is around 34g.
Other materials for a 40x30cm panel come in at:
3mm birch ply: 252g
3mm PVC foamboard: 76g
10mm VHG EPS: 36g
10mm Gatorfoam: 36g
5mm Gatorfoam: 18g
There's a whole range of posts from p57 on different materials. At the end of the day, it's what sounds best that matters. High density EPS seems to get very good comments overall. I'm wondering if it's the lack of paper or other surface coating.
My plan when I return from a short trip away is to compare:
1. Free floating VHG EPS
2. VHG EPS attached to a frame BIF style (actually neoprene rubber in my case)
3. My own panel suspension system where the panel is attached to an oversized frame via neoprene rubber. (Think of a conventional cone speaker where the paper or other materlal cone is attached to the frame either with rubber or foam). A gap of around 1cm between the panel and the frame seems to work well.
Pway.
zenker is an engineer and sets himself a goal to change things like radiation patterns and so forth.
This is not going to increase the quality of the sound,but in certain circumstances (like most patents)it would be useful ?
What he does is very interesting ,but most of it is of no use to me as my only goal is to produce the best sounding panel possible.
In other papers he compares other speakers to dml ,the dml does not do well compared to the other speakers.
This is not surprising as he is using inferior materials and techniques .
But for general low quality work around buildings and kitchens and so forth,he thinks they are acceptable.
It all depends on what you want from a panel,you can manipulate them to improve measured performance in certain areas, but I have found it will usually have a negative effect on the sound quality of the panel.
I have also found that what is good for one type of dml panel is not necessarily good for another type of dml panel.
It would be so easy if it was.
Steve.
zenker is an engineer and sets himself a goal to change things like radiation patterns and so forth.
This is not going to increase the quality of the sound,but in certain circumstances (like most patents)it would be useful ?
What he does is very interesting ,but most of it is of no use to me as my only goal is to produce the best sounding panel possible.
In other papers he compares other speakers to dml ,the dml does not do well compared to the other speakers.
This is not surprising as he is using inferior materials and techniques .
But for general low quality work around buildings and kitchens and so forth,he thinks they are acceptable.
It all depends on what you want from a panel,you can manipulate them to improve measured performance in certain areas, but I have found it will usually have a negative effect on the sound quality of the panel.
I have also found that what is good for one type of dml panel is not necessarily good for another type of dml panel.
It would be so easy if it was.
Steve.
Spedge:
I think Zenker's goal is the same as yours - to optimise the quality of the sound. Whether it be the LF or HF response, the dispersion pattern, impulse response etc. He always makes an argument based upon previous work, and investigates what effects the quality of the sound.
I think Zenker's goal is the same as yours - to optimise the quality of the sound. Whether it be the LF or HF response, the dispersion pattern, impulse response etc. He always makes an argument based upon previous work, and investigates what effects the quality of the sound.
So what would you use or recommend to use to fill the low end using panels? A common regular sub bass driver box?
Thanks. Another google search says PVC foam can have density as low as 45 kg/m3, but I cant haven't found density figures for other products than the one I linked to. The 210 you quote could be very good. DO you have a product link for this?
The PVC foam products I've seen have a glossy surface (for printing on), and are harder than XPS/EPS. Thin and relatively hard is good because 1) the material needs to be much thinner than the wavelength of the bending wave it's carrying (generally the assumption is 6 times smaller for bending wave papers) and 2) a harder surface means less energy is lost to the foam compressing under the high accelerations (forces) at high frequencies. The Dayton guide to exciters also mentions that high compressive strength is better.
For XPS, my experience has been the same as what I've read elsewhere on this forum - the hf stays very near the exciter and does not propagate far, nor does it properly penetrate the foam. It would seem to not to be acting as a traveling wave, or the energy is absorbed too quickly by the foam, either at the exciter interface or as it propagates.
I believe this is why high density EPS grades are better too - higher compressive strength, and available down to 10mm thickness. Ive not tried it yet because for high densities I would need to buy a large quantity.
Pway
This is what I found. I'd only looked at the top density and missed the other two! PVC Foam Sheet, Tape & Board Manufacturer | Alanto Looking further I have also found it in densities in the 40 range.
This is what I found. I'd only looked at the top density and missed the other two! PVC Foam Sheet, Tape & Board Manufacturer | Alanto Looking further I have also found it in densities in the 40 range.
I can only speak about my own experience, but I've had success with open baffle bass. However, you need a room that will take it. Otherwise I'd probably go for a sealed box design with maybe a 12 inch driver. This was certainly the late, great Siegfried Linkwitz preference.
I like the 'idea' of full range drivers, especially with the ability to avoid crossovers in the all-important midrange area. I'm also not a huge fan of using power and performance sapping crossover components if I can help it.
However, I also like large scale orchestral works and these can move a lot of air. This leads one to two possibilities: a large full-ranger, or a smaller full-ranger plus bass support for say up to 300hz.
However, this then gives is issues with (a) treble extension and (b) treble beaming.
I was looking for a solution that (a) avoided crossovers in the midrange (b) gave clean bass (c) avoided treble beaming (d) gave sufficient treble extension (e) gave a bit of flexibility in seating position.
As well as moving enough clean air in the bass department, I also like 'air', treble extension and a soundstage that falls behind the speakers as well as offering height.
In my experience of trying many speakers and DIY speaker projects (usually dismal failures), and becoming tired of the typical 'point and squirt' delivery of traditional boxed speakers, I have found that Open Baffle bass together with medium sized DML panels have been the only speakers that have delivered the most of what I like.
I look at it in the same way that one would look at a live performance. Sound emanates from all directions with many reflections from the venue. My OB bass plus DML approach gets me closer to what I might experience at a concert in way that no other speakers have done for me to date.
I should stress that I am on a very limited budget. I have heard amazing systems at hifi shows but at prices that are quite eyewatering.
Oh. That won't be suitable I think, because it's open-cell foam, presumably more like a kitchen sponge than a rigid panel.
Yes but now we're back to density 500 I think. Foamex seems to be the same type of board I linked to originally.
Foamex Board | PVC Foam Sheet | PAR Group
Foamex Board | PVC Foam Sheet | PAR Group
3mm White Foamex
I put some sample dimensions in - 400x300x3mm and it came up with a panel weight of 36g. That gives a density of 100.
In other words, 10mm VHG EPS and 3mm Foamex come in at the same panel weight.
I put some sample dimensions in - 400x300x3mm and it came up with a panel weight of 36g. That gives a density of 100.
In other words, 10mm VHG EPS and 3mm Foamex come in at the same panel weight.
Pway.
I'm all for extending the HF and LF of dml as long as the panels can handle it and it does not seriously effect the sound quality.
As for restricting the omni directional sound of the dml ? and reducing the decay time ?
If you have a panel that sounds very good from the get go, you don't need to do all the things he is suggesting.
If I followed his suggestions in his papers I'd end up with a fairly poor sounding panel.
But he is designing for use in car doors, walls,and anywhere the panel can take over from low quality speakers, so I can understand the problems he is trying to overcome.
If he has made a high quality dml panel speaker I'd be very happy to read about it ?
Steve.
I'm all for extending the HF and LF of dml as long as the panels can handle it and it does not seriously effect the sound quality.
As for restricting the omni directional sound of the dml ? and reducing the decay time ?
If you have a panel that sounds very good from the get go, you don't need to do all the things he is suggesting.
If I followed his suggestions in his papers I'd end up with a fairly poor sounding panel.
But he is designing for use in car doors, walls,and anywhere the panel can take over from low quality speakers, so I can understand the problems he is trying to overcome.
If he has made a high quality dml panel speaker I'd be very happy to read about it ?
Steve.
Carlmart.
I don't personally have a preference for subwoofers ,as long as they sound good.
I have heard good and bad of all kinds of loading.
But if you are running them up to say 300hz they must sound good in the lower midrange.
OBs would be good for this but may not satisfy the very deep low end ?
It's down to your personal tastes .
Steve
I don't personally have a preference for subwoofers ,as long as they sound good.
I have heard good and bad of all kinds of loading.
But if you are running them up to say 300hz they must sound good in the lower midrange.
OBs would be good for this but may not satisfy the very deep low end ?
It's down to your personal tastes .
Steve
I'd definitely like to try some of that. So 'foamex' must be a generic name for a range of products. I hope it's correct, hard to believe it can be 5 times less dense and fulfill the same function!
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I'm trying to clear out some of the old panels in my room.
These are test panels and are mostly not needed any more,so it's the tip for most of them.
These are the ones I can get to in my room at the moment, there are more behind the curtains and under the stairs and dotted around the house and loft.
It's time to sort out my room for listening to music and not as a work room.
Fun as it has been , it's time for me to relax and enjoy the music.
Steve.
These are test panels and are mostly not needed any more,so it's the tip for most of them.
These are the ones I can get to in my room at the moment, there are more behind the curtains and under the stairs and dotted around the house and loft.
It's time to sort out my room for listening to music and not as a work room.
Fun as it has been , it's time for me to relax and enjoy the music.
Steve.
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Steve,
I've ploughed through about 40 pages of the old Audiocircle thread. In it, I found reference to your suspension ideas.
And yes, whilst experimentation is fun and part of the learning process, my dodgy back and aching limbs mean that my efforts need to be very tightly focused. So it's going to be the ultra high density EPS for me I think - 10mm x 400mm x 600mm from here: EXPANDED POLYSTYRENE SHEETS FOAM PACKING VARIOUS THICKNESS AND GRADES | eBay I bought some of the second highest grade 25mm EPS from them before and it seems to be very good quality.
I'll probably go with a minimal suspension setup - just enough to stabilise it in a room that tends to be a thoroughfare with lots of air movement. Freely attached exciters too with no spine.
One thing I need to check up on is whether you 50/50 PVA both sides to the sanded surfaces. My better half already has some mixed for sizing walls before she wallpapers a room.
Some Tectonic exciters arrived just before I came away for a few days break, so I will be cracking on in a few days time.
Simon.