I have done very little testing with ply panels, except whizzer cones and paper strips and now cling film.
I intend doing some more odd things with this ply panel when I have finished testing Eucys dome.
ultra high density EPS sounds like it is going to be very rigid, what thickness is it and size, I have no idea how this will sound.
I would expect a similar frequency performance to the ply (rigid) panel , but be far more efficient.
Maybe you could ,as it is sooooo cold, just sand the area you intend to glue the exciter on ,a few inches.
Then apply the pva to the sanded area, this way you can listen to the basic panel and compare the difference when summer finally comes.
My wife thought it was highly amusing yesterday ,seeing me in my room wearing a coat ,scarf and bobble hat 😬
I thought it all sounded a bit muffled, until I realised I'd pulled the bobble hat over my ears 😂
I have found that cleaning up the sound from within the exciter ring area is very important, reducing distortions and harshness and improving clarity .
There are different ways this can be done depending on panel materials and tastes.
I am always looking for new ideas to fix this problem.
Steve.
@Veleric
Well the sample turned up and if that is an EPS layer I am a Hamster and you can call me Shirley.
It’s a hard black polymer and an A3 panel weighs 475 grams. I will be returning the panels and asking for a refund.
I am now interested in skinning EPS with a thin Alu sheet …
Burnt.
Hi Shirley 😀
The eps will heavily damp the Ali panels, so you will probably have a very inefficient panel.
I coated a 5mm eps panel ,one side only though, and it was very dead ,worth a try with two Ali sheets , maybe ?
I found gluing 2 sheets of very thin Ali together a better option with good hf.
Not too large though.
Steve.
Hi Shirley 😀
The eps will heavily damp the Ali panels, so you will probably have a very inefficient panel.
I coated a 5mm eps panel ,one side only though, and it was very dead ,worth a try with two Ali sheets , maybe ?
I found gluing 2 sheets of very thin Ali together a better option with good hf.
Not too large though.
Steve.
Burnt,
Bummer.
If you try skinning EPS with aluminum, you probably want a very thin EPS sheet, otherwise it could be monster stiff. What thickness of aluminum do you have in mind?
Eric
You'd have to use contact spray or epoxy resin as an adhesive?
I've tried this, and the result is okay-ish. I used 20kg/m3 EPS, 10mm thick, and kitchen alu foil @ 6.5g/m2. I think the final panel weight (600mm x 410mm) came out to 290g including adhesive. But 10mm is too thick for EPS, and because of its low compressive strength, the highs get lost (Thomas suggested that I measure front and back when doing FR testing to confirm the highs actually do or do not transmit through the core.)
For me, a better solution would be a higher density EPS (or maybe XPS) and maximum 5mm thickness.
Yes, very stiff indeed. But I got an Fc of 2,140Hz to my surprise... I expected much lower.
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Three way comparison on a 30x40cm 2mm thick ceiba ply panel secured to a frame at regular intervals.
YELLOW - Standard panel with no bits added on
PINK - Panel with aluminium 30mm 'dome' fashioned from a food tray
GREEN - Panel with pea sized bit of blutack on the front in the exciter area.
All measurements taken from my listening position. 1/6th octave smoothing.
The green peak between 6k & 10k is interesting with the blutack.
The aluminium dome offers a bit more between 1.8k & 3k.
I wonder what happens with the dome AND the blutack. Only one way to find out...
YELLOW - Standard panel with no bits added on
PINK - Panel with aluminium 30mm 'dome' fashioned from a food tray
GREEN - Panel with pea sized bit of blutack on the front in the exciter area.
All measurements taken from my listening position. 1/6th octave smoothing.
The green peak between 6k & 10k is interesting with the blutack.
The aluminium dome offers a bit more between 1.8k & 3k.
I wonder what happens with the dome AND the blutack. Only one way to find out...
Attachments
Sorry I have a problem that I really can't solve, my vibrating plate is carbon and nomex the problem is that I can't stabilize the 4 exciters in the back, basically they croak at low volume due to the weight of the magnet, to solve go I mounted a perforated grill thinking I could use the central screw but for some strange reason it doesn't work if I press too much it changes the sound, I also tried to screw it on the lugs but since there is no thread it doesn't seem to hold up. Then it must be said that the magnets move at a high volume, in short, a problem that seemed simple has become a nightmare. I kindly ask you for a solution if possible because I really don't know how to solve it.
I forgot if I position the panel with the exciters horizontally
holding it on the frame everything is fine as soon as I put it vertically it starts to vibrate because the exciters are inclined
Thank you
I forgot if I position the panel with the exciters horizontally
holding it on the frame everything is fine as soon as I put it vertically it starts to vibrate because the exciters are inclined
Thank you
I've reduced the amount of blutack by 75% to the size of a Waitrose petit pois rather than a Co-op garden pea. It has smoothed a peak at 11k and shifted it to the left. Overall response above 10k is reduced, but more easily fixed with EQ.
PINK - Plain panel
GREEN - small blutack
PINK - Plain panel
GREEN - small blutack
Attachments
If you have a powerful, heavy exciter, then its magnet needs to be anchored (screwed or glued) onto a substantial brace that extends onto both sides of the frame.
You have to be very very careful that the voice coil is not under stress when at rest. It must not be angled, or shifted left/right/up/down. It has to rest in exactly the same position it does when it's not mounted to anything.
Lordtarquin.
I was going to suggest using a much smaller peace of blu-tack .
The blu-tack is reducing the peak at 11k too much and also filling in the suck out at 8k .
with the right size, and weight of blu-tack these two will level out.
what is more worrying is the roll off above the 2k to 3k points.
Steve.
I was going to suggest using a much smaller peace of blu-tack .
The blu-tack is reducing the peak at 11k too much and also filling in the suck out at 8k .
with the right size, and weight of blu-tack these two will level out.
what is more worrying is the roll off above the 2k to 3k points.
Steve.
The thinnest I can get at the moment is 0.5 mm Eric. I think if I go any lower I will be in foil territory where the physics of the EPS will dominate
Burnt
Grazie, si infatti stavo cercando di fare esattamente quello che hai detto, il problema è che usavo quel sistema dayton che permette di avvitarlo all'adattatore, questo ovviamente ti costringe prima ad avvitare l'eccitatore e poi a stabilizzarlo dietro , ma visto che non ci sono riuscito dovrei agganciare tutti e 4 gli eccitatori al pannello posteriore e poi agganciare la membrana davanti. Questa cosa rende le cose dannatamente più complesse a causa dello spessore del telaio di 5 cm. Volevo chiedere ma se il magnete è agganciato posteriormente con una piastrina che a sua volta è attaccata al telaio su due lati quando il magnete arretra non crea problemi?