[Gregory Roig]

Those will look awesome too!  It seems that for best sensitivity and detail I'll need to go with a poly panel. Any idea of difference in sensitivity between the two mediums for a given panel size?

  Need to think through the mounting and protecting of the poly for transportation.  Ideas welcome!

[OB_Newbie]

I wish I had measured more closely but from the hip.  I'd say 3-4 dB difference between the XPS and ply... being a heavier material, the dynamics, detail and high freq extension was also constrained on the ply panels.

This was on a thinner 1/16 ply not the 1/8 that Odal suggested but given the above I didn't pursue the thicker ply... someday though I want to try it with the 1/8" as they do look nice.  For protection, what about metal grills... this is what was in mind when I thought about the PA line array.  If you make the panels a bit smaller, the cross frame support pieces would add support to the metal grills and the frame in general.

Dye the panels black, coat the frames with Acry-Tech DuraTex and cover front and back with black metal grills... ought to look clean and professional... not that I've been thinking about this since you posted...   

Here are some metal grills.  More $$$ than I thought but given the overall low cost and good sound quality its still very cost effective overall. 

http://www.amazon.com/SHEET-BLACK-SPEAKER-WOOFER-CABINET/dp/B00MY6WAOW
 
 

[sedge]

Gregor
Sensitivity and detail is not the main issue here,if you have 40 ,50, or a 100 watt exciters ,the panel will only take so much before it reaches saturation point , I can do this with my 10 watt exciters on my eps panels(this is loud),smaller panels will reach saturation sooner , ply panels could reach the same volume levels before saturation but may take the full 40,50,100 watts ? A 100 watts exciter on a poly panel is ok but you might only be able to use 10watts before you start to have problems.
For pro work I would think you would need a speaker that reproduced clean clear sound to a large area ,minute detail that I love in my audio room from my poly panels (the guy at the back of the choir scratching his nether regions ) is not going to be appreciated by the audience .
So how loud the panel you use can go and how acceptable the sound is for the job you wish them to do is probably the starting point, you need to attach them to different panels and see what happens,it's the only way to learn and can take a long time , hopefully not as long as It did me.
Steve

[sedge]

OB_newbie
I'd say the difference in db between the ply and xps is more in the region of 10 db,the ply 3x2ft x3mm in the home is a very good full range speaker(40 hz to 20k),providing you use a hi powered exciter of course and make sure no LF bellow the 40 hz can cause problems,voices and instruments all sound very good ,I'm sure lots of people will like these as they are easy to make and very easy to listen to.
Should have posted this on the other site really.
Never mind.
Steve

[sedge]

I should have said eps not xps , I only have xps in 5mm thickness, the 25mm eps is the loudest material I have come across so far.
Steve

[OB_Newbie]

OB_newbie
I'd say the difference in db between the ply and xps is more in the region of 10 db,the ply 3x2ft x3mm in the home is a very good full range speaker(40 hz to 20k),providing you use a hi powered exciter of course and make sure no LF bellow the 40 hz can cause problems,voices and instruments all sound very good ,I'm sure lots of people will like these as they are easy to make and very easy to listen to.
Should have posted this on the other site really.
Never mind.
Steve

Eww, ouch.  That is a serious loss in sensitivity.   With every 3dB requiring a doubling of wattage a 1inch EPS/XPS driven by 4 watts would roughly require 40+ watts for the same output.

On my 1/16 ply it would less than half that easily.  Driven by my 15watt class D amp there was not a great difference.  I went with the thinner ply because I was concerned about sensitivity and dynamics.  I really want to go back and give the ply panels a listen.

I enjoyed them but missed the dynamics but need to strengthen the panel and treat with a hard finish... sure there is a lot more performance I can get out of them.

Also want to go back and try to double up shellacked cardboard... they seem much harder after a year plus of curing. 

[sedge]

You can xo the ply panel at 200 to 300hz or more , this stops the exciter overheating for the Same output.
Steve

[sedge]

not sure if this thread is dead or not but I will be posting pics and details of a ply panel that has a fr response frome 50hz to 20k with good volume from a 10 watt exciter,. this is all I have I'm afraid ,but would recommend a more powerful exciter for pro use and a higher XO,say 100 to 150hz or more depending on power output .
it will be much the same as I am posting on the NXT thread, but a more robust exciter should be used.
steve

[sedge]

this is My old rigid framed dml panel from 2016 better late than never i suppose, this is 2ftx3ft 3km ply i also have a couple of 6ftx2ft panels as well ,I have just posted this to start with to test how to post pics ,more to follow.
Will also take pics of the response when I get time.
Thay are practically full range if i remember ,I think something like 50Hz to20k we shall see.
Steve

[sedge]

Thought I would show the 6ft just for clarity,I used studwork timber mainly because it was cheep ,using a more substantial timber would probably sound better but this was an experiment so it could all have been a waste of time.
Everything was glued and screwed firmly down ,braces were put on the large and small ply panels the small one was glued to the exciter the large just had some foam between brace and exciter the second large panel had the excited free floating and the panel was 3mm hardboard ,that's about it really they went together very easily considering my woodworking skills.
The only drawback was i only had 10 watt exciters ,but that was plenty enough for testing and in the end the bracing increased the sound level compared to the naked free floating panel ,which was nice.
Now all I need to do is lump around a load of large panels in a small room and do some measurements oh what fun.

[sedge]

This is the 6ft ply had to lean this one up against the wall.
Notice the dip and the bump about the 10k region .

[sedge]

This is the 6ft hardboard.
Same dip and peek at 10k.

[sedge]

Same 6ft hardboard  with slight improvement without eq in the 10k area.

[sedge]

This is the 3ft ply panal




Starting to get cocky now 2 pics on the same post.
Same 3ft ply panel 10ft into room.
That's about it really ,pretty basic can't go wrong ,glueing  the exciter to the spine will protect it if the panel is dropped but I'm afraid ply panels tend to bend and distort with time,some foam could be better but not so safe.

[sedge]

These are the cramped conditions ,surprised I get anything decent.
And yes those are AA  batteries ,I think I used them to fill in some dips in the frequency response in the 100hz to 300hz area,I think there was another one but it fell off at some point.
So as I said pretty basic really ,but it works,obviously a more robust panel and exciter should be better ,RIGIDITY in the frame is the main thing so no 1inch soft wood or the like you don't want to damp the panel you want to increase the reflection back into the panel.
I think that's all so I'll be signing off.
Steve
Didn't mean to do all of this in one go ,I'm done in ,it's half one and I'm of to bed .
Good night.

[sedge]

Just remembered that in the pic of the rear of the 3ft panel there is a brace (should have been a lot more substantial) that helps deflects the strong standing wave that large panels have and usually shows up on large drumming sounds.

I would advise against using too small a panel as you would end up with a very hard as glass sound even with 3mms panels.

[sedge]

I should emphasise that I literally through these panels together without any thought to use golden ratios or shapes ,the panel was 6ft so half was 3ft,I was surprised and pleased with the sound they are not shouty or harsh sounding they also sounded good outside,not sure the neighbours though so.
The smaller panels for acoustic pro use maybe as long as you're not playing heavy pounding music ,they would need some minor tweaking for hif use and a sub to handle the lows.

I intend to turn them round and use them as room sound absorbing panels,could even leave the exciters on the panel,easily reversible for a laugh.
Anyway if i remember anything else ,which I might do,I'll add to the post.
Sorry it took so long.
Steve

[sedge]

Well that didn't take long.
Just remembered what I was thinking of doing to offset the warping panels.
The idea is to support the exciter let it have free movement back and forth and minimise wobble caused by the unbalanced exciter and the wires,I never did test this  properly .
So you would need a flexible strip of material say about 1inch wide and maybe 1 or 2mm thick or more depending on material , you'd have to try different lengths to see which works the best.
You'd then have to try out different methods and materials to attach the strip, maybe Dowling or preferably maybe XPS if the strip was Ali it could also help cooling.
Getting a bit carried away now must stop.
So this could sort out  4 problems in one  go.
Also of course mounting two exciters in push pull mode and bolted together through a hole in the panel could work ,did mean to try this as I only have 10watt exciters,the output would increase as would LF ,not sure about HF and exciter noises  but could be alright for pro use?
Better leave it there for now.
Steve

[xsuper9988]

OB_newbie
I'd say the difference in db between the ply and xps is more in the region of 10 db,the ply 3x2ft x3mm in the home is a very good full range speaker(40 hz to 20k),providing you use a hi powered exciter of course and make sure no LF bellow the 40 hz can cause problems,voices and instruments all sound very good ,I'm sure lots of people will like these as they are easy to make and very easy to listen to.
Should have posted this on the other site really.
Never mind.
Steve

Hi Sedge
I'm just getting started in OB
I have heard YAMAHA NS15 from my friend
But because it's an very old speaker
So i can't research it
And NS15 looks like DML
Because after hearing that time
I started to research and will build OB
But these days I found DML information
So I'm looking into DML and OB differences

I found from your article that DML seems to be able to reach low frequency of 40Hz
And you've been playing DML since 2015
If I want to assemble DML(40Hz~20kHz)
Can you give some assembly recommendations?

Thank you very much for your reply and help


This is my first novice post
Anyone who has listened to OB and DML, can you share the difference?
https://www.audiocircle.com/index.php?topic=185615.0

Yamaha NS15
https://therobbcollections.blogspot.com/2016/09/extremely-rare-japanese-stereo-speakers.html

[xsuper9988]

I confirmed today that the YAMAHA NS15 series is still a cone speaker, but this is a hard foam cone, and then it has a very small XMAX, which seems to have a little DML prototype