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Can't remember if I posted here or over at Parts Express, but I wonder if we should establish a common, easy and quick to build reference panel with a widely available exciter. This will be a panel that we can all compare against different panel designs. We have difficulty explaining differences because we have no reference to compare to.Curious what others on this forum think about this idea?
1. Rigidly mounting the panel to a frame results in more low frequency output? Makes sense to me as the overall weight of the panel now includes the wood frame.
I don't know what thickness your ply panels are ,but as you say, your panels sound like they are already heavily into dml mode,extra bracing might not help?Am a little puzzled why you are using square panels ,is there a reason for this?What position do you place the exciter to help prevent the stronger standing wave resonances caused by square panels?
As for exciters, my current favourite is the Dayton Audio DAEX30HESF-4. It can managed high SPL without distortion on Re-Board, has plenty of shove for the bass and seems a lot less prone to wobbling and voice coil droop than the DAEX25FHE-4.
Hey Steve - I was a bit hesitant to buy square panels as well but that's the only thing they had pre-cut...and I have to say that close to <10F temperatures with my saw in an unheated garage made my decision easy I haven't really had time to play them or optimize them much, but I ran a quick sweep before my computer decided to do an automatic upgrade that froze the computer. It follows about the same profile as the 4 x 2 panels which is my favorite size but cuts off the LF little bit higher: ~40Hz, and high end for the 30HESF starts to drop little bit over 10k Hz, and then dips down 10db. The only exciter I have managed to consistently get flat to 20hz on wood is the 25FHE, which has a smaller mount ring. I really think the larger mounting rings on the 40W exciters cuts the HF. I didn't have them free-floating so I had some of the typical dips and peaks in the LF. I currently have the exciter mounted in monacor position 1 so I can do like for like comparisons, but I have found that the position on wood requires a bit more fine-tuning by ear/mic to get right due to the woods areas with different densities.I tried a square panel in XPS before like the early ones OB made, and those were not too bad either.
OB_NEWBIEThis was the first eps panel I ever bought,as you can see there is a chunk missing from the bottom right side ,this was the part that broke off as I was flying across the car park,away from my car!This turned out to be lucky,as I had missed running into the parked car's so far,but was running out of space.I had now managed to stop but I was now flying a 6x4ft Kite above my head ,I managed to walk backwards towards my car dragging the panel with me.The fun really started when I got back to my car ,as I had to land the panel like a plane by the side of my car and cut it up I had to slide across the panel to hold it down while I opened the car and get out the knife ,measuring tape and wood,for a straight edge.You know that moment after you've managed to finally get it all cut up and in the car,where you stop and nonchalantly look round to see if anyone was watching,I couldn't see anyone ,but always will be a little suspicious,there could have been person's crouching behind car's clutching their stomachs in need of medical attention This was the panels setup in my living room,notice the missing piece glued back in place bottom right I'm showing this as the one on the right was large and square,I played a recording of big Ben over these panels and it sounded fantastic , I seem to remember that the larger the panel the less importance the shape made, but we are talking large.I certainly wouldn't recommend using a small round or square panel as this would cause problems,and if used,offsetting the exciter is a must !To me,the sound came mainly from the centre of the panel and gave a strong image even when walking between and around the panels,the rest of the panel seemed to disappear,these days I tend to forget this and regard this as the norm,that is until I listen to NORMAL speakers ,even very ,very expensive ones at that,but they just don't sound REAL anymore !!!!I'd sit in front of my speakers and say wow listen to that sweet treble or midrange ,cool,NOW ,with the panels I listen to the music and the instruments,no hifi,no amps,no cables,just live music.Nowadays when I go to audio shows I just sit there thinking ,oh dear ,what have they done!!!!Steve
Have just finished the frame on the ply panel,will wait a few days before measuring to see if anything out of the ordinary happens,not yet used a cross brace to support the exciter,but don't expect much to change in the low end as I roll them off heavily below 50hz anyway,but we will see.Seem to remember the 50-50 eps panel rolled off heavily at about 50hz when the cross brace was installed.Steve
OB_NEWBIEThe eps I use has no holes in the surface and the surface is quite hard,I haven't a clue what grade it is ,at a guess I'd say probably a medium?I can only find the low grade in the shops at the moment ,too many holes in the surface for my liking,that's why I'm playing around with others materials at the moment ,so hope they bring back the good stuff as ordering from the manufacturer is expensive.Mmmmmmm as I'm typing this ,I just thought I could buy the 6x2ft 3mm ply ,and solidly mount in a frame,if it doesn't perform well I can easily saw it in half,then I will still have two 3x2ft panels that I know perform well.Solidly mounting them on the floor might help the low end performance, the only worry would be that the larger panel might cause a bit of low end boom.My memory is getting sooooo bad,I just remembered some more mods I was going to try out on the ply ,I will get there eventually ,just too much going on in my life at the moment How much pva you apply to the panel is always going to be a personal choice,it's a very much like the light delicate paper cone choice or the doped paper cone or any of the other types of cones ,which do you prefer,all of these cones have their champions,and usually perform well in certain area's ,I think it usually comes down to which annoys you the least,I have used many ways to damp the self noise of panels and cones , but usually you end up damping the sounds you love too Steve