[sedge]

bowerR64
with a small panel of that size using ali , I would expect the panel to reach 20k .Try it first and see,save money and time .good luck.

[sedge]

on my left I was running a 2 ft x1ft panel  xo to a sub , on the right I had a 4ft x 2ft panel  full range .The sub 15 inch ran up to 300 hz aprox .If I cut the lows to the sub there was a lot les LF power [and boom !] but also when I cut  the lows to the panel only ,there was a lack of slam ,I have noticed this on  other large panels I have made.A large panel can give stunning slam .A large 15inch LF unit in a box  may give a lot of bass  [boom ] but when it comes to real  slam  unless on a very  large panel you end up with a very sad[ thonk!]
I may have to blend the two to get the best of both worlds ,we will have  to see?

[bobloblob]

Sedge,

3M claims the tape that ZYGADR recommended early in this thread is heat-resistant, so that is still probably best for exciter-to-panel gluing.  If you are just trying to mate two solid surfaces where there is little sheer force, maybe this is a place where superglue will work.  Don't know how resistant most super glues are to heat, but I suspect they do well, and the glue line can be quite thin.  In fact, the thinner the glue line is (without squeezing it all out of the joint) the more resisant to sheer force and tearing it will be.

I am happy to hear that you are playing around with bass augmentation.  I have noticed that most subs don't seem to have that "slam" that you mention.  That's why horn subs began to interest me.  The ones I have heard have the "slam" factor, which I interpret as dynamics.  What I am hoping for, though, is that the dipole sub configuration of Martin King's will integrate well with these panels and give that slam.  He uses 18 inch high Q (and inexpensive) woofers.  I am also hoping that large panels can be stacked on top of these.  In the best of possible worlds, these panels could be run full-range without filtering, with the subs coming in at the very bottom to add depth and power.  If not, maybe a lower crossover, say at 100 or 150, will keep the panels happy.  I really wish I had the time and money to play around with these now, but it will have to wait.

[BowerR64]

What i want is to have good midrange and high end. I guess i will wait and try them see if they are bright enoug for me before i order the tweeters.

If they sound ok i want to mount them on my side walls near the front of the room and the back then use the tweeters to direct the higher end twards the listening position if that will work?

I thought about wedging one side as well  like 1-2" that would lift it and position the face of the panel twards the seating position.

[captainjack115]

Depending on panel size, weight, stiffness and amounts of damping in the panel, my plywood panel seems to go from 20 k to 250 htz in pretty much nxt mode. Below this I am sure it is a piston. As a contrast I tried Foamcore again (as the sound was dull and boomy). [/b]

Oddly, I use 20"X30" black foam core to conduct tests, using just one exciter per channel. Near field pink noise is pretty flat from 30 to 16,000.

Placing the board on the floor causes an immediate drop in bass below 60 hz. The boards are not cut off at the corners, but bass was kind off buzzy and not clean. Mounting the boards along the long sides directly in line with the exciter produces clean and deep bass. I have four dozen exciters and plan to expand my prototypes to 24"X72" and run 8 exciters per board. They will be mounted on the long sides as in the small version. Before I do that, I'll sprinkle some salt on the front surface of the 20"X30" single exciter board and run a sine wave sweep for examination of the wave pattern. A bit "Caveman" perhaps, but I think there's something useful to be learned in doing so.

Far field pink noise tests are very interesting! It makes virtually no difference in spectrum analyzer readings where the microphone is placed. Chaos of the bending waves coming off the front and rear of the panels seems to even things out. This may account for the stereo image to remain intact throughout the listening area.

Most curious!!!!

This technique delves into areas that are not entirely charted (even by NXT).

I think if we persevere, we will find what works and what doesn't work. I know from experience that pure science does not always work as expected. I have considerable technical background, but a lot of Thomas Edison too!
Nobody likes to waste time and money only to have their efforts dashed to the ground in failure. We have a challenge here and in my opinion it's worth pursuing. We may not get the results we hope for right away, but half the fun is in the tweaking.

I for one, love a challenge!!!!

[usp1]

Depending on panel size, weight, stiffness and amounts of damping in the panel, my plywood panel seems to go from 20 k to 250 htz in pretty much nxt mode.

Sedge,

Is your plywood panel 3-ply baltic birch or something else? Am I understanding you correctly that you can get 250-20K from the panel at the same time. Or is it that it is possible to get freq in that range but not all at the same time.

[BowerR64]

For some of you guys that have played around with these before what does the size change?

Smokinjoe used what i think he said a 12"X12" if i change the demensions a little to make it more rectangle what would this do to the sound?

I would think the smaller the surface area the less low end?

I have some little kenwood rear speakers that are 5X7 X5 deep ide like to replace these with some panels. THese dont get much bass at all but the midrange and highs i want to keep just lose the big speaker.

It would be cool if i could replace it with a picture, or what appears to be a picture with a frame and stuff.

[usp1]

I made some small panels 15"X20" from foamboard. I cut these from a piece of 20x30" foamboard which I was using to experiment. The 20X30 was decent...probably 100hz-12khz. The smaller panels are quite bad. I did not test them but probably 200-10khz. Of course I had to reduce the number of exciters as well so I am not sure if that had anything to do with it.

[BowerR64]

That doesnt seem that bad. Would you compare it to a little cube speaker? better or worse?

Somthing that sounds a little more full then a typical cube speaker, those plastic ones you get with most 3 piece computer setups or the small home theater in a box setups.

Somthing i thought of was those music cards you can get at walmart or somthing that when you open them they play music or a short recorded clip of audio. They are like a flat speaker, i wonder if i rob a few of those from some cards if they will go a little higher then what the NXT and foam core will go.

Keeping it flat and soem what hidden but try and cover more of a range?

I ordered some of those onkyo 6X9 blow out tweeters with my tranducers but i think they might be to thick and bulky.

Man i cant wait to get these this is goign to be FUN! 

[usp1]

I made those for my son who wanted to replace some swan m200 speakers from his crowded desk. The Swan m200s were the unpowered slaves which I got from theaudioinsider. The M200s were hands down better. The small panels were more like cheap clock radio speakers. I think it is important to go big with these panels to get good sound.

[BowerR64]

I made those for my son who wanted to replace some swan m200 speakers from his crowded desk. The Swan m200s were the unpowered slaves which I got from theaudioinsider. The M200s were hands down better. The small panels were more like cheap clock radio speakers. I think it is important to go big with these panels to get good sound.

Yeah i understand that but im not looking to replace everything. Im looking to replace the satellites. I still plan to use a hidden subwoofer wich can be and is already hidden nicely. I hope i get them tomorrow i can play with them myself im just excited and want to talk about them a little.

I went out today and looked around for some things to mount them too besides the foam core. I tapped on almost everything i picked up next to my ear. I see why now smokinjoe use the sheetmetal. Once i tried this wow it was so bright and tinny sounding.

I picked up 3 sheets 6X18X.025 thick i figured i could cut these in half. cut 2 in half for front L/R rear L/R and one full sheet for the front 

[sedge]

captainjack115
nearfield responce with all the panels so far tested seam to be very good as you say ,they would make great headphones exept for the 2 two foot panels stuck to your head
I too  have also noticed that pushing the side of the panel firmly against a wall does seam to improve the Lf.I have only used one exciter per panel so far in all my tests,I only have a small music room [converted garage] and so the volume is not a problem even though I do like to play music at realistic levels[which is why I have been exiled to the garage] .when my friend came over i was holding the panel in front of me while playing pinknoise,I was trying to show him how the LF changed depending on how you held it.I said to him if you hold the panel edges each side of the exciter you can see on the deq that the LF goes lower and more even,his answer was  [quote- I dont have to look at the graph  I can feel it ] so we changed places so that I could hear it too .I had heard it but in  testing it on my own I had thought the sound was just  traveling through my body.ITs good to have a second pair of ears and hands to help sort things out.
Im not sure if this is going to help anyone or just leave us scratching our heads again?

[sedge]

usp1
my 3 ply plywood panel was from a 1960s  bedroom draw unit,Idont know the wood type.
the 250 to 20k aprox  is looking at pinknoise on my deq .I was very impressed considering it was a single driver .Not sure how many single  coned units could do this,if any?.

[captainjack115]

captainjack115
I too  have also noticed that pushing the side of the panel firmly against a wall does seam to improve the Lf.

One thing I failed to mention was that I mounted the panels on foam, they were not on a solid frame. (Controlled Flexing?) I just didn't want someone trying this without knowing they would need a soft mount on both sides of the panel. I stopped worrying about watts and monitor the exciters for heat with a hand held laser thermometer.

Jack

[BowerR64]

Has anyone else tried the metal plates like smokinjoe?

I had a thought about cutting a hole in the top of the foam that is mounted infront of the metal. Maybe would act more like a tweeter? Just somthing a few inches round.

Another thought i have is, are these things directional? Do they sound better on the back of the panel or do they sound the same on both sides?

Say i cut 2 holes one for a small suface mount tweeter and one for the transducer then mount it to the back panel (from the front) then cover the front with speaker cloth so its just a thin wafer like thing?

[j gale]

I have to 2nd most of what Ziggy said. The panels are the closest I've had to natural sound even with their imperfections or limitations. I think all too often guys are looking for something that just is not present in real music. I have never heard so called pinpoint imaging at real events. I guess that some would describe the real thing as unacceptable. Getting rid of the box, crossover and differing materials and different sized drivers makes a huge difference when trying to approach natural sound. I have an attic IB with a couple of 15'' drivers. Best arrangement I have used over the years. Seldom turn them on now. If your panels are big enough you don't need a sub. I hope to see improvements from better exciters and panel material, but I don't think small pannels will ever deliver much. You have to go big. aa aa

[bobloblob]

ZYGADR

My comments above were based only on what I have read in some of the other posts, as I haven't had the capability to build the panels yet.  I was only thinking out loud about what direction I may take, but, of course, that may change when I can get going on this and have a completed pair.

I too don't hear what I would call "slam" from a double bass, but I was surprised when I heard a string bass on Bruce Edgar's system.  On nearly every other system I've heard, the louder the music gets, the more the bass seems to sink into the background.  Still there, but it didn't "bloom" with the rest of the music, if you get my drift.  If the panels can provide this, I will truly be a happy camper.  As I wrote, I was surprised at a cello recital at just how much sound a cello could put out, and how most speakers distort it by subduing the lower registers at volume.   I was working on a piano at the time (my profession for 35 years), and the sound came through concrete and set up a tingle through my legs.  I guess my point there is that, while I've often heard cello before, I had never realized that it is one of those instruments you feel as well as hear.  I could hear the cello and identify it well enough on a normal speaker, but that bone conduction level of sound has always been missing, something similar with a string bass, at least at times.  I've heard almost no regular speaker do that, except for Klipschorns et al., and I am not looking for horns.  Even most standard subwoofers sounded dead to me in that respect. If the panels can do all of that, fantastic.  Even if they don't quite do it, your description of them makes them seem like what I have been looking for, and I will fill in where necessary, if it ever is.  No slam at all on the panels (pardon the bad pun), just saying that it wouldn't bother me at all if I have to add a bit.  I'm hoping not to, though.  The potential here is sounding better all the time.

I will reserve comments now except where I might have something to contribute.  Keep up the excellent work

[captainjack115]

As a side job, I have engineered over 9 CD recordings for a local recording studio.

I have to remember not to refer to you as "Ziggy".

Anyway, Life is funny in that we run into people that share a common interest.
I built a recording studio for the radio station I engineered in the mid 60's.
The difference here being that I was cutting master discs on a lathe.
Where has the time gone?

Flow of consciousness is sidetracking my thoughts.

Despite using electronics to enjoy music, I prefer listening to live unplugged music whenever possible. Bass is tough in a listening room, my room has a lot of gain below 30 hertz. Jazz with acoustical bass sounds pretty good for the most part. Artificial bass is quite tactile and impresses the heck out of the average person.

I followed your posts for years on that "other" forum about your experiences with NXT technology. Your two ears, observations, and continuous reports have been invaluable to all that have read what you had to say.
It's possible that people may think you're trying to clone Podium's design, but you have actually expanded the principal and continued the progress towards a better sounding loudspeaker. The fact that you've been so willing to share your discoveries both positive and negative, has been most gracious.

I don't know about Australia, but here in the U.S. high end audio establishments are few and far between. Large cities are still carrying the good stuff, but where I live it's all mainstream garbage.

My point is that it sounds like you could find yourself in that high end speaker business, if you have the time for more R&D. Money??? Get your speakers to a
CES for auditioning, you'll find a backer!

Jack

[captainjack115]

ITs good to have a second pair of ears and hands to help sort things out.

I wish I could get my better half to hold a panel for me!  aa
She'd want to put on a pair of ear protectors, than ask how long she has to stand there. (SIGH) The life of an audiophile can be a lonely one.

[jeffac]

OK, reality check noted Siggy,

Gatorfoam panels are not the "PERFECT" solution but work great when large. Finally got some 3M tape on the weekend, albeit the thinner F9469PC version. Time to buy some gatorfoam as soon as I get back from Perth WA, leaving this Saturday 

Ziggy, if you're around, I'd love to call in for a listen to your BBBs 'big black beasts" and discuss some ideas I have.

One being "rigid coupling" of the front and rear Luxcell sheets of the gatorfoam, possibly around some exciters in a hexagonal pattern for example, and maybe at edge positions too. Based on discussions of foam board characteristics, just maybe such better surface coupling could negate some of the transmission losses in the foam core and extend/boost HF that touch that folk have been so concerned about. So what is rigid, light, thin and "wood", because wood is good, that could do the job. 

How about these.  aa



And Siggy, thanks for your enthusiasm in reporting your adventures with these panel speakers, I can see this thread outlasting the 'Gravity Well of A Dark Star" that was the inspiration for this Circle and introducted me to the joys of boxless speakers.

Again, looking forward to the chance of catching up with you, if not on the weekend, sometime whilst I'm over you way.

cheers.. jeffac