[j gale]

 I understand the frustration. People who have heard  my shellac treated cc panels pictured back a few posts are astounded . Can't believe that a piece of cardboard can deliver superior sound. One guy once planted in my chair  stayed for hours I couldn't get rid of him. They all love the sound but don't do anything about it. I haven't been moved to experiment further lately,  but no doubt will have to try the Monacor placement. I would encourage all to share any info about your own panels good or bad. This thread contains a body of knowledge that is priceless. Zygadr don't be discouraged. The majority are just waiting for perfection and then they will jump in Personally I have enjoyed the experimenting and anticipation of the results and disappointments have been few. I can't go back to horns,OB's,TL's etc. either.

[zygadr]

Thanks guys for your welcomed encouragement.

It is great to hear that the work put in to this project has indeed inspired people to build their own speakers and appreciate the incredible sound that eminates from such a simple yet effective system.

I sat down again for a long listening session last night starting with DAB radio followed by a long list of CD's.
 Later on I went upstairs and watched some T.V. I was watching the images but not paying attention to them as it soon became apparent that it felt as if I had just been to and listened to live musical performances from around the world. Why?..........because not at one time did I have to think or worry about whether the audio system was accurate,whether the crossover needed tweaking (as there is NO CROSSOVER ), or whether I was dead smack in the middle of ''the sweet spot'' for imaging? I could go on, but I think you will all get my point as to what it's like with D.I.Y. audio :especially speaker systems.

Each listening session has been the same since the panels came on board : you forget about the individual audio components due to the fact that these panels envelope you in a large open sound field and makes you ''listen'' to the ''music'', not the reproduction of it. The panels are capable of transporting you to the recording venue in a very convincing fashion.
All this from a couple of large sheets of C.C. and some funny vibrating stick on things.............AMAZING!

[emailtooaj]

Hey all 
Zy don't fret over the non reply's.
I had stumbled into this project about the same time you started this venture and I have to say... you along with many others have made this a very encouraging project and one that made me look to perfect the imperfections (like the exciter design!). My heart has been in this since day one... unfortunately time hasn't 
I have to admit that I've been so happy with my EPS/Epoxy/el'cheapo's set up, that I haven't felt a need to make any changes!! There for the lack of any posting's along the way.
Screw the back seat, couch slouch, internet troll scrutiny. If they can't get off their asses and build some themselves then they deserve to live in the "lifeless" audio world they've created.
Their loss, not yours or ours!!!
These panels are nothing short of amazing when it comes to "true" sound reproduction.
Of course there are some great sounding traditional speakers around that will give you goose bumps, but until they listen to a finished panel speaker, they'll never have the opportunity to experience what it's like to have goose bumps, picking their jaw off the floor and having their blood tingle throughout! 
Listening to Music on these panels is a near religious experience. I like to call it an Ear'gasm. 
That being said....

I would really like to try out the CC for the next round of building. It would help me (and I hope others) to consolidate a optimal "near" end project build.
So here I go....
1) What is the best C.C. option? Single or Dual cushion?
2) What is the common CC panel size to use/recommend? 
3) What is the optimal CC thickness?
4) What is the best to harden the C.C.? Shellac, epoxy, etc. etc.?
5) What exactly is the Monacor placement and is there a diagram or photo showing optimal exciter placement?
6) What has been the most successful exciter to use? And how many per Panel?
7) What is the best Beer to drink while building these? (This is of utmost importance  )

As a side note...
If your trying to use Shellac to harden the CC and having trouble getting the Shellac to impregnate the CC throughout. May I suggest (if no one has already?) to make a vacuum jig of some sort, to pump the air out, while at the same time forcing the Shellac to get "sucked" into the C.C. more thoroughly.
I'm not sure if this would make the CC curl up though? I would think if you vacuum form it, let's say 5 mins, take the CC panel out, and lay it flat to harden (dry), you should be able to keep it from curling up?
Just a brain fart 

I'm hoping to get back with you guys with my next exciter design and posting some pics. I'm getting all my parts in for the jig so I can start building them. Hoping to have a prototype in a month or so? It's a very tedious project...lol

Peace

[j gale]

Hi Emailtooaj,   My 2 cents.  1. I like both single and double cushion. I'm using single mainly because I no longer have a local supplier for double.
                                            2. I believe the larger the better. Small is a waste of time. 30x60 inch or75x150 cm I consider to be minimum.(based on trying many sizes.
                                            3.Not really a choice available here
                                            4. I think shellac. I have tried some plastic type finishes and prefer shellac--non toxic, dries fast, seems harder (good) than minwax wood hardener, is natural rather than man made and so seems to sound better.When a coat is added it meshes with the previous coat rather than being another layer sitting on top. I believe it continues to get harder over time.
                                           5. see reply #1755
                                           6. I've tried several. Best so far is Dayton DAEX58FP from Parts Express. 4 per panel, any more not necessary. Also 4 or 9 gives a balanced load where other combinations don't.
                                           7. The one you like. Too much will cause the law of diminishing returns to kick in.

[zygadr]

Greetings Emailtooaj!
It's great to hear that you are enjoying your panels and have also discovered their ''magic'' as well. Yes, they are truly marvelous beasts aren't they?

j gale has answered your questions quite thoroughly. I can add the following also based on my experiences so far

1. I am using double cushion C.C. at the moment. It is a bit stronger but slightly heavier than the single cushion stuff.
2. There is no ''common'' size, but I found 5.5 feet X 2.5 feet to be a reasonable size with good bass output.
3. I have 4mm single cushion (the thickest they make) and 6mm double cushion. You will find that the two types have different sounds. The twin cushion is better damped but has lower output than the single cushion which is it's strong point. Single is not as strong a double cushion, but this can be worked around.
4. You know me...........I am a fan of the ''MOTHER OF TONE'' philosophy, so I say SHELLAC is the best coating to use inside and outside of the C.C.
j gale has done this with good success.
5. As per j gale's answer
6. As per j gale's answer. I am using 4 exciters + 2 el-cheapos (pics coming soon)
7. anything that makes you feel good about your project

Looking forward to your exciter design. With the help of this forum, we may revolutionize DML technology forever!!

[zygadr]

Had a musician friend pop over this weekend to listen to my speakers.
He belongs to and plays with two continental style trios : Accordion, violin and double bass. I have personally engineered 6 of their CD's over the years.
He sat down and listened to a variety of music : classical, jazz, world and some miscellaneous music.
After 60 seconds on the first CD played, I looked over at his expression and nearly bust in to uncontrollable laughter!

When the session was over, he turned to me as said (quote) '' after all these long years of hearing all your different and expensive systems, you've finally done it!..............you are are genius!..........the double bass in that jazz trio is EXACTLY how I hear it each time  we perform. Everything is so real.........it's just like a live performance..........no question about it..................how the hell did you  come up with such realism from two sheets of cardboard for heavens sake???????????''

He awaits next weekend with great anticipation, wanting to hear Beethoven;s ninth symphony ..........IN FULL!

[zygadr]

Had a musician friend pop over this weekend to listen to my speakers.
He belongs to and plays with two continental style trios : Accordion, violin and double bass. I have personally engineered 6 of their CD's over the years.
He sat down and listened to a variety of music : classical, jazz, world and some miscellaneous music.
After 60 seconds on the first CD played, I looked over at his expression and nearly burst in to uncontrollable laughter!

When the session was over, he turned to me as said (quote) '' after all these long years of hearing all your different and expensive systems, you've finally done it!..............you are are genius!..........the double bass in that jazz trio is EXACTLY how I hear it each time  we perform. Everything is so real.........it's just like a live performance..........no question about it..................how the hell did you  come up with such realism from two sheets of cardboard for heavens sake???????????''

He awaits next weekend with great anticipation, wanting to hear Beethoven;s ninth symphony ..........IN FULL!

Sorry to blow my own trumpet guys, but I just had to share this experience with the comments of a musician.......not an ''audiophile''

[exspec]

I have dabbled in open baffle and am seeking the next step... Have I found it? For experiments sake, how are these for starting to experiment? I have H frame open baffles I may utilize with these for fun as well.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=309-149

Look forward to hearing this type of speaker.

[zygadr]

Hi exspec. Welcome to what is without doubt, the greatest open baffle/planar speaker posting on the planet!
The exciter you have linked is great for experimenting with.
You will need to remove the exciter from the white plastic ''frog'' like housing, bypass or remove the small brown thermistor, leave the double sided tape over the foot though(important). Buy 8 of them - four per speaker, and find some large corrugated cardboard(at least 4ft X 3 ft )and you are ready to start.

The four exciters are wired in parallel/series configuration to maintain eight ohms. Suggest you use the Monacor placement diagram for the positioning of the exciters (look back on some recent posts for that information).

Good luck and ask questions if you are unsure of anything.

[j gale]

I second the recommendation for the Monacor configuration. I was happy with 4 exciters 1 foot apart on my 5 foot x 2.5 foot panels. I changed 1 to the Monacor config. and listened for a couple of days. When listened to close up the one with the old arrangement had more self noise. There was a constant drone that the Monacor one doesn't have. At a distance it's not really noticed. After changing the second panel over the difference is not subtle. My wife noticed even though she doesn't pay much attention to what I am doing. I didn't think having 4 exciters that close to each other would be better, but it sure is.

[zygadr]

Glad to hear that you could easily tell the difference with the'' Monacor positioning'' method j gale ......b.t.w...........like your ''spine adapter'' for the new placement
The good thing about this simple fractional formula is that it applies for any size panel and most likely any ''type of panel material''.

I suspect that it is based on NXT's positioning software, but the good news is that it works a LOT better than Podiums method that we have been so accustomed to over the years.

Congrats to all of us...............another step forward has been successfully made towards the almighty ''DML PANEL''

[wires]

Hello all. Long time listener, first time caller. I've been following this topic off and on for the last year and a half and appreciate everybody's willingness to share their ideas and results and especially Zygadr's persistence on the subject.

I originally came across this thread while researching DML panels to build my own invisible speakers. I am certainly not an audiophile, and I knew that I would be sacrificing some degree of audio quality for aesthetics, but as I researched available products on the market and learned more about DML and NXT, I started to realize that this really is a better way of reproducing sound. While my ultimate goal is not the same as yours, I have learned quite a bit along the way that might be of use to you, and I am especially appreciative of your research into panel materials. My personal project stalled last year for various reasons and every so often I come back to it as I did today, discovering your updates which sound exciting to me.

I've done a lot of research into NXT, including reading many of their patents and technical notes, as well as experimenting with NXT System Designer (Pansys). First I would like to point out that what you are calling the Monacor method of exciter placement, is actually the NXT method as outlined in their patent filings going back to at least 1995. Monacor did do a better job, though, of explaining it in useful terms. Perhaps one of the more helpful patents to read is 6,904,154 (http://www.google.com/patents/US6904154) which describes an "acoustic device" in 76 pages. They describe how it's important to place the exciters in positions of high vibrational activity with regard to resonant modes, thus activating more modes. Their instructions are to use the intersections of lines 4/9, 3/7, and 5/13 of the length of the sides from each corner, avoiding using the same ratios for one corner (e.g.- don't place an exciter at a point 4/9(length) and 4/9(width) from one corner. They state that 4/9 and 3/7 are the preferable ratios, but that 5/13 is also effective and will allow for placement of more exciters since up to 24 ideal locations (per their patent) can be identified using these ratios. Here is an image from one of the NXT technical notes which explains why their funny locations work better than a "straight down the middle" approach:



The orange areas represent good exciter locations because they are active in more resonant modes. The blue areas are poor locations because they are nodes where there is relatively less motion in resonant modes. As you can see, there are several blue nodes right down the middle of each axis.

Another helpful tip that can be garnered from the NXT patents involves favorable panel dimensions. They list two ratios that are supposedly the best for rectangular panels. The gold ratio is 1.134:1, and the silver ratio is either 1.37:1 (patent) or 1.41:1 (technical notes). There are also favorable ratios listed for elliptical panels. This is not to say that panels of other dimensions cannot be utilized, just that doing so will require more attention to modeling to determine speaker placement and possible dampening of unwanted resonances.

I already mentioned that my personal goal has been to build a quality, invisible, in-wall speaker. There are several on the market that utilize DML principles, but most of them were beyond my budget. The affordable ones were of inferior construction and had been discontinued, although while looking up sources for this post I discovered that they may be back on the market. I was able to obtain samples of two different products to experiment with.
1. Amina AIW5X (http://www.ceiling-speakershop.co.uk/shop/invisible-speakers/amina/aiw5x.aspx - over $1800 each!): This speaker uses a metal frame with 4 rigidly mounted HIAX25C15-8/SF exciters. The panel is constructed of aluminum honeycomb sandwiched between kraft paper. It can handle 80W RMS.
2. Onsia in-wall speakers (http://www.onsiaideas.com/in-wall.html - were $102/pair when discontinued in early 2012; now seem to be available for $119): Consists of a 24x24" panel of polystyrene core foamboard with a molded plastic frame. There are 4 exciters on the in-wall model and 2 on the in-ceiling model, and these are much smaller exciters than on the Amina. The drivers are mounted with foam to the plastic frame. Power handling is 50W RMS/100W peak for the in-wall and 25W RMS/50W peak for the in-ceiling. At least, those were the figures for the speakers before they were discontinued. The new website lists both models as 25/50 so perhaps they've done away with some of the exciters on the in-wall.

The problem I have in testing these speakers, as well as testing my own creations, is that to properly test them they need to be mounted in the wall and skimmed over with drywall compound. My wife will not allow that kind of experimentation. I have listened to the commercial speakers freestanding, and they both sound tinny. Their documentation, though, clearly states that they will not perform appropriately until completely installed and broken in.

My two attempts at creating speakers have been with HIAX32C20-8 exciters that I got last year, using foamboard and gatorboard panels. Neither seemed to reproduce the higher frequencies well. At this point my project lost steam. I wanted to try some honeycomb panels, but could not find a supplier anywhere near to me. I also wanted to try the higher power HIAX25C15-8/SF exciters, but was told by Hi-Wave that because of the expense of manufacturing these, they only did it for large orders. They never even really gave me a quote, and now it seems that they aren't even listed on the Hi-Wave site. Amina must have a contract manufacturer because they appear to still be producing their speakers. Or, perhaps, they just order in large enough quantities that Hi-Wave will work with them.

I did spend some time playing around with NXT System Designer and it is a powerful program. However, it had limited usefulness for my project because of my difficulty defining the boundary conditions of a panel that is mudded into a wall. I think it would be much more helpful for a freestanding panel. It is also somewhat limited in that the materials database I have access to is somewhat dated and doesn't include the current Hi-Wave exciters, although their data sheets include most of the relevant info. Still, the materials database does have some interesting info on panel materials that some of you might find helpful.

One reason why I think my panels didn't sound great had to do with the self-supported mounting of the HIAX32C20-8 drivers. As Zygadr pointed out, I think that mounting the full weight of the driver to the panel affects the acoustics. It may not be much of a problem for a heavy glass panel, but I think it does adversely affect the lightweight panels we are using. Perhaps it could be optimized if I could figure out how to model this type of mount in Pansys. I did email Hi-Wave at one point about this issue, and their engineer agreed that for my application, it would be better to mount the driver to a frame rather than to the panel. The Amina and Onsia speakers both have the driver supported by a frame which is then attached to the panel via adhesive foam.

At any rate, your success has given me new energy in my quest and I'm eager to try some of the additional materials. Anybody know of a supplier for Re-board in the US? I might also look at the thin plywoods, since that should hold up well in a wall. One other detail that I will work on if I get a winning combination of driver and panel will be a power limiting circuit. Both the Amina and Onsia speakers include circuitry to protect the drivers. They also both have high-pass filters.

Zygadr, I will also PM you to share my NXT info if you are interested.

Thanks,
jbm

[zygadr]

Hi and welcome to this forum wires
Thank you for posting the information you have discovered in your journey into DML's.

Yes, we have now discovered that correct positioning and mounting of the exciters is more critical than first thought just as your image indicates 

In regards to your panel material attempts not sounding good comes down to a couple of possibilities. Foamboard comes in many varieties. I once tried a foam board from an art supply shop. It had a softish core and was coated with black paper on both sides. It sounded terrible..........vitually no  highs and lousy output.
Gatorboard on the other hand was much better, BUT, it too (due to a softish core), had an obvious attenuation in the high frequency department.
It was only when we started to experiment with expanded polystyrene that the sound became clearer and louder. Single cushion corrrugated cardboard(especially when treated with Shellac resin) produces the best sound so far and I am very happy with it.
In your case, thin plywood will provide a very good crisp sound but you will loose out in the sensitivity/output department.This may not be a problem if you use more than 4 exciters on a mid size sheet of ply. The ply can be hidden and plastered over I suppose?

Anyhow, keep us posted with any new information that comes to hand. Another brain thrown in to the mix is allways welcome.

[emailtooaj]

Hey all and Welcome Wires!
Wires that is an awesome find on the visual chart. When looking at it, it validated exactly what I have experienced with these panels. If you flip that photo 90 degrees it would represent (to a "T") how my panels act and where the vibrational (and dead) points are. I have my two exciters located at the 1/3 and 2/3 points of my panel length, right down the middle. So I guess I found, by sheer luck, the optimal exciter placements if you go down the middle 

I have shipping to me 25- 24"x48" double face CC sheets. So I can't wait to try this CC experiment. Will hope to give any updates in a few weeks 

I've been busy making my VC jig to experiment with my new exciter design. Here's a sneak peak...



Sorry photo is sideways...don't know how to rotate the image?

I know it doesn't look like much now from the outside...but it's what's under the hood that counts 
I have the voice coil wired at 2 ohms for now. I plan to get these to 6 ohms or possibly 8 if I have room on the former. I may just go to 4 ohms and call it a day!
I also need to cut the height of them down. They stand at 2.30 inch tall and I only really need them at 1.5 in.
Outside diameter is 2.68.
After playing around with different magnet positions I think I found the optimal spot. And man...It has some major energy output. I even had to brush some epoxy on the spider to stiffen it up to tamper down the excess vibration.
Once I get the CC in I'm hoping to get these exciters in a more permanent stage and really try them out on the CC
Can't wait!!!!
Will keep ya posted.

Peace

[zygadr]

Your D.I.Y. exciter looks very interesting emailtooaj!

Tell me, is that brown plastic looking thing on top of the spider going to be the ''foot'' of the exciter?
Have you used any old speaker parts in your design?

There are many cheap full range twin cone speakers with reasonably large magnets that can be modified to make an exciter.
I believe one of our forum members on this thread have already done so?
This would be a lot easier perhaps? The spider would need to be stiffened and the basket/cone assembly cut away and discarded.
Overall sensitivity and power handling would be considerably higher than the exciters available to us at present.
Some food for thought?

[emailtooaj]

Hey Zy,
Yes, the brown part is the Kapton former. It looks ugly in this picture because it was my first shot building from concept to prototype.
And yes it will be the Foot to mount onto the panels.
This is, in a way, a more traditional build to the standard Voice Coil...ie, Kapton Film VC former, spider and coil.
The difference is the "way" I'm winding the wire on the former. It's in no way similar to regular voice coil windings.
So your suggestion about using a cheap full range speaker and modifying it unfortunately won't work in this design. It's a great and appreciated thought though
I literally have to build everything from scratch to make this design work.
Not trying to be to secretive here, but I will give more details on everything once I verify my findings and have a more functional design to share with everyone.
I would like to do some YouTube tutorial videos in time. Just need to get everything correct first.
But all is very promising so far!!!

Speaking of the "foot"... has anyone come across a place to buy the plastic feet like they have on the cheapo exciters?
I sure as hell can't find them anywhere   

[zygadr]

Sounds great em.! Can't wait to see how you go with it.

On the plastic foot................why not rip one off a cheap exciter?

[emailtooaj]

Thanks Zy for the encouragement 
I've been slacking off the past months but now have the drive to get this project moving forward and hopefully completed.

On the plastic foot................why not rip one off a cheap exciter?

LOL, I did try that  Their diameter is a tad to small for my beginning design. I build the former jig for a 1.00 inch I.D. and the cheapo exciter former is smaller.
I guess I can build a whole new jig and match to the cheapo sizes? 
Really wish I could find someone that sells just the foot rings. Would make life so much easier 

Anywho!
Will chat with ya'll later!

Peace

[unnnot]

Hello I have long been following the theme of the use NXT speakers for high quality sound reproduction. What a pity that the industrial options are either not readily available or expensive. Although the technology of production and materials are cheaper than traditional speakers. This motivates speakers to produce a self-representation is often not having the proper use of materials and the installation places of exciters.
I have had several attempts to manufacture homemade NXT speakers.
http://forum.ixbt.com/topic.cgi?id=12:48770-3 
http://forum.ixbt.com/topic.cgi?id=12:48770-4
 Material of  panel -expanded polystyrene of high density. It covered with two layers of acrylic paint for increase in rigidity.
Sorry for bad English.

[zygadr]

Hi unnnot.
Expanded polystyrene is still a good material to use for these speakers. Yes it can be made more rigid by using epoxy coatings which is better than standard acrylic paint.

If you use the Monacor suggested placement of the exciters, you will have the exciters at their best position as far as we have discovered here on this site.

Have you made a set of panels that are to your satisfaction?............sorry, I can't read Russian, if that is your language in the links?