[Squibby]

Hi everyone...

I have been following this thread quite avidly for a few months now, and i have to commend everyone on their efforts so far.

I'm not an audio tech nerd but the proposition of something which can produce omnidirectional sound and have a small footprint immediately caught my attention.

As such i have a confession to make.....As a a keen carpenter, my thoughts immediately turned to using guitar/violin/cello construction principles as a basis for a design and i have been working on designing and building a lightweight frame and panel which is as freely suspended as possible when attached to a wall or stand. I am in the final phases of the build and only have a few details to iron out, together with the electronics (exciter placement,etc). I have already modified a lepai amp to be used in conjunction with the panel exciters and the results have proved positive so far with a noticeable improvement in sound quality after the mod.

Many of the design features and components have been selected according to what i have read over the course of this thread and as such i feel the need to "pay" you guys back with some info and some pictures which i will post in future once the panel has been glued together and tested with all components attached.

Given my love of certain materials i am still convinced that wood will offer the best tonal qualities (at least for acoustic and classical music), and after a little research i would suggest the use of maple and/or spruce for both the panel and frame (they are used in guitar/violin/cello construction due to their inherent tonal and ideal resonant qualities caused by having an ideal density). It seems that a panel around between 2 - 3.5 mm thickness will yield the best results...maintaining rigidity yet being lightweight. As cost is still factor, I'm using 3mm birch plywood as the panel material for the prototype.

From what i have seen on this thread, the problem has always been a way to freely suspend the panel yet have it either attached to a wall or a stand and i believe my design caters for this.
I do however have a couple of doubts regarding the sag that can occur on the exciters after time, and the glue/tape used to attach the exciters to the panel.

I am using visaton (60 s) exciters. I have 4 which i am hoping to use on a single panel in order to produce stereo sound (both left and right channel on the same panel). I am hoping that this wont cause any problems in the sound, but i have my doubts.

Also i hope someone can guide me as to the best substance to use to stick the exciters to the panel...any suggestions would be greatly appreciated. I have noticed that most are inclined to using the 3m tape, but i was hoping to use something a little more permanent such as an epoxy glue or likewise, but again, I'm not sure how this will affect the resonances produced.

As for the sag which can occur over time with these little exciters, I'm hoping someone can come up with an elegant solution which doesn't involve turning the panel 180 degrees every so often or fixing them to a rigid spline. If i find that nothing fits the bill then i may well just have them unsupported and see how they devolve over time, in order to make improvements for the next build (the one I'm building is considered a prototype and will be given away to a friend).

Any suggestions on the points I've raised will be greatly appreciated and i promise to post some pictures very soon.

Many thanks for a great thread, awakening my interest and motivating me,

Squibby.
   

[Squibby]

Hi guys,

here are a few grainy pics (apologies for the quality) of the progress so far...



rear view of panel showing supporting lightweight frame


close up of joint on supporting frame


center panel which will be attached to the vesa wall support

It may be a little difficult to imagine what its going to look like at this stage but the center panel will "float" in the center square space on the rear of the panel courtesy of plasti-dipped cord (in order to isolate and dampen hence the myriad of holes around the frames), and the transducers will be attached to the panel using the monacor layout. still a ton of work to be carried out, but i did promise some pics and hopefully those of you with a little imagination can envision what its going to be. I've also decided to abandon the stereo sound (ie two channels) on the same panel and am instead opting to supply the amp with a mono line (summed stereo) input after the bluetooth receiver and before the amp (as this particular amp cannot be bridged apparently...please feel free to correct me if i'm wrong) and then only use one channel frorm the amp for the output to 4 visaton exciters/transducers wired in series/parallel. does that make sense to anyone? it kind of does in my head and in theory should work. enjoy the pics and please get back to me with any possible improvements/criticisms.

all the best,

Squibby.

[j gale]

 Hi guys,  I just noticed that Parts Express has several new exciters under the Dayton name. I'm wondering if you find any of them interesting. Some higher power units there too.

[mightym]

I saw those too.

Ditto on the high power units.  Some of them look very much like the Podium style units. 

Placed an order for bits to complete a class D amp I'm building last week, added some of the buyout exciters to the order to "play" with.  The amp should be finished today.  I want to experiment with those exciters if I get the time.

I've got an idea for a DML I've been rolling around in my head for months to try and get into 3D ( actually built...).

John

[exspec]

I've got some of the Buyouts in the post. This is gonna be fun!

I am wondering if anyone would be willing to discuss using the transducer from 150hz or so up to 10,000hz and crossing to a ribbon tweeter. One of the DML speakers I saw looked like a horizontal MTM using a ribbon in between two panels. Sadly with only 8 transducers, the MTM orientation isn't possible, but an MT is if I utilize my dipole planar tweeter. My active crossover can be run 2 or 3 way.

It seems that golden ratio, and the Monacor placement of a quad of transducers is a safe design principle to follow. Since the panel won't be used for HF as much, what would you recommend as a suitable material? Is the shellac and single ply CC still suggested? As for size, the 2x6ft panel is a bit too large for me. It's possible, but would be curious as to which of the panel sizes and materials would be worth trying to find a nice blend for the intended range. My bass is covered by a pair of large Hframe open baffle 18's per side, and feel a large panel as a mid will be easier to blend than a small cone driver.

While the idea of a Full Range panel is tempting, I am skeptical that the HF of a panel will be to my liking, but will try it. Can't help. Ur assume I will be going to a three way with a ribbon/planar tweeter to feed my HF desires. if I choose to try different panels, is there a current favourite method of temporarily attacking the coils to the panel? 3m tape still suggested? Thanks for this thread and your helps.

[Abelma]

[

[oldschoolVlad]

Hi Zygadr, hi Folks!

Thank you all for sharing your experience in DML building. I am another one inspired by your success. Being a speakers hobbyist and an amateur pianist I always pay attention to the naturalness of sound. And what can be more natural then vibrating wooden plate like guitar deck or piano soundboard? So when I found out about NXT speakers advantages, a decision to go that way came without any doubt. My goal for now is a system 2+1 similar as Wharfedale Loudpanel PPS-1.
I’ve read this thread from A to Z, I’m following the events and now waiting for some Daytons from PE. I expect it will be a long road to get perfection, so I guess I have to start from single CC  . I would like to drop here some problems to discuss .

The exciters. In a previous life I used to dig in the “Loudspeaker Design Cookbook”, so let’s see what we’ve got today from hi-end’s point of view .  I mean T/S parameters:

Le - the voice coil inductance, reducing inductance close to zero dramatically improves pulse response. Inductance is the main reason for odd harmonic distortion more audible than even harmonic distortion. Low Inductance = Low Non Harmonic Distortion;
Mms - the weight of the voice coil assembly, the lower – the better;
Cms - the force exerted by the mechanical suspension. It is simply a measurement of its stiffness;
BL - the motor strength of an exciter, the higher – the better;
RMS – power handling.

   type               Le (mH)   Mms(g)   Cms(mm/N)    BL(Tm)    RMS (W)    $
-----------------------------------------------------------------------------------------------
DAEX25SHF-4       0,41       1,3         0,0001           4,29         20           35
DAEX58FP             0,47       9,95        0,05               5,0          25           15
DAEX25FHE-4         0,1       1,61       0,0003           3,63         24           8,3

Just three interesting ones: DAEX25SHF-4 – the flagship, DAEX58FP – the crowd favorite, DAEX25FHE-4 - a new dark horse. And I bet on a dark horse guys. It has 4 times lower inductance (lower distortions),  the flagship’s low suspension stiffness and low moving mass, and it motor strength is 0,7 of the maximum in range. I think 4 of these for the 0,35m2 panel will be enough. What can you say guys?

Also I think if it will be a good reason to reduce the surface area in contact with an exciter to meet the wavelengths size. In the Monacor docs we’ve got 4 points to mount and they came from NXTs math, so these are mathematical points with zero diameter. Maybe the best way is to excite panel points with the minimum area possible?

Regards,
Vlad

[exspec]

http://www.ashleydistributors.com/category/cardboard?PHPSESSID=228bbaec3b6727f1b9881497069065a4

Does the honeycomb cardboard offer any benefits over the shellac and corrugated cardboard? Would it still need shellac added to it to make it sufficient, or would the benefit of the honeycomb be enough strength? Or is it too thick? Thanks.

[oldschoolVlad]

As mentioned in this thread the honeycomb cardboard has too big self-damping (lack of highs in the output). Furthermore the 1/2” thick one IMHO will be too heavy. Best results was achieved with a 2 ply 1/4” CC.

[zygadr]

Hi guys!!!!!
Still listening to the CC panels with a top of the range high powered Pioneer receiver.

It appears to me that the sound has gotten a lot better with time.............1year + 
The sound has a lot more highs, greater micro dynamics and stunning macro dynamics.............this is with the Dayton units that I have been using  for some time now (higher power versions).
I am still to use Shellac treatment for both the inside and outside areas of the CC and am still designing the final frame and suspension method for the panels.

I have discussed the use of various Balsa woods available at hobby shops and am in the process of purchasing some Balsa planks which will be laminated to form a large panel to test as an upgrade to CC.

In the past, there has been no question as to the superiority of wood as a panel material, so..................let's see what happens eh??

[j gale]

Hi Zygadr,   I have noticed that my cc  panels have gotten better with time as well. I put it down to the shellac aging (getting harder?) I also think that shellac treated panels are more stable because of being sealed by the shellac. So changes in humidity would have less effect.  If you shellac yours I think they need a month or so before they are judged.

[zygadr]

Hi j gale.
Surprised (but not really? )that you too have noticed something positive occurring sound wise with your shellac treated panels. I think that as everything is moving as a giant sound producer, including the exciters, the sound waves may eventually be easier to generate after all the components have broken in?...........who knows?

I have no shellac on mine as yet, but will have to do so very soon. The balsa wood trial so far has produced some peculiar results : lots of wooden plank ''ringing'' and other related damping problems.  Don't really know if it's worth carrying on with this.

Anyhow, good old CC ! ............cheap as hell, should have been crap, but produces heavenly sound..............if you're prepared to wait for that ''golden break in moment''      

[G Georgopoulos]

hi

i now think obs are the best...

thanks to all of you and audiocircle!!!

[OB_Newbie]

Hello zygadr and crew!

Can NOT believe I missed this thread... of all threads to miss... arg!  I can't even say how excited I am to try a build.  I am absolutely loving my OB's right now but these panels sound right up my alley.   

I read from the start of the thread and read for hours late into the night last night and only recently skipped to the end to see that much has changed.  Is there a post that summarizes the latest "best" setup?

Exciter placement I have, CC for the panels (is there a recommended source for quality, large panels in the US?) I know.  I'm most unclear about the latest method to suspend the panel on the frame... is there a "best" method as this point???  Also recommendations on exciters would also be appreciated.  See PE has added new drivers recently.  Appeared the power handling is the most critical but would appreciate guidance on a few of the most used/best exciters as well.

Thanks to zygadr and all of the guys on this thread.  AMAZING WORK and CAN NOT WAIT to hear these things SING!!!!

Kind regards,
Rich

[zygadr]

Hi Rich!
For CC, use the single  cushion(layer)  in 4-5mm thickness. Most of the CC out there is good enough quality wise so I would not worry about that. Use the shellac coating and treatment covered in this thread also.

Suspending the panel in a frame has been covered a few times in this thread. Use forum member j gale's method a few pages back and you can't go wrong (photos included).

As far as exciters go, you can use the square, black base type by Dayton or Visaton (same thing) but use the highest power rating type...............even if you go with the new types offered by Parts Express.

Good luck and let us know how you go.

[mightym]

I'm wondering about the efficacy of mounting the panels.

I've accumulated almost everything I need to proceed with a build, but wondering whether to build with a frame surrounding the panels, or to just mount the panels "bare" only supported enough to take the strain off the exciters.

I know Ziggy has run his without frames, but that was a long time ago back in the early postings.  Is there any comments to be had regarding frame or frame-less mounting for the panels? 

Inquiring minds want to know....

John

[OB_Newbie]

Hello mightym,
Been really thinking this aspect over as well.  Not so much frame or no frame strictly but the specific technique to relieve the exciters from the weight of the panel.  A frame is traditionally used to receive the spine of exciters and to suspend the panel. However I'm wondering about this approach which is in the PE information regarding exciter construction (https://www.parts-express.com/resources-buyers-guide-exciters). 

I am considering the "Compliant suspension at a center location with free edges" configuration in the PE link above however it would be slightly different and hopefully offer some (slight) advantage.  I would mount my exciters to a spine using Monacor placement and then to the panel so the edges are free for better high frequency response.  Then would add some type of support mechanism to relieve the voice coils of the exciters - the idea would be to use 2 small wood/alum dowel (as far apart as possible for stability) attached between 4 exciters with 2 matching holes in the panel... the panel will essentially rest on the 2 dowels. 

Liking this idea as it seems that of all places on the vibrating panel to attach some type of panel support, the location between the 4 exciters would be the most chaotic and certainly does not appear to be an area where good music would radiated from.  So why not use this space to better use with a light and as *compliant as possible* support mechanism is the thought... not rigidly mounted but it would be interesting to listen and assess the differences between rigid and compliant mountings.  Of course its all tradeoffs... with free edges I'd likely have to dampen the edges with felt dots/triangles, paint, ??? to quiet the panels (another topic all together I'm sure).

Has anyone listened to the traditional frame mount like j gale's for instance vs. a completely free edge mount???

Thanks in advance!

Rich

btw I have CC and exciters are coming from PE.  Should be here in a few days.  Can't wait to listen and experiment!   

[mightym]

Thanks for your reply OB_Newbie.

I had not seen the link on PE's site, thanks for that. 

When I made the post RE: the frame or frame-less question, I was trying to figure out what I was going for in respect to appearance, and sonics too.  I have my own idea about the mounting of the panel, and after posting yesterday I went back and re-read a number of articles and information sources Including:  The 6moons review of Podiums model One,  The Visaton, Monacor, and NXT application papers, and some of the information contained here on the forum.

I also attended the Lone Star Audio Festival the first weekend of May in Dallas.  There were a number of OB speakers both commercial and DIY.  There was a 2 way based on Martin Kings design, with interchangeable small fullrangers, and Brad Bakers big Hawthorne based system using a large backless planer over a specially ordered 15" midwoof and a pair of Augies on each baffle providing the foundation, a very nice sounding if a bit imposing set-up.  I consider Brad a friend, after several years of listening to his DIY offerings at the LSAF, I spent quite a bit of time in his room.  John Busch brought his commercial version of the Manzanita.  I've heard John's stuff for several years now, everything from an 18" co-ax to a single panel hosting 2 18" high Q woofers, a single 10" mid and dome Tweeter on which he played the overture from "Also Sprach Zarathustra", at over 100Db at the couch......truly a visceral experience.  The gent sitting next to me on the couch commented afterward that " All I need is a cigarette, and a change of underwear".  This years commercial Manzanita offering was very smooth and were I in the market for such, instead of building my own, I would have bought them on the spot.

All that was to preface what I now have in mind for my build.

I'll start with a roughly 4" deep frame surrounding, with about 1/8" clearance a treated CC panel that is calculated at 1:1.41 to be 23.75"wide by 30"tall.  These will sit on top of a sub, and be crossed at aprox 160Hz to the panel.  The front will be covered with an audio transparent fabric to hide the panel.  The exciters will be mounted Ala' Monacors application guide.  The panel will be supported above and below the exciters in areas that are indicated as relative nulls on the centerline of the panel as I was able to ascertain from some study of images of the relative motions of the panels when producing a variety of frequencies.  The suspension will move with the panel in pistonic motion, and serve not to dampen but support the panel.  If damping is needed, I'll add felt, or foam rubber damping after assembly and measurement with my mic.  The panel edges will be free.  The exciters and suspension will be supported by a central spline on the rear of the panel.

This design is a combination of a lot of different sources/ideas, and I have no idea if it will give me the sound I'm looking for, but it's designed with my best understanding of the synergy of the materials, and with much learned from reading this forum thread for several years....  Supported with my own experimentation regarding materials and formats.

I hope to go 3D with this sometime this summer, I will report and provide images at that point.

John

[emailtooaj]

Sup everyone!

Man, feels like forever since I've last check in on this thread 

Was catching up on the reading and had to post this after reading mightym's last post. When he mentioned looking into building a combo sub/panel unit.
I was also looking to head that direction also, after perfecting the final panel setup/material choice and then implementing this sketch up I did back in the day...


Hope this photo is right side up for you all 

For what it's worth Mightym, I was doing a lot of research and head scratching trying to figure how best to match the characteristics between the flat panel and sub.
IMO what I think would be the best setup (this is what I plan to build before I die  ) would cross the panels with a Horn Subwoofer. Which is what I was trying to draw up in the sketch.
I absolutely agree with you to suspend the panel at the center point (that is a null point) and it won't affect the Sonics.
That is how my current panels are built as you may be able to see in this pic....



I used a closed cell rubber sheet and cut into small strips (1/4" W) for the hanging suspension. They are mounted at the top and bottom centers. Everywhere else along the panels edge is open air. This has worked perfectly w/o issues, and no coil drops in my el'cheapo exciters.

For the horn sub I was heading into designing the box/cabinet with either a 6" or 8" high power sub in mind.
As you all may know, the flat panels produce a very tight, fast and accurate sound... from low end to high. IMO a horn sub would best match these same requirements, and you can tune the horn design to naturally drop off at a determined frequency without having to get into using passive active crossovers.
But it does make the build more challenging with this type of design!!!
Since most boxed subwoofers today have a tendency to be muddy/sloppy sounding, I just think matching a panel speaker with a traditional boxed sub would be like wearing new pair of glasses... one side fitted with superior optical quality lens and the other side fitted with Plexi-glass 
Just my 2 cents though 

Peace!

[mightym]

Hey AJ,  Long time....

I'd really like to see some more pics of your panel if you have them.

Have you considered a tapped horn like the THAM 10 HTL on Martinsson's Blog?  LINK:http://www.martinsson.cc/blog/index.php (scroll down a bit)

Or possibly one of JBell's creations over on DIYAudio???

They are pretty compact for a horn, and might give you the sound you are looking for???

Just sayin'

John