[TexBear]

Thanks Odal et al -
Have family visiting just before the holiday, so haven't had a chance to get to the 2'x2'x1" panels. I did demo the 2'x3'x2" XPS panels for family members, and they loved the sound, and amazed at the materials. Hope to post more soon.

[OZZIOZZI]

Hi Odal can you post pics of how you have constructed your panels, including bass drivers.

Up to now I have been running my panels fullrange with just the panel and one exciter on an 1/8" ply panel, 3/4" or 1" polystyrene. I haven't had a chance to obtain some Ultra high density polystyrene as Bendingwave has suggested. I suspect the best material for panels is a high tech composite, thin, light but rigid and internally damped made of unobtainium  (aircraft or highend yacht materials seem likely candidates)

A laminate panel probably made of end-grain balsa covered with rigid surface layer(s) is used in the Goebels very highend DML speakers, but even they have resorted to bass helper cone drivers and passive EQ, Zobel circuits and peak removal circuits to achieve a good sound -- reading between the lines in their adverts, reviews and website waffle. This is a BIT difficult to build for the average handyman.

 I am still debating whether to XO passive or active. If I go active and bi-amp the XO point and level matching can be easily adjusted to get best blend between OB bass and panel lower mid-treble. I can also experiment with asymmetric XO as some people have reported with cone driver OBs. XO  at different freqs for low- and high-pass can alter the apparent midrange sound, for either "laid back" or " bright" sounding system. These experiments are harder and more expensive with passive XO, especially when large inductors and capacitors are involved at 100-200 Hz. I have limited time and budget so active XO is more likely.

Re. Rattles etc, I haven't finalized mounting of panels, but they seem to buzz even when hand held or mounted on blocks of foam rubber at different points. I think I will have to commit to semi-permanent mounting methods and be prepared to throw away my failures.

Ozziozzi
PS you were right about the audiocircle forum. The next page has formatted correctly.

[Bendingwave]

One of the down falls with experimenting with these exciter technology is that you will be throwing away a lot of your failures in the beginning just from attaching and retaching of the exciters as either the exciter will break or the panel will break or both when trying to detach them as one or both of them will give and I prefer to break the panel material instead of the exciter when trying to remove them....I use a thin knife or xacto blade to remove them.

Also I dont like the 3m adhesive tape that comes with the exciters as they are not permenant and over time will come off plus like I said even the type of adhesive used to attach a exciter to a panel can effect its sound....my adhesive of choice is 2 part EPOXY, prefer the 5 minute epoxy so it sticks fast.

Also someone on this topic mentioned about using GRAPHENE material which is very very expensive, way more expensive then even nomex honeycombs.

[Odal3]

No pictures handy but I did a writeup that kind of details how my panels are made. Just realized it was almost exactly 2 years ago: http://139.162.105.238/index.php?PHPSESSID=8hon0mcfq1nvbncfs98o6rc0s6&topic=70541.msg1443096#msg1443096

I normally run 1 exciter (unless I need extra volume) and place it close to but not exactly at monacor number 1 (I move it around a little bit to fine tune the sound)

I'm of the opinion that there is not just one perfect way to get to good panel sound, but there are many good ways as described in the thread and elsewhere. We all also have different preferences in terms of sound, music listen to, availability of material, and of course how important the look is (WAF). Pros and Cons with all of them. I have to say that the real fun part has been the ease of experimentation.

I never got my XPS panels to a point where I preferred them to my birch ply but that could just has to do with user error on my part or perhaps the way I had them and my system setup at the time. At the same time I fully understand why some people like the XPS and lighter material better with the benefits it comes with. My advise is to try a couple of the approaches you feel has potential and then judge and hear for yourself. User Sedge has for example a couple of good write-ups earlier in the thread.

If you use ply, my experience is that 1/8" is not stiff enough and "overbends" = doesn't sound so good when turning up the volume due to strong "vibrations". If you can live with lower volume (still loud enough for me), try 1/4 ply as well. It my experience it gives much better bass. However, if you cross them as high as you mentioned it may not matter.

Have fun and enjoy!

[Odal3]

One of the down falls with experimenting with these exciter technology is that you will be throwing away a lot of your failures in the beginning just from attaching and retaching of the exciters as either the exciter will break or the panel will break or both when trying to detach them as one or both of them will give and I prefer to break the panel material instead of the exciter when trying to remove them....I use a thin knife or xacto blade to remove them.

Also I dont like the 3m adhesive tape that comes with the exciters as they are not permenant and over time will come off plus like I said even the type of adhesive used to attach a exciter to a panel can effect its sound....my adhesive of choice is 2 part EPOXY, prefer the 5 minute epoxy so it sticks fast.

Also someone on this topic mentioned about using GRAPHENE material which is very very expensive, way more expensive then even nomex honeycombs.

Good points! When I do the first rough run on a new panel, I actually start out with the 3m adhesives to try out if the panel has potential. I keep the 3m adhesives on while tweaking the panels and once I'm happy, I mount them permanently with the epoxy.

Edit: I probably should say used to since it has been a while since I had the time to play with new panels.   

[Bendingwave]

For experimenting purposes I use the 3m tape that comes with the exciters as its easy to remove without damaging either of them.....but when I compared  the same type of exciter, one using the 3m tape and the other using 2 part epoxy, the 2 part epoxy sounded better probably due to it being HARDER then the softer 3m tape adhesive.

Also I was reading that link you posted above of OB newbies post saying that XPS/EPS has a livelier knock while the ply is dull.....IMO most likely due to the EPS/XPS panels being way more easier to vibrate and transfer the vibrational energies throughout the material....if the material is too dense its harder to vibrate....a material that is LIGHT, softer and less dense is easier to vibrate.

I just played some Al Jarreau (after all) on my 5.1 (EPS) panels and they just sound so amazing. 

[Odal3]

Absolutely agreeing with you on the lighter vibrates more easily, etc. and the theory has always made perfectly sense to me. I have really tried to make it work, but somehow I always end up going back to ply. To me the ply added the depth and details of acoustical instruments such as piano, cello, etc. as if I was playing the piano myself. So while I perhaps lose out in some areas, I feel I win in others    I guess it's just a preference thing. I started some projects to combine both approaches in multi-panel set up, but never finished.

Really happy to hear you are enjoying your set-up!

[Bendingwave]

Odal3 have you tried the Ultra hard density EPS?...it makes a big difference compared to the standard and low grades as the UHD EPS is more accurate and tighter sounding then the lower grades....combined that with some dampening coatings on the front and back of the UHD EPS will bring out more of the depth and details of acoustical instruments similar to ply wood but with higher out put and imo the best of both worlds...I still  get goose bumps every time I play the Duende track from Bozzio/Levin/stevens. 

 I am glad I am finally done with most of the experimental stages so I can finally enjoy my panels after almost 3 years of experimenting with my panels 3-5 days a week I am finally satisfied enough with the sound of my panels.

I am not saying there is no room for improvement but for now I am content enough with the sound.

I am still waiting for someone to invent a teleportation machine so we can all come over to each others houses and listen to every ones designs. 

[Bendingwave]

Speaking of BASS....Some say these exciters dont have that "slam" factor compared to conventional cone subs which is true to a degree most likely due to the physical limitations of the exciter because the most powerful of all exciters only handles 40 watts rms.....imagine if Dayton Audio made a huge 200 watt rms super high shove exciter made just for subwoofer application I would assume they would produce a good decent amount of slam if designed right.

My single 40 watt rms DAEX30HESF-4 used as a sub panel with a sub amp produces a good amount of room filling bass...this type of bass wont hit you in your chest like a conventional (200 watt rms) 10" or higher cone sub but you will hear the bass which sounds very convincing and full sounding.

https://www.youtube.com/watch?v=huuw6UiewOs    Listening to the bass in the (20 sec. mark) beginning of that track on my sub panel is what partially gives me goose bumps every time I hear it combined with the other acoustics on that track make it a pleasure to listen to it time and time again.

Oh I also forgot to mention that my bass panel is only 16inches by 22 inches....the misconception that one needs huge/big 2ftX4ft panels or 4ftX8ft panels to get enough adequate amounts of bass response is not true.

[OZZIOZZI]

Bendingwave, if you listen to an intimate acoustic jazz trio, for instance, often the piano, bass and drums are only amplified (if at all) by a PA system. and if they are well balanced, the players don't drown out each other. 

It is only when acoustic bass or drums are close miced and played through a powerful PA with usually a large amps and subwoofer that there really is "slam" in the bass, drums and even other instruments. Of course, with rock or all electric bands electric bass has slam from the player's own amp and then that is amplified (usually at stadium levels even in an enclosed space). Do you remember the movie Spinal Tap where the stage amps were turned up to 11. I used to drive a PA for a 10 piece band and everyone always wanted to be louder than everyone else in the foldback and house mix!!!! After a while you just run out of headroom, even with a powerful PA, and just end up with distortion.

For acoustic groups DML loudspeakers CAN produce the **actual** level of the performance for someone seated in the audience. Unfortunately, a lot of people are used to highly amplified music at concerts and try to recreate that SPL at home and they complain about lack of bass output. I am as guilty as anyone in complaining about this, but it is a false expectation. If you want concert levels get a good pair of headphones.

Just my 2c worth.

Ozziozzi

[Bendingwave]

Bendingwave, if you listen to an intimate acoustic jazz trio, for instance, often the piano, bass and drums are only amplified (if at all) by a PA system. and if they are well balanced, the players don't drown out each other. 

It is only when acoustic bass or drums are close miced and played through a powerful PA with usually a large amps and subwoofer that there really is "slam" in the bass, drums and even other instruments. Of course, with rock or all electric bands electric bass has slam from the player's own amp and then that is amplified (usually at stadium levels even in an enclosed space). Do you remember the movie Spinal Tap where the stage amps were turned up to 11. I used to drive a PA for a 10 piece band and everyone always wanted to be louder than everyone else in the foldback and house mix!!!! After a while you just run out of headroom, even with a powerful PA, and just end up with distortion.

For acoustic groups DML loudspeakers CAN produce the **actual** level of the performance for someone seated in the audience. Unfortunately, a lot of people are used to highly amplified music at concerts and try to recreate that SPL at home and they complain about lack of bass output. I am as guilty as anyone in complaining about this, but it is a false expectation. If you want concert levels get a good pair of headphones.

Just my 2c worth.

Ozziozzi

I hear what you are saying Oz.....I for one cant stand concert level spls they make my ears bleed, giving me a terrible headache all the while making me nauseous. lol.....I prefer room filling sound at moderate levels.

I just finished making a dedicated tweeter using a Dayton 13mm exciter attaching it to a 1 inch square of 99% pure titanium foil....I am experimenting with different capacitors to see which one will blend the best with my panels....so far Ive tried a 3.3uf, 2.7uf, 2.2uf, 1.5 and a 1.0....most exciters seem to drop off at around 10k and above hence why the 1.5uf and 1.0uf sound the best to my ears....the 3.3uf and 2.7 sounds a little too bright on certain type of acoustics and it does add that extra sizzle/siblance to the vocals but can be a little fatiguing...so its either the 2.2uf,1.5uf or the 1.0uf.

[OZZIOZZI]

BW, a bit off-topic, but I am a sucker for that sizzle from the cymbals and hi-hats. I can hear it on my panels, but it sounds like they are a long way off at the back of the stage.

I have four EMIT Infinity tweeters from a couple of old RS7s  that I was thinking of using for top end sparkle. Quote from an old post on audioreview forum "EMIT's are not ribbon speakers. They are planar magnetics. Planar magnetic speakers have a voice coil printed on or attached/glued to a diaphragm.
The name EMIT means; electromagnetic induction tweeter." They are like a Magnaplanar panel in miniature.
The Virtually weightless diaphragm and voice coil are supposed to extend to 45KHz so if you like annoying bats...
So not DML spakers, but at least planar diaphragm. Not much piston behavior going on 6K - 45K

And inside
note break in voicecoil.

You can always get some silver conducting paint (used for repairing windscreen demister traces) or copper ribbon and put a voicecoil on the back of a  polystyrene panel...then some strong magnets...do it in one small spot and you have an exciter built into the panel. 

Ozziozzi

[Bendingwave]

Hey OZ

If you look at the front panel of the bertagni speakers there is a half circular crater in the top corner of the panel....This circle is used for the high frequency exciter, but what is this circle for and what does it do?....Its simple it is a WAVE GUIDE....utilizing this circle makes the highs sound more FORWARD, then sounding like they are way off at the back stage.....I applied this same method to my dedicated exciter tweeter by using a wave guide and the highs sound more forward in the sound stage.

[Odal3]

Odal3 have you tried the Ultra hard density EPS?

No - never had a chance. I have only used what I can found at the US home improvement stores (Home Depot, Lowes, etc.)

Re bass - my experience is that bass is relative to size of panel, not necessarily power rating of exciter - the bigger panel the lower bass.

I tried once putting multiple 40W exciter like I saw in one of the tectonic videos - the 1/4in birch panel was not stiff enough resulting in a lot of rattle due to "over-bending". Perhaps you need a different design altogether if you have very powerful exciters. ?

[Bendingwave]

No - never had a chance. I have only used what I can found at the US home improvement stores (Home Depot, Lowes, etc.)

Re bass - my experience is that bass is relative to size of panel, not necessarily power rating of exciter - the bigger panel the lower bass.

I tried once putting multiple 40W exciter like I saw in one of the tectonic videos - the 1/4in birch panel was not stiff enough resulting in a lot of rattle due to "over-bending". Perhaps you need a different design altogether if you have very powerful exciters. ?

Ah ok, HD. and Lowes dont carry the higher grades or at least the ones in my area did not have it.

Bass is relative to the size of the panel but only to a degree as it is just one component of the whole which ALSO includes the exciter as well as the type/size/power handling of the exciters matter just as much as the panel size.

I keep on hearing people saying the bigger the panel the lower the bass BUT there is a degree or limit to how much a exciter can vibrate and saturate a panel and it will depend on the TYPE of EXCITER hence why the TYPE of exciter plays in important factor as well as panel size...what good is low bass if its INAUDIBLE and or combined with HIGH levels of DISTORTION due to the exciter only being able to handle 4 watts max?

I do not believe in a one size panel fits all exciters or vice versa....I feel there is a right size panel for the right type/size of exciter like a perfect ratio blending the two....if the panel is too big for that exciter the bass can sound muddier or if the panel is too small for that exciter you will lose low end extension so one has to compromise between the two to have it just right where one has low end extension as well as accurate bass.

The biggest size panel I have used is 4ft.X8ftX2inch thick.....a single 40 watt DAEXHESF30-4 could not IMO saturate that big of a panel on its own...maybe if I used multiple (2-4) exciters it could have saturated the panel but my design does not call for multiple full range exciters.....my design uses only 2 exciters with one of the exciters only used as a high frequency driver.

I dont know what techtonic video you are talking about but the podium speakers use multiple exciters and I am pretty positive there were not any rattling....so yes , DESIGN is very very important when dealing with DML panels.

[Bendingwave]

Another thing I wanted to add about rattling could be due to one not using a spine.....when I first designed my DML SUB panel using the DAEX30HESF-4 40watt rms exciter, I wanted to try it with out a spine and just let the exciter free float on the panel....at low to somewhat medium volumes it sounded clean with no rattle but as soon as I cranked up the volume the excursions/thrust would make the back of the exciter rattle because since nothing is securing the magnet part that magnet part starts to rattle like crazy from higher excursion but as soon as I put a spine to hold the back/magnet in place the rattle stops because the exciter will now push on the panel instead of pushing off of the back side of the exciter where the magnet resides this is WHY I feel a spine holding the exciter in place is necessary. This is most likely the reason Bertagni and Podiums speaker designs utilized a spine.

[oldschoolVlad]

I noticed with some of the higher powered exciters that they have a horn or waveguide as part of the cooling vent.



I wonder if you could use this same idea to boost the output from the rear of other exciters. Scuse crude drawing, but you get the idea


Ozziozzi

No, guys, that "horn" has nothing to do with the sound, its just a part of magnetic motor assembly - magnetic flux conductor to the voice coil. When I designed my custom exciter with the simulation software called FEMM, I found that shape of the flux conductor is most efficient. Thats all about motor efficiency, nothing more. By the way, on the picture one can see the most efficient custom designed exciters. I guess DAEX25SHF-4 has the same design.

[Bendingwave]

Ahhh so the exciters with just the single hole in the middle is just part of the magnet assembly, which I assume is totally different from the exciters with VENT holes.

[oldschoolVlad]

Every single hole in the middle is a vent one, a horn shaped hole is a result of motor design.

[Bendingwave]

ah ok got it........have you tried the Dayton Audio DAEX25SHF-4?