[unnnot]

Hello Zygadr. Really my language Russian. These panels were made as experiment. To check possibility of their hommade production. Exciters were made of dynamic loudspeaker. Their placement corresponds to a golden ratio. Sounding especially the first option (with one activator) the bright. Percussion, string instruments, wind instruments, vocal sound very not bad. However  irregularity  (lifting) of the amplitude-frequency characteristic near 3-8kHz is felt. I think it occurs because of a ratio of the parties of the 140mmx680mm panel and low damping. My wharfedale pps-1 sound more evenly, but isn't so bright.

[lilbiscuit]

To anyone who has crafted an excellent pair of panel speakers...

Trying experimenting with running those in parallel with your best "non-nxt" speakers. Place the panels on the outside of your conventional speaker pair.

Dial the panels down 3-6db from the conventionals...

Press play (or lower the needle down onto the revolving disc)....

 

[emailtooaj]

Well, finally got my Cardboard sheets in. No real apparent delivery damage 
But, after looking at the way the cardboard is manufactured I thought I just check in with the guru's out there before I moved onto the next step.
I got 2x4 ft. panels (double sided) and the flutes run horizontal and not vertical down the panel.

__________
|                |
| ------>     |
|                |      ^
|  <------    |      |
|                |      |
|                |    4Ft
|                |      |
|                |      |
|                |      v
|                |
__________

Question is... Will this affect the sound at all? 
Has anyone played with different configurations with the flute running Vertical or Horizontal?

My other question is regarding the Shellac, to be waxed or De-Wax?
 
My one last question, I promise... How far does the shellac penetrate into the cardboard? Does it get adsorbed down into the flutes by just applying it thickly onto the surfaces?
The reason I'm asking is I believe treating and hardening the flutes does/will have a significant role in transferring sound/vibration effectively from the rear of the panel to the front.
That being said, does anyone have an easy and confident solution to properly wet/soak the flutes for best treatment   

Peace

[zygadr]

j gale should be able to answer your questions emailtooaj.

From what I have found in the past, it does'nt matter which way the flutes run in regards to sound quality.
No,............just coating the faces will not penetrate through to the flutes.
The flutes need to be ''injected'' with Shellac - slowly and methodically, allowing time to dry before moving to the next one. You can work on every second or third flute until you have done the entire width of your panel, let dry and do the opposite end the same way. Then, go back to the first side and do the ones you skipped before.

[emailtooaj]

Thanks for the reply Zy!
Treating the flutes sounds labor intensive 

Some other questions I should've asked in the last post...
Does the CC (in your experience) have a tendency to want to curl up or warp while applying the Shellac while it's wet?
Also, how many coats should be applied for rigidness? One, two...more?

I realized that in manufacturing the CC they obviously use a glue to mate the flutes with the front sheet and back sheets of the board. Has anyone experienced that binding glue to deteriorate by using the Shellac, since Shellac is basically a solvent and may dissolve the glue?
Any issues with the faces coming apart over time?
Don't want to hear distorted panels due to that 

Sorry so many questions.

Peace

[j gale]

Waxed shellac will be harder to bond exciters to. Treating the flutes is easy. Just don't drown the cardboard with too much shellac all at once. I used a plastic bottle with a nozzle like plastic ketchup bottles in some restaurants. I set my panel in a piece of aluminum gutter with the panel leaning against a counter ,so self supporting. slowly draw the nozzle along letting a small amount run down each flute. No need to squeeze the bottle. It doesn't take very much. The gutter allowed me to reclaim any shellac that made it all the way to the bottom. Flip the panel and repeat. It will have to lay flat on a table or floor to dry. Mine didn't curl. Drying can be hurried with a shop vac and small nozzle drawing air through the flutes. After dried I went back and repeated the process. Later I used two coats on the surfaces. I don't know if three would have been better. With shellac adding another coat is easy. I think cardboard is made with a water soluable glue so not affected much by solvents like alcohol. There are pictures in the 1st half of this thread showing cardboard being treated with tung oil? The experience with shellac appears to be about the same. My flutes run horizontal as well. I have had panels with vertical flutes too. I don't believe it matters as to sound.

[zygadr]

j gale, what mix or concentration of flakes to alcohol did you use?

[j gale]

Being the lazy sod that I am I used a product called Zinsser bulls eye shellac. It is a 3lb cut and has wax. They also have a 2lb cut sealer with no wax. The wax hasn't been a problem. It's an American product probably available in most places. Surface coats were applied with a small roller.

[emailtooaj]

Thanks for the reply j gale!
Great idea using the bottle and gutter technique. I'll trying that!
Any issues with the squeeze bottle plastic softening/melting with the Shellac? I assume there isn't since that's what your recommending.
Zinsser has two shellac products. One is the regular with wax. The other product is called "SealCoat" which is de-waxed. They classify it as a Sanding Sealer. Unfortunately I can't find anyone that carries the "SealCoat" from Zinsser, just the regular Zinsser Shellac.
I bought from Lowes a brand call Deft. It's label says Lacquer Sanding Sealer, just like the Zinsser "SealCoat" is classified. No where on the can does it state it's a De-Waxed Shellac. I'm just assuming it is going by the verbiage of Sanding Sealer. We'll see?
Ordering flakes will be my next option if this stuff doesn't work. 

[jonnoshore]

Do these "NXT" DIY panels act as an multiple source OR as a planar source which is effectively open baffle... just wondering if wall placement or 1-2 metres from the rear wall is ideal..

I suppose what I am trying to say is... Do they act as a dipole?

[zygadr]

Yes, they act as a planar speaker or dipole. As a matter of fact, as there is no null zone when you stand directly between the speakers, they could possibly be classed as being part omnidirectional??
They do need to come away from the walls by about 3 feet minimum for best sound. The depth of the soundstage is truly unique...........different to other panel speakers for sure.

[b2m]

Hey everybody,

I just want to clear up that I'm still in the game. I got two panels of reboard (which sounds great in first tests) but due to lack of spare time, I couldn't build them into soundboards yet. I'll keep you posted as I got some more time on my hands atm.

regards
b2m

[b2m]

Hey,

I now built the boards with 2 parallel and 2 serial per re-board connected to my Kenwood RA-5000. Sounds quite good but honestly, under 100Hz there isn't much left, I guess I'll add a conventional subwoofer to help in the bass segment. As it seems to be necessary to burn in the Dayton exciters I'll play them for a week before making the final decision.
I don't know why but they seem to be quite quiet. Any reason besides low efficiency on the exciters side? Do you have to turn the amp way more up using NXT-Speaker compared to conventionals?
I like the sound although I'm not sure whether it is really alot better then on the 3mm corrugated, but I used 2 component epoxy to glue them on the reboard, which is so stiff that I'm confident that they'll stay on and keeps me from building a frame.

Any thoughts or questions?

[b2m]

Alright, I just realized I made en error in the cabling, I'll fix that tonight, may very well be the reason that die Boards are so quiet.

[b2m]

Hey everybody

I'm kind of bummed out. I mounted everything and got the cabling right and tested it against my normal speakers (Teufel Omnitron) and well... The Teufel win in every aspect. Seems I got a little overwhelmed with the nxt thing, my setup is worse in the highs as well as bass-department. The whole dayton-board sounds extremely muffled.
I don't know if it is the reboard, in direct comparison it sounded at least as good as corrugated board, although I never directly tested cb against my Teufel.
I'm not sure I will keep on trying right now, any ideas besides trying another material?

edit: As Re-Board seems to be out of the game (I used 1200*700mm boards and the monacor placement) CC seems to be the best option. I guess noone has tried CFRP as of now?

edit2: I just reread some of the thread and saw that zygadr had a problem when not building something to support the Daytons. Is that really so much of a difference that the sound will improve significantly?

[emailtooaj]

Hey everyone!
Hope all is well !!!

b2m... Sorry to see that your not satisfied with the Re-Board trial. Don't get discouraged though 
There is a reason this tread is 91 pages deep thus far...It all comes to trial and error, finding the happy medium is not a one shot process!
I can't speak of the Dayton exciters you used, but I don't think that is where the issue lye's with the lack of sound quality your experiencing.
I would have to blame it on the Re-Board itself.
Because Re-Board has a  cardboard honeycomb center, there is no way to "stiffen" or "harden" the center of it. I would say without a doubt that the honeycomb center is absorbing the exciters energy, instead of transferring it.
The honeycomb is great for the rigidness of the panels as a whole, but... without being able to treat the center of the flutes (like you can with CC) it's just killing the effectiveness in transferring sound from the back to the front of the panel.
I know you didn't want to hear this but you'll have to find a different material.
Rearranging the exciters won't give you any better sound IMO.

Even though you used epoxy to mount the exciters (which I myself highly recommend) there's possibly a way to get them off the panel w/o much damage.
By experience , you can drop the panel (on it's end) on a hard floor. Epoxy isn't very resistant to sudden/hard shocks. The exciters should "pop" off.
I would suggest you tape the back of the exciters to the panel, so if you try this, they won't fall onto the floor; Protecting the exciters from further damage.
I will tell you this, depending on the way you epoxied them, you may loose the plastic mounting "foot" with this process. But... at least you'll be able to reuse the exciters for different panel materials.
You'll have to improvise attaching another "foot" though.
I can give you more suggestions to remount them if needed. Just let me know  I'll be more than happy to help.

[b2m]

Hey AJ,

thanks. You may be right about the absorbing. I think I'll just cut the exciters off with stanley knife and sand them down. I'll report if that works out fine, otherwise I'll come back to you.

I guess you haven't tried CFRP? When I've got some more money on hand, I think I'll try that.

[zygadr]

I agree with emailtooaj. The Reboard is killing the sound of the exciters.

I discovered this when I ripped apart a sample peice and realized
 that there is way too much happening inside between the faces. The trick to a good panel material is the efficiency in the way that it allows the sound and vibrations to pass through the panel. If it's too soft or too thick, the high frequencies will not pass through. Also, the exciters need to be held on a rear spine and only touching the suspended panel with double sided tape, otherwise, output and sound quality will suffer further.

I still think the best sound I obtained was with 2.7mm plywood, but due to it's weight, the output level was seriously compromised.
Shellac treated C.C., single cushion, is the way to go at this present point in time (or forever.........who knows??).

C.C. has the ability to throw a huge deep sound stage that cannot be forgotten once heard...............such is the nature of the beast.

[b2m]

Hey Zyg, single cushion CC is probably what I will go back to, but first I wanna try CFRP, it is such a lightweight and stiff material that it just might sound good.
After that, I think I did enough testing and will go the tried and tested CC

Thanks for your input, guys.

[emailtooaj]

Hey All,

b2m, I haven't tried CFRP yet. My pockets aren't deep enough to try that out yet 
If I was to try it, I would be very particular about the actual inert material used to make the CFRP since there are many ways to make one... in terms of the type of resin used, the composite used ( Kevlar, carbon fibers, fiberglass, or even aluminum).
Carbon Fiber itself may have a very "dead" sound? I don't know for fact though.
I would think the best mix would be epoxy and either fiberglass or aluminum.

I have actually looked into using carbon fiber and fiber glass to make my voice coil formers, but shied away due to cost and the various ways they may effect the sound.

When it comes to the actual panel material, Zygadr correctly stated "The trick to a good panel material is the efficiency in the way that it allows the sound and vibrations to pass through the panel".

I'll even go a step further and say the best "efficiency" stars at the voice coil all the way through to the front of the panel.
Since "sound" is vibrations, choosing the right materials to transfer the vibrational energy (without lose) is critical in having a great, accurate sounding efficient panel speaker.

*** Side Thought*** If I had more time to make my own panels from scratch, I would try to find a veneer sheet of Maple or Spruce (.5 to 1.5mm) epoxied to HDPS- the Blue sheet (4mm thick or so), and mount the exciters onto the veneer side.
I would imagine you could get a great tone from the wood and the HDPS would help keep it rigid, light weight and to some extent help amplify the sound from the veneer.

There are so many possibilities out there 
Trick is keeping it simple and not to get overwhelmed. 

Keep us posted with your results b2m if you decide to try out CFRP  We would love to hear what your thoughts are on it!

Hope to talk to you's guys soon!!

Peace