NXT.......rubbish??....THINK AGAIN!

HenryPercy · « **Reply #140 on:** 3 Oct 2009, 01:52 am »

Thanks, Copperhead. Very good info.

Donka · « **Reply #141 on:** 3 Oct 2009, 05:49 am »

Copperhead,

That's interesting info on the exciters and Gator Board. The enhanced properties of the white board sounds like it would be a better suit.

I just spent 2 hours stripping the cases and the sticky foam ring off 36 exciters. It was quite easy by pulling outward on the arms to break the glue bounds around the perimeter, then taking cable cutters make 2 snips in the side wall of the plastic so you can fold back the outer shell and easily finish peeling out the exciter.

I purchased the clearance white ones and they came in flats of 20, as 10 pairs of 2 pre-wired in series. I was hoping I could just desolder the resistor and capacitor, however it's going to require a jumper or resoldering the lead wire from the coil to the adjoining wire terminal. I wonder the difference in sound by leaving them on?

I plan on reserving 2 sheets of GB and 20 exciters for my final setup, however want to experiment with remaining board and exciters. Can someone suggest a smaller scale layout, using the 4' width as the height of the speaker panel, this way I figure I could make at least 3 test panels and use 4 or 5 exciters per, then experiment with placement, adhesive, and mounting options, also take some measurements along the way.

Copperhead I too am interested in trying a ribbed design, and tried finding photos or descriptions of the "sound-bridges" but have yet to find anything worthwhile. If you look at the housings the exciters come in it seems apparent that having some sort of mounting system that enables a level of push-pull action between the exciter and panel is key. I left the 4 remaining exciters in there housing to experiment with as is.

Copperhead · « **Reply #142 on:** 3 Oct 2009, 06:49 am »

Hi Donka,

Really glad you're in a position to experiment. The Podium 0.5 is 55" x 23.625", so keeping the same ratio, would give you 48" x 20.6". That measurement probably
included the frame. If so, your test panels are right in the ballpark.

I'll be very interested to see if mounting them to a frame has any effect. Compared to standing on the floor, having an entire short side damped, plus the point where
they lean on something, I'd expect it could only be an improvement.

Remember to compare with and without corners. (rounded) All the commercial designs employ this, and it's also why I'd be reluctant to suspend the panels by their corners.

Donka · « **Reply #143 on:** 3 Oct 2009, 07:15 am »

Well I searched a bit more and found a 6Moons review of the 1.0, in which one panel was damaged on arrival, and he flew out and fixed it. Some interesting tidbits but nothing concrete, based on their description the picture of the panel with the covering peeled back, those 2 white globs should be mounting points, however since they're asymmetrical, who knows what the other side looks like under the cloth

From link: http://www.6moons.com/audioreviews/podium/1_2.html

"It was first necessary to take off the honeycomb from the still attached remaining exciters. First the four braces that form the connection between frame and panel needed removal. This meant slicing the glued-together pieces of white spongy material in twain. While operating, Shelley shared story after story about his never-ending quest for materials that could help him create this loudspeaker. The marshmallow-like putty now dissected was one of these special materials. Even the putty used to seal the speaker wire into the spinal groove is special. It is easy to work with, does not harden, is gentle to the insulation and prevents the cable from vibrating."

" Next was reattaching the severed braces between frame and panel with another type of glue. "

Copperhead · « **Reply #144 on:** 3 Oct 2009, 07:34 am »

The description of the "sound bridges" is cryptic. Are they made of a soft marshmallow like material, or is that what glues ithem
to the panel? Do they help to hold up the panel, or is it suspended from the spine via the glued on exciters?

"the putty used to seal the speaker wire into the spinal groove", could be replaced with plasticine. "Easy to work with, does not
harden, gentle to the insulation".

Donka · « **Reply #145 on:** 3 Oct 2009, 08:07 am »

I figure the panel is primarily supported by the exciters and spine, and from the description of the "bridge" material it sounds like it would sag and possibly tear if supporting any kind of weight.

The question for me turns to whether this is enhancing the sonic properties, or is it there to support the panel for stability in transport. Shipping them flat with the panel only supported by the exciters on the spine would be asking for damage. The material almost sounds like memory foam, or maybe a closed cell foam, which is glued in place to bridge the gap but have the least effect on the panels movement when playing music.

EDIT: The more I think about it, the frame seems to be there more for visual and finished good purposes. You know something to stretch grill cloth on and protect the panel from damage. I think the spine is the key.

FullRangeMan · « **Reply #146 on:** 3 Oct 2009, 12:02 pm »

Quote from: Copperhead on 3 Oct 2009, 07:34 am

The description of the "sound bridges" is cryptic. Are they made of a soft marshmallow like material, or is that what glues ithem
to the panel? Do they help to hold up the panel, or is it suspended from the spine via the glued on exciters?
"the putty used to seal the speaker wire into the spinal groove", could be replaced with plasticine. "Easy to work with, does not
harden, gentle to the insulation".

Hi guys,
I think if this mashmallow secret matter is black it can be the Sorbothane Rubber used in equipment feets!!
Sorbothane rubber is very gelly and sticky...
There is no close-up photos to find throug on the 6Moons test.
Best

jonners · « **Reply #147 on:** 3 Oct 2009, 08:02 pm »

This all looks very interesting and I think my curiosity is about to lead to an order for some drivers.

Meanwhile, I came across this site, which has some good explanations and links to technical papers etc: http://www.nlightnspeakers.com/

Donka · « **Reply #148 on:** 3 Oct 2009, 09:33 pm »

Well I have 2 test panels up and running. I cut them at 9/4 ratio of 48" X 21.33" on the table saw. The placement for 4 exciters is 12" from top and bottom, and 8" between. I mounted the exciters using Rite-Lok SB16-28 using 5 points around the perimeter of the "foot". The 1st panel has exciter's with both cap and resistor removed, the second is with only the resistor removed. You can tell the fully stripped panel #1 definitely has an increased base response over #2.

I measured the resistance of a stripped exciter at 4.3 ohm and a series pair at 8.7. With the 8" spacing it is just possible to leave the pairs already wired in series. I am running the setup off a Pioneer 50w Class D Ice amplifier designed specifically for a 4 ohm load. It won't be until later today or tomorrow that I will have time to setup the microphone for some measurements.

What do guys think I should test for the panel #3, I was thinking:

1) trying completely stock, in the housing with the spider glued as well.
2) stock minus the plastic housing
3) combination of a series pair with the capacitor, and another pair without.

I read further into one of the patents listed earlier and there was some interesting information regarding exciter offsets on a rectangular panel. It spoke of designs either boxed or near boundary creating a baffle effect for increased lower end. It also spoke of slots or other cutouts to relieve nodes on the panel, asymmetrical ribbing, and also asymmetrical core construction to vary resonance across areas of the panel. Pretty interesting stuff, which only add more dimensions, however I am liking Zig's apporach to copy something that is known to perform. Overall from what I gathered the vibration is rather elliptical and ideally you could use and elliptical or circular panel for smaller apps, however the corner rounding on rectangular panels is key to diffusing unwanted end-vibrations.

Again I want to thank Zygadar for doing the initial testing and throwing it out there, I have to say $20 worth of exciters, $36 worth of GatorBoard when I factor in delivery is sounding pretty damn good right now.

I will say my current panels are not HiFi but they are designed for testing, and I hope that going full scale will really open things up, granted i haven't even tested mounting methods or otherwise, they are currently leaning against 2 tall chairs which is blocking the majority of the rear sound. Time to fire up the saw again and make some stands real quick.

EDIT: the 3M tape just arrived!

Copperhead · « **Reply #149 on:** 3 Oct 2009, 11:52 pm »

Hi Donka,

"The more I think about it, the frame seems to be there more for visual and finished good purposes. You know something to stretch grill cloth on and protect the panel from damage. I think the spine is the key."

I think you may be right. The "sound bridges" might not be doing anything positive for the sound. they could just be the best compromise he could come up with
to attach the panel and frame. If we can do away with any aesthetic advantage the frame offers, and maybe safety, if kids or animals are involved (for the speakers, not the kids and animals), this project can be very much simplified.

Your earlier post about doing away with the frame and mounting the panel directly to the spline is a good one. just deciding on the mounting points. Jim (j gale) was
thinking of trying something similar.

Try rounding the corners on one panel and see what happens.

As far as damping or tuning the panel, Ziggy mentioned using thin splotches of bluetac in various positions earlier, (inexpensive and reversible), and Podium do it by selectively plugging the holes in the spline behind the magnets. There are endless possibilities.

Copperhead · « **Reply #150 on:** 4 Oct 2009, 04:50 am »

Donka, if you haven't already cut it up, how much of the sheet do you have left?

Earlier Fullrangeman mentioned using the golden ratio. It might be interesting to know if a different shape sounds or measures
differently. I think I read that Shelley Katz said the size they chose was determined by the best use / least waste from the nomex
sheets. You never know, that could be far from ideal.

Keen to hear what happens when you test a stand / spline too.

No pressure or anything.

FullRangeMan · « **Reply #151 on:** 4 Oct 2009, 05:04 am »

Quote from: Copperhead on 4 Oct 2009, 04:50 am

Donka, if you haven't already cut it up, how much of the sheet do you have left?
Earlier Fullrangeman mentioned using the golden ratio. It might be interesting to know if a different shape sounds or measures
differently. I think I read that Shelley Katz said the size they chose was determined by the best use / least waste from the nomex
sheets. You never know, that could be far from ideal.
Keen to hear what happens when you test a stand / spline too.
No pressure or anything.

Hi folks,
Please do not cut GatorFoam panel before reading

the link about panel sizes/proportions earlier on this thread, perphas a post from Angaria
There are some Width/High proportions the are recommended by NXT company, out of this sizes will be spurious resonances.
I already choose my size (75cm x 196cm) it is Golden Ratio (2618), there are others suggestions on this paper that are not GR throug,
but works as a NXT panel.
Good Luck

Eduardo AAVM · « **Reply #152 on:** 4 Oct 2009, 05:25 am »

Hello, I read about your exciting NXT project I am also thinking on building something like that but how or where did you get the NXT panels ?

Can you share the info ?

Thank you

Copperhead · « **Reply #153 on:** 4 Oct 2009, 06:03 am »

Fullrangeman, isn't the golden ratio 1.618?

FullRangeMan · « **Reply #154 on:** 4 Oct 2009, 06:10 am »

Quote from: Copperhead on 4 Oct 2009, 06:03 am

Fullrangeman, isn't the golden ratio 1.618?

Yes, it is 3 proportions (1,00 x 1,618 x 2,618). As I want a tall panel I choose 2618. The 1618 size is too square for my personal taste.
I do not see 1618 size in the NXT company recommend proportions, but I may be wrong.
Kinds.

FullRangeMan · « **Reply #155 on:** 4 Oct 2009, 06:16 am »

Quote from: Eduardo AAVM on 4 Oct 2009, 05:25 am

Hello, I read about your exciting NXT project I am also thinking on building something like that but how or where did you get the NXT panels ?
Can you share the info ?
Thank you

Dear Eduardo,
The best NXT panel Zygadr found is the matter GatorFoam made by Alcan Composites. My project details are back on page 10, feel free to use.
Now from the paper plans only I think the option one with 21cm is better than the 23cm. The ''21cm plan'' can be used with 8 or 9 exciters.
Kinds

bobloblob · « **Reply #156 on:** 4 Oct 2009, 09:12 am »

Just a not-yet-thought-through thought here: what about making the spline somewhat higher than the panel, then putting an eyehook (anything else would serve, but I am using eyehook here for clarity) near the top. The panel could then be suspended from this either directly or with a line or cord of some sort, taking the weight off the exciters. Should simplify the build some for those who want to try mounting the exciters to a spline, but not have the panel pulling down on them. Or a T-brace could be placed at the top of the spline so that two suspension points could be fashioned if more panel stability were desired.

Donka · « **Reply #157 on:** 4 Oct 2009, 10:02 am »

Copperhead,

I purposely didn't make a 4th test panel so I could test the larger remainder (30x48") vs the others. I also chose the wider 4:9 ratio for the test panels so I could always cut them down to slimmer ratio's for further testing. On the offcut, I haven't decided whether to go with a different ratio or a radically different shape like an ellipse or trapezoid.

After the tape arrived, I outfitted the 2 remaining pairs that I had left completely stock in the plastic spider housings, then walked out on the catwalk and stuck them to a window (roughly 5' X 5') outside the family room in a random sort of diagonal pattern. Boy I was blown away by the low end, it was rattling some linear lighting in the soffit above the window indoors. However the upper end was very constrained. So now I am thinking that the frame and boundary restraints may add significantly to the sound, though I can't saw whether this applies to the podiums. Or should I say it's seems definitely possible to tune the response by using different mounting techniques, just depends on how much time and labor you want to put forth making a more extravagant setup. Anyhow after that I had to revert back to finishing the networks for some TL speakers I built.

More building and testing tomorrow during football.

Copperhead · « **Reply #158 on:** 4 Oct 2009, 11:32 pm »

I wonder how much of that extra bass was produced by the window frame , and how much by the heavier and stiffer material (glass).
What would happen if the panel was made of two different materials? Would you lose cohesiveness or gain some omph, (technical term).

usp1 · « **Reply #159 on:** 5 Oct 2009, 12:46 am »

Donka,

Where did you get the gatorfoam for $36. I have 10 pairs of the exciter arriving next week but still have not been able to find a good source for the gatorfoam or the 3M tape. The online sources seem to require bulk purchases of both.