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

Copperhead · « **Reply #160 on:** 5 Oct 2009, 04:22 am »

I don't know if this has already been posted, but is very interesting reading about panel material, (stick with it, it gets very specific).
http://www.freepatentsonline.com/EP1322135.html
I need to get a sample, but everything is so expensive in Australia.
The Podium 1 is supposed to do 30Hz to 20KHz (+/- 3dB), using 5 exciters on slightly smaller panel than Ziggy's, which only gets
into the 50's? I know Gatorfoam is convenient, but it isn't cheap here, so I'm still going to explore other materials.

jeffac · « **Reply #161 on:** 6 Oct 2009, 12:16 am »

Anyone provide me the OEM exciter diameter, guessing about 3" from pics but exact would be good to know as I have a few on their way to AUS. Just wondering what 3M tape width would be neat and easy for fixing them to a panel.

bytheway · « **Reply #162 on:** 6 Oct 2009, 03:28 am »

I finally took the time to read over this thread, and I'm convinced I've got to give it a shot.

Has anyone tried out the $16/pair dayton exciters vs. the $5/pair cheap-os? I assume from the thread that removing the housing from either of these models is a must? So you don't use the spider mounts at all, right?

Has anyone made perfectly square panels? I ask because I figured you could make a full 5 point surround system out of one standard (4x8') gator panel:

3 - 4' by 2' panels for front right, left, center
2 - 2' by 2' panels for rear right, left

I have no idea if the 4' by 2' panels would be too small for mains, if so it might be better to use 2 gator panels to get the 5 speakers.

As I'm just beginning, I'd love any thoughts or recommendations.

FullRangeMan · « **Reply #163 on:** 6 Oct 2009, 04:08 am »

Quote from: bytheway on 6 Oct 2009, 03:28 am

Has anyone made perfectly square panels? I ask because I figured you could make a full 5 point surround system out of one standard (4x8') gator panel:

BYTHEWAY,
The panels sizes must follow the NXT Company recommendations, outside this is a danger of bad sound, anomalous resonances etc
I do not remember if the 1/1 proprortion (square) are recommended, please read a link in the past pages that talk about proportions and inform us for register on this thread.
Regards

bytheway · « **Reply #164 on:** 6 Oct 2009, 05:36 am »

Found some info in the google patent doc:

One possibility is about 13.4% from square (0.882 or 1.134)
another mentioned is 37% from square (0.63 or 1.37)

Those are still pretty square from what most people have been building.

usp1 · « **Reply #165 on:** 7 Oct 2009, 05:34 am »

My $5 exciters arrived today (I have 10 pair just in case I mess up) I located a local source for the Gator foam but it is still pricey - $65 for a 4'X8' sheet. I hope Donka checks this thread soon so I can find if there is a cheaper source. Still trying to find a good source for the 3M tape.

I spent the last 30 mins playing with 2 pairs of the exciters. Without removing the caps or resistors I just tried placing the exciters on a few different materials. The best result I got was from a small sheet of coroplast that I had lying around. Sounded like a boombox. I was using 4 exciters in series without actually attaching with tape or glue. The highs were rolled off and the lows were non existent but this was simply plopping 4 excites with the built in wire that they came connected to. This surely seems to have a lot of promise. Will report back when I have all the required material and after I try it out.

Copperhead · « **Reply #166 on:** 7 Oct 2009, 06:42 am »

Hi Ziggy, did Erling make it around to hear your speakers?

Waiting with bated breath to hear how they compare to the Podiums.

FullRangeMan · « **Reply #167 on:** 7 Oct 2009, 06:54 am »

Quote from: Copperhead on 7 Oct 2009, 06:42 am

Hi Ziggy, did Erling make it around to hear your speakers?
Waiting with bated breath to hear how they compare to the Podiums.

Me too!! Waiting...

Donka · « **Reply #168 on:** 7 Oct 2009, 07:31 am »

Hey USP1,

Sorry I decided to go the diy PCB route for these double-decker switchable networks and spent all of Sunday fabricating and soldering, with no time to spare for NXT. Therefore I haven't had a chance to test further due to busy-work and real work.

Regarding the Gator Board, the price I mentioned was in reference to the 2 test panels which I have less than 1/2 a sheet into, hence the lower price. I bought a 3 pack from U-Line (I also buy other packing and supplies from them), and since I'm within 50 miles of one their warehouses it only cost $26 for freight, which was well cheaper than my time to go pick it up from my nearest plastics supplier that carries it. I also order the 1" tape from them since they can do overnight Saturday delivery. The 1" is shy of reaching all the way to the edges of the foot. The acrylic is rather elastic so one could possibly try to stretch it, though it is a pain to handle due to said elasticity and stickiness. Overall I think I may use 3M DP801 acrylic adhesive on my final version, or at least test it since I have some lying around.

Hopefully tomorrow I will get a chance to finally take some measurements.

usp1 · « **Reply #169 on:** 7 Oct 2009, 01:08 pm »

zyagdr - you are right about proper mounting and taking out the cap and resistor. Last night I got home very late and the box had arrived so I was like a little kid trying the exciters on every surface I could easily reach. I am going to order the gatorfoam today and it will take a few days to get here so it probably will be next weekend before I can hear some serious sound. I was pleasantly surprised how good the coroplast sounded even though i had the exciters just laying on top of it and without the surgery on the exciters.

Donka - I am going to get the gatorfoam (4'X8')from a local sign company. They agreed to cut it to size for me. I am thinking of cutting it down to 2 2'X5' . That leaves me 2 2'X3' panels to experiment with before I use the larger panels.

bytheway · « **Reply #170 on:** 7 Oct 2009, 07:15 pm »

Just found a local supplier of gatorfoam in SLC, Ut. $45 for an 8x4 sheet of 3/16"

I think I'm in business, just need to get the exciters ordered and decide on sizing.

BrunoB · « **Reply #171 on:** 8 Oct 2009, 07:34 am »

I measured the Dayton DAEX25 (unmodified) impedance curve in free air:

and when glued in the center of a piece of glass (size is about 50 x 30 cm):

I was surprised to see the very low frequency of resonance of the device when it is glued to glass.

Bruno

FullRangeMan · « **Reply #172 on:** 8 Oct 2009, 07:47 am »

Quote from: BrunoB on 8 Oct 2009, 07:34 am

Thanks Bruno for lets us know this graphics. These Dayton exciters are really very good, seems easy to drive.
54 ohms is low and the peak is very slender.

usp1 · « **Reply #173 on:** 8 Oct 2009, 12:42 pm »

What are the possible substitutes for the 3M 9473FC tape that zygadr recommends for mounting the exciters? I cannot seem to find it in single roll quantities. Most online locations are selling it in casepacks.

j gale · « **Reply #174 on:** 8 Oct 2009, 03:38 pm »

Hi USP1, I got mine from ULINE. (a single roll of the 1") Their online site lists prices for single rolls. It is expensive though. Jim

usp1 · « **Reply #175 on:** 8 Oct 2009, 03:58 pm »

Thanks j_gale. I misread their site. Did you buy the 1 inch? I am afraid that it might be just a little too small. Would using two 3/4 width side by side be better?

j gale · « **Reply #176 on:** 8 Oct 2009, 04:52 pm »

The 1" is a little too small. I just added another piece to make up the difference. As someone else already said it is difficult to work with because of the stickiness and its tendency to roll and ball up. We need a source of this already cut to size to make it really easy. Maybe Ziggy could go into that business

gunn234 · « **Reply #177 on:** 9 Oct 2009, 06:47 am »

I got a question zygadr. I couldn't recollect all of what you had found was important as far as placement was concerned since I've heard you say that the sound travels well throughout the room and yet you had still been playing with placement in the learning process.

What I am getting at basically is that I would like to mount the DMLs to the ceiling as aesthetics are important to the wife. I can suspend them a 3/4 of a foot away and it is an acoustical ceiling none-the-less. It is sloping about 25 degress, but the listening area is seated 60 degrees off axis.

Do you think I can have success with this set-up? If so, it is worth while for me to embark on this project.

Thanks in advance for any input you may have.

Copperhead · « **Reply #178 on:** 9 Oct 2009, 11:48 am »

Looking back at the Diyaudio thread, "Greenvalve" suggested that the Dayton exciters were different to the Sonic Impact Soundpads
Ziggy is using. Has anyone got the specs on the Parts Express and Dayton exciters? Do they both have neodymium magnets?
What sensitivity? I saw an exciter claiming 100Hz-20,000KHz. Is this better or worse than the two popular choices? Is greater power
handling an advantage in this application?
So many questions.

FullRangeMan · « **Reply #179 on:** 9 Oct 2009, 12:46 pm »

Quote from: Copperhead on 9 Oct 2009, 11:48 am

Looking back at the Diyaudio thread, "Greenvalve" suggested that the Dayton exciters were different to the Sonic Impact Soundpads
Ziggy is using. Has anyone got the specs on the Parts Express and Dayton exciters? Do they both have neodymium magnets?
What sensitivity? I saw an exciter claiming 100Hz-20,000KHz. Is this better or worse than the two popular choices? Is greater power
handling an advantage in this application?
So many questions.

Hi Copperhead,
This is a link to DAYTON exciters at PartsExpress, http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-375
They have just 6W RMS, so more exciters is better, if you remove the plastic case the cooling will be very eficient indeed.
A bigger 30/40mm or more exciter is better (it will have more brute force to drive the panel), but bigger exciters have to be fixed in a spine column and this demand a lot of research to have good sound. So the Dayton 25mm is my personal choice.
Regards