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

HenryPercy · « **Reply #80 on:** 19 Sep 2009, 01:37 am »

Zygadr & j gale -

Very interesting posts. A few questions if you don't mind. Did either of you try or consider two or more rows of the exciters? Intuitively that's what I would have tried first, but I'm not sure it makes sense.

I gather the Gatorfoam board is supported only by the floor or whatever it sits on. If a spline is added, would the design be such that the exciters would support the Gatorfoam instead of vice versa? This appears to be the way the Podiums are built, but I can't tell for sure.

Can either of you estimate the frequency range of your speakers? Do you think the response is fairly flat within their ranges?

Thanks. I've got some Gatorfoam in the garage which was destined for a Christmas display project, but that will have to wait now that I've ordered some exciters.

I'll post whatever happens. Thanks for your help.

HenryPercy · « **Reply #81 on:** 19 Sep 2009, 02:08 am »

j gale - A few more questions, if you don't mind.

What was your theory is adding the frame? Obviously it would add better protection and perhaps appearance, but does it have an acoustical effect? Did you try them with and without the frames?

Hope I'm not being a pest.

This stuff is fascinating to me.

j gale · « **Reply #82 on:** 19 Sep 2009, 04:48 am »

Henry, Let me say first that Ziggy has been playing with this much longer than me. I added the frame to be able to have the panels free standing out into the room rather than just leaning against the drapes. By attaching the panel at just a few small points using flexible neoprene weatherstrip all the rest of the panel edge is free to vibrate and I reasoned that bass should not be impacted because this allows quite a bit of movement. As I already said, with one mounted on the frame and one just leaning I didn't notice a difference. As to a double row I guess more exciters would give more volume depending on how they are wired,but Podium uses only 5 centered and evenly spaced. I assume that they experimented with all sorts of combinations. It could be that they found that less is more. If you have enough exciters it wouldn't hurt to experiment. Adding a spline should theoretically make the exciters more efficient at lower frequencies. With their backs against the wall so to speak they should be able to push harder. (more dynamic) I do think that response is fairly flat. On material that I am familiar with nothing sounds out of place. They are far better than I thought they would be. I've had DIY open baffle, BIB's MLTL's horns etc. I like what I am hearing with these.It makes me want to see just how far I can go with it. Jim

scorpion · « **Reply #83 on:** 20 Sep 2009, 09:27 pm »

Hi zygadr,

Unlucky, I updated my profile so my email is now visible, please try again !

/Erling

HenryPercy · « **Reply #84 on:** 20 Sep 2009, 11:55 pm »

Good info, Zygadr. Thanks.

HenryPercy · « **Reply #85 on:** 21 Sep 2009, 03:29 pm »

Zygadr - More good info. Sorry, but what's a BMR?

FullRangeMan · « **Reply #86 on:** 21 Sep 2009, 09:44 pm »

Quote from: HenryPercy on 21 Sep 2009, 03:29 pm

Zygadr - More good info. Sorry, but what's a BMR?

Maybe Basic Membrane Response ??

HenryPercy · « **Reply #87 on:** 22 Sep 2009, 07:07 am »

Quote from: zygadr on 22 Sep 2009, 06:29 am

BALANCED MODE RADIATOR : B.M.R.

Ah! Gotcha. Thanks.

gilbodavid · « **Reply #88 on:** 23 Sep 2009, 07:46 pm »

My $5 exciters have arrived God they are small! they were out of their boxes all over the large box they came in. are they quite hardy? there's no obvious damage. now for some gatorfoam to buy... this is very interesting!

BrunoB · « **Reply #89 on:** 24 Sep 2009, 12:56 pm »

I came across the Dayton exciters on a German website:
http://www.intertechnik.de/index.html/JTI2bmF2aWQlM0QxNzY4JTI2bGFuZyUzRGRlJTI2c2lkJTNEN2QzNzA5NDc1MDEwM2Y1NTdlODVlMjNjNDE2YWQ0ZmQlMjZiJTNE.html?detail=53270&suchwort=NXT

Bruno

rhing · « **Reply #90 on:** 24 Sep 2009, 01:10 pm »

Quote from: gilbodavid on 23 Sep 2009, 07:46 pm

My $5 exciters have arrived God they are small! they were out of their boxes all over the large box they came in. are they quite hardy? there's no obvious damage. now for some gatorfoam to buy... this is very interesting!

I bought my $5/pair NXT exciters from Parts Express and they came packaged in the same way. Even though the package was a jumbled up mess inside, the exciters are in fine condition.

If you live in the U.S., I would check out Piedmont Plastics for the Gatorfoam:

http://www.piedmontplastics.com/html/prodname-Gatorfoam-21.htm

For $63, they will sell an entire 4 ft. x 8 ft. x 3/16 in. sheet and cut it to two (2) 24. in. x 6 ft. panels. They have a location within five miles of my home, so it's very convenient for me.

usp1 · « **Reply #91 on:** 24 Sep 2009, 09:34 pm »

So has anyone else been able to get the same results as zygadr. This seems like such an easy project and zygadr has been generously detailed in his instructions so I am surprised not to see many more success stories.

zygadr....Does the gatorfoam visibly vibrate when exciters are on? Otherwise it might be cool to make a video screen out of gatorfoam and have it serve as both the screen and the speakers!

usp1 · « **Reply #92 on:** 25 Sep 2009, 12:14 pm »

Thanks zygadr. I am going to try and do this if I can find a source for the gatorfoam locally. Did you figure out the best way to mount/frame the panels. Have you considered suspending them in a frame with fishing line and using fishing line to tension them from below so they do not flap around.

BrunoB · « **Reply #93 on:** 25 Sep 2009, 07:21 pm »

zygadr,

if you would listen to one of your speaker from a very short distance, say 1m, how is the sound?

Thanks,

Bruno

HenryPercy · « **Reply #94 on:** 26 Sep 2009, 06:33 am »

Quote from: usp1 on 24 Sep 2009, 09:34 pm

So has anyone else been able to get the same results as zygadr. This seems like such an easy project and zygadr has been generously detailed in his instructions so I am surprised not to see many more success stories.

I plan to provide a success story as soon as my exciters arrive.

They should be here next week.

smithie · « **Reply #95 on:** 26 Sep 2009, 06:11 pm »

hi guys
just joined this forum so better say a quick hi....hi!
anyway been reading this thread with great intrest and it all sounds very exciting and tempting,years ago i had some tdk nxt speakers and was well impressed with the sound they dished out,so a grown up advanced speaker would be really intresting,which this project seems to be.
what i would like to know is has anyone taken any messurements that have them up and running? i know messurements are not the be all and end all to the sound but there a referance to start with.
i would be very intrested in the freq response your getting...you say the bass is good....how good and how low are they going...thats where the messurement bit comes in!
other then that its been a exellent read and intresting project,would love to hear them,i shall follower this thread with intrest and maybe have a crack at them myself,at the mo i have so many projects on the go i dare not

good to see/read about people thinking outside the book...which is what this forum is all about isnt it.
all the best
smithie

bobloblob · « **Reply #96 on:** 26 Sep 2009, 08:21 pm »

Had an idea for a mounting method for the Gatorfoam. I don't know what the downside may be, but I thought this may be of interest at least.

There was a project years ago that made a woofer by cutting away nearly all of a standard woofer - the cone, surround, and two of the four legs of the basket., leaving only the motor and two legs. Then a membrane was formed by taking two sheets of mylar, spraying them with contact adnesive, then placing a slightly smaller sheet of soft foam between them, gluing them to the soft foam and to themselves beyond the end of the soft foam, and then this sheet was glued to a frame made of 2?x4?s. Then the motor (voice coil and other parts) was attached to a support and glued to the membrane mounted in its frame. This made a dipole woofer with a large flexible membrane rather than a stiff cone. Apparently the concept was very successful at delivering bass.

It seemed to me that some of this may work as a way to suspend the Gatorfoam. It could either be encased in the two sheets of mylar, or narrower strips of mylar could be fastened around the Gatorfoam, only covering a bit at the edges, with mylar on either side of the Gatorfoam and sticking to itself between the Gatorfoam and a frame. If more damping were needed, a strip of soft foam could also be encased in the mylar around the edge of the Gatorfoam. In a way, this would be somewhat like a surround on a conventional cone driver.

This should be dead easy to try, and both cheap and reversible. Saran Wrap (a brand name for a plastic wrap) is actually no more than a very thin, strong mylar sheet. Most of these plastic wraps are polyethylene, which may also work. Saran Wrap adheres well to surfaces without adhesive, and peels off with no damage, and can be tightened with a hair dryer.

I don?t know whether those of you who have already built the panels have decided that they are better without having the exciters mounted on a support column, but with this type of frame, you could go either way.

One other thing: I had read, a couple decades ago, that tall panel speakers will sound clearer and have better bass if they are propped at the top by a brace mounted as the third leg of a triangle when viewed from the side. Maybe this would apply here also?

Just a few thoughts that I thought may be worth considering. Or not.

FullRangeMan · « **Reply #97 on:** 26 Sep 2009, 11:21 pm »

Quote from: bobloblob on 26 Sep 2009, 08:21 pm

Had an idea for a mounting method for the Gatorfoam...

Hi Blob,
The panel must be as light as possible. The spinal support column as the Podium speaker add cost, may need reseach as it add a compliance effect, and do not work with the small 25mm Dayton exciter Zygadr and others have used, a free panel have lower FS than a fixed, it need a new bigger exciter that is unavaliable to us individuals, the China makers sell it only to NXT licensee firms by order from NXT Company.
This image below is a beauty Neodymium 30mm VC exciter with 4 holes to screws hold it at a colunm etc, This Chinese maker do not sell few units, only large quantities, but only to firms NXT licensee (no exceptios). So the Dayton exciter is a bless to us amateurs.
Regards,

bobloblob · « **Reply #98 on:** 27 Sep 2009, 12:26 am »

Hi FULLRANGEMAN,
The panel - still just the Gatorfoam, but now surrounded by the mylar - would be effectively the same weight as freestanding, no added mass that should matter, as the thin mylar would add almost no weight. Also, it could be done this way either with or without a brace in the back. All this would do is give the panel some suspension and the ability to be put in a frame. What I don't know is whether mounting it like this would compromise any of the qualities Ziggy has discovered so far. I've seen mention of suspending and/or mounting the Gatorfoam with fishing line, rubber cords, and so forth. I just thought this may be more effective, while offering some distinct advantages. It's also dead easy to test, requiring no more than some Saran Wrap or the equivalent, and a frame to fit it in. The Saran Wrap should hold well enough by itself - it's very clingy - that no adhesive would be necessary, at least for a trial, so it is reversible, with no damage, and little expense involved. The Saran Wrap would only have to cover a couple of inches of the Gatorfoam at the periphery, and on both sides, to give adequate hold. i don't know how much if any space there should be between the Gatorfoam and the frame, but that too would be testable. I wrote that one could use soft foam between the mylar at the edges, and this just in case there is noise from the movement of the mylar, or as extra damping at the Gatorfoam's periphery.

I only mentioned the possibility of the brace/support because Ziggy I believe had mentioned the possibility of the eventual sag of the voice coils in the exciters. The frame would prevent the panel's weight from being supported by the exciters if it were mounted on a brace. If freestanding rather than braced, this method would take the weight of the Gatorfoam off of itself and transfer it to the frame. Perhaps an advantage, but I don't know. This is just a proposal of another possibility on this very interesting project. Also, I like cheap, easy to test, and reversible tweaks, which this is.

FullRangeMan · « **Reply #99 on:** 27 Sep 2009, 12:42 am »

Dear Blob,
This issue is out of my expertise, I will let it to Zygadr, but it looks a good idea.
Kinds