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

el`Ol · « **Reply #660 on:** 14 Jan 2010, 08:44 pm »

Quote from: bobloblob on 14 Jan 2010, 07:37 pm

Amazing old radio, but the language loses me. Is that a linaeum-type driver?

The diaphragm is kind of a half linaeum. The drive unit is an electromagnetic one, with a vibrating core and a fixed coil.

j gale · « **Reply #661 on:** 15 Jan 2010, 02:48 am »

Just a couple of thoughts. I 'm using 8 exciters and haven't really experimented with much else. The panels will play incredibly loud without much power. When 1 or 2 are used has sensitivity been a real problem? The numbers do sound bad. Ziggy, I thought you progressively added exciters without noticing a down side. If it means revisiting the whole question of spacing and numbers of exciters that's OK. What we have so far is pretty darn good. Better is welcome. After all mainstream guys (boxes,cones domes etc.) are still bashing away at it and they have a hundred years under their belt. Compared to them our frustrations are small. Taking the weight of the panel by fixing it at 2 or three points on each side does not cost anything sonically. I thought it would but it doesn't.

el`Ol · « **Reply #662 on:** 15 Jan 2010, 02:58 pm »

Quote from: zygadr on 15 Jan 2010, 03:05 am

Have a look at the above exciter..............it has much more power handling, a 2 inch ferrofluid voice coil, can be FREE MOUNTED.............WOOHOO!!!! and nearly 3 times the BL force factor of the Podium 1's best and NXT's best exciter!!!!

Re also contributes to the electrical damping, so as it is a 4 Ohm driver you can more or less multiply the value with sqrt(2) compared to an 8 Ohm driver. I wonder how such an insanely strong motor shall produce any bass.

BowerR64 · « **Reply #663 on:** 16 Jan 2010, 06:19 pm »

I have a set of pioneer towers i use for home theater. I noticed inside the filters in the cabnets have 2 caps one on each tweeter and midrange.

All of the audio is running threw a disk type what i thought was a cap but it appears to be a resetable fuse.

My question, the 2 parts on these transducers look to be 1 frequency filter and then 1 resetable fuse.

Does anyone know if its a fuse or a cap? also if its a cap what is the value of it?

The one on the second transducer says 80uf, i went back threw about 20 some pages but i cant find any info on the other cap value.

If its a resetable fuse maybe i should keep it hooked up?

akreig2 · « **Reply #664 on:** 16 Jan 2010, 08:14 pm »

Quote from: BowerR64 on 16 Jan 2010, 06:19 pm

Does anyone know if its a fuse or a cap? also if its a cap what is the value of it?

The one on the second transducer says 80uf, i went back threw about 20 some pages but i cant find any info on the other cap value.

If its a resetable fuse maybe i should keep it hooked up?

The two passive components are soldered on the transducers to provide a high pass filter. So the large one is the capacitor and the small one you are questioning is a PTC resistor. If you are trying to use the transducers as full range speakers then you should remove both....

BowerR64 · « **Reply #665 on:** 16 Jan 2010, 09:02 pm »

Quote from: akreig2 on 16 Jan 2010, 08:14 pm

The two passive components are soldered on the transducers to provide a high pass filter. So the large one is the capacitor and the small one you are questioning is a PTC resistor. If you are trying to use the transducers as full range speakers then you should remove both....

why remove the resistor? wouldnt that keep it from blowing? posibly taking the amp with it?

usp1 · « **Reply #666 on:** 16 Jan 2010, 09:55 pm »

Sitting here listening to my white gatorfoam panels with two exciters. The panels are being driven by a rogue tube amp.

Listening to Jane Monheit sing. Simply wonderful!

Yes some of the very high frequencies are rolled off...yes the very low bass is missing...but the rest is simply beautiful. And it cost me less then $100 for this!

Sometimes we forget to just listen.

jeffac · « **Reply #667 on:** 17 Jan 2010, 01:21 am »

Quote

jeffac,.....If you're still watching this thread, I have come accross some TUNG OIL in our large local Hardware store. There are a few varieties.......water and oil based. I presume you used the oil based one?

Is this worth a try with a large sheet?......if so, which TUNG OIL type exactly do I need?

Back again

Bloody rained here nearly every day over Christmas, then visiting folks, back for a few days at work and now just home after 2 weeks away for a wedding and work. Stuffed. Anyway, all this has hindered attempting to Tung Oil coat, inside and out, my large cardboard panels.

What I have at hand is a leftover 4L tin of Cabot's Floorguard Satin Tung Oil enriched floor sealer. Turps clean up. Did a great job on my floors and diluted 1:1 with standard turps, worked well at stiffening the small test sheet of corrugated cardboard. I should treat my small panels with a single exciter and see how the sound alters. But now the sun is shining, I'll have a go at treating the large panels. I have 50 mL syringes to help get the mix down the long inside corrugations, hopefully with it soaking through all of the internal ribs as well as the outside carboard sheets. Will report how I go with this, fingers crossed . .

And for the record, from my experiments so far

Panel edge fixing, by creating a bend in the cardboard has little effect on bass output and is probably better than having them flap violently, as the tops of my small panels do.
Plus if anyone is lacking HF output from their panels, try face mounting a naked piezo tweeter cone on a small separate panel, thin cardboard will surfice, as this to me blends quite seamlessly with my exciter panels, is blisteringly fast and dynamic but silky smooth and adds great focus to the soundstage. And they're only $3:50 ea on ebay, so nothing substantial lost should they not be to your liking, but I think they will.

cheers..jeffac

jeffac · « **Reply #668 on:** 17 Jan 2010, 05:51 am »

OK

All went well with carbboard panel treatment with the Floorguard Tung Oil

, except for the bloody wind wanting to blow them over all the time.

The syringe method to get the 1:1 Tung Oil:Turps mix down the corrugations worked fine, as you can see from the pics, with the panels inverted and injected from either end, and then brush finishing on either surface side with a couple of coats as it sucks it up so quickly. Used about 250 mL of the 1:1 mix per 1200 x 750 mm panel.

They're drying now and I'll let them cure "to hard" for a few days before fiting an exciter. So ... so far so good. Will these make good sounding panels? Don't know but based on scratch and ping tests with my trial cardboard sheets, stiffened cardboard seems to have the panel qualities we're chasing.

comparison of what treated and untreated panels look like

injection just underway with panel #2

panel #2 just before being flipped over to inject from the other end

And in the process of treating the panels, one thing that is obvious which distinguishes them from Nomex, is that rather than having closed cells that might generate resonances, the corrugated ribbed structure of the cardboard has openings at either end, which might just afford the same kinds of benefits as a vented magnet of a woofer, maybe.

cheers..jeffac

j gale · « **Reply #669 on:** 17 Jan 2010, 06:01 am »

Was it a measured amount down each opening?

jeffac · « **Reply #670 on:** 17 Jan 2010, 06:16 am »

Hi Jim,

Sorry, I didn't measure this, just watched it flow down the holes until the track was a little from the bottom as I didn't want too much of mess with it running out. Some did of course and panels being placed on waxed "advertising" catalogues, I could suck most of this outflow back into the syringe. Quite cool to watch it run down the tracks as being diluted in Turps, the cardboard wets essentially instantly.

cheers..jeffac

j gale · « **Reply #671 on:** 17 Jan 2010, 06:33 am »

Jeff, A brilliant effort. Thanks for the pictures. I hope the outcome is a great success. Please let us know as soon as possible. If it works out, I want to try it with some double walled cardboard since although the flutes of both layers run the same direction they are staggered and with the extra layer of paper in the middle it should all come out very rigid indeed

even though still only 6mm thick.

jeffac · « **Reply #672 on:** 17 Jan 2010, 08:37 am »

Hey Jim,

I've just been looking at that very stuff "double corrugated cardboard with the corrugations offset" as whilst I was away, my son bought an big Epson printer for his new business and its box is made of this stuff with a glossy plastic-like outer coating for all the printer blurb. I was interested in it for the same reasons, "nice and rigid" and not much thicker than the panels I'm playing with now. Maybe time too upgrade from my dinky "toner cartridge box" panels to mid-sized "printer box" panels whilst that tung oil cures.

cheers.. jeffac

vaugi · « **Reply #673 on:** 18 Jan 2010, 01:54 pm »

Hi guys, I'm not an audiophile or any good at electronics in anyway, funnily enough I got here from a link as an NXT shareholder.

I'm looking to get my hands dirty and try out a pair, seduced by trying out what I invest in and a super cheap pair of good speakers. I'd be interested to hear how anyone in the UK has gone about making a pair of these as

a) shipping is quite expensive on the buyout speakers from partsexpress (60$) so making it not so cheap
b) trying to find gatorboard here is diffucult, anyone found a supplier? Nearest stuff I keep coming up on is the foamboard stuff you can get on ebay (any view on whether this would be an ok, cheap, starter?) e.g. http://cgi.ebay.co.uk/FOAMBOARD-5mm-A2-20-sheet-pack-Foam-Core-Board_W0QQitemZ290338805524QQcmdZViewItemQQptZUK_Crafts_FramingMatting_EH?hash=item43998a9714

thanks to all the others who contributed on the thread, reading 40+ pages over the past few days has given me something interesting to do!

BTW, I found you could possible get these from a clearance outlet on ebay and rip out the 2 exciters for a similar delivered cost as the partsexpress. Should be the same type of exciters?
http://cgi.ebay.co.uk/ACOUSTIC-SOLUTIONS-NXT-PORTABLE-IPOD-SPEAKER-NEW_W0QQitemZ350223167586QQcmdZViewItemQQptZUK_CE_MP3Access_RL?hash=item518aed7062

Pinco Pallino · « **Reply #674 on:** 18 Jan 2010, 09:41 pm »

Please forgive me if I am saying something you all are fully aware of: NXT had an early American predecessor in the 1960s called Bertani, if I remember correctly. It was a fairly large rectangular open frame speaker with a sandwiched polystyrene diaphragm driven at the center by a moving coil motor. It had a pleasant sound (like all open baffles) and no bass to speak of. However, they sold quite well for a number of years before the company went bust.

bobloblob · « **Reply #675 on:** 19 Jan 2010, 12:18 am »

Yes. Those were the Betagni. Here is a pair advertised on Audiogon:

http://www.audiogon.com/cgi-bin/cls.pl?spkrfull&1267943785&/Bertagni-Electroacous-SM-28

Here is some more info on it:

http://www.audiokarma.org/forums/archive/index.php/t-20057.html

Here is a "picture" of the BES/Sound Advance flat panel speaker:

http://www.soundadvance.com/index2.htm

Good that you had mentioned it. I had forgotten the name of these.

Zygadr-

If you are looking for something to stiffen the cardboard, here is a product I mentioned in an earlier post:

http://www0.epinions.com/content_171240230532

I've used it on rotted wood, and it has an amazing ability to soak deeply into it, and it gets very, very hard. It also requires no catalyst. I've also used Cure-Rot, a two-part epoxy, which acts similarly, but it requires a catalyst, and is much more expensive.

The Minwax product may penetrate well enough that you would only have to coat the two faces of the cardboard to have it travel through and soak the corrugations also. I would certainly only buy a small amount and test it on a small piece of cardboard first.

bobloblob · « **Reply #676 on:** 19 Jan 2010, 12:27 am »

Zygadr-

The cardboard bent because the solution on the side you painted would have caused the paper to expand on that side.. The bend probably would have decreased when it dried. The best way to prevent/minimize it is to coat both sides at the same time. Also, don't put them in the sun to speed drying, as that will cause the sides to dry at different rates, again causing bending.

As far as the speakers you owned operating pistonically, I don't think they could have been pure pistonic. At some point they must have transitioned into bending wave, and then perhaps also to DML. Just surmising, though.

This can be crazy-making sometimes, huh? Hang in there.

cometarossa · « **Reply #677 on:** 20 Jan 2010, 06:02 pm »

Quote from: zygadr on 20 Jan 2010, 08:03 am

.....................is there anyone out there????

Ack! Dayton DAEXSFH are out of stock until 2/13

jeffac · « **Reply #678 on:** 20 Jan 2010, 11:16 pm »

Quote

jeffac...............has that bloody stuff dried yet or not?

Quote

.....................is there anyone out there????

Bloody hell.... Pressures on....

OK, storm came through Sunday night.. again.. just as well I predicted this and moved the panels into the garage. So humidity has been shocking and although the panels were still a little 'smelly' yesterday, the Floorguard has set nicely, and this morning smell is almost gone and the panels are "nice and hard".. must have popped a blue pill

And FYI, by injecting the Floorguard down the corrugations first, and moving rather quickly in doing this, as with coating the cardboard faces, I had no trouble whatsoever with curling. Mind the panels have bends at each side along a corrugation to help avoid them wanting to warp vertically, which they were doing without it. And as cardboard sheets increase in size, from what I've seen, paper quality and rigidity seems to drop somewhat, although this will be corrected by Floorguard or similar stiffening treatments. Just something to look out for.

Anyway, this morning I scratch and ping tested the small trial sheets of cardboard I treated some time back as well as the large sheets just treated .... and they have the same desirable qualities. Post treatment, "generally stiffer" with scratches louder, crisper, seemingly closer and with probably better HF transmission. Pings crisper, more dynamic but with less ringing (damping seems better).

So..... all good to boogie..

Hopefully I can get to stick a couple of exciters on them tonight. I also intend to have a play with "hanging" them from the rafters.