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

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oldschoolVlad

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2980 on: 16 Aug 2017, 08:13 am »
Nope, but its parameters tells it is a real winner for use with full range panels. An extra upper highs level is expected.

Bendingwave

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2981 on: 16 Aug 2017, 08:52 am »
It seems to have the highest output of all the exciters, but not so sure of its overall sound quality....I hear people say the Ultra is the best sounding exciter but its fragile and not reliable since it has quality control issues hence why I have not tried it yet......I wonder if anyone here has tried both the Ultra and the DAEX25SHF-4 for a comparison.

TexBear

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2982 on: 23 Aug 2017, 12:32 am »
I haven't tried the DAEX25SHF-4, but every Ultra I've ordered (4) has broken within moments of installation, and I've been very careful with them. Finally gave up on those.

Bendingwave

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2983 on: 26 Aug 2017, 09:35 am »
I was wondering if P.E. has fixed the problem with the Ultra exciters by now as its been a while since people have been complaining about its reliability.

Mean while I am still experimenting with my panels and I have found a way to increase bass response as well as the high frequencies out of any panel size...I wont say how as I am still trying to get it patented  :lol:

Bendingwave

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2984 on: 7 Sep 2017, 01:30 am »
When it comes to building cross overs I am far from a expert....Bertagni speakers use just a non polarized eletrolytic capacitor as there cross over.......I figured I would up grade my cross over design to this> https://www.parts-express.com/5-khz-high-pass-8-ohm-crossover--266-474 and I also tried with these 2 way cross overs> https://www.parts-express.com/dayton-audio-xo2w-2k-2-way-speaker-crossover-2000-hz--260-140 ....I figured this up grade in cross over would increase the sound quality.....when I compared them to my Bertagni speakers they didnt sound the same meaning they sounded a lot worse as they seem to be darker sounding and being somewhat less open with even less imaging.....I thought the dayton high pass cross over would sound better then a mere electrolytic cap but I was wrong...Using just a electrolytic cap as a high pass crossover like Bertagni design, just opened up the sound of my DML panels....The cap is 50 cents while the Dayton high pass is around 5 bucks and the Dayton 2 way cross over is like 23 bucks, money wasted. LOL

Bendingwave

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2985 on: 10 Sep 2017, 11:34 am »
This is when one takes bending wave technology very seriously with vast amounts of resources and technology to back them up.

https://www.youtube.com/watch?v=YOy4XmVICRw&t=127s

https://www.youtube.com/watch?v=XgoMMihVVu4

https://www.youtube.com/watch?v=n2Lq19U7t8E

https://www.youtube.com/watch?v=QGFFKe-7SYA


CXW1219

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2986 on: 11 Sep 2017, 02:20 pm »

Hi!

I have been using NXT speakers since the turn of the century; and have always been a strong advocate for them  :thumb:

This however is my first foray into DIY...

My test rig:
2x A1 foamboards each with a single DAEX58FP.

Was somewhat impressed by the sound possible from such a simple setup: I am now excited and driven to find the best possible I can reasonably achieve with DMLs.

I have therefore ordered a pair of DAEX32EP-4 'Thruster's.

What panel shall I seek next?

Safe default would be more foamboard (upsize to A0)
BUT
Has anybody tried anything like:

https://gilmanbrothers.com/boards/eaglecell/
or
http://www.qkhoneycomb.co.uk/

Apologies if this has been covered before - I have read these threads religiously for a while   :o

Many Thanks

Ben

Bendingwave

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2987 on: 11 Sep 2017, 09:31 pm »
Hey Ben, welcome to one of the longest thread on the forum.

The Thrusters, IMO should be a increase in sound quality over the DAEX58FP.

I have not tried the Eagle cell boards but they look promising....Two main factors in determining sound quality in a desired material is it has to be very light weight but at the same time very rigid/dense.

My material of choice is (Ultra High Density) UHD Expanded Polystyrene, which is very light but rigid. Thickness preferred is 1-2 inchs thick.

Thinner materials produce more bass due to being able to flex more so then thicker materials and thicker materials produce better highs due to being more rigid/dense.

Also the highest excursion exciter IMO that I've used is the DAEX30HESF-4 as I am even using one of them as a sub panel with a sub amp pushing around 50 watts.
« Last Edit: 12 Sep 2017, 09:46 am by Bendingwave »

CXW1219

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2988 on: 12 Sep 2017, 06:00 pm »

Thank you for your reply;

One of the things this mission has taught me is that it is extremely difficult to order certain materials 'off the peg' from the internet. I have now emailed several companies offering to pay for very small (ie=2) samples of various composites: I have received NO replies  :cry:.

Any UK DMLers with tips beyond foamboard?: Even HD/Ultra EPS or similar XPS is evading me. I did get some rather low density EPS from B&Q but the panels sounded AWFUL.

As an aside, I do find the staging of these speakers remarkable -  I still find myself turning around "Where did that voice come from..who is in the house? Oh it's on the recording..." LOL

Thanks
Ben

Bendingwave

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2989 on: 12 Sep 2017, 10:50 pm »
Hey, Ben.....yes one of the main problems holding people back is not being able to afford or aquire certain types of materials to experiment on as it can get very costly.

I buy my UHD EPS from a dealer on Ebay....although its not cheap , its not as expensive as nomex honeycomb.....I can get 10-2ft.X4ft.X1inch thick panels for around a 100 bucks not including shipping....so its basically like 11-12 bucks a panel.

The strongest trait of these DML panels is the MID RANGE/VOCALS....as I agree with you that it is so life like you would swear another person was in the room with you. LOL...the sound stage,imaging and detail are just some of its other great characteristics.....the down falls is that they lack lower bass levels usually around and below 60hz dropping off even further as it goes down....They also tend to lack in the higher frequency range as most exciters schematics seem to show most of them to start dropping off at the 5-6khz and even more so at the 10khz.

Even my chihuahua gets startled sometimes when I watch movies on my DML panels.  :lol:

« Last Edit: 13 Sep 2017, 12:28 am by Bendingwave »

CXW1219

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2990 on: 13 Sep 2017, 09:41 am »
Does this seem like the current state of play?:

(Amp output)
Exciter
Number            (I am using single, but I note most manufacturers use multiple)
   Mix         (??? Any value to adding 'tweeting' exciters)
Position         (Off centre improves chances of Modal operation)
Adhesion to panel (ds tape, superglue, epoxy...)

Panel
Material
   Solid vs composite   (Poor adhesion -> HF 'pops')
   Density         (Lower density easier to drive)
   Thickness      (???)
   Flexibility      (High gives good LF response)
   Compressibility      (Low gives better HF response)
Area            (High gives better LF response)
Aspect Ratio         (???)
Edge termination      (I get the feeling that contraining the edges reduces response)
Mounting

Room position

(Ears)
Cleaned

Feel free to fill in some blanks...

BendingWave: Vocals YES blew my sister away with some Amy Winehouse today...
« Last Edit: 13 Sep 2017, 04:18 pm by CXW1219 »

CXW1219

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2991 on: 13 Sep 2017, 08:15 pm »
Uh-Oh: Lack of materials has driven me to this - I suspect this could all end in tears, and the introduction of child labour (My daughter has smaller fingers than me).


Bendingwave

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2992 on: 14 Sep 2017, 01:39 pm »
The number of exciters used all depends on ones design.  Most manufactures like NXT and Podiums use multiple exciters to increase out put levels....using only one exciter per panel is the most simplest and easiest way to implement it in ones design.....When using more then one exciter on the same panel is a lot harder to get right as there will always be over lapping waves, the goal is to minimize it as much as possible.

IMO using a exciter as a tweeter has great value since my design calls for using 2 exciters on the same panel, one running full range while the other is used as a tweeter with a high pass crossover to help aid and increase the higher frequencies.

I prefer directly in the center.

Adhesive of choice is 5min. 2 part epoxy as its very strong and you only need a small amount as thinner is better (too thick causes too much dampening) and IMO seems to be better with high frequencies.....down fall, its PERMANENT....trying to remove it will cause slight to severe damage to either the panel or the exciter or both.....for experimental purposes one can just use the 3m adhesive tape that comes with the exciters or buy your own 3m adhesive tape......even the TYPE of adhesive one uses can change the sound of the panel.

DML panels are very susceptible to change in sound meaning even the slightest off set or nick in the panel can change the sound....Even a slight change in the positioning of the speakers can change the sound from it sounded good one day to not so good the next, but once dialed in they sound really good.

Stiffer and thicker panels do not flex as much so less bass but they produce better highs....while thinner panels or panels that can flex more produce more bass but less highs......The goal in my design is to combine the two together on a single panel with various thicknesses and various rigidity....EPS material suits my needs the best as EPS is easy to sculpt various thicknesses through out the panel and the 2 part epoxy can be used to make certain areas of the panel more rigid.....The down side is all my panels are hand sculpt so they are not perfectly accurate, this is where a CNC machine would come in handy if you can afford one or know someone who will let you use it.

Panel shape IMO and design requires a rectangle shape with all four corners rounded.....edge termination is used on the edge of the four rounded corners in which I use double sided tape....bass seems to radiate towards the corners of the panel...what the double sided tape does is it prevents the bass waves from escaping through the corners and pushes it back into the panels for more pronounced and better bass response.

My panel designs are mounted to a frame using foam from frost king which also acts as a dampening in which its cut into 1 inch pieces and spaced 1inch apart with gaps inbetween so that the panel is not over damped....I also use a spine to hold the exciter in place in which it increases accuracy and clarity....my frames are also mounted on a permanent stand base.

Tips to increase sound of DML panels.....Panels should always be placed on the ground or fairly close to the ground for the most BASS....placing panels too high like on book shelves or any place high decreases the bass.....Using isolation platforms directly under the base of the DML panels tightens up the sound for better more accurate bass as well as mids and highs.

Last but not least all exciters are not created equal....some exciters have better bass then others usually the bigger exciters or the exciters with high excursions/out put....some exciters have better highs like the smaller 13mm exciters most likely due to it being the similar in size as a 3/4 inch tweeter which also limits the high levels of midbass/mid range out put that the bigger exciters tend to have....The only exception to the rule in which I just fairly recently discovered is the Dayton weather proof exciter > Dayton Audio DAEX25W-8 Waterproof 25mm Exciter 10W 8 Ohm....I just recently bought a pair because its on sale now for $15.60....This weather proof exciter is my new go to exciter to be used as a tweeter...before the weather proof exciter I used the dayton 13mm exciters for the tweets.

For the lowest of lows one can just add a subwoofer (prefer the flat cone subs like the RBM or the new Dayton shallow mount flat cone sub)

Also for those that do not know BMR technology is basically a exciter transducer created and designed by NXT, even though this technology was used way before NXT coined that term BMR.  :lol:

Inspiration and props for my design and what got me into DML panels is Dr. Jose Bertagni. Here is a little info of Bertagnis speakers reviewed in a hifi classic> http://www.hifi-classic.net/review/bes-sm300-289.html

Ive been obsessed with these DML panels for the past 2-3 years as you can get sound quality that equals speakers costing 1-2k but at a fraction of the cost. LOL plus these panels have a unique sound from the traditional cone speakers, one will either like it or hate it as its all personal preference. When designed right they sound pretty friggen good.  8)




CXW1219

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2993 on: 18 Sep 2017, 04:13 pm »
Hi!
Sorry to have gone dark...stupid work & family getting in the way of DML development!

I have been sourcing materials and my first progression from simple A1 foamboard shall be this:

PANEL: Thick black (PVA'd) A1 paper sandwich with paper honeycomb core; vacuum glued with PVA.
EXCITERS: Single 'Thruster'

I shall post pictures of assembly and provided commentary on performance etc.
In the meantime I shall post some measurements of my current foamboard so we can have an objective idea of where I am and how things go...

Ben

CXW1219

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2994 on: 19 Sep 2017, 09:33 am »
Test 1:

Mic equidistant to panels @ 1m, mic at mid height of panels, angled at 45 degrees to mic.



Bendingwave

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2995 on: Today at 12:45 am »
So how did you like the sound of your panels? Describe the pros and cons. Thanks.

CXW1219

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Re: NXT.......rubbish??....THINK AGAIN!
« Reply #2996 on: Today at 09:26 am »
Hi.
In a nutshell: They sound great. On par with ~£1k speakers, but they are not without a few specific drawbacks but none are 'dealbreakers', Let me explain:

Setup:
Dayton Thruster on Cheap Black (!) 3.5mm A1 foamboard, paper backed & untreated x2.
Wharfdale sub xo @ 55Hz
Cyrus 7 amp (30wpc), Cyrus Stream XA (24 192 DAC)
(Written listening to Black Sabbath)

The Good:
The most striking thing for me is the way these speakers can 'teleport'* you into a recording. Live music recordings can seem unnervingly real .
As I have mentioned before, I often find myself being surprised by a sound or instrument on a recording  - as if it were in the room. The effect feels similar to listening to bin-aural recordings on headphones.
This phenomenon is not limited to a sweet spot in the room either - one can move around and this still occurs - and you almost feel like you can move and stand 'next to' an instrument (I know this makes no sense).

The Bad:
The good mid-range performance payed for by loss at either end of the spectrum.
Bass comes off better than treble, though: One can turn up the volume and the bass is 'there' - but no low-lows. If you want 'slam' then you need to turn the sub on. At higher volumes though there is additional noise added lower down which I think is due to internal resonance of the panel. I THINK better adhesion between panel material may fix this.
Incidentally, I have arbitrarily decided that bass response is best if the panels are AT LEAST the panels height away from any wall or large area surface - this does preclude wall mounting which may be most people's main reason for using such panels.
Treble somehow falls off a cliff. This means that cymbals sound indistinct and 'smeary'. I find it odd that the panels can present such a convincing sound stage with relatively little treble response.

The Ugly:
Well actually they are not, even in their current superminimalist prototype stage the panels are not aesthetically displeasing.
BUT
They are super-fragile; and highly sensitive to any contact from surrounding objects - which will create noise or effect sound directly.
Only a couple of weeks into this project and the panels have already suffered a few gouges - although they have been handled more frequently than I would a normal pair of speakers (in the course of finding best position, moving around, changing exciters etc).

TBH I love they way they SOUND. Even in their prototypical foamboard guise, I would reasonably happily keep them as-is. My first thought was to keep the exciters and replace the foamboard when it gets too bashed up: simply treating these panels as 'disposables'. That being said, I am interested to quantify the influence of the following factors makes on sound:
Less flexible sandwich skin
Higher core rigidity
If my next sandwich prototype sounds significantly better (Stiff Black A1 paper skin + 1 cm paper honeycomb sandwiched with PVA glue) I may reconsider my disposable panel philosophy.

Thanks!

Ben

Other Disorganised Ponderings
1. I notice that the panels sound 'not so good' when I first power them up, then better as I use them more: Is it just me or has anybody else thought this?
2. Seen these?: https://www.kickstarter.com/projects/vetr/panl1-speaker-system-by-vetr-audio-ditch-the-box/description
Note their frequency response curve - do they get those highs by using small stiff panels? Do you think they have sandwiched, or just plain CF plates?



vs mine:


* https://open.spotify.com/track/3CKPWOuEBXLn8jWsGtkIfb as an example
« Last Edit: Today at 05:08 pm by CXW1219 »