Aura NS6-255-8A 6" in a 12 L ported box

ATAUDIO

Member
2011-05-01 10:56 am
Wien
I am planning to put those drivers each in a box of about 20 x 30 (baffle) x 20 cm (deep) box, (8" x 12" x 8") as a woofer only. That would account to 12 l , a little less than 1/2 cu. ft. I would like to make a cutout port on the shorter side, about 20 x 2.5 cm (8" x 1"), deep as needed, probably about 15 cm (6") as a port.
The midrange-tweeter would be stacked over, in a separate chamber.
Do you think it is feasible? Could you give me some hint how to to simulate it? I am a total beginner in this field.
I do noot need exceptional bass, 80-100 Hz cutoff would do for me.

If the box would be too small, I could put it in communication with the midrange chamber, getting about another 8 L, so a total of 20 L, a little more than 2/3 cu. ft.
 

jReave

Member
2012-10-30 4:34 pm
Don't port it at all - leave it sealed for an f3 of about 75Hz.

Do not under any circumstances use the same chamber for the woofer and the mid - they each need their own separate space.

There are many free programs to simulate box responses - I'm fond of Unibox, UniBox - Unified Box Model for Loudspeaker Design, but you must have Excel. Try WinISD if you don't, LinearTeam

No offense intended, but if you can't figure out how to model the box response, I don't know how in the world you are going to figure out how to correctly implement a 3-way cross-over?

Perhaps start instead by following a proven design that uses that Aura driver:
The Aurbacks Aura NS6-255 and Vifa BC25SC TM
The Maurbacs Maurbacs NS6 MTM
The Stentorians Speaker Design Works

Best of luck
 

SpirosZ

Member
2013-01-18 11:27 am
WinISD suggests a 45.6 lt vented box tuned at 40,5 Hz.
In a 20it box tuned at 45Hz you get -4db at 53 Hz and still a nice down-sloping curve with a slight rise at around 100Hz.
However the slot will have to be 28cm long using your 20X2.5cm slot dimentions.
Alternatively you can use 2 round 3cm 81mm long ports or a 14cm long 20X1.5cm slot.
With a higher tuning (i.e. shorter tube/slot and >60Hz) you will get a nasty peak around 90hz and booming one note bass.
Download WinISD and do some simulations yourself.
No way I would put it in a 12lt enclosure.
That woofer needs a large box.
 

ATAUDIO

Member
2011-05-01 10:56 am
Wien
Thanks to both for the very informative posts.
I feel you are expert in this stuff.
I must tell you this is none audiophile project.
It will be some kind of portable PA stuff, for semi-professional use.
So I need to put some other 8 ohms in parallel to the Aura to get all the possible spl out out my TDA2020 at 12 V.
I will put a Celestion Neo 5" full range, crossed over at 125 Hz with a simple 150 uF, as a mid range. The Celestion extends up much more than the Aura, around 9k. The tweetwer is a piezo (Peavey I guess) that I will simply slap in parallel , counterphase and I may adjust only with a resistor of 10 Ohm or so. The latter is intentended only for the super highs while the Celestion will take care of the 5k - 9k range.
So, common box, maybe I will cross the Celestion higher. This will improve weight, btw.
Also, is it possible to simulate boxes with different drivers inside and crossover component?
My idea, at the end, is to bring the toy outside, put a measuring microphone in front of the box and do a nice 50-15000 Hz sweep with the generator and just get the amplitude plot.
Does it make sense?
 

ATAUDIO

Member
2011-05-01 10:56 am
Wien
I see your point.
But my goals are mainly portability and budget.
The Eminence stuff is a very good PA driver but it is heavy and overkill for a TA2020.
I have already the said drivers, and I should be able to put together a system (2 boxes, cables, amplifier,battery) in 10-12 Kg.
The drivers costed me alltogether about 50 EU.
I had also considered a solution like yours, with a 8" guitar neodidium driver (I believe it was a Peavey stuff) , but I cannot find it anymore.
 
SpirosZ,
If this is just to experiment with and learn the simple thing would be to just run the two aura speakers in parallel and get the impedance you are after which would be 4ohms. It would be a mono setup that way, but you sound like you are trying to learn. I have a case of those speakers sitting in storage, they are very good for the price, really amazing really for such a small speaker with the neo magnet system. They sound okay, nothing special, but much better than most other little speakers like this. If you can run with an 8 ohm load just run one in each box, your amp should do that, probably safer for it as the impedance could drop fairly low in parallel. I would run them as a two way with an inexpensive dome tweeter and you will be very surprised in the sound. Try something like a 1" soft dome from Audax, they aren't very expensive and work well. I am thinking of a TWO25AO an excellent sounding dome tweeter.
 
If you don't need anything below 80Hz, then a sealed 12L box will work fine. Qtc is about .779. Xmax will be exceeded with 10W producing 98.5dB's when content is below 80Hz.

Calculating the true Xmax on an overhung driver is a little more problematic.

In a normal driver the VC is longer than the magnetic gap, so Xmax is simply reached when the VC starts leaving the magnetic gap. However, much of the VC will always be outside the magnetic gap.

In an overhung driver like the Aura NS6 the VC is shorter than the magnetic gap. By the same logic as for a normal driver then the Xmax would happen when any part of the VC starts to leave the magnetic gap.

However, that is not the true Xmax. The true Xmax is somewhere between none of the VC having left the magnetic gap and half of the VC having left the magnetic gap (the latter is usually considered the Xlim of an overhung driver).
 
I see your point.
But my goals are mainly portability and budget.

Have you checked out my Boominator MINI project Boominator MINI (development thread) - Speakerplans.com Forums - Page 1

It uses those Aura NS6 drivers in a very small sealed cabinet. Q is roughly 1.1 in this case because a slight mid-bass increase is desirable with the NS6 due to it's slightly decreasing output in the mid-bass. It's primarily designed for outdoors use or in relatively large rooms with problematic acoustics like kitchens as an extra speaker. Also college dorm rooms would be a good use.
 
Saturnas,
You have reversed the term, this is an underhung voicecoil design. The coil is shorter than the magnetic gap length, overhung has the coil longer than the gap, hence the term overhung. The aura is a solenoid designed magnetic circuit with radial magnet section, a very cleaver application of neo magnets when they first came out. The limitation on excursion on the Aura is the surround, you just plain run out of movement due to the limited physical length of a half round surrounds dimensions. The other limit with the Aura is the voicecoil which is a very small gauge wire on a small 1" former.
 
Saturnas,
You have reversed the term, this is an underhung voicecoil design. The coil is shorter than the magnetic gap length, overhung has the coil longer than the gap, hence the term overhung. The aura is a solenoid designed magnetic circuit with radial magnet section, a very cleaver application of neo magnets when they first came out. The limitation on excursion on the Aura is the surround, you just plain run out of movement due to the limited physical length of a half round surrounds dimensions. The other limit with the Aura is the voicecoil which is a very small gauge wire on a small 1" former.

Yeah. Sorry about that. Hope everyone gets the point still.

And yes, Xlim is reached before half the VC has left the MG on the NS6 due to other limitations.
 

ATAUDIO

Member
2011-05-01 10:56 am
Wien
Yes, I have, and I believe we discussed already about that in another thread. I really like your idea, but for my application I need marked difference between front and rear in outdoors, or on top of a small improvised stage. And of course all the SPL that I can get for the money.
I will have at least a microphone hung there, so you better know where you are firing your power.

So seems I am going to a have bass reflex cab with the Aura of about 15 l, and a sealed mid + treble of 9 l with the Celestion and the piezo. Between the tops will seat the electronics, in the middle.
WinSD seems do not complain too much of a 15 L Bass reflex tuned at 45. The only parameter that I do not really understand is the Ql , that is set to 0.7 I believe there is a lot of assumption behind that.

After I may experiment cutting a cuople of 55 mm holes between the bass and mid boxes (that I can easily glue back) but the logic seems against that.

Also I am not sure if is better a slim and deep port or a large and shallow one? They simulate the same,the latter would have weight advantages, but I have always seen that good sounding boxes have quite deep ports, something half way.
 
Last edited:
fatmarley,
They are actually fairly well behaved little speakers, the bottom end is a little light. I have some that I used as early prototypes for a speaker cone development that I cut out the cone and replaced it with a cone of my own design and they did sound better but you can't buy them so that is a moot point. I think that they were originally designed to be used in high end TV sets before flat panel designs made that impractical. They are so light they would make a nice portable two way system with the Audax I sighted earlier.

ps. ATAUDIO,
Do not put a port between the bass and mid section you will only proceed to modulate the mid-range driver and mess that all up.