Aura NS6-255 and Vifa BC25SC TM

[donradick]

Re: Aura NS6-255 and Vifa BC25SC TM

I ordered the parts to build these. Should be here by the end of the week.

I am going with a design closer to the Green Mountain speakers .. smaller cabinet, slanted front.

I am hoping to get 15 liters out of it. I will be using a 2" port that is 8" long (according to Speakerbuilder Pro 2.0)

Does this sound about right?

What frequency are you trying to tune the box to?
I doubt you can get more than about 50 Hz F3 out of a 15 liter box.
Here's a quick and dirty box calc url, which is usually pretty close to
more rigorous design tools. It gave me this:
.6 ft cube box, 2 inch port, 4 inches long = 50 Hz tuning (Fb)

http://www.the12volt.com/caraudio/boxcalcs.asp#por

Note that this is only a box calc. To determine the actual FR and system F3, you need to consider the woofer parameters. I use WinISD (Excel) and Jeff Babgy's Response Modeler.

[rhubarb9999]

Re: Aura NS6-255 and Vifa BC25SC TM

Tuning it to 50Hz would be fine. These are going to be nearfield so they will never be very loud. I can also EQ if need be.

I cut the boxes today .. mostly glued together and drying now. Crossovers are built.

Final dimensions ended up at 8"W x11"H x12"D (internal). The front is sloped 15 degrees.

Since they will only be 3 feet away from my head, should I offset the tweeters?

This is probably just going to be a prototype cabinet. It is my first attempt at something other than a square box. I built it out of leftover MDF (1/2" for the sides, top and bottom, 3/4" for the front and back). I am already thinking of something more advanced .. maybe a slot port. If these turn out to be too small, the next version will be bigger.

I am sure I will have more questions as I get closer to finishing them.

[donradick]

Re: Aura NS6-255 and Vifa BC25SC TM

don't worry too much about the tweeter horizontal offset - I did that because Response Modeler predicted a slightly flatter baffle response.

The 15 degree slant on the front baffle will mess up the phase tracking a bit.
I'd advise to just build it and listen - you'll probably still like it a lot.
If not, you'll have ideas for new boxes!

Tuning it to 50Hz would be fine. These are going to be nearfield so they will never be very loud. I can also EQ if need be.

I cut the boxes today .. mostly glued together and drying now. Crossovers are built.

Final dimensions ended up at 8"W x11"H x12"D (internal). The front is sloped 15 degrees.

Since they will only be 3 feet away from my head, should I offset the tweeters?

This is probably just going to be a prototype cabinet. It is my first attempt at something other than a square box. I built it out of leftover MDF (1/2" for the sides, top and bottom, 3/4" for the front and back). I am already thinking of something more advanced .. maybe a slot port. If these turn out to be too small, the next version will be bigger.

I am sure I will have more questions as I get closer to finishing them.

[rhubarb9999]

Re: Aura NS6-255 and Vifa BC25SC TM

Did you use any stuffing?

[donradick]

Re: Aura NS6-255 and Vifa BC25SC TM

Did you use any stuffing?

No stuffing - I used cheap 1 inch thick craft sheet foam from Walmart.
Assembly tips are to cut it with scissors and use hot glue to attach it to the inside of the box.

[[email protected]]

Re: Aura NS6-255 and Vifa BC25SC TM

Many thanks Don. I have rarely commented on speaker building threads but feel such a debt of gratitude that I must add my encomium. Here is my story:
I started out buying the Aura NS6 to drop in a pair of abandoned T-lines that I was going to "cut-down" and use one of my leftover tweeters from yet another project. Just a slam-bam build to see what these budget speakers might do. The "cut-down" did not go well and by the time I had removed the baffles and old speaker cut-out holes I didn't have enough volume left. Hmmm. (OK, I still want to make a 'quickie', what-to-use, what-to-use?)
To make this long story shorter, the quickie it was not! I used 1/2 of a 4' sonotube for the main cabinet with a 'crescent' sand filled sonotube behind it. With all the bracing, baffles and stiffeners it resembled the internal structure of an airplane wing. (sorry I didn't take pictures along the way...it was going to be a quickie).
I am very, very pleased with the results. I have been building speakers for 40 years. I listen to classical music and these do a wonderful job, top to bottom.

[donradick]

Re: Aura NS6-255 and Vifa BC25SC TM

Thanks so much for the compliment!
Beautiful build. I voiced these with several classical selections, and they sounded balanced top to bottom, with very good imaging. We are fortunate to have such nice drivers available at very low prices.

[ameuba10]

Re: Aura NS6-255 and Vifa BC25SC TM

wow, i really like the look of these in a tower! good idea using the sonotube to get the curved back...i may steal that idea for later ;) BTW don, i am wrapping up the boombox version. got one xover soldered up, and ill do the other once i get home. just a few things here and there and itll be done. ill post teaser pics when i get home.

[donradick]

Re: Aura NS6-255 and Vifa BC25SC TM

wow, i really like the look of these in a tower! good idea using the sonotube to get the curved back...i may steal that idea for later ;) BTW don, i am wrapping up the boombox version. got one xover soldered up, and ill do the other once i get home. just a few things here and there and itll be done. ill post teaser pics when i get home.

Take your time on the crossovers, and be sure to label all the inputs and outputs - I've messed up "simple" crossovers more times than I care to adm - oh wait - is this a public forum?:o

[ameuba10]

Re: Aura NS6-255 and Vifa BC25SC TM

oh believe me i understand! i already had one little issue that i had to work out. but for my first set of xovers i believe i didnt do too bad. im more upset at my poor craftsmanship on the box itself, not to mention my lack of a router for fancy roundovers and flush mount drivers :p

[Leroy R]

Re: Aura NS6-255 and Vifa BC25SC TM

Don, I'm trying to build these at the moment, but I've run into a problem. I have the enclosures built, but I'm not finding anything that tells driver placement dimensions on the baffle or port placement on the back. Can you post those dimensions or point me to where they are posted?

[donradick]

Re: Aura NS6-255 and Vifa BC25SC TM

Don, I'm trying to build these at the moment, but I've run into a problem. I have the enclosures built, but I'm not finding anything that tells driver placement dimensions on the baffle or port placement on the back. Can you post those dimensions or point me to where they are posted?

Sorry Leroy - my bad.
The exact placement on the baffle apparently exists in a scribbled "shop copy" printout. With my current work schedule (12+ hour shift), I won't be able to find that piece of paper until Thursday night. In the mean time, I never worry too much about port placement. Port is centered on the back about 2-3 inches down from the top. PM me if I happen to forget...

[donradick]

Re: Aura NS6-255 and Vifa BC25SC TM

One of these days, I should post a nice drawing. For now, this is what I built:
Overall baffle dimensions: 9 1/2 W X 16 H
NS6 woofer: centered left to right (4 3/4 inches), center of woofer is 9 inches from the bottom of the baffle.

Vifa BC25 tweeter: 14 inches from bottom of the baffle to center of the tweeter, tweeter center is offset left of right of baffle center by 1 1/4 inches (mirrored offset per pair). Or you can think of it as the edge of the tweeter is about 5/8 down from the top, and about 1 7/8 in from the respective left or right baffle edge.

Port is centered left to right on the pack, center of hole is about 4 5/8 down from the top of the box.

[Leroy R]

Re: Aura NS6-255 and Vifa BC25SC TM

Thank You for the quick response. I work 12s too, so I know how long those days feel.

[piazzafatb]

Re: Aura NS6-255 and Vifa BC25SC TM

Hi Don
I do this baffle for a specific situation. I cant put the tweeter closer. :(
2 3/4" separation.
How could this affect the sound.
Thanks