My first speaker project

[db!]

Hi guys,

As I mentioned in the intro section, I am new to the audio scene. Throughout the process of collecting parts and planning my tube amp project, I've been hit with another dilemma; a good pair of speakers.

I am looking to build a simple pair of "desktop" speakers utilizing either the HiVi M4N or the HiVi B3N. The recommended box volume for the two drivers are 4L and 2L respectively. Would a straightforward MDF rectangular box(of the appropriate volume) work properly? I know that square boxes should be avoided but it's the only design I can build without screwing up(My woodworking is atrocious). Are there any other "tweaks" that can be done/added to a square box to improve the performance? Also, since the M4N is classified as an "extended range woofer", would it require a set of tweeters to handle the highs?

I apologize if these questions seem stupid or trivial to you guys. I'm still trying to "finding my way around" so to speak.

Cheers,
db!

[Pit Hinder]

db!,

Square is quite OK, but play with your pocket calculator first. Inner width/depth/height...not two of them should be the same.

[mightym]

here's one using the HiVi drivers thats already been thrashed about and by all accounts sounds quite good.

Simple to build, inexpensive too.



http://undefinition.googlepages.com/...ightsensations

Paul hangs out over at TechTalk forum at PE regularly.

Hope this helps.

John

[underwurlde]

I have just built a pair of uFonken speakers.

Words cannot describe how happy I am with them!

Cheers,

Andy

[chrisb]

When you say "square" do mean that all the corners/joints are square, or that all the outside panels will be the same dimensions? The latter would be a cube, and should probably be avoided, except perhaps for small sealed sub-woofers.

If you mean the former, remember that it's just as hard to cut parts to exactly the right dimensions and squareness, regardless of the relationship of dimensions (aspect ratio) of the 6 sides that create a "standard" box. There are certainly some aspect ratios to avoid, and some that have sonic and aesthetic advantages.

I'm a big fan of the "golden ratio" approach. It's not all that hard; once you've settled on the net internal volume of the enclosure (ported or sealed), use a cube root calculator to determine a central value, then divide and multiply that dimension by 1.618. Unless you're building a Swiss watch, rounding to the nearest 1/8" or so is perfectly acceptable.

Then add allowances for material panel thickness and that's it. Cutting them perfectly and assembling will be a bit trickier.

For example a 1 cu ft box (internal) would result in

12" x 12" x 12" = 1728"^3

12/1.618 = 7.416 ~7.375"
12x1.618 = 19.415 ~ 19.375"

7.375" x 12" x 19.375" = 1714.6875"^3 - a difference of less than 1%

If you have CNC cutting machines available with accuracy to tenth of a mm (sorry to switch units of measure), you could probably reduce that difference to even less - but considering the manufacturing tolerance of drivers that you'd be installing, rather a waste of time.


Of course, you need to predetermine if your diver of choice will actually fit in a Golden Ratio box, with appropriate "breathing room", clearance from rear panel for voice coil vents, etc., and how the resultant width might affect calculation of BSC if any.

[chrisb]

Originally Posted by underwurlde

I have just built a pair of uFonken speakers.

Words cannot describe how happy I am with them!

Cheers,

Andy

- pretty cool, aren't they?

It could have already been answered, but what amp? For my own taste the FF85K is far less tolerant of digital and chip amps than other Fostex or Mark Audio drivers.

[picowallspeaker]

Chris ,sorry for this mean question. You said "Golden ratio" and the relative allowance of small errors in the box measures ;then , referring to a particular model by Fostex , you said that it was behaving differently depending on which amplifier. Do these statements contradict themselves ,in the way that each driver can be put in different cabinet ratios ,following each its own way depending by its unique parameters ?
Bye

[planet10]

2 Litre = 2000 cm^3
cube root = 12.6 cm
12.6 x 1.618 = 20.4 cm
12.6 / 1.618 = 7.8 cm

204 x 126 x 78 mm internal

4 Litre = 4000 cm^3
cube root = 15.9 cm
15.9 x 1.618 = 25.7 cm
15.9 / 1.618 = 9.8 cm

257 x 159 x 98 mm internal

Sealed is very tolerent of variation of the volume... stuffing makes them seem bigger.

12mm ply would be fine for the little box, 15mm for the 4 litre, at least a size thicker if you use MDF.

dave

[db!]

Hey guys, I appreciate all the info.

By square, I meant to say rectangular; I apologize if this caused any confusion. Most of the rectangular designs are relatively large and utilize complicated waveguides and such; this is beyond my size limitations and building abilities.

I have reviewed the "overnight sensations" design and I feel that it's well within my compatibilities. My only gripe is the size; it's a tad bit longer than I'd like it to be. Would it be possible to build it smaller as a sealed design, then use stuffing to artificially increase the size?

Just for curiosity's sake, is there anything particularly disadvantageous of a perfectly square box?

Thanks in advance!

[planet10]

Originally Posted by db!

Just for curiosity's sake, is there anything particularly disadvantageous of a perfectly square box?

A resonance can build up between parallel sides. A square box would have all parallel sides producing the same resonance.

A rectangular boxes spreads the resonances out.

dave