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Old 12th November 2012, 08:10 PM   #11
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Best to try and avoid having the same dimention twice, otherwise you will get stronger standing waves at the frequency equal to the distance. 5" being around 2360 Hz..
something like 141 X 108 X 91mm internal which is a ratio of 17:13:11 would probably work well. Though may not match your asthetics

that's 5.55" X 4.25" X 3.58" (with 10% added to your original).

It would be best to use one of the longer dimentions (5.55" or 4.35" for the depth to reduce reflections of the back wave back througn the cone, thogh it may not be an option considering the driver size

Also you need to add the volume that the speaker will displace. as a rule of thumb you can add about 10%.

edit:fixed the dimentions. the spreadsheet had some garbage in it!!

Tony.
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Last edited by wintermute; 12th November 2012 at 08:24 PM. Reason: original dimentions way out.
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Old 12th November 2012, 08:25 PM   #12
sreten is offline sreten  United Kingdom
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Hi,

3" drivers need about 2 litres sealed to work best, around 1L is too small,
and there is not point going over 3L sealed,with drivers of around 1L Vas.

The B3S is not as good as the NS3 in the bass.
http://zaphaudio.com/audio-speaker18.html
http://zaphaudio.com/archives.html

rgds, sreten.
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Last edited by sreten; 12th November 2012 at 08:39 PM.
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Old 13th November 2012, 02:48 AM   #13
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Ok, so what about this as the inside cavity dimensions? I drew a circle just to indicate where the driver would be

Click the image to open in full size.

Its volume runs in at around 2.5 liters....(assuming my math was correct).

I figure I would have two side by side, sharing a divider wall.

Last edited by scales11; 13th November 2012 at 02:51 AM.
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Old 13th November 2012, 01:53 PM   #14
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I had planned on two of these speakers setup literally side-by side. But, given their proximity, would it just make sense to have a single speaker? This is serving as an internet radio/boombox...
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Old 13th November 2012, 06:21 PM   #15
Nanook is offline Nanook  Canada
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Default A suggestion...

Seek out the very good, and very inexpensive Vifa coaxs from ApexJr. Add a suitable crossover, and build a pair of boxes, BR type. 2 of my simple projects are on the Vifa projects page, the Retro and the "tubes". Both sound better than their simple construction or my abilities might suggest. Their is also a boombox type loudspeaker, and a pair of traditional cabinets from Steve Schenkel.

Please note that I have no affiliation, professional or otherwise with Apex Jr.

And the result? A great sounding compact speaker (the retros or the boxes mentioned above), that should cost you less than $100 a pair that are great on their own, can be used as a desktop speaker system, and can be migrated to a HT system or college room or den.

My suggestion is the construction of a pair or enclosures so that the ability to re-purpose them in the future without further work is a no-brainer.
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Old 13th November 2012, 07:04 PM   #16
chrisb is offline chrisb  Canada
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Quote:
Originally Posted by scales11 View Post
Ok, so what about this as the inside cavity dimensions? I drew a circle just to indicate where the driver would be

Click the image to open in full size.

Its volume runs in at around 2.5 liters....(assuming my math was correct).

I figure I would have two side by side, sharing a divider wall.
If those are internal dimensions, I think you're actually at 186.5 in^3 = 3.05 liters - if sealed, probably not much of an issue.

How about trying to apportion dimensions (for each compartment) on a GR basis? - IOW, .618 x 1 x 1.618

I use a cube root calculator to find the central value based on the net volume, then factor the other 2 from that figure

In the above case, those numbers would work out to 3.55"D x 5.75" W x 9.3"H. - might be a bit shallow, but you get the idea..
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Old 16th November 2012, 02:37 AM   #17
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Yep, I goofed up that fraction, must have typed it into calc too quickly.

I am still a newb, can you help me understand why I would want to

Quote:
...apportion dimensions (for each compartment) on a GR basis? - IOW, .618 x 1 x 1.618
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Old 30th November 2012, 02:44 PM   #18
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So I got two of the B3S drivers.

I typically learn more when I am DOING something and observing the results. So, I decided to play around with different enclosure dimensions. I thought just for the heck of it, I would make a cardboard box (just because it was quick and easy) with internal dimensions of 5",5",5" (I also realize this is bad because it can create standing waves?).

Regardless of my perhaps obvious flaws in this demo, the speaker sounded surprisingly decent, at least to my semi-picky ears. However, I do notice a buzzing-vibration occurring at some points of certain songs. Obviously, I would like to get rid of this buzzing and am looking for some insight.

So, my final build will be
-Use mdf or plywood and I was contemplating using the high-pass filters Zaff mentions: Zaph|AudioZaph|Audio
But, I do not want to have a subwoofer in this system since it is to be more of a self-contained stereo speaker box.

-I will have two of these drivers side by side but would however consider adding a tweeter

-I was also going to line the insides of the speaker box with some sort of dampening material

-I could alter the dimensions so that they were not all the same, if it really helped

Any other thoughts?
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Old 1st December 2012, 06:31 AM   #19
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I went down the same road a couple of months ago. Started even with cardboard prototype. The buzzing sounds does probably come from vibrations of the walls, or leakages. Will most likely disappear if you just build the final box rigid enough.

I used the NS3, but I ended up adding tweeters since the dispersion of high frequencies, in my opinion, was pretty bad. I suspect the BS3 has similar high freq dispersion.
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Old 1st December 2012, 12:11 PM   #20
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I see, I suspected that I may want to add a tweeter. I suppose for that kind of build, I will want to have a high-pass filter for the tweeter, and a low-pass for each B3S?

If I am not mistaken, I don't really need to size out a compartment for a tweeter, I can just throw one on there correct?


mrduke,
How can I check for distortion and the dispersion you mention?
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