Uber cheap, yet amazingly good.

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I don't know why I started this project, I must have been bored. But what started out as boredom ended up what will probably replace the speakers I have now. Total cost of drivers, about $50 usd, price of xover, well probably not much, I just used parts from my junk drawer (one of them). These really sound nice, I get alot more bass than I was expecting (good down to 45Hz), and the highs go all the way up (I don't feel the need for a super tweeter). There's a $12 TB W3-871S and a $10 Stryke SA-071, both in an open baffle. Total time of construction, an afternoon (although I haven't finished them yet as you may notice). I just think these sound great, and with the low price if anyone's looking for a dirt cheap quick and easy project to build, you can't be disapointed with these.
 

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There are panels at the bottom next to the woofer acting like sides (folded baffle, and they also let the speakers stand up on their own). The SA-071 has a 6dB xover at 100Hz, while the W3-871S is run fullrange (drops off naturally around 100Hz). The oxver consists of a resistor and cap for the woofer, and two resistors to bring down the FR due to losses in the woofer xover. I haven't countersinked the driver yet, and I haven't finished the "cabinets" yet, so they're not quite done (I might fool a bit with the xover as well), but as they are they're better than my Vifa MTMs (P17WJs and D25AG) that you can see parts of in the pic.
 

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Nice project, JoeBob

JoeBob

This is something anyone could build.
Simple but good.
Open baffle with stands as well.

The main sound is given by the interesting Tangband W3-871S.
You made a great choice there!
I know from my own experience,
that with even a 4" middriver (Focal)
you don't miss the upper freq much.
The Tangbands 3" probably goes even higher.

This is such a project we REALLY
could call DIY - when it is at its BEST :)

/halo enjoys
 
As for finishing, that's what I've been thinking about. I was thinking of instead of countersinking the driver I'd add a layer a black felt over the whole front baffle, paint the sides and then cover the back with that material you usually use in the front of drivers (I'd use it to hide the back of the drivers). The only thing I'm not sure what to do with are the connectors (right now I have wire directly soldered to the drivers).

The more I listen to them the more I like these, much much tighter bass than I've ever heard. Midranges are outstanding. It doesn't sound like the sound is coming from the speaker, but instead it just sounds like the sound is "in the air" and I'm hearing it. I'm not good a describing the sound of stuff, but these sound better than my $1000 cnd BR pair I spent a month building (kind of annoying, why didn't I build these first?).
 
frugal-phile™
Joined 2001
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JoeBob,

An excellent example of a Frugal-phile(tm) speaker. I've heard the W3-871 and it is quite a value. It and almost any suitable effiencent bass driver would work.

I have 2 TB projects on the go. The one with the fancy OEM 3" TB will be an open baffle but i will probably do a TL on the bottom (still have to find a suitable driver).

You might improve performance if you offset the driver from the middle. Here is a couple graphs Olsen did:

An externally hosted image should be here but it was not working when we last tested it.


dave
 
Magnetic flux decreases approximately according to the cube of the distance so while the flux strength may be very strong a couple of cm/in from the magnet, it has dropped off by a huge amount once you get a couple feet away. It takes quite a stong magnetic flux to affect a hard drive and the magnetic flux must also be rapidly changing. All things considered, it's not impossible to affect magnetic media with a magnet but it's not particularly easy to do under most normal circumstances assuming some care in placement is taken.
 
Well Dave I tried to do just that, but so that it didn't look too bad I made it just slightly off center, the distance from the center of the driver with the two sides and the top differ by about an inch each. I don't know if that's good enough, but they sure sound nice.

I was thinking of your frugal-phile phylosophy when I built them, instead of going with a larger FR driver and adding a super tweeter I thought it would be cheaper to use a smaller FR driver (cheaper than a larger one) and throw in a bass driver (I had a few SA071s lying around).
 
frugal-phile™
Joined 2001
Paid Member
JoeBob said:
use a smaller FR driver and throw in a bass driver

With all the small FRs being developed for computer speakers and for little HTs this is a new frontier (well not really -- i've pulled apart a few vintage systems with woofers and mid-tweeters).

(I had a few SA071s lying around).

A propicious driver to have around... about the right sensitivity. And a driver i'd like to try out some day.

dave
 
I'm experimenting with a thing called 'nitrile rubber' to cover the baffles on my open baffle speakers. It is rubber with foam, and is 6mm deep. Once screwed in it rebates the drivers and looks pretty good.

Some shots are here:

Rubber shots

Regarding the offsetting of drivers, it seems those tests were done with a square baffles. which I'm told is the worst shape for an open baffles. Your rectangular baffle should be much better.

Steve
 
sfdoddsy said:
I'm experimenting with a thing called 'nitrile rubber' to cover the baffles on my open baffle speakers. It is rubber with foam, and is 6mm deep. Once screwed in it rebates the drivers and looks pretty good.
Some shots are here: Rubber shots
Steve
Here is a detail picture from
sfdoddsy's link

Nitrile rubber:
 

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JoeBob said:
I don't know why I started this project, I must have been bored.

This is great! I have been thinking of doing a speaker using a TB 3 incher and this MCM 10 incher (96dB sensitivity!) for sometime now. I have been debating between sealed box (separate for both within a common box) and open baffle. Sealed box: complex box construction (relative to open baffle). Open baffle: unexpected bumps and dips, and probably a crossover on TB to improve power handling. Since you are getting good results with open baffle, maybe I should give it a try (can always construct a box later).
 
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