Super cheap bookshelves

[BoomieMCT]

I was bored because my wife was making a pie so I decided to make some true "bookshelf" speakers. These are meant to be put in a bookshelf with books and such. As such I figured I could forgo a BSC circuit if I could keep the face of the enclosure flush with the books in the bookshelf. Lying around the house I had some MDF, some 6" PVC and two Tang Band W3-593's (that were on sale for a whopping $8.88).

So, after fiddling with Unibox a bit I came up with a decent response for a vented enclosure. I didn't want to build a port so I sized it so that the depth of the port would be 3/4" - the same thickness as the MDF. This way I would only have to drill a hole (or holes as it turned out). I didn't feel like using my circle jig to drill a 1 1/8 inch hole, so I drilled four 1/2" holes instead (with a power drill).

I didn't have any binding posts so I just ran a wire through one of the ports and hooked up the two speakers. Considering my wife isn't even done baking her pie I'm very impressed. The highs are very clear and the soundstage is pretty big. Vocals sound great and are super-clear. There is a bit of a rise way up (the FR says 8kHz up) and output only goes to about 100Hz. I'm surprised at the articulation of these $8 drivers. I've been doing an A/B switch between these and a hand-me-down Bose Acoustimass system I also have hooked up to this reciever (MSRP $400 - I use it when I'm playing video games). The Bose has more bass (bloated "bass module bass" but bass nonetheless), but nowhere near the clarity from mid-bass up. I think for everything except death metal I prefer the $20 set though.

I've included a FR - please note this is on a driver that has not yet been broken in. Also, one of the four ports is covered by the wire (I have no binding posts lying around). I'll update as I play with these.

[gychang]

please put up some more pics as u proceed. gychang

[BoomieMCT]

gychang wrote:

please put up some more pics as u proceed. gychang

No problem. Right now the only things to remember is 10" of 6" pipe and four 1/2" holes for ports. I'll post more as these develop. For now they will need a few days to break in.

[JCD]

I LOVE that you did this! True DIY if I've ever seen it.

I do have one question though: your "ports" -- are they just holes drilled in to the front? Or are there actual tubes behind it?

Again, I love this story!

JCD

[BoomieMCT]

JCD wrote:

I LOVE that you did this! True DIY if I've ever seen it.

I do have one question though: your "ports" -- are they just holes drilled in to the front? Or are there actual tubes behind it?

Again, I love this story!

JCD

First off, when these are done they will be pretty! They won't always look DIY - they look like they do now because they are just prototypes.

The ports are just drilled holes. I was trying to tune it such that I only needed ports 3/4" long (the thickness of the MDF) so I wouldn't have to fuss with a tube. I got even lazier by sizing multiple ports to the size of a simple drill bit so I wouldn't have to mess around with my circle jig. Plus, the four holes look cool . Sure, on unibox the tuning is a tad high and there should be port noise at 100 Hz or so. Also, because they are small holes there will be more drag on the moving air as there is more surface area for the air to move against (kind of like a narrow slot). None of this has been a real problem so far - I didn't expect to get much output below 100Hz and my first FR backs that up. I could have tuned it lower, but with only .5mm of linear excursion I wanted to focus on the range where the driver operated better instead of making trades for a bit of bass.

I'm going to pick up some cheap binding posts at RatShack today and see how it sounds with all four ports free. I'll also probably screw the caps in and add some padding on the back cover. If I'm really lucky I may get to paint too.

I do have to figure out one thing though - where can I put the binding posts that these will still fit in a bookshelf? If they are in the back they will push these out too far. The side? The front?

[BoomieMCT]

I was tired of y'alls DIY comments , so here is something a bit more finished looking with a slightly more broken in FR. Oh yeah, one port isn't plugged anymore too. These are fun to listen to - that driver can really move air through those ports! Any chuffing isn't audable to me though.

[BoomieMCT]

With more breaking in, here is an on-axis (green) and 90 degree off-axis (purple) plot. The off-axis plots were with one of these speakers sitting on its back. Granted my studio is hardly an anechoic chamber but I'm impressed with these little guy's off-axis performance.

[JCD]

BoomieMCT wrote:

I was tired of y'alls DIY comments , so here is something a bit more finished looking with a slightly more broken in FR. Oh yeah, one port isn't plugged anymore too. These are fun to listen to - that driver can really move air through those ports! Any chuffing isn't audable to me though.

You misunderstand me.. I loved the "rustic" look!

I still love those things. Maybe I missed, but now that they're a little more polished, what do you think of the sound subjectively at this point?

JCD

[BoomieMCT]

JCD wrote:

You misunderstand me.. I loved the "rustic" look!

I still love those things. Maybe I missed, but now that they're a little more polished, what do you think of the sound subjectively at this point?

JCD

Absolutely great for vocals and acoustic guitar. A bit lacking on bass (surprise). Even before I tested them I noticed that the sweet spot with these was larger then normal - I expect that is because of their good off-axis response. I can definately see why a lot of people swear by 3" full rangers (all my full rangers to this point have been 4").

For a while I had them hooked up with my 8" TL sub. I thought the combo made a pretty good music machine for a wide range of genres.

[blk_addr]

I gotta say, Boomie... these inspired me to try out my first build! (Plans can be found at http://www.avsforum.com/avs-vb/showthread.php?t=871840)

Maybe when I'm done with those, I'll do a pair like yours to replace the PC speakers... looks really quick and fun.

[BoomieMCT]

blk_addr wrote:

I gotta say, Boomie... these inspired me to try out my first build! (Plans can be found at http://www.avsforum.com/avs-vb/showthread.php?t=871840)

Maybe when I'm done with those, I'll do a pair like yours to replace the PC speakers... looks really quick and fun.

I'm glad I could be an inspiration! BTW, I've used the W4-656's before and like them very much. Make sure to chamfer out the space behind the driver or you will raise your Fs too much!

[blk_addr]

ah man, I knew I'd seen your name around before, but couldn't remember where... even browsed around trying to find your post again! I guess you could count this as a double-inspiration, because I decided to follow your second build choice. Let me know if you have any advice or words of wisdom

[BoomieMCT]

blk_addr wrote:

ah man, I knew I'd seen your name around before, but couldn't remember where... even browsed around trying to find your post again! I guess you could count this as a double-inspiration, because I decided to follow your second build choice. Let me know if you have any advice or words of wisdom

Well, I made my W4-656 project kind of undersized because I had a limited space to fit it in my living room. I probably need to make a notch filter around 7kHz for it too - I just haven't gotten around to it.