Powered Bookshelf Speakers

[Rich G]

After a few months research and soaking up as much knowledge as possible these will be my first DiY speakers.

These were designed for music only to be run off of the computer in my office which is a small ish room (11' x 11' x 9'). I listen to music with alot of bass (think Massive Attack or Bassnectar) and I like it loud. I thought I could pull it off in a medium sized (for a bookshelf speaker) box and not have to run a seperate sub.

I decided to go powered because they were going to be hooked up to a computer, I didn't want a seperate amp in the room as one more thing to turn on, and I wouldn't have to deal with a passive crossover. The idea was that I would EQ any irregularities out of the response with the computer.

The components I used are:
6-1/2" Woofer: Peerless HDS PPB 830874
1-1/8" Solk Dome: Dayton DC28F-8
Full range plate amp: Dayton MCA3545

The box is 11"w x 17"t x 10"d with roughly 15L of internal volume. I had some sheets of 3/4" (16mm) baltic birch laying around so I used that instead of MDF.






I tuned it to 40Hz ish so that the woofer wouldn't unload.
The green line is the woofer in free air and the orange line is the woofer in the box




The elbow in the port sits pretty close to the amp. On a side note I offset the amp catty-corner from the drivers to try to balance the weight of the box so it wasn't too heavy on one side.




Here's the final response. This is on axis, non-gated, in the room at the listening position. Plots were taken at max power. The purple is the FR before EQ and the orange is after EQ, both have 1/3 octave smoothing.



I only have a 10 band EQ right now, I'll probably grab my E-Mu card out of my other comp so I can have customizable EQ options.


Final thoughts: They work great for what I wanted, loud deep bass. They don't have any problems playing bass heavy music tracks at full volume (106db). They run into some probems with movie soundtracks that have < 30Hz material in them. And I still need to paint or finish them.

[xavier]

Nice wave guide, port and recessing of drivers. What kind of amp(s) did you use?

[Taterworks]

Looks to me like your tweeter could use some series resistance to decrease the level. You're already doing your own measurements, so that puts you way ahead of a lot of the other n00bs.

[Rich G]

Nice wave guide, port and recessing of drivers. What kind of amp(s) did you use?

I used the Dayton MCA3545 full range plate amp. It has a small amount of hiss at full power but at 2 yards away it all but disappeared. I ended up using the 2.2K crossover with the bass boost enabled.

[emilime75]

Would you please show/explain how you made the tweeter "waveguide" and woofer recess the truncated framed woofer? They both look very good.

[Rich G]

Would you please show/explain how you made the tweeter "waveguide" and woofer recess the truncated framed woofer? They both look very good.

They were both cut on a cnc machine. However, the woofer recess can be exactly duplicated with a circle jig, a straight edge (or straight piece of material), spending some time getting a good layout, and a steady hand with the router.

The wave-guide can be approximated with a circle jig, a ball end router bit, calipers, and a bit of preperation. I'll try to do a quick write up about how to do it some time this week.