March 24, 2007

Stereo System for Noah


What do you do when greeted with rain on a Saturday morning? That's right, you tinker in the garage.

Todays project was one I had been contemplating for some time... ever since this box of 22 little speakers (known as NSB's, short for No Stinking Badges) mistakenly landed on my doorstep. Noah has been asking for a stereo in his room, and I was just dying to build him some little speakers to go along with my old Denon 2-channel receiver and single disc CD player.

I had considered also using some larger speakers to fill in the low-end, but in the end I opted to run a pair of NSB's per side... a sort of 'mini-array'. I didn't have the crossover parts on hand to get a good match between the drivers, and I didn't want that large of a cabinet sitting on the dresser. I decided that I can always add a little sub later if he starts asking for more bass.

I measured the drivers with my Woofer Tester, and then modeled response in BassBox (a computer program that models frequency response). I decided on a small .08 ft^3 cabinet stuffed with poly-fill... frequency response graphs show a couple dB bump right around 200 Hz, and then rolling off rapidly below that. The very low inductance made for a nice model on the upper end of things... showing usable response well out to 5 Khz+ (still, these were just models, and I was a little skeptical of the upper end response).

The actual exterior cabinet dimensions are 10.25"H x 5.5"W x 5"D. My total cost for the project: $0.00. The box is built from scraps. The speaker wire was leftover from a project last summer (a customer paid for it). Polyfill and screws are from other projects.

A close up of the NSB 'mini-arrays'.

We plan to fill screw holes and paint the cabinets eventually, but I wanted to make sure they sounded OK before I went to all that trouble. I will let Noah choose the paint color. :-)

Noah had to listen to one of his CD's at first, but then it was time for me to try some of mine. I popped in my Pat Coil CD to do a quick test and was very pleasantly surprised. I was afraid that the bump @ ~200 Hz was going to cause problems, but I really can't say that I noticed it. The rapid rolloff below that point was very much evident, though. I was most impressed with the upper end extension of these little guys... I'd easily surpasses the performance of the *cough*BOSE*cough* (audio 4-letter-word) Twiddlers. Cymbals were crisp and the overall image was actually very good. The midrange seemed to get a little overwhelmed with complex passages, but I won't really complain considering the cost.

It was a fun little project... and it was especially fun having Noah out there 'helping' me. :-) And he couldn't be happier with his new stereo...

Noah's stereo.

March 19, 2007

What's On Your Workbench?

Rich's entry about his gorgeous new workbench (Part 1 & Part 2) gave me an idea for a new entry of my own... workbenches.

I built my workbench about ten years ago, using mostly scraps left over from our backyard fence. The corner and intermediate posts are pressure treated 4x4's, and the cross-braces are all 2x4's (if we ever have an earthquake I'm ducking under the workbench!). The shelves and the first top layer are all 3/4" plywood, and the overhung top is 3/4" medium density fiberboard (MDF) -- I overhung the MDF edge about an inch and a half in case I need to clamp anything to it.

Above the workbench, I put up pegboard and hooks, a shelf, a parts organizer, and a few ugly but cheap cabinets. I also had some dedicated electrical outlets installed just above the work surface -- I need enough juice to run a computer, test equipment, and audio gear; all at the same time.

While Rich's bench is both beautiful and functional, mine tends to be more one dimensional, and I don't mean on the side of beauty...

My work bench in its natural state.

So what is on my workbench? Well, besides a lot of clutter, you will find a lot of audio gear and test equipment -- a computer, a 12V power supply, a fully operational workbench audio system (consisting mainly of older car audio equipment), raw speaker drivers, a few CD's, a cordless drill and charger, and various other random tools that I may have been using for recent projects.

During the winter months, the workbench often becomes a catch-all for whatever Steph doesn't want in the house. Since my garage is neither heated nor insulated, this usually isn't a problem... but once spring rolls around, it's time to make it functional again.

Rich's workbench has several features that I think would be very handy... I could list them, but if you just follow the 'Part 2' link above, he pretty much points them out.

My friend Roger built a nice workbench a few years back as well. He incorporated a lower height section of bench surface for working on taller projects... and it serves as a work station for the kids. I wish I had something like that for Noah, but for now, he just uses my Stanley Folding Workbench and stands on a step-stool.

So, what's on your workbench?

December 28, 2005

A gift for me? Or for Steph?

As some of you know, I am what some would consider an 'audiofile', or some would consider me to be an 'audio geek'. Not only do I like to listen to music as it was meant to be heard, but I also enjoy playing around with audio equipment (measuring, tweaking, listening, etc).

Well, for the last year, our family room has been home to a monstrosity of a subwoofer. It follows the form follows function philosophy, and it works just fine for me... but it doesn't score very well when it comes to WAF (Wife Acceptance Factor). So, I spent several hours over the weekend putting my subwoofer in its new home... and I got it done just in time for our Roth Christmas gathering. So the question still remains, is it a gift for me? Or a gift for Steph? Since I could have lived with the old setup indefinitely, I would have to say that it was a gift for Steph...

Here are some before and after photos:

The yellow arrow points to the old subwoofer cabinet, with the amplifier on top.

The new, all black subwoofer cabinet with the speaker hidden behind a grill and the amp mounted to the back of the cabinet.

Here are a few other photos for those who might be interested in more than just the black box:

Front of the sub with grill removed.
The amplifier mounted to the back of the sub enclosure.