SDA 1C dovetailed walnut project

OK, it has been much longer than I anticipated, partly because I took so long to complete the tung oil finish, and partly just time taken to get around to posting pictures, but...

Firstly, I found Larry had no more tweeter or binding post rings available, so I decided to make my own. I cut the binding post rings using a bench grinder, drill press, hole saw used previously for a bathroom project and a lot of patience. I cut the tweeter 'rings' in a similar way using a couple of different size hole saws to make the odd shape.

I then did a lot of reading up on weld nuts, brazing, acetylene etc before deciding rivet nuts looked like a better idea. In theory to fit a rivet nut into sheet metal you simply drill a hole, insert it and use a tool much like a rivet gun to squish it slightly. In practice I found the tool is expensive and the hole has to be very precise to get the rivet to both fit, then sufficiently tighten. After some failed attempts I decided to solder the rivet nuts into the slightly too large holes I drilled. This worked incredibly well and easily, and the solder seems more than strong enough for the application. A coat of black paint hid any grinding and solder ugliness!





The custom tweeter rings provided for the possibility of using M4 philips head screws to mount the tweeters, matching those holding the plastic front plates to the magnets. I'm quite pleased with the look of these, even though they don't really "match" the screws holding the bass/mid drivers in:


I lost count of how many coats of tung oil, sanding with fine sandpaper and 0000 steel wool it took, but finally I was bored enough to convince myself the finish was sufficient and buff it with a wool pad:




Fortunately the drawn out schedule did give me time to fit gimpod's boards and Cardas litz chassis wire (thanks to nspindel for lending me the solder pot necessary to make use of this wire practical!)

Finally upon reassembly and basic testing, I listen to a few familiar tracks I noticed some unwanted vibrations. This iOS app https://itunes.apple.com/us/app/signal-generator/id409241018?mt=8&at=10lGyj&ign-mpt=uo%3D8 proved useful in eliminating them. As I slowly swept from 1hz to 20kHz and back I found and fixed:
- Chassis wires between the binding post cup and board vibrating against each other.
- Chassis wires to the tweeters vibrating against the chassis.
- Thin flexible copper wire between the connection spades and mid/bass driver coils vibrating against *the cone itself* (gently pulling them away was the fix)

I highly recommend anyone who hasn't already done so use a similar app or an actual physical audio signal generator to find and eliminate nasty buzzing both in the speakers and in the room itself - the overall effect on sound was significant, and your chances of finding them all by playing music is slim.

It's been way too long to objectively say whether the 1Cs sound 'better' and during the project my amplifier has been re-capped anyway, but I'm happy with the sound and the new look gained wife acceptance factor (at least to the degree possible with speakers of this size!)