Monday, April 18, 2011

Phase IV Mk2 construction underway

After very little thought, I decided to see if I could improve on the Phase IVs. A new cab design was created in Sketchup (which I'm now getting better at using) in fairly short order. Judith was asked for her thoughts on the three variants I generated (each with slightly different baffle widths) and she chose the right one.

A weekend of fairly hard work, and not all of it plain sailing. I built part of a new pair of cabinets (this time I decided to build a pair). I'm not cabinet maker so I'm learning as I go, and almost all is trial and error. On Sunday there was a lot of error. The plate joiner joints between the side panels and the corners weren't at all clean and didn't have any structural strength, something which became very clear when I kicked one of them (to test the gluing, not out of frustration that the join wasn't mating cleanly - honest guv).

I'm going back and forth between the real artifact and Sketchup, updating the drawing as I make small adjustments in the process of building. For example, I added the cabinet bracing to the drawing and found that there may be a problem with the brace hitting the back of the mid range driver. We'll see soon enough. I'm quite pleased with structure in the back half of the cabinet. Now, I need to think about how best to build the fronts.

I ordered the drivers today (two 8" Silver Flutes for the bass @ $36, a 5 1/2" Silver Flute mid $20, and I've got some Vifa D27TG-45 tweeters to use up). I also ordered some ferrofluid in case the poor HF response (6db drop >15kHz) of the D27TG-45s has something to do with the old ferrofluid. I've no idea but it's worth a try. If that doesn't work I'll try replacing the voice coil.

One nice thing though; I was looking at either the Vifa XT25BG60-04 or the XT25TG30-04 as tweeter if I can't the the D27TG-45s to brighten up at the top and the mountings are identical. So if I can't get a pleasing sound from the D27TG-45s, I can swap them for either of the XTs without rebuilding the baffle (which is good because this time they're going to be glued not screwed in place).

The other change I'm anticipating is putting the crossovers inside the cab (a bit radical, I know). The drivers will be here by the weekend (I hope), an incentive to get the cabinets finished.

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