Sunday, June 12, 2011

Setback

Today I realized the second cabinet has to be rebuilt. Painting it before it was finished structurally cause the wood to swell and bow, and go out of true. The baffle, which was not yet in place, was now too wide at the top and bottom and too narrow in the middle. Neither the baffle not the cabinet could be planed into shape any more, and no amount of coercion was going to get the baffle to bed into the cab properly. While I could have simply made a new baffle, the bow on the cabinet walls was such that I decided that it would be easier to start anew. Having dismantled the cabinet with a mallet (most satisfying), and looking forward to another three weeks worth of work, while I know that was the right thing to have done, have to say I'm a little despondent about the setback. The mistake was the result of a false economy in time and money.Live and learn I suppose.

Wednesday, June 1, 2011

Conception to realization

Conception

Realization

One done

One of the cabinets is finished. Looks better (I think) than the Mk1. Sounds OK through the first order Mk 1 crossover, but measurement and testing begins this afternoon.

Several lessons learned this time. First, don't use a light colored primer under the black spray on the front. The smallest scratch and it shows through. Second, make absolutely sure that joints are sealed. I discovered that the bass cab isn't air tight. The hole must be fairly small but it's enough. Whether this matters much I don't know yet.Another is don't use Duck masking tape to prevent the wood getting painted. It makes a real mess coming off leaving glue and bits of paper all over the wood. I've still got to figure out the painting. The red spray pain has left a fine stippled effect which is not what I wanted.  And I spent some much time sanding and priming and re-sanding and re-priming... 

This design uses two silver flute 8" drivers in parallel for the bass but one is a 4 ohm with a 3mH inductor in series with the driver. The ideas was to give a little boost to the very low (<100Hz) frequencies which these drivers don't handle overly well. We'll see this afternoon whether the idea worked.