Sunday, April 28, 2013

Bandmaster Build Part 4: Sorting Out The Cabinet





Once the weather warmed up enough to think about getting the cabinet shaped up for my 5E7 Bandmaster build I had to devote a little thought to making up a fixture for finishing the cabinet. I went out to the garage to see what could be found and settled on a pair of sawhorse leg connecters I'd purchased a while ago for the workbench project. A few chunks of 2x4 and some self tapping screws and I had it. Adding the extension made it easy to add a counterweight in the form of a cinder block that happened to be wandering by.

As I started putting the first coats of shellac on the cabinet-about which more anon-I discovered that the cabinet had been built with a seriously warped on one side board. I emailed the fine folks at Weber and they were good enough to provide another cabinet at no cost-props to them.

A few more weeks elapsed before the new cabinet arrived Friday last, but in the meantime I had had some time to think about the shellac finish and the prospects for getting a good application without discoloration-it is very easy for the end grain of the cloth to absorb the shellac which leads to permanent discoloration. It's liveable but I'm a perfectionist.

Some folks use Minwax Honey Pine polyurethane finish, but I don't like the look of the stuff at all-it's got a bit too much green in it and is far too slick for me, and I'm going for more of a tobacco coloration.

So I decided for my second try I was going to take my time and anoint the cabinet with clear shellac from the spray can, but that I was going to give it plenty of time to dry-like, a day or so, and pay special attention to the end grain of the fabric. Also, I decided I was going to build up the sealer coat substantially. So that's the plan and it's now baking in the sun after the second application.

I will probably give it another coat of clear and finish off the rattle can before I attempt to color it. I do have a can of clear shellac and I may try that as well. The object lesson is to take the time to build up a solid undercoat and properly seal the fiber. A light scuffing between coats after the shellac is properly dry is a must.

For those of you who haven't yet tried this, you need to assemble a spray can of Zinsser Bulls Eye clear shellac, a pint of their amber shellac, a quart of denatured alcohol, some green Scotchbrite scuff pads, a good brush, and some painter's tape. A fixture like I built can be thrown together in a few minutes.  All this can be found at any hardware store, so take the opportunity to shop locally and use environmentally friendly products from renewable and sustainable resources-which shellac and alcohol are, but which polyurethane most surely is not.

As a point of information, shellac is a refined naturally produced resin that primarily comes from India. The resin itself is produced by insects and it is deposited on twigs and small branches of host trees. You can read all about the production process here.

Although shellac dries to the touch in about thirty minutes, it's still not cured and that's where being in too much of a hurry can take a good job and turn it into an unsightly one.


Saturday, April 13, 2013

Bassman Hack








Here's an interesting Bassman a friend of mine recently acquired and sent over for service. According to the tube chart it is an AA864 but it's a hybrid between the AA864 and AB165 layouts. Well, nevermind.

What's interesting is the hack somebody laid on it. I guess the idea was to be able to run a tape player through it or something. I really do not think the guy knew what he was doing and it looked pretty nasty-not to mention he had the plate supply going through these pots whatever they were supposed to do. And a redplating power tube.  And some extra high quality soldering of the grounds. But nevermind.

It all came out easily enough, it got serviced and recapped, new power tubes and plate load resistors, and things were reassembled According To Leo. Some plastic plugs from the local hardware store were the best I could do with the drilled out holes on the back panel.


Friday, April 12, 2013

Gee, Ma, It Followed Me Home. Can I Keep It? The Excelsior Americana




Here's an interesting amp that followed me home the other day. It's an Excelsior Americana accordion amplifier, and it sports some unusual equipment-a 15 inch speaker, two 8 inch speakers, two tweeters, and a pair of EL34 power tubes.

It is rumored to have been made by the Sano people in New Jersey but I cannot confirm that. I was able to lay hands on a more or less complete set of schematics and they are reproduced here. It's pretty clean but needs a bit of work to get everything running properly-the vibrato does not work, the reverb just barely, and the controls are noisy as all getout.

Still, the guitar channel sounds a lot like a Fender of the era, with a fair amount of sparkle. And who knows, with the right accordionist you could stir up some real fun and polka.

Plus, it's weird and nobody else around here has one.