loudspeaker enclosure finish(varnish?)

[Mark4583]

Ive picked up a couple books on building loadspeakers, Say's to use MDF or Plywood.
If you went with cabinet grade plywood like Oak or Birch, could you not finish it in a Varnish, shellack or a Laquer ?or will that effect it in some way?
Thanks

[FLZapped]

Ive picked up a couple books on building loadspeakers, Say's to use MDF or Plywood.
If you went with cabinet grade plywood like Oak or Birch, could you not finish it in a Varnish, shellack or a Laquer ?or will that effect it in some way?
Thanks

Your best bet would be to go ask these guys, very serious woodworkers there:

http://www.madisound.com/cgi-bin/discuss.cgi

-Bruce

[MCH]

Yes you can use a varnish, or lacquer, or poly, or paint etc. There is no effect on the sound. But your choice of plywood could be. I highly suggest you use the Baltic Birch if you use a plywood only. The Baltic Birch has 13 plys (3/4") of veneer which practically eliminates any voids that could cause problems with unwanted sounds (like buzzing). Cabinet grade plywood such as oak or birch, only has 7 plys (? for 3/4") and has voids in the lamination process. Cabinet grade only means it has a nice finishing side on both sides.
Baltic Birch is used in lot of the high end equipment cabinets (speaker cabs) for electric guitar. It is much more durable than MDF and weighs significantly less.
What I did for my cabinets (the rectangular type) used 1" mdf and then sheathed it with 1/4" plywood such as Baltic Birch. I even used the 1/4" Oak ( I love the look of oak). I found the 1/4" oak was fairly consistant for being void free. The 1" mdf has great dampening qualities. I built a set of 5 AR.diy for a nephew with 1"mdf sheathed with 1/4" oak. They had no ill effects and sounded great.
This is just my experience.

[poneal]

polyurethane is a hard clear finish and easy to apply. You will need a spray gun or spray in a can to apply lacquer if you want decent results. If using spray lacquer make sure you put on a few coats of primer and sand it smooth before applying lacquer. Don't mix lacquer and enamel. The lacquer is hotter (chemically) than paint and will cause paint to bubble. Use a colored lacquer if you want it black or white, etc. Spray the lacquer on in very thin coats so as not to run. Let dry in between coats. You will need to sand between coats with finer and finer grade sandpaper up to around 2000 grit for a piano finish. Good luck and have fun.