Volti Audio - 2015 Klipsch Khorn Restoration

4.2015 - By Greg Roberts

Page Two

Starting the veneer now.  I'm using a paper-backed, rosewood veneer that comes in 4' x 8' sheets.  The supplier uses raw wood 'leaves' of veneer, he trims them, and then in a bookmatch pattern, joins them together and glues them to a paper backer.  The sheets are then run through a sander.  When I get the product, I have to figure out how to best use the veneer for the pieces I'm covering - always thinking about the 'picture' on the various panels of the speakers.   Here's a sheet being cut for the tophat pieces.

The modified Khorn bass horns, with their enclosed back cabinets, just barely fit into my 4' x 8' vacuum bag.  In this picture, we are installing the front 'smoothing panel' of 1/4" Baltic Birch plywood.  The sides you see in the bag are pieces of 1/2" Baltic Birch plywood that are being used to cover the side horn outlets of the bass horn.  Later, these pieces will be used to cut the side grill frames.

The next few photos show the process of veneering the tophat pieces.  First, the tophat edgebanding is installed with the iron-on method.  The edgebanding is trimmed and each side of the panel is sanded to prepare for installing the veneer.  I use 'cauls' of 1/4" Baltic Birch plywood, covered with a Mylar sheet.   The cauls are placed on top, in between, and on the bottom of the panels, and the veneer sheet is in between the caul and the panel being veneered.  The cauls distribute the clamping action of the vacuum bag, and protect the edges of the veneer (that overhang the panel).  The Mylar provides a smooth surface against the veneer, and makes it easy to clean off any excess glue that leaks onto the caul.

So, here's a caul that has been sprayed with Spray 77 adhesive

Here is the Mylar being installed

The veneer is taped to the caul with small pieces that just catch the edge of the veneer

A 'sandwich' is made of caul/veneer/panel/veneer/caul/veneer/panel/veneer/caul.  The middle caul is double-sided with Mylar.  Two-part urethane glue is rolled onto the panels as this sandwich is made.   The edgeband veneer has been taped to make trim-sanding and glue removal easier.

Now into the vacuum bag for five hours

And out come glass-flat veneered panels, ready for trim-sanding

The cauls were made for the largest tophat panels - the tops, then cut down for the next size down - the bottoms, then cut again for the "B" panels, then a final time for the tophat sides and the pieces for making the "B" risers.   If I was doing Khorns like this regularly, I would have cauls for each of these panels that I use over and over.

Here's a panel that has been trim-sanded, ready for final sanding and detailing

The next few photos show how the risers are made.  I veneered pieces of 3/4" Baltic Birch plywood and then ripped them down to 1" side strips.  I then use a jig that I made for my table saw, and with the blade tilted to 45 degrees, and each strip clamped into the jig, I get a perfect miter cut each time.

I then lay out the four mitered strips on a flat table and tape underneath where they join with masking tape

I glue the miters with Titebond glue and then fold the whole thing together.  The corners are held tight with extra tape if necessary, and they are checked for square before the glue sets up.

Bass horn grill frames ready for paint

Bass horn carcuss ready for paint

Beautiful Rosewood after second coat of clear gloss lacquer.

Regarding the finish - when my customers approach their speakers, I want them to immediately recognize that it is real wood they are looking at.  By using a satin lacquer finish that is not too thick, it allows the natural little imperfections of the wood, and the grain of the wood to come through just enough that it is immediately evident that the finish is real wood.  A satin finish is not as 'flashy' as a gloss, so it does not distract from the wood as much.  Contrast that with the perfectly glass-smooth, plastic-like coatings of thick, glossy lacquer that you sometimes see over wood, which to my way of thinking, don't convey the essence of natural wood nearly as well.

So my final spray of finish is a satin lacquer, but I start with two coats of gloss lacquer.   Lacquer starts out as a full gloss mix, and to make it satin, solids are added to the mix to tone down the gloss.   Multiple coats of satin lacquer creates a build-up of those solids on the surface, which can dull the clarity of the grain lines and color of the wood.  By using gloss for the first two coats, I am able to sand-seal and build up the finish without adding those solids, and after topping off with a satin, I end up with a finish that has good clarity, allowing the sharpness and detail of the wood grain to come through, with truer colors.




Page Three