Speaker Related Projects

   3-Way High Efficiency Speaker
(Lavoce, Dynaudio, Foster 3-way. October-2023)

   LCR MTM 3-Channel Speaker
(Three MTM Speakers in One. July-2023)

   Mini7bt - A Minimus 7 Portable Bluetooth Speaker
(Minimus 7 and Dayton Audio. Spring-2022)

   2-Way Ribbon Tweeter Speakers
(Vifa and Pioneer. May-2020)

   Transmission Line Speakers
(Aborted attempt at a TL. September-2012)

   Acoustic Research AR-4x Rehab
(Rehab of a garage sale find. January-2016)

   Infinity RS-4000 Rehab
(Rehab of a garage sale find. June-2015)

(A tall, thin, upwards firing omnidirectional speaker. May-2010)

(A powered subwoofer using a 12" driver and 15" passive radiator. Jan-2010)

(A computer speaker; redux. December-2005)

(A computer speaker in a light canister. Jan-2005)

(10" vented subwoofer in a cardboard tube, powered by a Parapix amp. May-1999)

   MTM Center Channel Speaker
(A Madisound design. Nov-1997)

   2-way Surround Speakers
(5" woofer and 1" tweeter. July 1997)

   3-piece mini system
(6" DVC bass module mated to 4" car speaker. June 1997)

   3-way Vented Floorstanding Speaker
(vented 10" woofer, 5" mid and 1" tweeter in a 4 ft tower. Summer 1995)

   NHT1259 Subwoofer
(A 12" woofer in a sealed architectural pedestal. Winter 1994-95)

   Inexpensive Speaker Stands
(Particle board, sand and spray paint. Fall 1994)

   2-way satellite
(6.5" woofer and 1" tweeter. Summer/Fall 1994)

Audio Electronics Related Projects

  900 MHz Audio Receiver
(Better use for bad headphones. Jan-2008)

  Buster - A Simple Guitar Amp
(Perfect for the beginner. Jan-2010)

  A PC-based Audio Console
(Use a PC to play tunes. Jan-2010)

  LM-12 Amp
(Bridged LM-12 opamps. Aug-2003)

(A CD player and FM tuner from spare computer parts. Oct-2002)

   Quad 2000 4-Channel Amp
(Premade modules by Marantz. May-1998)

   Zen Amp and Bride of Zen Preamp
(by Nelson Pass. Apr-1997)


  Using Wood in Speakers FAQ
(Work in progress)

   MDF FAQ for speaker builders

   Woodworking Tools for the DYIer
(HomeTheaterHiFi.com Oct-1998)

  Some Thoughts on Cabinet Finished for DIY Speakers

   Large Grills Made Easy

   Some Parts Suppliers

Other Useful Stuff

   DIY Audio Related URLs

  Veneering Primer
(by Keith Lahteine)

   How to get a Black Piano Finish
(by DYI Loudspeaker List members)

   Sonotube FAQ
(by Gordon McGill)

   Excerpts from the Bass List
(Oldies but Goodies)

DIY Loudspeaker List

  DIY Loudspeaker List Archives

Creating a Black Piano Finish

The following were posted to the DIY Loudspeaker list.

From: Delwin D Fandrich
Date: Tue, 21 Jul 1998 10:42:35 -0700

OK. About that "Piano Finish" we hear so much about. There are two distinctly different finishes being talked about here. The traditional "hand-rubbed" piano finish and the more recent "high-gloss" finish. The high-gloss finish is polyester -- a plastic. Since we don't care for the look that this finish gives to pianos we don't use it and I'm not qualified to comment on its application.

The hand-rubbed finish is usually nitrocellulose lacquer. This material is quite easy to work with, just remember that it is extremely flammable -- explosive even -- so take care. It also stinks and it's not real good for your insides. You will need lots of ventilation, both to reduce the fire danger and to reduce the wear and tear on your lungs and your brain.

The following procedure works for both clear and colored lacquer finishes. If you are using black, I'd suggest using an automotive acrylic lacquer. Especially if you want a high-polish finish. Traditional nitrocellulose tend to look a bit blue or gray when polished out.

  1. Surface preparation. All surfaces must be sanded to a dead flat finish. We dry sand with an open coat aluminum oxide paper -- not stearated -- starting (usually) with 120 grit and working up through every grit to 320. When sanding flat surfaces the paper is always used with a firm rubber sanding block. All surface dings, scratches, blemishes, etc., are filled or fixed after the first sanding with 120 grit. All imperfections must be fixed before either the stain or the first coats of finish are applied. (The obvious exception being with a black finish which can be patched at any time.) After the final sanding we "break" the edges to a nice uniform radius using 220 or 320 grit paper backed up with sensitive fingers.

  2. If the wood is an open pore wood and the finish is to be closed pore, the next step is to pore fill. Pore filler is a silica base material that is thinned to approximately the consistency of heavy cream and brushed on both with and across the grain. Pore fillers can either be applied in their natural color -- a light creamy tan -- or stained to accent the pore texture of the wood. Once the pore filler is partially dry (the surface is just dull) it is wiped or scraped off across grain. A tiny amount of pore filler will be left in the open pores of the wood leaving the surface quite flat. Allow the remaining pore filler to dry for at least 24 hours and sand the surface lightly with 220 grit and 320 grit dry paper.

  3. If the wood is to be stained, now is the time to do it. We also stain the wood of pianos that are going black. It helps later when Johnny runs into the leg with his new toy truck and chips the finish. There are a variety of different types of stains available. Books have been written on the subject. For most amateurs the selection is going to be somewhat limited to what can be found at the local HomeBase or hardware store. These are usually oil based or water based stains. All I can say here is to follow the directions on the can.

  4. After the stain is dry apply the first coats of finish material. You can use sanding sealer if you wish, we do not. Sanding sealer is simply lacquer with some additives blended in to make it easier to sand. If you've done your prep work well you won't have to do that much sanding anyway and lacquer without the added stearates bonds better and is more durable.

    (Note: If I were putting a black finish directly over MDF or particleboard, I'd first spray on a coat of black or dark gray automotive primer. These are very heavy bodied filling primers designed to fill in rough metal work and leave a fairly smooth sanding surface. It might take two coats.)

    We spray three coats of lacquer straight over the stained wood surface. Allow this to dry (we allow 24 hours) and wet sand with 320 grit wet-or-dry paper on a firm rubber sanding block. Don't over do this. You're only trying to knock off the high spots here. Lacquer chemically bonds to lacquer so you don't need to "rough-up" the whole surface. You're getting rid of raised grain, dust particles, etc. (You didn't get any runs in the vertical surfaces, did you? If so, sand them out also.) What you don't want to do is sand through your nice new surface into the stained wood.

  5. Spray three more coats of lacquer on the surface. You're more experienced now so you won't get any more runs, right? Again, allow 24 hours of drying time and wet sand with 400 grit paper still on a firm rubber block. This time you want to sand the surface pretty well flat. Always sand with the grain and be extra careful around the edges.

  6. Spray on three more coats of lacquer. This time let the surface dry for at least three days. Wet sand, starting with 400 grit paper and working through 500, 600. If this is to be a "hand-rubbed" finish stop here. The final rub is most easily done with plastic wool sheets (the white kind without any built in abrasive) and pumice or rottenstone. If you can't easily find these, good old Ajax will work. So will automotive rubbing compound.

    If the finish is to be more highly polished, continue sanding through at least 800 grit. Now switch to polishing compounds. We use 3M, but McGuires (sp?) is more commonly available. Visit your local auto paint store. There are about a million different compounds available and I don't even pretend to keep up with them. Find someone at the store who knows what they sell -- if you can -- and ask. The final polish will be done with a random orbital buffer. These might be available for rent. Otherwise, check Sears and/or head back to your local auto paint store.

The above is not intended to answer all of your questions about finishing wood. It's a complicated subject, but it's not an impossible subject for one who has already figured out how to build a speaker system. If all of this whets your appetite for fine finishing, might I suggest two excellent books:

  • Understanding Wood Finishing by Bob Flexner (Rodale Press), and
  • Spray Finishing by Andy Charron (The Taunton Press).

Achieving a fine finish on your work is not all that difficult. It does require some knowledge of the the materials you use and the proper techniques used to apply them. And some patience. Good luck.

Del Fandrich
Piano Designer & Builder Hoquiam, Washington USA

From: Keith A. Lahteine
Date: Sat, 18 Dec 1999 12:27:18 -0500

Dear List Members :

I'll tell you how I apply a gloss black, or any color for that matter, painted surface.

Before I got involved with loudspeaker systems, full time, I ran a cabinet shop and built quite a few specialty furniture items. As well as build the items I had to finish them. About 25 years ago I had a friend who was employed as a yacht painter. Most of the yachts he painted were wooden. He worked for a very high priced "Yacht Yard". One of the Crosby families from Osterville on Cape Cod. I used to marvel at the finish he achieved with a brush. There was no way you could apply quite as durable a finish by spraying. I'm in no way against spray painting but for M.D.F. it would be close to impossible to tell the difference between a brushed and a sprayed finish. Brushing, for one thing, puts down a much thicker and more durable finish, not to mention much less costly. People get so hung up on automotive type finishes they forget or don't appreciate the fact that your working with a cabinet not a car. No matter what type of final finish you choose the preparation work is very important. I'm just trying to stress that you don't need to use a spray finish to achieve a very good result. A a matter of fact brushing will get you a much thicker, more protective, finish. I always recommend oil base paint as well. It might just be me but I've never seen as good a finish achieved with latex paint. For a prime I like something like a white shellac such as "BIN" or "Stain Kill" either of these can be darkened for the black finish paint. If you leave it white it's a little harder to cover. Put the prime on before you do any filling. Trying to use something like "Spackle". Any fill on bare M.D.F. may cause the fill to shrink a bit. It works a lot better on the primed M.D.F. "Spackle" comes in two weights, regular and light. The lighter is just that, a little lighter. It will, also, dry more quickly than the regular consistency. The light sands more readily as well. This might be something to consider if you plan on using a lot of it. In any event it, usually, takes two applications of fill to complete the job. An initial sanding with about a 120 grit followed with a 220 grit is about right. I like to sand everything with, either, finish sander or a random orbit and about 120 paper . After this the prime is then applied. When the prime is dry lightly skuff it with 220. I like to wipe down the piece after sanding with a rag or paper towel dampened with alcohol or water. The alcohol dries a lot quicker than the water. After this your ready to apply the "Spackle" fill. A regular putty knife is, usually, all that's required. The reason I suggest two applications are in case any deep or extensive fill areas are encountered it can take a couple of fill applications to cover them. Sand any fill areas with a wood block to maintain flatness. Depending on how much leveling you have to do, either, 120 or 220 paper is desired . In any event finish with the 220 as a final prep. for finish paint. Remember the last step before your finish paint is that wipe down with the damp rag. Picking the proper finish paint is a very important step.

A few years ago I worked for a cabinet company in "Palm Beach County", Florida. Whenever a painted finish was requested there was only one place that was considered for supplying the paint. The "Benjamin Moore" store. There is No.1 in paint and No.2 is a long way back. The "Benjamin Moore" is that good. They have an oil based finish called : "Impervo" . This comes in a satin or a gloss finish. I use the satin finish no matter whether I want a gloss or a satin in the end. I believe it takes three coats of finish paint to do an adequate job. Each coat is then lightly sanded with a 220 grit paper or a 400 (wet or dry) before the next coat. If a final gloss finish is desired the third coat of paint is then followed with a few coats of gloss urethane. As a matter of fact even if your after a satin finish the gloss urethane is a good idea. The final coat of urethane can then be followed with, either. pumice or rotten stone to achieve the satin finish. After everything is dry a good coat of paste wax will preserve the whole business.

Good Luck : Keith

P.S. Here are a couple of tips. For brushing a good oil based finish use a good "China Bristle" brush. About two inches is good. Surprisingly those, inexpensive, foam brushes work, pretty, well too.

From: Ed Heath
Date: Fri, 12 Jan 2001 12:47:22 -0500

Flat black spray paint and 0000 steel wool, then several coats of spray polyurethene, buffed between coats, will produce a finish that can't be told from the labor intensive real thing. You can determine the amount of gloss by choosing the grit of the wet dry sandpaper that you use for the last coat of clear Poly. Use High gloss, because it is harder, and you can bring the gloss down to wherever you choose with the black sandpaper. Use paint thinner with the wet/dry sandpaper, rather than water. An initial coat of thinned low density (Red Devil) spackle. It sands easily, and will fill all of the irregularties in the surface. Block sand the spackle.

Date: Fri, 12 Jan 2001 21:17:31 -0500

It is possible to give this treatment as much depth as wanted, by numerous coats of gloss Poly that are alternated between sanded and unsanded high gloss with the sanded coats applied while the unsanded high gloss is still very slightly tacky, so it will adhere well over the unsanded high gloss. This method gives the illusion of depth by leaving reflective layers beneath the polished layers. It is not as hard a final finish, so I do not really recommend it, but it will give depth, and will eventually get quite hard, but it takes a long time. I really do not know how one would get more "depth" without endless numbers of sprayed lacquer layers, which is just an unreasonable amount of intense labor.



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