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Minimus 7W - Turning a good original cabinet back into a great original

VA1DER

VA1DER

Member
I have been lucky/blessed/obsessive enough to find three sets of original, 40-2039 no-suffix Minimus 7W with the walnut veneered baffle. There are a lot of speaker refinishing threads, most of them by people far more experienced in woodworking than I am. But I thought I would share my experience very lightly refurbishing a pair in already pretty good condition to look superb. I am aiming this at people at a very moderate level of skill who want their Minimus 7Ws to pop.

Requirements:
  • Minimus 7W walnut veneer (or similar) speakers in good to moderately rough shape.
  • Boiled linseed or Tung oil (see below)
  • Sponge brush
    Most people say to avoid sponge brushes for boiled linseed oil, but I love them for speaker refurb. They can be "painted", swabbed, dabbed, and pressed with equal ease to work the oil in to problem spots.
  • Cotton swabs (off-brand can be better)
    These are being used her for the front (if you have an original Minimus 7W with the veneered baffle), so I find off-brand is better as they aren't as soft and don't spread oil where you don't want it.
  • Paper towel
  • Small exacto-style knife (for paint)
  • Magic Eraser or similar melamine sponge
Oil: Your choice of oil depends on whether you want a slightly golden "kissed" tone (boiled linseed) or a more neutral darkening (Tung). I don't think the manufacturer was completely consistent in their use of oils, as I've seen batches a very neutral brown, and some quite golden. I myself prefer boiled linseed, and this minor restoration was done with that. I find that boiled linseed brings surfaces back from quite variegated/spotty wear back to a consistent look without sanding better than tung.

Before:
Here are the sales photos of the Minimus 7Ws I bought. The seller didn't post photos of the bottom of the speakers, but I knew what to expect. Bottom photos are mine taken on arrival:

s-l1600 (1).jpgs-l1600 (5).jpgs-l1600 (6).jpg
s-l1600 (8).jpgs-l1600 (9).jpg

s-l1600 (7).jpgBottom1_Pre.jpgBottom2_Pre.jpg

Identify trouble spots for pre-treatment:
  1. Dented dome. I hate that. The longer it's left, the harder it is to get the creases out. People that leave dents in their domes need a dent in their dome.
  2. Paint splotch. I don't know what it is with people who own wood speakers, but every pair I have ever bought used has had paint on them somewhere. They are inevitably magnets for catching paint drips. The previous owner did the worst thing possible with this one, which is partially wipe it then leave it dry. The owner basically worked into the grain for me. Thanks.
    Note: if you get paint on your wood speaker, get it ALL off immediately, or let it dry fully when it can often be pried off as a whole chip.
  3. Bottom weat-through
Other than the above, there are scratches and dings and lined intents (don't use a speaker as something hard under your paper to write on) but the BLO should take care of it.

Dented Dome:
The different methods of Dome1_Post.jpggetting domes to round again is covered elsewhere in more detail than I'm going into. These are treated silk domes, so responsive to a light suction, but not something I'll use a vacuum on. I treated mine treated mine with the french-kiss method.

I will note that you can disassemble an SD-51 tweeter and actually pull the dome off for proper reconstruction. If you decide to do this, then a ping-pong ball is almost exactly the right size to push in from the back. I don't like doing this, though, because getting the dome back on can be very tricky given the strength of the magnet.

I might have considered disassembling if mine turned out worse than this. The remaining dimples may self-resolve over time and use, or with continued occasional smoothing. The vibrations of playing sound can actually work dimples out sometimes. Some gentle heating can also help, but this is also dangerous. I am going to give this some time and see how it in after a month or two of usage.

Paint Splotch:
PainSpot1.jpgI can't fault the general shape of these 43-year old speakers, but lord save me from people who work paint into the grain!

So, what I have to consider here is that I have maybe half a millimetre of veneer thickness, that walnut grains are deep anyway, and to sand this down enough to get at the bottom of where paint is inside the grain I a) risk going below the veneer depth, and b) will certainly end up with a spot that lacks grain depth.

I do not ever recommend chemical paint stripping, unless the entire speaker is going to be stripped. Any sort of chemical spot removal will leave a mark that stands out through any number of later oilings.

My treatment plan is removal of surface pain residue with a magic eraser (this will also remove some finish coloration along with some of the paint smudge, but that's ok, because it won't leave chemical marks), followed by grain surgery with an exacto knife.

Yes, I use an exacto knife. To clear out a grain channel of embedded paint, put the exacto knife point down inside the grain channel, and slide it backwards along the grain channel. The back of the point sliding through the grain channel will scrape the bottom and walls and can clear it of paint. This is tricky work, but can go surprisingly quickly. There are 12 or so grain channels filled with paint in this splotch, and it only took me about ten minutes to clear this. Don't worry too much if you are taking away some finish as you dig the paint out - it's to be expected. Just be careful you're not enlarging the grain channel too much. Whatever finish is taken off here, the BLO will fix nicely.

To Be Continued!
 
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Pain Splotch After Surgery:
Here is the the same spot after treatment with the magic eraser and surgery, both before and after oiling:
PainSpot1_Post.jpgPainSpot1_PostOiled.jpg
It's hard to tell there was even an issue here.

Bottom Wear-Through:
It was originally recommended to me to sand the finish right off and redo for this kind of variegated wear. I have discovered a better method. The perfect thing to do for pre-treatment of this area, is exactly nothing at all. Whatever oil the manufacturer actually used, the boiled linseed oil I favour is compatible enough that I've found for even highly variable wear and complete wear-through of spots, that the re-oiling will take care of it nicely.

Now that pre-treatment is done, the main event:

Re-Oiling
As stated in the supplies section, I use foam a foam brush for the main oiling. Generally a 1.5" - 2" wide, cheap disposable foam brush.
  1. Get a brush ready and open up your bottle of oil
  2. Start a stopwatch or timer. You will want to remove any excess oil about 20 minutes after applying. If you apply at a steady rate, and then wipe off at about the same rate, then a reasonable method is to start the timer when you start applying the oil, go over both speakers, then start wiping off at the same spot you started applying after 20 minutes or so.
  3. Spread out a couple sheets of paper towel and pull the front grill off the speaker and set aside.
  4. If you are using a 1 litre/quart bottle of oil, you can just hold the flat of the brush over the top of the bottle and upend it very briefly to get some oil on the brush. You don't need much!
  5. I tend to put the speaker standing up, start with the top, then pinch the speaker between one of the plastic pegs and the back an rotate it onto one side, and repeat. It won't hurt your work if you are laying an already oiled side down on the paper towel as you do this. If, however, you really want, you can instead to it all with the speaker resting on the pegs. I did my first set this way, but subsequently discovered it didn't harm the job at all to set a done side on the paper towel as I rotated through.
  6. I work against the grain first, then with. This gets a little oil inside the grain. The beauty of a foam brush is you can sweep, you can dab, or for spots you really want to work oil into, you can place the brush flat against the spot and press it in with your finger.
  7. Sometimes sweeping away from the direction the brush is tilted can help spread the oil better, especially when you're spreading around small amounts.
  8. Really can't stress enough how little oil you actually need.
  9. As you rotate the speaker, be careful of secondary transfer to the speakers and rubber. YOU DO NOT WANT OIL ON THE WOOFER RUBBER SURRPOUND.
  10. Once one speaker is done you can lay is gently on the pegs to dry when you work on the other.
Ok, your speakers are re-oiled and looking sharp. About 20 minutes has elapsed, and you can start removing.
  1. Fold a paper towel in half and half again. Wipe away all excess oil. There shouldn't be much excess anyway.
  2. Spend about as much time per side as you spent applying the oil. You're not just taking off the excess, but also doing the final working of the oil into the wood.
  3. With a spot of the paper towel that has some oil, but which isn't saturated with it, press against the wood and buff just a little.
  4. Again, be mindful of the front and the rubber.
If you are lucky enough to have an original 40-2039 with the walnut veneered baffle, then once the above is done and all sides of both speakers have had oil applied and been wiped dry, then:
  1. Get about 10 cotton swabs ready
  2. Lay your speakers on their backs on clean paper towel.
  3. Fold a paper towel tightly up and hold it against the top of the oil bottle and upend to saturate a circle of it with oil, then set it aside. This is what you'll use to apply oil to the head of the cotton swab.
  4. Restart your 20 minute timer or stopwatch.
  5. Press a cotton swap against the saturated spot on the paper towel and roll it a bit.
  6. Use that to carefully oil the baffle veneer. You can press the oil into the edge corners this way, and even work a swab in between the two speakers carefully.
  7. Off-brand swabs are a little harder and reatain their shape better, but do take a little longer because they don't spread the oil quite as far. Sort of like coloring with a sharp pencil crayon rather than a dull crayon. Takes longer, but you have tighter control.
  8. BE VERY MINDFUL OF THE SPEAKER RUBBER
  9. ALSO BE MINDFUL THAT WITH THESE CHEAPER SWABS THE STICK OF THE SWAB CAN ACTUALLY DENT THE WOOD SO DON'T PRESS TOO HARD "POINT" ON. If you are pressing hard to get into a corner, press the side of the swab.
  10. It probably won't look really even at this point, but that's ok, when you wipe it off it will.
  11. Get all the cracks and corners and work around the pegs.
  12. Rinse and repeat for the other speaker.
After your 20 minute timer has elapsed, then you can start to use a folded clean paper towel to pull off the excess oil and make it look nice and even.

Final Results:

Front1_PostOil.jpgTop1_PostOil.jpg
LeftSide1_PostOil.jpgRightSide1_PostOil.jpg

On the much more battered bottom panel I have before and after:

Bottom1_Pre.jpgBottom1_PostOil.jpg

The dents on the bottom end up with a slightly darker "distressed" look that I personally find quite attractive. The rest of the wear spots are nowhere to be seen.

There is overall a slightly more gold tone with the boiled linseed oil, and I have seen some factory Minimus 7's look more yellow-brown than this.

Overall this is a very quick and relatively painless way of bringing back the wow in even some very worn wooden speakers.
 
Great job! Those look SO much better now. I have a pair of the white ones on my desktop here at work, but didn't know there were different versions of the walnut ones.
 
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