Saturday, March 4, 2017

DIY Auratone Mix Cube type speakers / monitors

I ordered a pair of paper cone woofers from MCM Electronics

5'' Full Range Monitor DriverBy MCM Audio Select (55-1595)MCM Part #55-1595


They were $9 each.  I saw that the Vas paramater was roughly similar to the size of my boxes, not perfect, but close enough to place a bet on it.  In the end, it worked out fine.

My oak-faced plywood came from Lowes.  I think it's 3/4" thick.

My dimensions are 7" x 7" x 7" except one of them came out about 1/4" less deep due to funky woodworking.  They sound close enough to be used as a pair, even though I would have rather them match exactly.

The speaker terminals on the back were from eBay.  They accept banana plugs or bare speaker wire.

Inside each speaker is some foam quilt batting from WalMart, commonly referred to as "polyfil" which is not the brand I found.  I stuffed quite a lot in there to try to get a little more artificial size out of them, I think that's how that works.

My first box used 6 wood screws per side.  But the second box I used only 4 screws per side and I like that design a lot better, it looks much cleaner.  Also my "countersink" holes were a lot smaller on the second box, which looks sharper.

I intended to fill the holes with dowels but in the end I just used some Wood Putty for the first time.  It's not pretty on the big holes, but looks OK on the smaller ones.  I also used it to fill in gaps in my funky woodworking.  Probably some wood filler would have been better, since it would have dried hard.  Wood Putty never dries, it's just like play dough or something.  If I had to do it again, I'd probably use wood filler stained to match the finish.

A few mistakes along the way were using files after the cabinet had been screwed together which lead to scratches.  Also the chisel idea was a disaster, do NOT use chisels on plywood, it just shreds big holes out of it.  My best method was to unscrew the side needing work and use a shinto to carve it down nearly flush.  All the flush sanding was done with an orbital sander using 60 grit sandpaper.  That gave some pretty clean edges.

Once the cabinets were screwed and carved and sanded flush, I took them apart with an impact driver and applied wood glue, then screwed them back together.

Then I sanded 120, 220, 320, and 400.  Then I cleaned with a blow can and some 99% rubbing alcohol.  Then I hand rubbed a stain.  I used some wood dye mixed with 99% alcohol, mixing amber and dark brown stains.

Let the stain dry and set for 24 hours.  Next day rubbed in some Tung Oil finish, 3 coats or so.

Let Tung Oil dry overnight, rough up with 0000 steel wool, clean, then apply another layer of tung oil.  Once again 3 layers or so.  Just keep rubbing on new layers until it looks glossy and wet after sitting for a few minutes.  The first couple of rubs will soak right in.  Once again, let dry overnight.

Then 0000 steel wool for the final matte/semi-gloss finish.  Then final assembly.  I used a very heavy gauge wire inside the speakers to connect the speaker terminals to the speaker.  I couldn't find my spade connectors so I just soldered everything.

I used a hole cutter for the back hole, it was slightly too large, in retrospect, but worked out OK.

The front hole was cut by hand and was a very good size for the speaker.  I just traced a circle, drilled a bunch of holes, and cut out the rest with a jab saw.  Then cleaned up the cut with files and rasps and such.

I had to use clamps to position the sides when drilling the initial screw holes.

The second speaker came out a lot better, and a lot faster than the first.  You will learn very quickly with a project like this what works and what doesn't.

In the end, they sound great!  And they look the business.  I will be adding this to my stack of studio monitors to complete the array.  They sound similar to the Avantone I used to own, although slightly different of course, due to the different driver.  They will serve the exact same function.  I even enjoyed listening to music on them.  It sort of reminds me of listening inside a car.  Glad to have captured something like that for my mix position.  All you get is midrange, but since there is no crossover, and no bass port, the "information" is very clear and reliable.  MCM claims a frequency response of 80 Hz to 15 KHz, but you can clearly hear that there is a big hump in the mids, which is exactly the point of a cube speaker like this.  I think it will be really good for focusing on snare drum, hi hat, and ride cymbal tones, as well as vocal/piano/drum/guitar balances, etc.

The main asset of these speakers is not having to pay $350 for a brand name.  Also I prefer the roughshod wooden appearance, and I will never have to get rid of these.  They can be something I am proud to own.

I'm sure someone with more woodworking experience, and big machines, can get a better result at a much quicker speed.  This was my first cabinet building experience, and I used only hand tools, so it did go on for quite some time.  By the time I got to the second one, though, the speed picked up and the work got a lot cleaner, so I am glad to have had the experience.  And I'm glad to have the bits and bobs out of my work area in the garage!  2017 is going to be about finishing projects and tying everything together for me.  I've got so much heat on the back burner right now.

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