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Just anther MFW-15 Sealed build (piano black finish)

post #1 of 24
Thread Starter 
Finally up to assembly on 2x MFW-15 sealed boxes. I went with 3.0 cu.ft. per:
Quote:
Originally Posted by robotbunny 
Panels: Volume: 3.373 ft^3
2X 19.25x19.25 - Front baffle and rear of box.
1X 19.25x19.25 - Double baffle
2X 19.25x18.5 - Top and Bottom
2X 17.75x18.5 - Sides

Bracing: Bracing Volume: 164.25 in^3
2X 2x18.5 Top to Bottom
2X 2x18.5 Fron to Back
2X 2x17.75 Side to Side

Driver Volume: 0.2

Net Volume: 3.078 ft^3

For bracing the idea was to break the panels into thirds; no more than 1/3 of the width/depth not being braced:

IMG_1716.JPG
(I subsequently added another brace perpendicular to the ones at the bottom of the box)



I used 3/4" cabinet birch from my local building supply. It pretty much sucked. Not only was there a void the entire length of the sheet (visible when I ripped it 2' wide), the veneer bubbled on me:

IMG_1756.JPG
(I cut the bubble out with a razor knife and filled with 2-part epoxy)


Tim
post #2 of 24
Thread Starter 
The Piano Black Finish

I am by no means a finish expert. My finish came out pretty good. People that look at it say "wow, you did that yourself?!" I look at it and say "hmm, I still see some scratches, and the finish isn't even".

If you are just messing around (like I was) and are willing to accept a pretty nice, but not perfect, finish (like I was), this is definitely something anybody can do.

If you want a perfect finish it is going to take a long time. A real long time. And it probably still won't come out perfect (at least, not for a newcomer).

What you need:

-a smooth surface to begin with
-a decent, sandable base coat
-a spray gun
-lacquer
-sandpaper: 320, 600, 1000, 1500
-a buffer and buffing wheels
-rubbing compound (any medium or fine cut automotive type)
-hand or machine glaze (another automotive product)

You are not going to get a nice finish unless you spend time on the prep. You need to apply filler to all of the seams and sand it smooth. I tried Evercoat metal glaze, which worked okay, but dried way too fast. I went back to the West System. The entire box should be sanded with 320 grit. Run your fingers over it-- you shouldn't feel any bumps.

Now apply three coats of the base paint. I used General Finishes Black Undercoat. It's a high solids water-based paint that sands exceptionally smooth. You are not going to get a good finish with some cheap latex paint from the big box store. They simply don't sand well. I sanded smooth between each coat with 320 grit. I didn't go crazy, just tried to even it out. Don't spend a lot of time sanding, otherwise you're sanding off most of what you just put on. If you're not accustomed to your random orbit sander, use a sanding block. Don't use a sponge on flat areas (they're good for rounded corners) and certainly don't try sanding with just sandpaper.

Tim
Edited by Mr.Tim - 7/29/13 at 5:52pm
post #3 of 24
Thread Starter 
Base Coat is Done...

After you're happy with the base coat (and do make sure you're happy.. any blemish left now will show up to haunt you), it's time to shoot some lacquer.

Lacquer, not polyurethane. There are oil- and water-based lacquers. Oil-based lacquer stinks to high Heaven. If you're going to use that, it HAS to be done outside and you need a respirator. Lucky for me, General Finishes also has a water-based lacquer, which is what I used.

This is where you need to make a choice. If you are going for the full-on no-holds-barred finish you are going to spend a lot of time at this phase of the project. You should spray at least 9 coats of lacquer.

I wasn't going for perfection, so I sprayed 4 coats. Four full, wet coats. Wet to the point that I did develop a run or two. I applied first coat, let it dry for a bit and applied a second coat. I let those dry overnight. Then I sprayed two more full wet coats.

This is what I ended up with:

IMG_1759.JPG

Tim
post #4 of 24
Thread Starter 
Lacquer is Sprayed...

Here's where you find out how much you screwed up in the first few phases of the project.

The worst thing you can do now is not wait long enough for the lacquer to dry. This is not an overnight event. I let it dry 1 week.

Start sanding with 600 grit:

IMG_1769.JPG

This is when you can see just how uneven your finish is. I used a cheap HVLP and put it on thick, so it's pretty uneven. If you have a nice 4-stage turbine and plenty of time to put on multiple thin coats, it probably won't be this bad.

All the dark shiny black spots are the lows.. the paper is knocking off the highs (which are now gray).

Here is is after the the first pass was completed and I'm starting the second pass:

IMG_1771.JPG

There are still a few lows (intermittent shiny black dots). I'm okay with that. If you are going for perfection.. keep sanding until there are no more shiny spots (and pray you put on enough finish.. otherwise you are gonna burn through the lacquer).

Once you have all the sides sanded smooth with 600, go over them with 1000 (or 1200, whatever you can get).

I should add that you are going to go through a lot of sandpaper. I went through 5 discs per box. Maybe if you have higher quality (or a screen setup), you can get away with fewer. Paper is pretty cheap anyway. You shouldn't have squiggalies (technical term) like you see in the photo above. That from the lacquer loading up on the disc (you will will little dots on the disc)

Tim
Edited by Mr.Tim - 7/28/13 at 1:38pm
post #5 of 24
Thread Starter 
Sanding is Done...

Actually, it's not. Now you need to get out the sanding block and 1500 wet sandpaper. I use a spray bottle with water and a little bit of dishwasher detergent to lubricate.

The trick here is to sand back-and-forth in a single direction. Don't go in circles. Don't go in multiple directions.

By going in a single direction, you can see if you got all the marks out from the sandpaper. If you see marks perpendicular to the way you're sanding... Keep sanding.

IMG_1776.JPG

Tim
Edited by Mr.Tim - 7/28/13 at 1:41pm
post #6 of 24
Thread Starter 
Time for Buffing

So here it is. The moment you've been waiting for. Instant gratification. Or more likely, the instant revelation of everything you screwed up along the way.

Time to break out the buffing wheel.

Apply a small amount of automotive rubbing compound to your wheel. How much? About this much:



Now start compounding. Apply pressure during the first pass. Not a lot of pressure, but some steady down pressure. Then apply light pressure with a second pass. Then a third pass with only the weight of the buffer. Last, apply a gentle upward pressure so the wheel is just kissing the surface:


"Gently now, you just wanna kiss the [speaker], just a little peck, a smooch like you're kissing your sister. "


Wipe away the little remaining compound and you have this:



At first you pat yourself on the back and think, "That's right! Who's the man? WHO'S THE MAN??"

Then you look closer and say "wow look at those tiny scratches I didn't get sanded out", or "wow you can see how uneven the base coat is" or the ever popular "crap, I f--kin burned through the finish there. And there.. Jeez and there"

But we're not done yet. If your OCD kicks in feel free to break out the sandpaper. Ya freak.

The rest of us move on the the glaze. Glaze will remove the small swirl marks from the compound and make the surface super smooth. I didn't link a pic because it looks the same to the camera. In reality, it wanted to slide off the bench when I was glazing. Definitely smooth.

Tim
Edited by Mr.Tim - 7/29/13 at 2:28pm
post #7 of 24
Impressive, sir! Very impressive! My hat's off to you for taking the time to do that. It looks amazing! I believe after all that effort, I'd have to set that out front in the middle of my theater with a big "Do Not Touch" sign on it smile.gif
post #8 of 24
Quote:
Originally Posted by Mr.Tim View Post

Then you look closer and say "wow look at those tiny scratches I didn't get sanded out", or "wow you can see how uneven the base coat is" or the ever popular "crap, I f--kin burned through the finish there. And there.. Jeez and there"
The key is not to look closely. It's amazing how hard it is to get a perfect painted finish on anything. Factory new car paint is as perfect as it gets - and you have to accept orange peel in it. Even the best repaint jobs will have dust or bubbles or over-spray in them somewhere (usually all three). I've never inspected a Steinway at the level that I inspect car paint, but I bet even though the Steinway is better than probably any aftermarket auto paint, it still can't be entirely perfect.

If it shines like Tim's does and it looks even from five feet away, it's as perfect as it needs to be. smile.gif
post #9 of 24
Thread Starter 
Quote:
Originally Posted by HopefulFred View Post

If it shines like Tim's does and it looks even from five feet away, it's as perfect as it needs to be. smile.gif

I agree, but it's good to know that up front. I'd hate for somebody to have high expectations of perfection only to be let down in the end.

Oh, and you're not done until you ding it installing the driver. Dangit.

Tim
post #10 of 24
Bravo Mr.Tim! Thanks for posting this!
post #11 of 24
That looks awesome man! Nice work.....
post #12 of 24
Thread Starter 
Quote:
Originally Posted by Martycool007 View Post

Bravo Mr.Tim! Thanks for posting this!

Quote:
Originally Posted by NicksHitachi View Post

That looks awesome man! Nice work.....

Thanks a lot, guys. It really wasn't difficult, but it is definitely time consuming.

I just got done stuffing and assembling them. If it's not a bazillion degrees outside after work, I'll get them measured (not that we don't have this config measured a dozen times already).

Tim
post #13 of 24
Nice!

Those did turn out nice smile.gif
post #14 of 24
Thread Starter 
Quote:
Originally Posted by powerlifter405 View Post

Nice!

Those did turn out nice smile.gif

Thank you! Again, they are not perfect when you get up close, but to the average person they'll look just fine smile.gif

I measured both of them, here they are powered by a NU1000:

mfw-15.png

Strange how one of them is up about 5dB at 10Hz, they are built identically the same. I did 3 sweeps and averaged for each sub.

Tim
post #15 of 24
So will these 3cuft sealed enclosures with the MFW-15 go lower and have as much or more output than a stock MFW-15 in its original AV123 cabinet? I have a MFW-15 in its stock cabinet powered by an EP4k, but am considering pulling the driver and building a different enclosure to play around. With.
post #16 of 24
Thread Starter 
Quote:
Originally Posted by Martycool007 View Post

So will these 3cuft sealed enclosures with the MFW-15 go lower and have as much or more output than a stock MFW-15 in its original AV123 cabinet? I have a MFW-15 in its stock cabinet powered by an EP4k, but am considering pulling the driver and building a different enclosure to play around. With.

I'm not familiar with the AV123 cabinet, but I assume it's ported. I'm sure there is a graph of the performance somewhere... It should be an easy comparison. Keep in mind this is 300w and they can take a lot more.

Tim
post #17 of 24
The
Quote:
Originally Posted by Martycool007 View Post

So will these 3cuft sealed enclosures with the MFW-15 go lower and have as much or more output than a stock MFW-15 in its original AV123 cabinet? I have a MFW-15 in its stock cabinet powered by an EP4k, but am considering pulling the driver and building a different enclosure to play around. With.

The ported will have at least a 3db advantage from 20-30ish Hz and the would track pretty close after on upwards with maybe a db or two edge to the ported stock MFW.

The sealed might have a db or two on the ported at 10hz but would still be prob at F6-F8 outside or aneholic.

So basically they would track:

10-20- Sealed only by a db maybe two
20-30- Ported by ~3db(alot)
30-80- Ported but only by a db or two.

Clear as Mud?
post #18 of 24
Thanks Nicks! I guess that I will just continue to use this MFW-15 in its stock cabinet. I don't want to loose anything between 20hz and 30hz. I wish that I was good enough with woodworking so that I could purchase some Dayton DVC 15's and pair them with some AV123 stock MFW-15 clone cabinets, but unfortunately that is slightly over my head at the moment.
post #19 of 24
I see that you were getting the same issue as I... After polishing, the surface comes out super smooth but the gloss seems to have some haziness under the surface... Not sure how to get around that.
post #20 of 24
Thread Starter 
Quote:
Originally Posted by Jon S View Post

I see that you were getting the same issue as I... After polishing, the surface comes out super smooth but the gloss seems to have some haziness under the surface... Not sure how to get around that.

I'll have to look at them again, they're behind the seats in my theater ATM. I'm not sure it's hazy.. I notice the imperfections in the base coat.

I would say the primary suspects for an imperfect finish are improper prep and cheap equipment. Both of which I have smile.gif

Check out this thread. He definitely seems to know what he's doing. Of course, it's an exponential amount of work. I was willing to sacrifice the finish to save time.

Tim
post #21 of 24
Piano Finish- Difficulty Level [Extreme]

They look good to me, ill bet its not that bad in theater lighting!

If the Piano doesnt work you can always de-wax and clear coat em for a faux piano look. However, they looked ok to me.
post #22 of 24
Thread Starter 
Quote:
Originally Posted by NicksHitachi View Post

Piano Finish- Difficulty Level [Extreme]

They look good to me, ill bet its not that bad in theater lighting!

If the Piano doesnt work you can always de-wax and clear coat em for a faux piano look. However, they looked ok to me.

I looked again and I'm not sure the finish is hazy. I think it's an issue between the base coat and the lacquer. I can also see some itty bits suspended in the lacquer from my not tack ragging (just wiped it off with a towel).

Like Nick said.. looks good from where I sit.

Tim
post #23 of 24
Hey Tim.. Glad you took the time to share your project with us. Nice work and nice job in the way you brought it across.. looking good man.
post #24 of 24
Thread Starter 
Quote:
Originally Posted by steve nn View Post

Hey Tim.. Glad you took the time to share your project with us. Nice work and nice job in the way you brought it across.. looking good man.

Thank you. I wanted to explain how the average Joe could get a decent finish. Like many things, it's not complicated, but it does take some basic knowledge. I also went for the "good enough" finish versus the crazy perfectionist finish, which I hadn't really seen documented before.

DO any of you have insight into the +5dB at 10Hz one has over the other? Test bed was the same (simply unplugged one, moved the other into position and replugged). The cabinets are identical. Could the drivers vary that much, or did I miss something?

Tim
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