MFW-15 Dual Opposed Build - AVS Forum
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post #1 of 319 Old 03-04-2011, 04:00 PM - Thread Starter
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Well I finally got my build completed. I was looking at replacing my THT's and SVS PB12-nsd with some sealed subs. I wanted to try to get to 10hz with some db's.

I was first looking at the Tempest X2's or some AV15H's, after posting some ideas on here I was getting recommendations for the FI drivers, Mach 5's, and the Dayton 390HF's. So I got to modeling, I was starting to like the Daytons for the price (1000$ budget for the drivers) I wanted to build at least 4 cabs so I could spread them around if I needed to.

One day I got on here and I had a PM from coctostan telling me to take a look at the MFW-15 drivers in a dual opposed sealed setup. So I got to modeling them, 8 looked real good in 4 dual opposed cabs at right around 6 cubes each. 6 cubes was a little small and gave me a Q of .82 but it did help control excursion (i have an EP 4000), and I figured I could stuff the cabs to give it a boost in apperent volume.

After I figured out this is what I wanted to try I ordered 10 drivers from Danny at GR research (I only needed 8 but what the heck), shipping took about 4 days to Ohio. Bought me 6 sheets of 3/4 aruaco ply, I should only need 5, but I had to borrow the truck, so I picked up 1 extra sheet (never did need it, I may use it for one of the other drivers).

So I started building:
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post #2 of 319 Old 03-04-2011, 04:01 PM - Thread Starter
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the outside dimensions for each cab are 23.5 x 23.5 x 26.5, with double baffles, and 2 window braces. I added 6lbs of polyfil to each cab, which should have gave me around a 25% increase in cabinet volume. The build was pretty straight forward and everything went together well, I used PL premium and an air nailer for everything but the baffles which I used regular wood glue and screwed them together and let them dry over night.
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post #3 of 319 Old 03-04-2011, 04:01 PM - Thread Starter
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post #4 of 319 Old 03-04-2011, 04:01 PM - Thread Starter
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post #5 of 319 Old 03-04-2011, 04:02 PM - Thread Starter
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post #6 of 319 Old 03-04-2011, 04:15 PM - Thread Starter
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Having trouble posting pics in the reserved spots.

Drivers arrived:
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post #7 of 319 Old 03-04-2011, 04:18 PM - Thread Starter
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More build Pics:
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post #8 of 319 Old 03-04-2011, 04:19 PM
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Nice work man!

This is really a dual-dual opposed build.

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post #9 of 319 Old 03-04-2011, 04:21 PM
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How did the sub boxes get shipped? Were they double boxed? Or did he tape 2 of them together? Just curious.
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post #10 of 319 Old 03-04-2011, 04:22 PM - Thread Starter
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All most completed:
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post #11 of 319 Old 03-04-2011, 04:26 PM - Thread Starter
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Quote:
Originally Posted by jpmst3 View Post
Nice work man!

This is really a dual-dual opposed build.
Yeah I guess it is

Quote:
Originally Posted by Erich H View Post
How did the sub boxes get shipped? Were they double boxed? Or did he tape 2 of them together? Just curious.
They were not double boxed, they probably should have been, Some of the foam gaskets on the front were slid from there normal spots and rubbing the surrounds. But this most likely wasn't from shipping just the way they are packed with only foam on the motor side. I just removed the foam and used a marker to color the paper material black, you cant tell the difference.

Yeah they were 2 boxes taped together.
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post #12 of 319 Old 03-04-2011, 04:33 PM - Thread Starter
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I use 1/2" roundover on the top and the front(s), I think it looks pretty good. I am thinking of painting them with Duratex, I used the truck bed liner on my THT's, while it looks good, the bed liner is just a little to rough for my tastes.
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post #13 of 319 Old 03-04-2011, 04:41 PM - Thread Starter
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Now for some measurements:

I have both a DCX and the BFD. I used a LP12db slope filter (10db boost)centered at 20 to boost the low end and used the BFD to EQ and apply the cuts needed to bring the 80hz end back down to reasonable levels. I watched WOTW with it at my normal listening volume and didn't hear any crazy sounds from the drivers. Here is my current EQ'd graph, no smoothing at listening position.

Edit: I messed up on my rew graph, forgot to reload my ecm8000 calibration file........
I will post a new graph tomorrow, the good thing is I shouldn't need to boost as much, embarrassing.........
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post #14 of 319 Old 03-04-2011, 05:08 PM
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Not bad at all!!

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post #15 of 319 Old 03-04-2011, 06:06 PM
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Wow seems as of lately there are quite a few people replacing their THT's. And I just built a dual opposed sealed Fi SSD sub. Small world.

Nice build.!!
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post #16 of 319 Old 03-04-2011, 06:18 PM
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That is a great deal on the drivers. The FR looks great too.

Do you have 2 EP4000 or one?

Also, what kind of SPL peaks are you getting from the LP?

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post #17 of 319 Old 03-04-2011, 06:31 PM
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Those measurements look great. I'm glad I was able to pick up so many of them for the next group buy. Should be awesome to see what people build with these cheaper drivers. Lilmike is working with them on a neat project for the masses too.
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post #18 of 319 Old 03-04-2011, 07:04 PM - Thread Starter
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WMD, I am only using 1 ep4000, during wotw I hit 120 a couple times. I am eqing out a couple of 10db peaks at 40 and 70 hz, I had the same modes with my other subs also. I havent pushed them to their limit yet, dont want to bust anything yet.

Erich,
They are one heck of a deal, I cant wait to see what lilmike comes up with he is a hornresp master. I do have 2 drivers left over.......
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post #19 of 319 Old 03-04-2011, 07:08 PM - Thread Starter
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Quote:
Originally Posted by chrapladm View Post

Wow seems as of lately there are quite a few people replacing their THT's. And I just built a dual opposed sealed Fi SSD sub. Small world.

Nice build.!!

Thanks, the thts are great also, I really just wanted to try to get lower. More or less the low cost drivers gave me an avenue to try it out and it worked!
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post #20 of 319 Old 03-04-2011, 08:01 PM
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How would 16 of those compare to 8 MalX's? with the same power (2 Marathon 5050's) and same size boxes (8 cubic feet for each MalX and 4 cubic feet for each MFW15)?

War Eagle!
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post #21 of 319 Old 03-05-2011, 02:58 AM
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I like your boxes. They don't look like they are six cu. ft. I should have took the extra steps to get the Aurucoply instead of the 3/4 mdf that now cost $31 a sheet(damn). Anyway I like your room and the new additions to it.
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post #22 of 319 Old 03-05-2011, 03:27 AM
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I never saw the backside of those cabinets? There is a woofer there isn't there?
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post #23 of 319 Old 03-05-2011, 06:39 AM
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Quote:
Originally Posted by auburnu008 View Post

How would 16 of those compare to 8 MalX's? with the same power (2 Marathon 5050's) and same size boxes (8 cubic feet for each MalX and 4 cubic feet for each MFW15)?

8 MalX 18s would win but it would be triple the price.

I thought of (4) MalX 18s but went with (8) Dayton HFs instead. The drivers were alot cheaper and didn't need a ton of power. I saved at least $1,500.

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post #24 of 319 Old 03-05-2011, 08:11 AM
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Very cool build!

Did you model these in Winisd? I can't figure out how to do dual-opposed.

Jon
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post #25 of 319 Old 03-05-2011, 08:31 AM
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Quote:
Originally Posted by jwh7399 View Post

Very cool build!

Did you model these in Winisd? I can't figure out how to do dual-opposed.

Jon

It is just 2 drivers in one sealed box. It models the same as a "normal" dual driver box.

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post #26 of 319 Old 03-05-2011, 08:48 AM
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Ahh, thanks WMD!

Jon
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post #27 of 319 Old 03-05-2011, 09:38 AM - Thread Starter
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Quote:
Originally Posted by louisdamani View Post

I like your boxes. They don't look like they are six cu. ft. I should have took the extra steps to get the Aurucoply instead of the 3/4 mdf that now cost $31 a sheet(damn). Anyway I like your room and the new additions to it.

I was going to go with MDF at first, glad I didnt the dust from the plywood was bad enough.

Quote:
Originally Posted by chrapladm View Post

I never saw the backside of those cabinets? There is a woofer there isn't there?

I can assure you there is another woofer back there, hard to take pictures of both sides ar once
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post #28 of 319 Old 03-05-2011, 10:14 AM
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Awesome build Wembley. I'm glad it is working out well. Do you think you could do REW distortion measurements similar to NotNyt's? I want to hear some subjective comments too.

Quote:
Originally Posted by auburnu008 View Post

How would 16 of those compare to 8 MalX's? with the same power (2 Marathon 5050's) and same size boxes (8 cubic feet for each MalX and 4 cubic feet for each MFW15)?

If you only account for overall displacement, the MX18s would win...but it isn't that simple. I'd take more surface area vs more excursion. The 16 15's will be moving less for the same amount of SPL down low. In my experience this results in a more effortless sound and better SQ. That's not to say the MX18s would sound like crap though.

The other issue is that a single EP4000 will push the MFW-15s to their limit. In the same size boxes (6 cu ft per MX18) that single EP4000 would give you about the same output if they are EQ'd to the same Q and Fc. The MX18 would pass the MFW-15's by with more power...but that means you need more circuits and more amps.

The reality is that neither setup will break a sweat at any "normal" listening level...like below 110-120db and likely all the way down to 10hz depending on room size.

A bunch of MFW-15s sealed are probably the most economical way to get down to 10hz and below.

The reality is that neither system
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post #29 of 319 Old 03-05-2011, 10:43 AM
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"I'd take more surface area vs more excursion."

wisdom in that comment.

...

nice build wembley.

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post #30 of 319 Old 03-05-2011, 11:00 AM - Thread Starter
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Thanks Coctostan, you are the one that turned me on to these and I am glad you did. As for THD measurements ask and you shall receive.

I have also attached a correct REW graph. I am only using 3db of boost on the low end to get these measurements.

Quote:
Originally Posted by auburnu008
How would 16 of those compare to 8 MalX's? with the same power (2 Marathon 5050's) and same size boxes (8 cubic feet for each MalX and 4 cubic feet for each MFW15)?

The MFW-15s are only rated for 225 watts so one EP 4000 will and do power 8 easily
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