Quad MFW-15 Dual Opposed - AVS Forum
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post #1 of 17 Old 05-18-2012, 09:24 AM - Thread Starter
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On July 14, 2010, I started a thread at the Seaton Sound forum about building a sub using MFW-15 drivers. At that time Danny or Erich hadn't yet obtained any drivers. I had purchased a Turbo kit for my MFW-15 cabinets and wanted a project for my left over MFW-15 drivers. Over two years later, I finally had some DIY dual opposed subs with the MFW-15 drivers.

In October 2011, I helped HuskerOmaha host a subwoofer GTG. In preparation for the GTG we had a lot of ideas and decided to build two LilMike F20's and four MFW-15 dual opposed subs. We also hoped to have a ported MFW-15, but I didn't find another driver for my cabinet. We want to compare alignments using the same driver. As the things progressed, we had more subs become involved in the GTG and our comparison never panned out. He ended up selling the F20's, I got rid of the Cherry Diamond MFW-15 cabinet, yet I still have the dual opposed MFW-15's.

I had a coworker build the cabinets since neither HuskerOmaha or I had the time or tools at the time to build them. He built all of them on a Saturday/Sunday morning and delivered them Sunday afternoon to HuskerOmaha's house.

The dual opposed subs are 22 1/2" wide x 22 1/2" tall x 24" long. I bought 3/4" 13 ply baltic birch for the outside of the cabinets ($75 a sheet) and 3/4" 13 ply hardwood birch ply ($32 a sheet) for the inside braces. It took 6 sheets total of plywood for all the subs. I entered all my piece sizes into Cutlist and it generated my cutlist for each sheet of plywood. I have attached the cutlist below.

The cabinets were puttied, sanded, primed, and painted black. The black paint hasn't held up well and was easily scuffed. I am redoing the finished look of the cabinets. I just bought a router and am rounding the corners of the cabinets and painting with Duratex. I am also adding feet. I hope to get them finished tomorrow.

The cabinets are 5 cubic ft interior volume and I also stuffed them with Acousti-Stuf Polyfill from Parts Express. The backside of the driver holes and the bracing holes are all rounded over. It cost $75 cabinet to get them built. The total cost for each sub including drivers, wood, screws, paint, stuffing, binding posts was about $385.





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post #2 of 17 Old 05-18-2012, 11:07 AM
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DD,

They look very nice. Do you have any close mic measurements of these and what are you powering them with? Thanks.

James
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post #3 of 17 Old 05-18-2012, 12:38 PM
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What kind of paint did you use?
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post #4 of 17 Old 05-18-2012, 02:13 PM - Thread Starter
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Originally Posted by Mrkazador View Post

What kind of paint did you use?

They were primed with Zinsser B-I-N and painted with Pittsburgh Grand Distinction Ceramic Flat Enamel in Magic Black. I am repainting them with DuraTex.
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DD,

They look very nice. Do you have any close mic measurements of these and what are you powering them with? Thanks.

Thanks. I had a pair of these at the KC GTG back in January. They were powered at that time by a Seaton modified Dayton SA1000 that was on loan for the GTG. I am now running a pair of these in my living room and they are powered by a stock Dayton SA1000 amp. I also have two Face F1200TS amps that I will use to power all four subs for testing. I am building an IB system with 8 drivers this weekend in addition to two other sub projects so these subs aren't my permanent subs. I will be selling them when I am done with the testing I want to do regarding multiple subs and stacked subs.

Many have said how they like the sound of these subs without any EQ. I don't really think they sound all that great by themselves. They have an inductance hump that needs to be brought down and the bottom needs to be lifted. However, once EQ'd they sound very good. Here is a close mic chart comparing the raw response to the EQ'd response. I haven't taken any measurements from the listening position yet. I used REW to generate filters and JRiver Media Center to add the filters, Linkwitz Transform, and limiting. Once I measure the transfer response in the room I can dial in the correct lift. With the limiter set in JRiver, I can play a pair of these at reference level without the amp shutting down or bottoming out.

Source: HTPC with JRiver Media Center
Audio Device: Steinberg UR824 flat to 5 Hz
Microphone: iSEMcon EMM-7101-CHTB with custom calibration to 5Hz. It is down .26 dB at 5 Hz and really doesn't even need a calibration file.




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post #5 of 17 Old 05-18-2012, 02:26 PM - Thread Starter
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Earlier this week I started on rounding over the subs and prepping for Duratex. Below are some picture that show the bracing, new roundover, and tools. I quickly sanded the entire sub with 100 grit to help the Duratex adhere better. You can see the butt joints in the second picture. The Duratex should completely cover those so they aren't visible anymore.




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post #6 of 17 Old 05-18-2012, 09:02 PM
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Glad to see this project finally take off. I was excited to hear those at the Omaha gtg and its unfortunate we ran out of time/ the technical difficulties we had with them.
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post #7 of 17 Old 05-18-2012, 10:19 PM
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I remember my impressions of these subs at the KC Blind GTG. I simply LOVED them for music and I suspect that adding 2 more of them would have put them up there for movies as well.

I felt that they were very similar to the SubM for music. I was oh so close to putting 4 of these in my room with 2 Dayton SA1000's.

I really enjoyed what I heard from these subs. And then you find out what they cost and you like them a little more.
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post #8 of 17 Old 05-19-2012, 12:14 AM
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your waterfall looks nice. no nasties in there.

a single location or multiple locations?

Listen. It's All Good.
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post #9 of 17 Old 05-19-2012, 05:42 AM - Thread Starter
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Originally Posted by LTD02 View Post

your waterfall looks nice. no nasties in there.

a single location or multiple locations?

It is just from the close mic measurement. I scaled it the same as Ricci's at data-bass.com, but my dB level wasn't as high for the measurement so I may not be showing enough decay.
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post #10 of 17 Old 05-19-2012, 07:30 AM
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DD,

Thank you for the reply and information.

What I am wondering though is since you mention that you are-have put in a LT on this, why are you pulling down the natural rise in the 40-60HZ area. I would think that you would try to get your modified response to follow that rise, than have it stay flat past 60HZ.

I am probably not asking my question the best so I have attach a screen shot of what I did to my subs using a Bassis and hopefully that shows what I am referring to.

James
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post #11 of 17 Old 05-19-2012, 08:08 AM
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Great to see this moving along. You can get your paint cloths and solder the same method we did other things in the past since I'm gone.

Waterfalls are cool
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post #12 of 17 Old 05-19-2012, 08:21 AM
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Quote:
Originally Posted by desertdome View Post

It is just from the close mic measurement. I scaled it the same as Ricci's at data-bass.com, but my dB level wasn't as high for the measurement so I may not be showing enough decay.


I am just curious as to how you think these sealed versions compare to original ported, and, stock, AV123 MFW-15 subs?

I have been kicking around the idea of picking up some of the MFW-15 drivers to use in a project. I want to build something that goes down to at least 20hz, and, has plenty of output from 25hz on up. I really like that thump in the chest that comes from some of the mid bass. I already have a single, stock MFW-15 subwoofer that I am using in my ht system. I am looking to build something that will sound better than the single and stock MFW-15 that I already have. Any suggestions?
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post #13 of 17 Old 05-19-2012, 08:38 AM - Thread Starter
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Quote:
Originally Posted by HuskerOmaha View Post

You can get your paint cloths and solder the same method we did other things in the past since I'm gone.

Are you still driving the white van and hanging out in the parking lot of Home Depot #3201?

Quote:


What I am wondering though is since you mention that you are-have put in a LT on this, why are you pulling down the natural rise in the 40-60HZ area. I would think that you would try to get your modified response to follow that rise, than have it stay flat past 60HZ.

I view it as an unnatural rise caused by high inductance. Mark Seaton likes to pull it down close mic and Bossobass does a notch filter at the listening position. They had some discussion at the end of the Ficar SSD18 Group Buy thread. If I don't pull down the hump and have the lift follow the rise, then the sub rolls off by 8 dB from 58 Hz to 100 Hz. Even with an 80 Hz crossover, the midbass doesn't sound as good in my opinion because of the reduced output in that range. By pulling down the hump, I get a flat frequency response extending to 175 Hz and the sub integrates with the mains better.
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post #14 of 17 Old 05-19-2012, 08:55 AM - Thread Starter
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Quote:
Originally Posted by Martycool007 View Post

I am just curious as to how you think these sealed versions compare to original ported, and, stock, AV123 MFW-15 subs?

I have been kicking around the idea of picking up some of the MFW-15 drivers to use in a project. I want to build something that goes down to at least 20hz, and, has plenty of output from 25hz on up. I really like that thump in the chest that comes from some of the mid bass. I already have a single, stock MFW-15 subwoofer that I am using in my ht system. I am looking to build something that will sound better than the single and stock MFW-15 that I already have. Any suggestions?

I've had the following in my room with the MFW-15 drivers or cabinet: Single MFW-15, dual MFW-15, single MFW-15 Turbo (Acoustic Elegance driver with MFW-15 cabinet), dual MFW-15 Turbos, quad MFW-15 driver dual opposed sealed. I also took an MFW-15 cabinet and put a Dayton RSS390HO-4 driver in it and powered it with a Dayton SA1000 amp. I blocked of the old amp hole with break metal. However, you can just remove the amp and caulk the hole that the speaker wires go through. This sub went to a friend.

If you want to go the cheapest route, then get the Dayton driver and amp and use your existing cabinet. I can give you the settings for the amp that smooth the driver's response in the cabinet. Although the driver has about the same listed X-Max, this driver seem much louder and has better sound quality than the stock MFW-15 driver.

Sandbagger and Mark Seaton designed the Turbo kit. They are currently working on sourcing a different driver and are close to a solution. You can read more in this [url=http://www.seaton-sound-forum.com/post/MFW-TURBO-Upgrade-3884379[/url]. I really liked my dual Turbo's. Two of them had the same output as four of the stock MFW-15 subs. They also sounded extremely good.

The MFW-15 dual opposed needs at least four drivers/two cabinets to have enough output. I don't think you would be satisfied with just two. Initially I didn't like them as much as the Turbo's, but with EQ I have greatly improved their sound quality. They sound different and I like the difference, but it is hard to tell exactly where that difference is coming from. I'm not sure if it is because they extend deeper of if it is because of the ported vs sealed or if something else it at play.
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post #15 of 17 Old 05-19-2012, 10:59 AM
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Quote:
Originally Posted by desertdome View Post

Even with an 80 Hz crossover, the midbass doesn't sound as good in my opinion because of the reduced output in that range. By pulling down the hump, I get a flat frequency response extending to 175 Hz and the sub integrates with the mains better.

When you say it doesn't sound as good can you clarify this? Do you think it's because it lacks the 'punch/feel' of mid/upper bass frequency or do you think it literally alters the sound? I would be curious to see differences in distortion graphs, waterfalls, etc with and without bringing the midbass down.
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post #16 of 17 Old 05-19-2012, 01:49 PM
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Quote:
Originally Posted by tgse3 View Post

When you say it doesn't sound as good can you clarify this? Do you think it's because it lacks the 'punch/feel' of mid/upper bass frequency or do you think it literally alters the sound? I would be curious to see differences in distortion graphs, waterfalls, etc with and without bringing the midbass down.

EQ will never change the maximum SPL or distortion at a given frequency. It does affect the relative balance vs. other frequencies. One very important detail to remember is that when many say they "matched the frequency response", it generally is not as precisely matched as you might think, and many forget about the out-of-band range.

In the end the biggest difference between various EQ methods or approaches lies in the range above and below what was smoothed. In this specific case, it's the difference of starting with a smooth response out to nearly 200Hz and a smooth fall off into the 2nd order roll off vs. a sharper corner at the top end with an earlier and faster roll off, and possibly a different shape to the low end roll off. While little blips in the response are not very audible unless music or a soundtrack highlights it directly, 1 octave wide variations of 0.5-4.0dB can be readily audible as tonal or quality changes.

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post #17 of 17 Old 05-20-2012, 06:49 AM
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Nice job on these, I have 4 of these myself, my cabs are slighty larger than yours at 6ft3. I really enjoy mine everytime I listen to them, esp when I think of the money I have in them.

Wem
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