Cinema F-20 Subwoofer Build - DONE!

[BigJim_inFLA]

In an effort to upgrade the low end of my HT on a budget I grabbed up a few of the last remaining MFW-15 sub drivers. Over on AVS, Lilmike designed a front loaded horn enclosure for this driver and I thought I would try a few. This design can produce high SPL from 20hz on up with relatively little power. I will be starting off with two, powered by one channel of my EP2500, and if results are as expected, I will be adding two more.

The enclosures use some big panels so I had to improvise a panel saw. A circular saw and an 8 foot saw board works like a charm.



After cutting the side panel, I lay out the folds of the horn and drill pilot holes to locate the inner panels.



The driver is mounted in a chamber in the middle of the horn so an access panel needs to be cut on one of the side panels.



Access panel cut.



Routing the 14" hole in the baffle.

[BigJim_inFLA]

The MFW-15 and its new home. These were a bargain at just under 80 bucks.



Installing T-nuts. A little bit of JB Weld to hold them and then press them in with a C clamp.



T-nuts in. The access panel with holes for SpeakOn connectors.



One for power from the amp, one for connection to the other sub. These subs will be run in series for an 8 ohm load. That will keep the power down to right around the drivers rated 225W.



Some more JB Weld to seal the inside of the connectors, don't want any leaks.

[---k---]

$80 8O Great value. Looks like a great project. I built my brother a Tuba HT sub w/ a Dayton DVC and a 240w plate amp. Based on that, I can't imagine needing 2 of these, yet alone 4! 8O

Keep us updated.

[BigJim_inFLA]

Assembly is pretty easy with PL adhesive and drywall screws. Start with the baffle and box for the driver.



And here is the completed horn awaiting the last side panel.



The driver is a tight fit through the access panel.



High output from a cheap driver at low power comes at a price, this thing is big!

[BigJim_inFLA]

Project finished! Here is a pic of the first one complete.



Here is my helper showing off the two after some flat black paint.



Tomorrow I move out the sonosub and replace it with these. I'll let you know how they sound.

[---k---]

Holy cow! Those are huge! 8O

That is crazy. Looking forward to hearing your thoughts on the differences between the two designs.

[BigJim_inFLA]

These are very impressive! They play louder and more effortlessly than the sonosub. The sono was tuned a bit lower, 15 Hz vs. 20 Hz, but I don't seem to be missing much. I am very happy with these, and they only use half the power I was pumping into the sono.

[---k---]

Yeah, that is the power of the horn.

Were you comparing 2 horns to 1 sonosub or what? Just curious.

I avoided posting thoughts on my brother THT versus my ported sub, just because it near impossible to do a correct A vs B listening of subs with reasonable effort and time. There are too many fan boys out there that will jump all over you if you don't jump through all the hoops and do the test perfectly. I don't have time to jump through hoops or to listen to fan boys. I listened to both, and my impression was that the THT had a lot more output capability, used a lot less amp, and had more output in that chest thumping range - the response seemed less flat and needing more EQ to get flat. But, compared to my ported sub, I noticed the lack of sub ~25hz range. There might have been more bang, but less of that subtle rumble - like the cars in Cars going around the track. I also preferred the sound quality of the ported sub. Bass seemed to have a more distinct start and stop - it was that elusive tightness. The THT was definitely a worthy sub. It came in less than $500 for driver, amp and wood. I was comparing it to probably $1200 comparable (though the price for the RL-p15 was MUCH less when I bought them). I think it would be a fun sub for most HT enthusiast. Audiophiles might want to look elsewhere (though they wouldn't like my dual ported either.) I could be very happy with just one THT in my family room. Those were just my opinions for causal listening...

[mackintire]

Still craving an "Easy Button Max" review for comparison.

[BigJim_inFLA]

Yeah, that is the power of the horn.

Were you comparing 2 horns to 1 sonosub or what? Just curious.

Two horns to one sono. The horns are a bit underpowered from what I've read. The driver is evidently very conservatively rated at 225 watts. I'm running 2 in series off one channel of my EP2500. These have been tested in other's f20s with about 300 watts and haven't had a problem.

I'm not sure what the THT is tuned to , but these are tuned to 20Hz and have great output down to that 20Hz. Output drops off quite steeply below 20Hz and distortion becomes very noticeable.

I don't notice the sound quality issue you mentioned. I have to tell you though, that these only cover 20-60Hz. I also run my mains full range, the bass bins are dual sealed RSS315's so that may be where I get the "tightness" you speak of. I may try running my NatP's without the bass bins and cross to the subs at 80Hz just to see what they sound like when asked to do a bit more.

I do agree these needed quite a bit more EQ to get flat. I still want to play with positioning some more, but there are only so many places you can put two huge boxes. I think placement is certainly the biggest drawback to this type of design.

[Edge540]

can these be compared to an IB set up at all? Im waffleing between 2-4 of these verses 4 18" IB3 for a theater set up.

[BigJim_inFLA]

can these be compared to an IB set up at all? Im waffleing between 2-4 of these verses 4 18" IB3 for a theater set up.

I've never heard an IB so I can't really compare, sorry. If you don't already have the drivers for these I'm not sure you'll be able to get them. There are other drivers that work well in this enclosure, but the cheap MFW's are all gone.

[dpc rep]

can these be compared to an IB set up at all? Im waffleing between 2-4 of these verses 4 18" IB3 for a theater set up.

I would think the extension of the IB would be far greater than that of the horns. The horns will most likely play louder, but at higher frequencies.

As for IB, mine will play 10 Hz at ridiculous levels ... I dont think many horns will do that 8)

[Edge540]

thanks for both your comments. I believe i will go with IB mostly because i am able to

[Txgrizzly]

These are very impressive! They play louder and more effortlessly than the sonosub. The sono was tuned a bit lower, 15 Hz vs. 20 Hz, but I don't seem to be missing much. I am very happy with these, and they only use half the power I was pumping into the sono.

Big Jim,
do the plans you have say which 15" drivers will work in this plan? i have Sonosub with a Dayton Audio RSS390HO-4 15" that i have been thinking of putting it into a THT

[BigJim_inFLA]

Big Jim,
do the plans you have say which 15" drivers will work in this plan? i have Sonosub with a Dayton Audio RSS390HO-4 15" that i have been thinking of putting it into a THT

Check out the thread at AVS, Lilmike's Cinema F20

He designed this for the MFW, which is a very close match to the Dayton DVC driver. Others in that thread have asked about which drivers could be used and Lilmike has been very helpful modeling different choices. I'm not sure if he modeled the RSS390HO or not.