[genjamon]

Hey folks,

I've been sitting on the fence regarding subs for way too long.  The rest of my system has undergone extensive upgrades over the past year and is really sounding very good.  Daedalus DA-RMa V2 speakers, Lampizator Big7 DAC, Line Magnetic 518 integrated amp.  Very high quality Zenwave cabling and power conditioning throughout.  Just need that audiophile quality low bass support with excellent integration.  The Daedalus speakers have really surprised me with their fullness down to their cutoff - around 35hz.  I currently use my old MFW15 subwoofer from AV123.  Yes, the amp blew up a long time ago.  I've been using a relatively decent plate amp external to the unit, bypassing the broken plate amp.  It's not customized to the woofer, cabinet, though, and doesn't have much flexibility with crossover settings/wiring either.  I also have a Behringer DEQ2496 that I use in between subwoofer and preamp outputs, to EQ the sub output.  From playing around with those EQ settings for best sound, I know that the Daedalus only need help below around 35hz or so.

So, I need a subwoofer solution that will integrate well with the Daedalus, which need a sharper integration crossover, not a gradual one with lots of overlap between mains and subs.  And I also need it to be audiophile quality for good perceived integration.  And I'm looking for linear extension down to 20hz.  I don't like leaving low synth, deep bass drum resonances, and other deep effects on the table if I'm going to be investing in subwoofing.  I'd like to make sure the subs truly do "sub".

So, I have this very nice looking MFW15 cabinet in Rosewood that is tuned for 18hz.  It's ported.  There's a Turbo upgrade to a high end 43lb driver, along with an Icepower plate amp drop-in replacement for the broken original, with lots of power.  I like the look, but I'm wondering if the Turbo upgrade would bring me sound quality that I'm looking for.  People say it's a large upgrade in sound quality over the original, and about double the output power.  But all this feedback is on AVS forum and so forth, mostly home theater folks around there. 

What would you all think about this solution, which would be cheaper for me than buying a new sub (or two) - versus a Rythmik solution.  I know the Rythmiks are designed with high musicality in mind, and not just output, and that the servo technology is really great. 

Thoughts?  Has anyone actually heard a Turbo'd MFW15 who also has or has heard Rythmiks?  Would I be so lucky that one of you has actually directly compared the two?

Thanks for any feedback.

[Early B.]

I have the MFW15 on my HT system and I also have Danny's DIY dual OB servo subs which use the Rhythmik 12" drivers. I do not have the turbo upgrade, but I also upgraded the amp/crossover. In addition, I upgraded the 15" driver in the MFW and it sounds far better than the original, but still falls short of being "musical" for a high end system.

I can tell you right now -- if you have Daedalus speakers, there's no point wasting time and money on an MFW option. Your bass needs to be at the same level as your speakers, and the OB subs provides the cleanest sounding bass I have ever heard.

[jparkhur]

I have had both and love them both for different reasons.  I purchased two MFW Turbo 15 kits and installed them with ease.  I have a room that is 20 x 30 with some funky corners.  The room is used for both theater (kids ) and two channel.  The turbos are great, shake the house, kill everything in its range, but I sold them because they were way too much for what I could take, they were really loud, well reproduced, and solid.  I kept the two twelve GR in sealed boxes because they fit better for my needs and cost was similar.  I have them set up for two channel audio and I also have them linked to the surround receiver to provide lower freq for movies.  I personally feel they are quicker and more responsive for my listening needs.  If I had room for both sets, I would have kept the Turbo's for fun, but I was unable to use them to their full potential, I could of used just One maybe, not two...over kill for me, which I like.

It was easier to match my needs with the controls on the Rhythmik sub, especially when using different upper drivers as I do frequently.  Hope this helps, both are great products-Motor City makes solid product as does Brian at Rhythmik    .  Feel free to contact me privately if you want.  If I had a small budget, bigger budget and huge budget I would go these routes.

1.  A sealed 12 or two sealed 12s.

2.  four OB 12's, two on each side.

3.  I got $$$$$   three 12's on each side, 6 total.   

JP

[genjamon]

Thanks for the feedback, guys.  This is purely for 2 channel audio, so the big boom and loud is not important.  But the lows need to scale with the music, integrate well, and also go low.  Going to 20hz or below with linear response is my concern with the smaller Rythmik stuff.  But I did hear the Super V's at RMAF in 2010 and heard some pretty impressive bass from that.  I had forgotten about the OB 12's as stand-alone option for music subwoofer duties.  And I also have some local audio buddies with woodworking expertise.  Hmm, I might need to consult with them about such options...

[glynnw]

I, too, vote for Danny's dual 12" OB design.  These have displaced the sealed box 18" subs I have been using for several years.  No boom at all, but beautiful sustained bass notes.  Great for 2 channel stereo.  For my TV rig I still use a Carver sub that will seriously rock the room when sound effects require it.

[genjamon]

I'll look into the OB12's for sure, but it would kill me to just abandon this Rosewood MFW15.  The cabinet's in perfect shape still, but it's not worth the shipping cost just for the cabinet without a real amp solution.  I guess I could just order the new Seaton Sound plate amp for $400 and not upgrade the woofer.  Then at least it might be worth someone buying, and potentially upgrading the woofer on their own later.  But would be a pretty expensive proposition to ship it, so would probably need to be a local buyer.  I'm not sure I can justify just storing it in case I'd want to use it in the future. 

Again, thanks for the input guys.

[Danny Richie]

I think these guys pretty much answered your questions. You had this concern as well...

But the lows need to scale with the music, integrate well, and also go low.  Going to 20hz or below with linear response is my concern with the smaller Rythmik stuff.

No worries there. Our 12" servo subs play flat to 20Hz and are -3db down in the teens. And that's in a small sealed box.

I sold a lot of the MFW-15 woofers when they came over with the AV123 stuff from Colombia. So I am real familiar with both options. The MFW-15's can hit good SPL levels even down low, but doesn't really compare to the servo subs for speed, accuracy, and sound quality. 

You won't need that Behringer DEQX in the signal path to muck things up either.

You might be able to sell the Behringer, and the MFW-15 with cabinet and be money ahead. A SW-14-04 woofer and the A370PEQ servo amp together is just $578.

[mojave]

I've owned two of the first batch of MFW-15 Turbos. Just to give you an indication of their quality, the current Magico subwoofers use a similar driver from the same manufacturer. I've used the Turbos in the same room as a sealed Rythmik F15 and much preferred the MFW-15 Turbos. Their clarity and musicality surpass most subwoofers. What is really nice is that a ported subwoofer will have a lower group delay in the music band (30 Hz and up) than a sealed sub and requires less power for the same output. This leads to less compression and distortion.

The current MFW-15 Turbo kits are even better. They feature a similar upgraded driver as before, but from a different world class builder. What really sets them apart is the new SpeakerPower amplifier. I've listened to quite a few subs with the SpeakerPower amps and the only amp I like better are the Cherry Maraschinos I use on my infinite baffle system. However, the Maraschinos can't provide enough power for most single driver sub systems.

I currently own 4 of the original MFW-15 drivers and have owned another 8 in the past. Even in multiples, these don't come close to the sound quality of the Turbo driver.

[Danny Richie]

Those 15" woofers have a LOT of moving mass. This means a LOT of stored energy and MUCH longer settling times, especially when pushed hard. They really can't be compared to our much lighter weight 12" woofers. Add servo control and the comparison is pretty lopsided. The speed and clarity of the servo 12's are in a different league. The paper cone woofers of the 12" servo subs also give them a more natural and more musical sound.

[Peter J]

genjamon, I sent you a PM about something that may be of interest.

[SoCalWJS]

I have an MFW 15 Turbo with the external Dayton/Seaton amp.

My 2 cents: Great for HT, much tougher to properly incorporate into a 2 channel setup. Very good output and rumble, but a bit boomy when you start getting into well recorded "fast" bass (for lack of a better description - you know most of the usual demo tracks that people use to demonstrate "fast" bass. The Turbo just seems sluggish).

A couple Rythmic Servos are a better bet. More flexibility in placement and you'll be able to even out some peaks and nulls.

I only turn on my Turbo for HT these days.

[mlbrand]

I have dual Turbo MFW-15's, and absolutely love them for HT, but don't use them for music. My LS6 mains have plenty of quality bass for music, but if I wanted more I would go with the servo subs.

[genjamon]

Again, thanks for all the great feedback, everyone. The OB dual sub option is starting to appeal to me more and more, especially if I could enlist the help of some locals in the build. I'm not finding any kits or instructions on the GR Research website. Danny, or others, could you direct me to the designs/instructions, or to where I could order flat pack for the cabinets?

One of my local buddies is Wayne (WGH), and he makes some really fine fancy doors for a living. I bet he could help me gussy up an H frame with some great veneer, maybe even some local mesquite.

[kgturner]

I'm using a pair of Rythmik F12SE with my Spatial M4 Turbo. I'm also using a Line Magnetic LM-518IA. This setup is strictly for 2 channel music only. I'm still working on fine tuning everything, but so far the setup is fabulous. The bass is tight, fast, and deep when called upon. I can't speak about the MFW or OB sub as I have no experience with either. My room is roughly 17 x 17 x 10 for reference.

Kevin T

[Oscillate]

"There's a Turbo upgrade to a high end 43lb driver, along with an Icepower plate amp..."

I have heard both the standard MFW15 and Kevin's (SandBagger) MFW15 Turbo in a
roughly 20' x 20' x 10' home theater when he first made the upgrade kit available. The
MFW15 Turbo was notably louder and tighter sounding than the standard MFW15. In
fact there was also an 18" sealed (Eminence driver) subwoofer there and the MFW15
Turbo was a lot closer in sound to it than the standard MFW15. But both versions
excel at home theater more so than music. For your needs the Rythmik DIY subwoofers
or Danny's OBs are probably the solutions you're after.

[WGH]

I bet he could help me gussy up an H frame with some great veneer, maybe even some local mesquite.

I'm thinking solid mesquite H frame. 

Does a OB sub need 3' behind it to sound the best?

[bdp24]

duh

[bdp24]

I've owned two of the first batch of MFW-15 Turbos. Just to give you an indication of their quality, the current Magico subwoofers use a similar driver from the same manufacturer. I've used the Turbos in the same room as a sealed Rythmik F15 and much preferred the MFW-15 Turbos. Their clarity and musicality surpass most subwoofers. What is really nice is that a ported subwoofer will have a lower group delay in the music band (30 Hz and up) than a sealed sub and requires less power for the same output. This leads to less compression and distortion.

The current MFW-15 Turbo kits are even better. They feature a similar upgraded driver as before, but from a different world class builder. What really sets them apart is the new SpeakerPower amplifier. I've listened to quite a few subs with the SpeakerPower amps and the only amp I like better are the Cherry Maraschinos I use on my infinite baffle system. However, the Maraschinos can't provide enough power for most single driver sub systems.

I currently own 4 of the original MFW-15 drivers and have owned another 8 in the past. Even in multiples, these don't come close to the sound quality of the Turbo driver.

Unless I am very much mistaken, it is the sealed sub that has lower group delay, not ported. At least, according to Rythmik's Brian Ding and, I believe, Danny as well.

[mlundy57]

Again, thanks for all the great feedback, everyone. The OB dual sub option is starting to appeal to me more and more, especially if I could enlist the help of some locals in the build. I'm not finding any kits or instructions on the GR Research website. Danny, or others, could you direct me to the designs/instructions, or to where I could order flat pack for the cabinets?

One of my local buddies is Wayne (WGH), and he makes some really fine fancy doors for a living. I bet he could help me gussy up an H frame with some great veneer, maybe even some local mesquite.

Here's a link to plans for a dual 12" H-Frame   http://www.gr-research.com/pdf/H-frame%202.pdf 

Jay (Captainhemo) is going to be offering flatpacks for three driver H-Frames but he may also offer some for dual driver H-Frames

I have also built wedge shaped cabinets for dual 12's. These act like a U baffle. If this style cabinet appeals to you let me know and I'll get the dimensions for you. In these pictures, the plinths are not yet attached







Mike

[mojave]

Those 15" woofers have a LOT of moving mass. This means a LOT of stored energy and MUCH longer settling times, especially when pushed hard. They really can't be compared to our much lighter weight 12" woofers. Add servo control and the comparison is pretty lopsided. The speed and clarity of the servo 12's are in a different league. The paper cone woofers of the 12" servo subs also give them a more natural and more musical sound.

If you take the mass of the driver diaphragm and coil and divide by the area of the driver diaphragm, one should be able to compare any two drivers.

The MFW-15 Turbo driver has .252 g of moving mass per sq cm.
The GR-Research SW-12-04 driver has .283 g of moving mass per sq cm.

Now lets take a heavy driver, the FI SP4 18D1 18" driver. It has .478 g of moving mass per sq cm. That is almost double the other subs. A waterfall chart accurately shows the settling or decay time of a driver. It shows how fast it returns to rest after the signal is removed.

Here is a the waterfall decay of the Rythmik FV15HP:


Here is the waterfall decay of the FI SP4 18D1:


You can see that the heavier driver returns to rest across the frequency range a little faster than the Rythmik driver with its servo control. The reason is that the motor of the heavier driver is so much stronger that the weight increase is easily overcome and doesn't affect the settling time.