[django11]

I picked up a mfw15 woofer and an SA1 amp from GR Research.  At first I slapped something together quickly in an open baffle style.  Great, great sound with music but I was hoping for something with more output to complement movies so I made a 20x20 sealed enclosure.  Now I can shake the house but I like it considerably less for music.  Would this be a common experience for those of you who have heard both?  Or did I do something wrong building the enclosure  (Which is braced BB plywood with a constrained layer and stuffed with fiberglass)?

I enjoy all types of music but tend to listen to more jazz, acoustic, folk, classical music.

[mcgsxr]

What you describe tends to mirror my own experience.

I have been running OB bass (a 12 inch woofer per side) for around 5 years now.  The bass is very musical, but in my room lacks impact.

As I recall, an OB woofer produces roughly 25% of the bass of a sealed woofer, so that tends to be the trade off.

As for the construction description of your box, it sounds well built and braced etc, so unless the specs of that particular woofer are not meant for sealed applications, I am not sure what else to say.

I run a ported 12 for my HT in another system.  Not that musical.  Buildings blow up real good though!

[django11]

The Dewalt track saw is about to come out and I'll just cut this puppy in half...  Any pics of your ob sub

edit: I think I saw them in your gallery...

[mcgsxr]

I have run different configurations of OB subs.

I currently use them on large winged flat (ish) baffles.

I have considered a move to U baffles, and have run H baffles in the past too.

What Xover and slope are you using both for OB and sealed?

[TRADERXFAN]

I picked up a mfw15 woofer and an SA1 amp from GR Research.  At first I slapped something together quickly in an open baffle style.  Great, great sound with music but I was hoping for something with more output to complement movies so I made a 20x20 sealed enclosure.  Now I can shake the house but I like it considerably less for music.  Would this be a common experience for those of you who have heard both?  Or did I do something wrong building the enclosure  (Which is braced BB plywood with a constrained layer and stuffed with fiberglass)?

I enjoy all types of music but tend to listen to more jazz, acoustic, folk, classical music.

I concur. The ob servo subs I have, while deep, have less visceral impact, in my experience, than a large boxed sub (for example SVS pci cyclinder)
But the ob servo sub much more musical.

But with OB subs you need a shelving filter, or you are probably not getting anything close to flat output.

-Tony

[TRADERXFAN]

Oops, I realize now the SA-1 has some kind of circuit for ob built in... so probably not the problem...

[zapper7]

For the best of both, what you need is an IB (infinite baffle) sub setup. This will require another room/ closet/ crawl space next to the existing room to get the effect. My music is just as nice as you are explaining with OB, but the theater is something you have to experience. Of course I have mine in a crawl space application which has the best effect for theater, but an adjoining room space would also do well.

infinitelybaffled.com

[django11]

What Xover and slope are you using both for OB and sealed?

I haven't a clue what slope is  .  I made a sealed version of GR Research N3 which don't go very low so I have been crossing over at 100.

[Russell Dawkins]

Infinite baffle is great and very effective - but it does eliminate one of the advantages of dipole bass, and that is that the bass sound outside the room is reduced because of the equal output into the room of positive and negative pressures which tend to sum to zero. This is appealing to me. I don't like hearing other people's music and I don't expect them to like mine.

In an ideal scenario, I would have dipole down to around 35 - 40Hz and monopole from there to 10 Hz, a range which is not perceived as music - or even "thump" to the outside listener but nevertheless contributes important stuff occasionally - the body of orchestral bass drum, lowest organ notes, the percussive pop of a plucked double bass, the impact of a slammed garage door, etc.

A closet does make a great enclosure, though. When I was young I used to babysit for a neighbor who was seriously into "hi-fi". He loved pipe organ and his phenomenal mono system had two 15" woofers mounted in a the wall behind which was a closet with winter coats. Pretty near perfect absorption. He was an early real DIY type - made his own turntable from scratch starting with a motor, a bearing and a cartridge. Made his own amplifier (Williamson tube), T.V. (Heathkit), furniture and - oh, yes - house!

[Danny Richie]

Your experiences are quite typical. There is nothing like the sound of the open baffle bass, but it starts rolling off pretty early and has little bottom end at all. You can boost the bottom end up to even it out, but you often run out of control and X-Max pretty quickly. I wish someone would come up with a solution for that.   

[Danny Richie]

I haven't a clue what slope is  .  I made a sealed version of GR Research N3 which don't go very low so I have been crossing over at 100.

100Hz is pretty high to be crossing those over to a sub. I'd run them full range. They will naturally roll off in a good range to cross them. Then set the crossover for the subs to between 45Hz and 60Hz to get good integration.

[Danny Richie]

Another thing you can do to get a little more output from the open baffle MFW-15 is to put the baffle in the middle of about a 12" to 13" frame (H frame style). This will increase the front to back cancellation distance and load the driver a little more. This will increase your output a little while still giving you the open baffle sound.

[django11]

100Hz is pretty high to be crossing those over to a sub. I'd run them full range. They will naturally roll off in a good range to cross them. Then set the crossover for the subs to between 45Hz and 60Hz to get good integration.

Thanks for the info. 
I have been running the N3s full range.  I do tend to to put the crossover on the sub amp a little higher though.  I'll fiddle with it when I get it back in an open baffle.

The IB stuff is interesting but I don't want to go there  ...

[Luigi]

I too have experienced the improved musicality but lack of slam from my 15-inch driver when used OB. But a kind of compromise is possible between sealed and OB.
What I did was install my 15 in a cylinder sub, stick it upright in a corner, and have the bottom end completely open. Using different height feet you can get a degree of sealed vs open baffle. This makes the bass fast and also somewhat more impactful than fully OB. Moreover, the cylinder design is compact if you stand it up. Mine's about 4 feet tall, but in a corner it almost disappears. Well, to me it does. To her it's like an ugly four foot cylinder.
I plan on creating another of these (when she's away) as I have another 15-inch driver (sourced from Kevin at DIYcable) so should be able to get back to about half of what a 15inch sealed driver can manage.

[JohnR]

Now I can shake the house but I like it considerably less for music. 

It may also be that there are other issues related to your room dimension and placement. It may be worth optimizing that or at least measuring the in-room response.

[versus rider]

I'm not sure what you are trying to do, but for music you don't need a sub, what I mean is, unless you listen to organ music you don't need to get that low. I am running Alpha 15's, one per side in OB in a narrow baffle around 70mm from the floor, with EQ, I get a flat response from 20Hz -200Hz. I recently took my speakers to a friend in France and he was gobsmacked at how good the bass was. On dance music he said it was like being in a club but with more definition. I get the same results in my room. I am not familiar with the driver or amp you are using but suspect that is where the problem lies. Alpha 15's and at least a 130w amp with good current delivery and its a no brainer. 

[richidoo]

I use twin AE Dipole 12s each side, with a cheap AudioSource 80W amp, I get all the bass I can handle, for big symphony bass drum crescendos, organs, as well as cranked up dance music. I can definitely feel the thump physically in the air, and a little bit in the floor, but it's not an assault like an action film home theater with multiple box subs or like MBL radialstrahler speakers. The detail and cleanness is amazing. I use only 1dB of baffle step correction and no boost, 5 feet front front wall in a very large room. I can plainly hear when I add a 1dB low shelf at 30Hz, it gets too punchy and unnatural, so I know they have more to give. The bottommost octave is mostly physical, so a little goes a long way for the music lover. Everyone has their own idea of how much is enough. I think this good low freq performance is due to the high Q of the drivers, low inductance underhung motors, strong solid state amp and good hookup wire.

Are you using baffle step correction? I think Linkwitz said you also need to add 6dB / octave for the faster rolloff of OB, but I can't remember for sure.  You may just need more boost to suit your own taste. Here is a good analog circuit for baffle step correction, to put after your source or between preamp and amp: http://sound.westhost.com/bafflestep.htm
Pay attention to the filter loading (impedance) recommendations.
Rich

[django11]

Sorry guys, I'm not very technical.  For measurement I have my measuring tape.  I also have a fantastic laser level  .  For the rest I just trust you guys and try it.  My sub amp :"The really unique thing about this amp is the output response. A special gain circuit has been designed that will mirror image the roll off of a sealed box or open baffle design."

I'm back in the open baffle and have a sound I really like.  Something is still vibrating when it gets loud though  .

[dcathro]

I picked up a mfw15 woofer and an SA1 amp from GR Research.  At first I slapped something together quickly in an open baffle style.  Great, great sound with music but I was hoping for something with more output to complement movies so I made a 20x20 sealed enclosure.  Now I can shake the house but I like it considerably less for music.  Would this be a common experience for those of you who have heard both?  Or did I do something wrong building the enclosure  (Which is braced BB plywood with a constrained layer and stuffed with fiberglass)?

I enjoy all types of music but tend to listen to more jazz, acoustic, folk, classical music.

How much stuffing did you use? Too much kills a sealed bass for music.

[django11]

I filled it about 2/3s  without compacting the fiberglass...