[drphoto]

Though I've not heard them, from what I've read OB bass systems seem like the way to go in terms of convincing sound reproduction. Plus, it seems like a cost effective solution.

Why then would anyone want a conventional box sub? Is it because OB sub drivers are pretty large (15"-18") and you can get away w/ smaller, more compact size in a box?

Can an OB woofer be simply mounted on a baffle, which is affixed to a base to hold it upright? (Possible w/ some sort of truss type braces for ridgity)  Think 'mini magnepan' for a mental image.

Now, are U-frame and H-frames more or less open ended boxes? What's the difference beween the two? Does the box contribute to the sound via loading, like a waveguide, or is just a way to make the baffle more ridgid?

I understand what a W-frame looks like from the drawing on the GR website.

If there is a thread or site that explains this, please point me there. I looked at the MJK article and it didn't really help me.

thanks

[hurdy_gurdyman]

Though I've not heard them, from what I've read OB bass systems seem like the way to go in terms of convincing sound reproduction. Plus, it seems like a cost effective solution.

Why then would anyone want a conventional box sub? Is it because OB sub drivers are pretty large (15"-18") and you can get away w/ smaller, more compact size in a box?

Can an OB woofer be simply mounted on a baffle, which is affixed to a base to hold it upright? (Possible w/ some sort of truss type braces for ridgity)  Think 'mini magnepan' for a mental image.

A practical OB can only get down to around 30 Hz. For people into pipe organ music, synthesized music with lots of deep bass and for those with home theater in mind, it's important to get deeper than 30 Hz. A box type sub is the only practical way to do this, or maybe an infinite baffle using an attic or basement.

Dave

[David Weil]

If there is a thread or site that explains this, please point me there. I looked at the MJK article and it didn't really help me.

There is a lot of information here and here

[Bob in St. Louis]

Dr Photo, I'll take a stab at a few of your questions if I may;

- "OB bass systems seem like the way to go in terms of convincing sound reproduction. ...cost effective solution..... Why then would anyone want a conventional box sub"
Yes, OB is very convincing, the most convincing detailed bass I've heard to date and (can be) inexpensive (although 'inexpensive' can be said for about any driver alignment). The reason why anybody would want something else....Well, personal preference mainly. Fast food is the least heathly food there is. There are so many better alternatives, but the industry appears to be doing pretty well. 
See what I mean? 

- "Can an OB woofer be simply mounted on a baffle.....Think 'mini magnepan' for a mental image."
Absolutely. You can't get any easier than a single piece of wood with legs on it.
Here's a couple (very poorly photographed) shots of my past and present bass baffles:



Regarding the other letters of the alphabet for bass driver alignment "U","H" and "W", I'll leave that for others to explain. In my opinion, "I" is the only letter needed to provide good quality (and quantity) bass.

Hope this helps.
Bob

[drphoto]

Bob, that sure looks like a pretty simple setup. Did they tend to 'skitter' around on the floor or does the driver actually not impart much energy to the baffle?  I would have thought you'd HAVE to affix the baffle to some sort of base.

Thanks for the replies guys. I felt sort of embarassed to post such naive questions.   

[Bob in St. Louis]

No reason to be embarrassed Doctor, not at all.

The driver is about 25 pounds, the baffle is 22"X22" by 2" thick hard Maple, so there's quite a bit of mass there. Sitting on Burber[sp?] carpet keeps it from moving. That paper cone doesn't have the kahunas to move all that weight. The baffle does have some energy transferred to it but not enough to have any negative effects.
The one 'odd' looking speaker in the background of the photo on the right was made from 1/2" OSB. NOT recommended. That's not enough mass at all, lots of vibration transmitted, but it still didn't have a problem with scooting around the carpet. These drivers on a wooden or ceramic floor may move around but I'm not sure.
But to answer your question, there's no base necessary. The floor serves as a boundary to help amplify the sound waves but is not needed for the structure to "work" per se.

Bob

[David Weil]

Burber[sp?]

Since you ask, it is Berber.

kahunas

That would be cojones. Excuse my French.

[Bob in St. Louis]

So a proper sentence with those words spelled correctly would be:
"My Berber carpet and cojones are the same color".
Right?

I wasn't sure about the Kahunas, but the spellchecker said it was fine. 
I stand corrected, thank Mr Weil! 

Bob

[David Weil]

So a proper sentence with those words spelled correctly would be:
"My Berber carpet and cojones are the same color".

It would be a proper sentence. After seeing a Berber the other day, it is hopefully not a true sentence.

I wasn't sure about the Kahunas, but the spellchecker said it was fine.

It was fine for the spellchecker, because the word exists as well. Kahuna is Hawaiian for priest, master or expert. You obviously know the meaning of the Spanish word cojones.

Oh, I'm wiseshitting again.

[Bob in St. Louis]

HAHA, Ok David, Thanks for the education. I don't mind being corrected when I'm wrong.
Now, back to our regularly scheduled programming. 

Bob

[Rudolf]

Why then would anyone want a conventional box sub? Is it because OB sub drivers are pretty large (15"-18") and you can get away w/ smaller, more compact size in a box?

That is one aspect. Another one is the need for a minimal front wall distance. A third one the disability of OB bass to deliver that one-note-thump many people seem to enjoy so much.

Now, are U-frame and H-frames more or less open ended boxes? What's the difference beween the two? Does the box contribute to the sound via loading, like a waveguide, or is just a way to make the baffle more ridgid?

All dipole frames are means to extend the way from the driver front to the driver back (dipole length), thus lowering the frequency of dipole loss. Rigidity is only a side effect. All frames are loading the driver to some extent (which is appreciated) and do form a quarter-wavelength resonant cave. Drivers in these frames should only work BELOW the resonance peak.
H-and U-frames are explained here:
http://www.linkwitzlab.com/models.htm#B
http://www.linkwitzlab.com/frontiers.htm#L
http://www.musicanddesign.com/u_frame.html
http://www.musicanddesign.com/NaO-II-U-frame.html

[drphoto]

Cool. Thanks guys. I'm pretty sold on trying the GR servo OB. It looks like I could go simple like Bob's example, and then adjust from there if needed.

[drphoto]

Anyone running their OB subs w/ monopole mains? Probably the opposite of what most people do. My mains will be the Merlin TSM-MMe, when I get them back from their upgrade.