[zipidachimp]

has anyone compared similar OBs as noted above?  3 ways don't appear all that popular. I've found that particularly with operatic vocals, the sub is all too obvious switching on and off when needed for brief periods.  wouldn't a 3 way be smoother? would a 3 way salvage some of the missing bass? 

[JLM]

Deep bass and OB don't go together very easily.  Blame it on the laws of physics.  So a 3-way is sort of pointless.  But the IB (infinite baffle, cousin of the OB) can certainly fill the bill if you have the house for it.

IB require 4 - 10 times the woofer's VAS behind the driver.  This typically equates to a space at the size of a closet.  Note that slamming doors in those closets/rooms can blow the cone.  On the plus side the normal installation limits frequency response to deep bass, so they can barely be heard if mounted on an exterior wall or attic.

You could look for a sub that simply stays on or a passive sub and run your own amp for it.

I heard Hawthorne Silver Iris (15 inch coaxials 2-ways in very small OBs) with and without twin IB and it made little difference, until you looked for extremely bass heavy material and played it fairly loud.

[hurdy_gurdyman]

Deep bass and OB don't go together very easily.  Blame it on the laws of physics.  So a 3-way is sort of pointless.  But the IB (infinite baffle, cousin of the OB) can certainly fill the bill if you have the house for it.

IB require 4 - 10 times the woofer's VAS behind the driver.  This typically equates to a space at the size of a closet.  Note that slamming doors in those closets/rooms can blow the cone.  On the plus side the normal installation limits frequency response to deep bass, so they can barely be heard if mounted on an exterior wall or attic.

You could look for a sub that simply stays on or a passive sub and run your own amp for it.

I heard Hawthorne Silver Iris (15 inch coaxials 2-ways in very small OBs) with and without twin IB and it made little difference, until you looked for extremely bass heavy material and played it fairly loud.

JLM's correct. It was my system he heard. If the bass is adjusted properly on an IB crossed low (mine is around 45- 50 Hz), it's barely noticeable on most material but really kicks ass when truly deep bass is present. My IB's are mounted in my attic. While playing strong deep bass, you can go outside and barely tell they are on. Even late night listening to pipe organ music or synth type music will not bother the neighbors.

Dave aa

[zipidachimp]

thanks for the info. saved me the price of 2 drivers.  my sub is on, but it's more obvious, less smooth transitions, with my OB, than with my other system. looks like I'll have to do some adjusting  with sub controls. 

[hurdy_gurdyman]

thanks for the info. saved me the price of 2 drivers.  my sub is on, but it's more obvious, less smooth transitions, with my OB, than with my other system. looks like I'll have to do some adjusting  with sub controls. 

Many sub-woofers are just not comfortable with keeping up with the very articulate speed that a typical OB has. Perhaps this could be some of the problem?

Dave aa

[JLM]

Subs should be adjusted just below where they are obvious on "normal" music.  Most folks starting out want to "play" with them (to experience them, get their money's worth out of them) and have them set too loud and have the high frequency crossover set too high.  Proper bass, just like the foundation of your home, shouldn't be overtly noticed, but also shouldn't be taken for granted.

It can be fustrating that, for the money spent, the sub has relatively little effect.  But that's the story of the bottom octave in general.  The challenge for most OB designs is that they need more help than just 20 - 40 Hz.  Typical subs don't work well much beyond 80 Hz.  The ear can start locating frequencies higher than that, resulting in a disconnected sound.  That's why they're called "subs".

[Bob in St. Louis]

........but really kicks ass .......

I Don't recall Dave ever saying that anything "kicks ass".  Not your normal choice of words Dave. 
That's funny stuff! 

Bob

[hurdy_gurdyman]

........but really kicks ass .......

I Don't recall Dave ever saying that anything "kicks ass".  Not your normal choice of words Dave. 
That's funny stuff! 

Bob

It was Saturday morning. All the kids were watching TV instead of browsing forums.

Dave aa

[zipidachimp]

another idea: any point in using multiple woofers?  why is that seen often?

[mcgsxr]

As I understand it, people use multiple woofers to make up for the delta in efficiency.  I forget the math (ok, I NEVER knew the math!) but the idea is that one sub in a sealed enclosure equates 4 free air (OB) subs.

I use one 12 per panel, and am fine with it for most music. 

If I had it to do over again, I would go with one 15 per panel.  Just cause!

[scorpion]

 zipidachimp,

You would do well by reading this recent study by Martin J King on passive OB design: http://www.quarter-wave.com/General/OB_Design.pdf .
A lot of understanding can be gained there. 

Many of us listen to B200 in OBs. I for sure would not hesitate a moment on building an OB with two Alpha15s and a B200 and as mcgsxr said this is just to match output levels of the different drivers and for Opera Arias you certainly would have a hard time to beat that combo. In fact you could spare yourself two woofers by building  a winged baffle of 40" x 40" dimensions, including wings.

/Erling

[zipidachimp]

very enlightening. I'll try and salvage my first attempt with a lower crossover,and sell them, and start a new design based on the info above. thanks.
I originally started out on this ob path to save me the price of a new pair of paradigm titans.oh well, at least I'm learning something.