Bass bin placement options

[coctostan]

I have been reading up on bass bins and I am curious about their placement in relation to the primary speaker they are supplementing. I notice that most people place them directly below the main speaker.

Is it possible to place the bass bin above or to the side of the primary speaker? I am only concerned with it being an acoustically sound idea. I know it may sound odd, look odd, and may present logistical problems.
Would there be baffle diffraction issues? What is optimal?

[ThomasW]

Bass bins aren't subs, since they run into the midbass range. This means they should be in close proximity to the other drivers, otherwise the phase is messed up and the stereo image blurs..

If they're off to the side or otherwise located, the crossover point needs to be 100Hz or lower. This doesn't take enough workload off the other drivers and makes for a very narrow passband when used with a sub. And that's not a particularly good idea........

So optimal is as one would imagine, directly below or above the other drivers...

[coctostan]

Ok, so directly above or below. Are there advantages to either of these configurations? I assume they should lined up with the mids (assuming a simple MTM) and the faces of the enclosures should be flush, right?

What about dual open baffle bins with one driver inverted? Could that be placed horizontally (drivers side by side), above or below the primary speaker?

[JonP]

Bass bins aren't subs, since they run into the midbass range. This means they should be in close proximity to the other drivers, otherwise the phase is messed up and the stereo image blurs..

If they're off to the side or otherwise located, the crossover point needs to be 100Hz or lower. This doesn't take enough workload off the other drivers and makes for a very narrow passband when used with a sub. And that's not a particularly good idea........

So optimal is as one would imagine, directly below or above the other drivers...

Something related to this, I've always wondered about height from ground, ground bounce enhancement/cancellation, and how one factors that into the picture? Lately I've been thinking I have less understanding of bass than I think I do... (or a whole lotta weird room modes...)

[dlneubec]

Something related to this, I've always wondered about height from ground, ground bounce enhancement/cancellation, and how one factors that into the picture? Lately I've been thinking I have less understanding of bass than I think I do... (or a whole lotta weird room modes...)

Jon,

I think this is often overlooked. You will have floor (or ceiling) bounce nulls based upon the listening position and ear height and the height of the mid and woofer. You want to be sure the nulls will take place outside of the passband. BoxyCad2 (free download) has a nice floor bounce calculator that estimates the best crossover point between mid and woofer based on their heights, the distance to and ear height of the listening position. I've found this to be a handy tool, not only in determining crossover point, but optimum mid and woofer height in a design. There are a number of other interesting calculators in it also.

Boxycad2

[coctostan]

Jon, that was where I was going next. It seems that people just construct boxes that work well as a stand with little consideration to driver spacing or placement on the baffle. Unfortunately, I am a newb when it comes to this stuff.

Bass bins are an option I am considering but I don't want something that is done haphazardly.

I will try the boxycad program to see what I can simulate.

[JoshK]

Another related question about bass bins, that I don't think I fully grasp, is how the crossover between the bass bin and monitor interacts with the monitor's crossover. For example, suppose we wanted to add bassbins to Natalie P's or Modulas. If we really want to take some of the midbass load off the Nat P's we'd need to hipass the Nat P's right? At what point does this hi-pass interact with the NP's passive xo?

[ThomasW]

If we really want to take some of the midbass load off the Nat P's we'd need to hipass the Nat P's right? At what point does this hi-pass interact with the NP's passive xo?

It best when all this is done with an active crossover, that way there are no big inductors to mess things up. Using 'good' passive components will be more expensive than using an active XO like one of the Behringer CX series

250Hz is a good upper limit depending on how well behaved the woofer is at higher frequencies.

[dlneubec]

Another related question about bass bins, that I don't think I fully grasp, is how the crossover between the bass bin and monitor interacts with the monitor's crossover. For example, suppose we wanted to add bassbins to Natalie P's or Modulas. If we really want to take some of the midbass load off the Nat P's we'd need to hipass the Nat P's right? At what point does this hi-pass interact with the NP's passive xo?

Adding a passive high pass to the Nat P will certainly have an efect on the crossover and it will need to be reworked for that. Another approach is to do the high pass actively. This could be done with a separate digital or analog active xover and amp or possibly with the preamp/Recievers built in crossover controls, depending on what your crossover needs are and what signal you want to send to the bass bin.

(edit) Whoops, I see Thomas beat me to it!

[coctostan]

Thanks for the help. I am thinking about building some U-Frame OB (convertible to sealed for experimentation as OBs are a new world for me) bass bins that will suspend from the ceiling. I am planning to cover ~70hz-250hz and use a DCX2496 for xover and eq. The drivers will probably be either the RSS315HF, Aura NS10/12 or the new DIYCable OB drivers.

The speakers they will supplement are most likely going to be either Modula MTMs or Lineup D44s. I might actually try some OB MTMs at some point.

Does this sound like a decent experiment? I figure if the OB sound is not good (because I screw it up) I will just convert to sealed bins.

[JoshK]

I was speaking of active crossover, but wondered if using an active crossover to hipass the NP would still interact with the passive xo?

[JonP]

I was speaking of active crossover, but wondered if using an active crossover to hipass the NP would still interact with the passive xo?

I would think not directly, since you have an amp inbetween... but, the active filter will have some amount of phase shift, and THAT might change things. Actually, it would only change things between the bass bin and the speaker... not affect the speaker itself.

But, I'd guess you might want some way to adjust the phase a bit between your bin and speaker. Hopefully that would be included in your active crossover.