DIFFERENT SUBS TOGETHER?

[mrbluster]

If matching stereo subs are not an option, what is the advisability of using two different subwoofers together? A B460 and Sub1500 for instance. I appreciate your thoughts.

Mrbluster

[Robh3606]

Depends on the subs. I have a stereo pair and an LFE. The LFE doesn't match the stereo subs. The stereo subs are more controlled and have a tighter sound than the LFE. When all three are running the LFE fills the others out a bit but also blurs things a bit. It all integrates fine you can't really tell what's doing what until you start shutting things down. If you were doing a seperate and different L and R I would be very careful making sure that they sound reasonably close, especially the transient part of the picture. The room sub interface can totaly screw up the FR on a matched pair because of placement so it's a tuff one to call.

Rob:)

[Mr. Widget]

If you were doing a seperate and different L and R I would be very careful making sure that they sound reasonably close, especially the transient part of the picture. The room sub interface can totaly screw up the FR on a matched pair because of placement so it's a tuff one to call.
For stereo music playback I'd go with matching subs. Back in the days of vinyl all VLF content was mixed into mono and so the recommendation was for a single mono sub as the L212 was designed. Today however there are many recordings with true stereo content in the VLF range.

For HT, I agree with Rob... it's a tuff call.


Widget

[louped garouv]

...Back in the days of vinyl all VLF content was mixed into mono ...

Widget

Is this still current practice in the studio for vinyl?

[Don Mascali]

For stereo music playback I'd go with matching subs. Back in the days of vinyl all VLF content was mixed into mono and so the recommendation was for a single mono sub as the L212 was designed. Today however there are many recordings with true stereo content in the VLF range.
Widget
"THEY" say that it is hard to locate a VLF source. This is true but in real life the transient attacks reach into the LF and are easy to place. IMHO it is better to have stereo subs and using two different speakers in the upper registers is not good. Draw your own conclusions.

Good listening with whatever you chose.

Don M

[grumpy]

another perspective, FWIW:
using two subs -may- give you an advantage in placement options ('cause you have two)
as well as offering the -possibility- of complementary outputs vs. simply summing the
peaks and valleys of identical units (of course it could just make a boomy mess too).
If I had both, I would try each and then both (you may not find that you need two, or
that you like the characteristics of one more than the other... OR you might want to run
one for stereo and one for HT...). I'm -assuming- summed/mono subwoofer use,
and have no issues with the other opinions/experiences stated.

If you have the capability to tailor the crossovers and response, great... if you have
the capability to measure what you're doing, even better :D -grumpy

[mrbluster]

[QUOTE=grumpy]another perspective, FWIW:
using two subs -may- give you an advantage in placement options ('cause you have two)
as well as offering the -possibility- of complementary outputs vs. simply summing the
peaks and valleys of identical units (of course it could just make a boomy mess too).

I am thinking along these lines with the hope of a flatter more even response than I currently have using my single B460 near a front corner. I also thought about crossing them over at different frequencies.

Mrbluster

[ralphs99]

Hi Mrbluster,

Assuming that a sub is not operated at too high a frequency, limited to say 100Hz, then there can be no transient information present in the sub's output. Transient information is a combination of harmonics of the fundamental frequency that are filtered out by the action of the crossover.

Below 100Hz the ear is non-directional and cannot distinguish the direction of such a sound. However a sub produces its own harmonic distortion that can be used by the ear to pickup directional cues when used alone (without the rest of the speaker system). A good sub produces relatively little distortion and this is masked by the higher frequencies present in the recording being reproduced by the rest of the speaker system, thus making the sub's location inaudible.

I don't believe that subs need to be used in stereo pairs, but there are major, major advantages to using multiple subs in the control of room modes. An excellent series of papers by J Toole describes a series of experiments and recommendations for using subs. These are essential reading!

Matched subs are probably better than unmatched, but the advantages of multiple subs far, far outweigh a single sub.

Cheers, Ralph

[Don Mascali]

Hi Mrbluster,

Assuming that a sub is not operated at too high a frequency, limited to say 100Hz, then there can be no transient information present in the sub's output. Transient information is a combination of harmonics of the fundamental frequency that are filtered out by the action of the crossover.

Below 100Hz the ear is non-directional and cannot distinguish the direction of such a sound. However a sub produces its own harmonic distortion that can be used by the ear to pickup directional cues when used alone (without the rest of the speaker system). A good sub produces relatively little distortion and this is masked by the higher frequencies present in the recording being reproduced by the rest of the speaker system, thus making the sub's location inaudible.

I don't believe that subs need to be used in stereo pairs, but there are major, major advantages to using multiple subs in the control of room modes. An excellent series of papers by J Toole describes a series of experiments and recommendations for using subs. These are essential reading!

Matched subs are probably better than unmatched, but the advantages of multiple subs far, far outweigh a single sub.

Cheers, Ralph



Crossovers aren't a brick wall. Even very high level cutoff filters allow an apreciable amont of info to pass.

[GordonW]

Crossovers aren't a brick wall. Even very high level cutoff filters allow an apreciable amont of info to pass.

And any non-digital (ie, made of standard analog elements) crossover close enough to a brick-wall filter to approximate its effects, will screw up the group delay to more of a detriment to the sound, than simply letting the sub "run up" into the midbass with a shallower slope...

I've learned to just go ahead and face it... just go ahead and use stereo subs. Much simpler than all the hoop-jumping required to make a mono sub work in a "non-localizable" nature as in theory...

Regards,
Gordon.

[mrbluster]

Thanks for all your input. As I mentioned in the beginning, I currently do not have the option of stereo (matched) subs. My concerns, as has been discussed, are transients, group delay etc. It seems my best option would be to use two different subs crossed over as low as possible (perhaps not at the same point) and letting the mains run full-range.

[GordonW]

Given your setup, that's probably the best plan.

The only alteration I might think about, is to, while using a low crossover, highpass the mains at the same frequency (or thereabouts) as you crossover the subs. I've even just put a small cap (for a first-order passive highpass) in line between the preamp and the main amplifier that's running the main speakers, to gradually roll off the bottom end at the same point the subs cross over (usually below 50 Hz)... and had it work with spectacular results...

Regards,
Gordon.

[MJC]

Thanks for all your input. As I mentioned in the beginning, I currently do not have the option of stereo (matched) subs. My concerns, as has been discussed, are transients, group delay etc. It seems my best option would be to use two different subs crossed over as low as possible (perhaps not at the same point) and letting the mains run full-range.
I don't have a problem using non-matching stereo subs. To look at my setup, it would appear that the two subs between the main L/R are identical, both B212s.
In fact after 20+ years of hard use, my original B212's amp blew up:( , so I replaced it with a plate amp from Parts Express. Then the 121A blew up:( do to being connected to an amp(the plate amp) with twice the power as the original, so I replaced the 121A with a Peerless sub driver(also from Parts Express) that was rated at 300w.
Those two subs are connected to my main L/R L212s, and I run those speakers as "large". The resulting sound from the L/R L212s and the two different subs sounds great.
I also have two sub1500s(placed at the mid-points of the side walls) connected to the 'subout' on the receiver. No matter how I listen to music, analog stereo,w/wo the sub1500s, digital stereo, 5.1, or 7.1 it all sounds great. Of coarse the Couple Charged networks, on the main L212s has alot to do with the quality of the sound.:)