|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
66.51.146.3
In Reply to: Are two subs really much better than one sub? I am posted by audiogatorjim on April 27, 2007 at 05:27:49:
Left right subwoofers prevent one particular standing wave between the side walls that causes weak bass at a narrow band of frequencies half way between the walls (frequewncies based on the distance between the walls).If you sit exactly half way between the side walls, which is not a good idea for the best possible sound quality, the bass may sound better with left-right subwoofers. This is impossible to predict without experimentation and measurements.
The "best" number and locations of subwoofers depends on which "expert" you consult. No two agree. And no two use the same bass attrributes/measurements to come to their conclusions.
Here's the right answer to control spending:
Try one subwoofer first.
If it is not sonically invisible, sharply restrict output over 80Hz.
If you are still not happy with it, and can't find a better location, build another one and place both subwoofers near the two main speakers
.
.
.
Follow Ups:
Having 2 subs means you can cross over at whatever frequency you like to your "main" speakers ... since you have a sub sitting right next to each main speaker ... so effectively, you've made them into "full-range" speakers?Whereas if you only have 1 sub - located somewhere in the room - if you allow male bass voices to come from the sub then you will be able to hear this different location vis a vis your main speakers?
Hence crossing over at lower than 80Hz (let's say 60Hz!) is vital
Regards,
You're not entirely correct. Actually, in a symmetric rectangular room, subwoofers located at the midpoint of the left and right rooms will avoid exciting all odd-order modes, not only the first-order one. This will have potential benefits for listening positions other than the one in the middle of the room, since non-first order modes will have nodes located outisde this position.However, as you note, experimentation and measurement are needed, particularly in real-world rooms where measurements and fenestrations (doors and windows) may not result in symmetric, rectangular rooms.
I mentioned only the first order side-wall-to-side-wall room mode because second order and higher modes are likely to be above the subwoofer's range.Reducing excitment of some room modes, or preventing some room modes by using multiple subwoofers, is a gamble because the primary bass problem in homes is INSUFFICIENT MODAL DENSITY for our ears to effectively one-third octave smooth the bass frequency response.
Therefore reducing the room's modal density is generally the opposite of what our ears want!
The right solution is to make the room surfaces more flexible, or to use a lot of bass traps to reduce bass reflections, so ALL room modes are weaker.
Placing subwoofers half way between walls means they will be located far from the two main speakers -- that makes the subwoofers less likely to be sonically invisible, and deteriorates a two-channel stereo image. Remember that the attack of bass notes comes from the front speakers mid-range driver (three-way speaker) or the bass-mid-driver (two-way speaker) -- so why would anyone want the rest of the bass note to come from their side, or from behind them?
Trying to prevent some room modes by using two subwoofers, or placing subwoofers in partial nulls to reduce the excitement of room modes, does not automatically improve the subjective bass quality.
One of the common problems is that multiple subwoofers are ALL placed on the floor where they fully excite the (frequently excited by music content) first-order floor to ceiling room mode (70 Hz. in an 8 foot tall room).
.
.
.
Woop. Forgot to mention: the potential benefit of the midwall positioning on the left and right walls in terms of odd-order modes along the front-back axis would be relevant only in larger rooms (hence the inclusion of the word "potential"). However, the mode cancellation provided by positioning the two subs on the left and the right would beneft ALL listening positions along the midline of the room, not simply in the center of the room.Also, in the second paragraph, the second "measurements" should have been "dimensions."
This post is made possible by the generous support of people like you and our sponsors: