davidro
Lunatic Member
Good point. I'd like to link that on that thread but am afraid of the unavoidable persecution
Distributed Bass
- Thread starter newguy1
- Start date
Good point. I'd like to link that on that thread but am afraid of the unavoidable persecution
GuyK
Addicted Member
Any sub in my room is gonna have to fire up to well beyond 80 Hz before it's capable of doing any stereo duty.
And according to the trend I saw here...
http://www.audiokarma.org/forums/showthread.php?t=628488
...I'd be inclined to say the same applies to most everyone else.
I interpreted the results as being most folks will want x/o theirs subs around 80-100 hz. Any higher than the results of the test indicate and you'll be hearing the same note from more than one source per channel for the directional frequencies (you'll hear them coming from the mains AND the subs), and this is a sure-fire way to muddy up a stereo image. That's the whole point of that test.
And it appears to me that the proponents of stereo over DB do not yet truly understand what DB actually does, or that "stereo s/w's" are merely a DB setup that has not been optimized. It's only a start.
GuyK
Addicted Member
It's going to take me some time to read this whole paper.
davidro
Lunatic Member
Oh they do understand all that, Guy.
But they refuse to concede that they can't hear the subs in that frequency range in stereo. They seemingly claim I'm this closed-minded Nazi who wouldn't respect their subjective perception.
But telling others you hear things like that is one thing. Telling them your perception is objectively verifiable is quite another thing.
I still get flamed though
PS: placing your main speakers on top of your subs is a sure way to add unwanted vibration to the mains cabs. But a particular individual thinks it's none of your business. Which is fair enough, only if you didn't post a damn thread seeking comments.
But they refuse to concede that they can't hear the subs in that frequency range in stereo. They seemingly claim I'm this closed-minded Nazi who wouldn't respect their subjective perception.
But telling others you hear things like that is one thing. Telling them your perception is objectively verifiable is quite another thing.
I still get flamed though
PS: placing your main speakers on top of your subs is a sure way to add unwanted vibration to the mains cabs. But a particular individual thinks it's none of your business. Which is fair enough, only if you didn't post a damn thread seeking comments.
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Based on your post just previous, you have a good handle on it :thmbsp:
GuyK
Addicted Member
David, if they ran the freq sweeps in the link tomlinmgt provided, correctly, they would be proven incorrect in their current understanding. Folks HAVE to understand there are two things at play here. First, the reason for a s/w in the first place is to bring a speaker systems response closer to flat along a broader spectrum, which either mono or stereo or DB does. Second, the purpose of DB is to bring the ROOM response into line by filling nulls or anti-nodes and cancelling nodes or resonant peaks, which mere stereo or mono subs do NOT do entirely because they simply cannot. Unless and until these fundamental differences are thoroughly understood you'll be trying to talk to closed minds.
GuyK
Addicted Member
Yes, I think I have a pretty good grasp of the concept. But it's not really that difficult. The fundamentals were presented high-school physics, and for me this was almost 30 years ago. Some of the nuances are a bit more involved, and I'm still pondering those. But the basics should be easily grasped if presented correctly. I wish I knew of a video that showed well how waves can cancel or peak when they collide, and how standing waves can interact with that. I think that once people could actually see what is happening some of the hubbub would die down.
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GuyK
Addicted Member
They actually dispute that sub-80Hz is non-directional. Nuff said.
And I'm supposed to be the closed mind excuse me
Then the linked test was not performed correctly or not performed at all or people don't understand what the results they got really mean, no? Although, the thread you got flamed in was not the same as the link tomlinmgt started (at least I think this is the case), so some of the folks in that conversation may not have seen the link. If instructions are followed, it's pretty conclusive. Also, some folks may not really know what frequencies might be in the music they listen to, so it could cloud their perception. So: http://www.independentrecording.net/irn/resources/freqchart/main_display.htm
GuyK
Addicted Member
Thanks, no, I read enough vitriol and close-mindedness in the daily newspapers. I don't need more.
I set up three 12" passive subwoofers powered by a single stereo amplifier according to the simplified information provided by this link, "Multiple Subwoofers after Geddes":
https://mehlau.net/audio/multisub_geddes/
By ear and without measuring, science plus art
https://mehlau.net/audio/multisub_geddes/
By ear and without measuring, science plus art
davidro
Lunatic Member
I don't blame you.
The way those mobs would rely on certain authority when it suits them and quickly discard it when it doesn't just because their petty setup had to be this indisputable, sacred thing really humoured me.
tomlinmgt
Lunatic Member
Yes, I agree with you completely, Guy. What I was implying by my comment was that a sub will have to play above (roughly) 80 Hz to, as you pointed out, produce a stereo image (through localization). I mean, isn't that the contention of the "stereo sub" proponents...the production of stereo images in the LF regions (first two octaves, specifically)? Not that I ever play my subs up that high (for the reasons you cited)....hence the comment's, um, tongue in cheek tone (though it was rather poorly delivered).
I'm of the opinion that it's the harmonics associated with first and (some) second octave notes that make them directional...not the fundamental note itself.
tomlinmgt
Lunatic Member
Good point. I'd like to link that on that thread but am afraid of the unavoidable persecution
Well, in the event there are any lurkers here I'll offer up the juicy bits...
In this investigation, bass management is assumed, i.e.
there is one and only one audio low frequency channel,
which is sent to all subwoofers. There are many
advantages to bass management and only questionable
advantages to using multiple bass channel
s (“stereo” bass
etc.). There is much debate on this subject. Much of it has
to do with the implementation of the bass management –
headroom, mixing of LFE etc. This is another subject
entirely, and is not considered here.
Some have argued that there is a subtle envelopment which
can occur at low frequencies when out of phase material is
reproduced on the left and right side of the listener [9]. This
has not been shown conclusively, and in any case is likely
outweighed by the more immediate advantages of bass
management.
Some will also argue that bass below 80 Hz IS localizable.
This is often the result of:
Port noise in ported subwoofers which are poorly designed
and/or overdriven
Non-linear distortion in subwoofers which are poorly
designed and/or overdriven
Visual cues or knowledge of the subwoofer location, which
in the absence of actual audible cues cause localization
Effective acoustical
crossover frequencies which are
actually higher than 80 Hz . Just because the electronic
crossover is at 80 Hz does not mean that the actual
crossover as measured in the room is at 80 Hz, especially if
the crossover is low order.
davidro
Lunatic Member
I actually offered that the perception may have stemmed from a bit of imagination, which according to the above is a reasonable view.
And you would be able to guess what the response might have been like.
GuyK
Addicted Member
I wonder about this. With many speakers the sound produced for low frequencies is so low that any harmonics might not be detectable even if the fundamental is. Isn't the amplitude of a harmonic correspondingly less than the original? And doesn't the harmonic get sent to the mains rather than the s/w? The amp/pre/crossover shouldn't be able to distinguish a harmonic in a recording from a fundamental; it's just another frequency that gets routed somewhere. On the other hand, if THE SPEAKER ITSELF is creating a harmonic when producing the fundamental, then it's entirely possible, and should be curable by using a better driver. I wonder if AK's resident Physicist could shed some light on the finer points of the relation of harmonics to fundamentals? Paging Guiller...
GuyK
Addicted Member
I did read this part earlier, and thought it very astute. Turning the knob until it reads 80 doesn't necessarily mean that's where things are set. If this is the nominal, and things are actually a bit higher, could explain the localization issues some claim.
davidro
Lunatic Member
With the subs localisation test I did in Michael's thread I actually realised that within my hearing's realm my subs had a pretty correct frequency filter; and my subs aren't really high-end like REL etc.
