It took me a long time to realize that my ongoing battle of either having way too much or way too little bass was the fault of dips and peaks. And the problem Mr Ed mentioned where I'd get it sounding what I thought was good and then I'd end up in a different location in the room and it would be awful.
It is a lot of work for to reconfigure for stereo bass I'm not ready to try that at this point.
For grins ans curiosity sake I have been experimenting tonight with mono front vs multi by turning off and on my rear and side wall subs.
The sound stage changes.
With multiple it seems larger and more 3 dimensional to me.
This is the most notable change.
For grins ans curiosity sake I have been experimenting tonight with mono front vs multi by turning off and on my rear and side wall subs.
The sound stage changes.
With multiple it seems larger and more 3 dimensional to me.
This is the most notable change.
I guess this is basically OPs guestions and I would like if more would chime in with experience.
From several experiments in my room I would say I have yet to experience multiple sub is definitely better than just stereo/towers. At first glance sometimes I get good results with sub, but after some time I feel some overhang/slowness.
What is your room like? Is it a dedicated listening room or theater room?
I have always had my system set up in the main living room, so the space is connected to hallways, stairways, or other rooms in the house. I don't know if I have really noticed "tempermental" bass tuning like this. So I'm curious.
Multiple subs was invented to fix low frequencies in rooms that have bad response, and where acoustic treatment is not an option or isn't enough. I think I recall Floyd Toole saying something to this effect
Speaking of that, I posted measurements over on the thread about my speaker build. https://www.diyaudio.com/community/...ting-multiple-subwoofers.401343/#post-7403576
I was comparing different configurations, and I was surprised by my stereo results--I had to invert phase on one subwoofer, but that was all I had to do to get a result that was comparable to the effect I got by "optimizing" the subs. You can download the measurements and view for yourself.
I'll have to test again, because I don't remember getting these results in the past, and I'm sure I tried this comparison before. But the truth is I can't distinguish between the two settings by ear.
It is a living room that is wide and then open into a kitchen with just a counter between with a hallway off of it. Sometimes I sit off to the side, and with a small pet I often end up on the floor in different locations, usually those were the worst. I thought about sound treatments but just wasn't into the look and there are limited places I'd want a sub to sit.
I tried two small subs and gave up on that and built a BassEQ preamp that has an adjustment that just lifts the frequencies below 500 to bring back a some of what stand mounts don't produce. It works like you put a point at 500 Hz and then just tilted the lower section up or down. According to REW I was able to get the bass pretty level down to the mid 30s in room at my listening level (which isn't very loud) and it lacked the peaks and valleys that I'd get with a sub, so I stopped bothering.
Inverting polarity could be a sign that the room modes were being pushed the wrong way. Perhaps it's a sign that their contribution was more significant that first expected.
When I tried inverted phase on my rear sub it definitely smoothed the response, but it didn't sound natural.
I also was very aware of that sub location at any level except substantially lower that when in phase.
I suspect as mentioned above it varies with room interaction.
What does "unnatural" sound like?
Given that humans have been proven to be unreliable in their ability to objectively judge sound of a speaker when they know what they are listening to, can you say what you actually heard? I would like to learn from the the comments people are sharing, but natural vs unnatural does not mean anything to me.
What I said about inverting a subwoofer was just an anecdote. For all I know I mixed up the wiring on my speaker, and inverting the signal just compensated for a backwards wire. (I know I can easily test, but that is not the point.) My point was that a simple adjustment seemed to offer as much benefit as a much more complicated and laborious technique. And when I am being as honest with myself as I can be, ignoring any presuppositions about how either version should sound, I have to say that I can't pick out anything in the resulting sound that would differentiate between the two.
But if you hear something and can describe what you hear, maybe I can try to listen for the same thing?
If you had a significant 'summing peak' of a frequency using twin subwoofers, inverting the phase of one
could definitely reduce that peak ( for a given seating position ) but other frequencies would certainly arrive
out of phase.
For people with very sensitive hearing, such a scenario can result in a feeling of something being wrong and "unnatural".
I remember walking into record shops and knowing strait away if they had speakers out of phase.
It gives my ears a strange feeling, and yes, something I would call "unnatural".
This is why EQ is far more desirable than phase inversion
could definitely reduce that peak ( for a given seating position ) but other frequencies would certainly arrive
out of phase.
For people with very sensitive hearing, such a scenario can result in a feeling of something being wrong and "unnatural".
I remember walking into record shops and knowing strait away if they had speakers out of phase.
It gives my ears a strange feeling, and yes, something I would call "unnatural".
This is why EQ is far more desirable than phase inversion
If the result was a flat steady state bass response, wouldn't that suggest flat phase as well?
I would add a few things.
All the usual good loudspeaker I have heard, all exhibit the same "woombf" in the bass, since they almost always use ports. Last time was Dali Epikore, and they still had that "woombf" sound, which to me is not satisfactory, since I do not mind a bit of overhang in the bass, as long as it is taught, deep and with enough volume to pressurize the room - effortlessly.
This is where - IMO - closed mains and subwoofers come into play. At the moment I have 2 x Satori WO24P in closed 75 liters, and 4 closed subwoofers - 2 x 12" and 2 x 15" - scattered around the room, but placed so that the two subwoofers on the right are connected to the right main channel - same principle goes for the left channel. In this way I have a hybrid between multi subs(often mono), and divided left/right subs. I sum(all receive the same signal) the subwoofers via my pre/DSP with the mains when I measure, to find the sum of how they produce bass in unison.
In my system, it delivers very deep and firm/dry bass over most of the area of my apartment, which I have tuned ever so slightly to the voluminous side - which means - that I have raised the lower bass a bit, creating some more tilt from lower frequencies to the upper.
To my experience, the combination of closed cabinets, subwoofers and a smooth downwards tilt from low to top, smoothly gives you a compensation for the Fletchy muncher theory, at normal listening levels. Leaving you with a fullness that does not boom, but augment the "fun" in the "thumb" when an artist tramps the stage floor and "whacks" on a drum. And the cool thing is that for example Erykah Badu does not sound boomy, but instead deep, detailed and engaging, leaving her voice clear, even though the rhythm of the mid-bass is tight, the very low is still full, and you can easily hear the notes change.
I just don't get that with conventional speakers, without subwoofers and EQ - no matter the price, brand, room, amplifiers or whatever you could think of.
So, what are your mains, subwoofers, room shape, setup, amplifiers, measuring technique? - so that we can compare and better understand the question
It seems that in this anecdote you are describing a passive multi-way stereo pair where one speaker is out of phase?For people with very sensitive hearing, such a scenario can result in a feeling of something being wrong and "unnatural".
I remember walking into record shops and knowing strait away if they had speakers out of phase.
It gives my ears a strange feeling, and yes, something I would call "unnatural".
This is why EQ is far more desirable than phase inversion
I agree that you can hear an issue in this case, but it is the high frequencies that give it away. My point is that according to the theory I have read, we don't hear phase or get directional cues from sub 100hz frequencies.
Of course there is the caveat that a subwoofer produces sound above the crossover frequency, depending on the crossover slope. In my case, I'm using -48db/ octave crossovers, (active crossover), so the subwoofer that is inverted is not producing higher frequencies we would need to really hear a phase issue.
However, I can also share the anecdote of visiting a friend's photography studio. I asked him how his strobes were set up, because I could tell that his background strobe was firing slightly after the main strobes. The fill strobe was light activated, so it was delayed, but he thought I shouldn't be able to see this small delay. So sometimes we can notice things we aren't supposed to notice.
But in the case of subwoofers in a small room, where the sub rolls off before reaching more directional frequencies, I have doubts. But at the same time, if there is some indication to listen for, I would like to know what that indicator is so I know what to listen for.
Subjective, yes. But it doesn't mean much. "Natural" is an interpretation of what you hear, and less a description of what you hear?
That would seem to make sense
When I'm designing passive speakers, I use an 'extension-lead Flip/Flop switch' to test phase orientation of any driver
from a seated listening position > it is very useful.
In your sub. scenario I would be fascinated to hear just the subs. with such a switch.
I actually suspect ( if they're left & right ) the out of phase pressure waves would still make my ears feel like they're being pulled away from my head.
Update: Largely thanks to Pano's comments about stereo subwoofers, I have changed the crossover on my speakers.
The "multiple sub" configuration required 100hz crossover for the 4 low frequency woofers, because I was treating them as 4 independent subwoofers.
But after revisiting the idea of stereo subs and getting comparable results, I've changed the crossover on the front woofer to 250hz. Now the front woofer is 50-250hz, the coaxial is 250-1200, and the horn is 1,200-20k. This small change made a noticeable improvement in clarity. When I switch back to the 100hz crossover setting, I hear a loss in low mid clarity, with it sounding slightly boomy. I didn't notice it until it was gone. I believe this difference is explained by the woofer on the 12" coaxial using a light weight paper cone.
I also changed the rear sub crossover to 150hz. This has improved the uneven response I always get just above 100hz. Because the subs are in a stereo configuration, I can use the higher crossover without any directionality issues.
I've tested all of these changes before. I think what is different now is I'm getting a better sense of what "really" matters. Like at first I was trying to get +-3dB response below 100hz, which was a lot of work to achieve when working manually. But if I allow deviation of +-5dB, setting up the subs is a lot simpler, almost effortless. And I'm not sure the difference is audible! Maybe someone out there can tell the difference, but the benefit of raising the crossover was much more significant than making the low frequencies perfectly flat.
The "multiple sub" configuration required 100hz crossover for the 4 low frequency woofers, because I was treating them as 4 independent subwoofers.
But after revisiting the idea of stereo subs and getting comparable results, I've changed the crossover on the front woofer to 250hz. Now the front woofer is 50-250hz, the coaxial is 250-1200, and the horn is 1,200-20k. This small change made a noticeable improvement in clarity. When I switch back to the 100hz crossover setting, I hear a loss in low mid clarity, with it sounding slightly boomy. I didn't notice it until it was gone. I believe this difference is explained by the woofer on the 12" coaxial using a light weight paper cone.
I also changed the rear sub crossover to 150hz. This has improved the uneven response I always get just above 100hz. Because the subs are in a stereo configuration, I can use the higher crossover without any directionality issues.
I've tested all of these changes before. I think what is different now is I'm getting a better sense of what "really" matters. Like at first I was trying to get +-3dB response below 100hz, which was a lot of work to achieve when working manually. But if I allow deviation of +-5dB, setting up the subs is a lot simpler, almost effortless. And I'm not sure the difference is audible! Maybe someone out there can tell the difference, but the benefit of raising the crossover was much more significant than making the low frequencies perfectly flat.