Thanks, this helps in rationalising that adding sources doesn't necessarily result in a net excess.
The speaker in the corner has its DI changed from it not being in a corner, but this has to be specified in the calculations. In the modal region, of course, this is not true, but the equations don't work there anyways..
DI is normally referenced to full space, isn't it? I think it should be in this case for a fair global comparison. Or were you talking about something else?
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By switching phases you mean changing it from 0 to 180?
Since I can't EQ all sources at once I'll have to set the same EQ settings at all subs and if that won't do I can tweak each sub individually.
Here is my ugly stereo response. A starting point. I'm not positive but you guys gave me some good guidance.
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Yes, it is reference to full space, but that doesn't require the source to actually be in full space. If it is in a corner then it has only 1/8 the space to radiate into so for an omnisource it has an 8 times larger DI (linearly not dB.) As the DI of the source goes up this multiplicative factor will go to zero.
True.
What do you think of the response I shown? Solvable with three or more subs?
Solvable by using more smoothing in your plot?
B.
Found this easy to understand:
Room acoustics - Wikipedia
Any experience with placing the subwoofer-woofer crossover frequency at exactly the Schroeder frequency?
Room acoustics - Wikipedia
Any experience with placing the subwoofer-woofer crossover frequency at exactly the Schroeder frequency?
Yes it is.
Not sure I understand. It's 1/48 smoothing which is basically no smoothing.
True.
What do you think of the response I shown? Solvable with three or more subs?
It's typical.
"Solvable" - not sure what that means here. I can guarantee that with more subs - more degrees of freedom - the situation can be improved.
The Schroeder frequency Fs is defined as a single frequency, but the fact is that it is a broad range of transition approximated by the calculated Fs and it is impossible to actually define a single frequency. I don't use a subwoofer-woofer crossover, but the main transition is certainly within the Fs range in my room.
None of the filters in my system are symmetric.
I don't know how many times I need to say this, but a HP filter on mains is only required if the mains are power limited. I do not use one in my current system, but have in the past used a first order HP at a low frequency just to limit the cone excursion. The LP on the subs is at a different frequency and all three subs used a different frequency and sometimes slopes. The bottom line is whatever works. This idea of "coherency" of the LFs is nonsense. We hear the sum total of all LF sources at LFs - basically steady state - not individual separate arrivals.
I don't know how many times I need to say this, but a HP filter on mains is only required if the mains are power limited. I do not use one in my current system, but have in the past used a first order HP at a low frequency just to limit the cone excursion. The LP on the subs is at a different frequency and all three subs used a different frequency and sometimes slopes. The bottom line is whatever works. This idea of "coherency" of the LFs is nonsense. We hear the sum total of all LF sources at LFs - basically steady state - not individual separate arrivals.
In my system I use an active LR crossover (100Hz, 24db/oct.) with a single active (corner) sub and two small active main speakers. IME this sounds better than full-range main speakers and 'overlapping' subs. There's no distortion from pushing drivers outside their comfort zone and there are no audible phase problems.
My listening space is about 5m x 8m x 2.5m (16ft x 26ft x 8ft). LF room modes are not a problem. There's a variable amount of bass (and mids and highs) in different locations, like close to a wall versus the geometrical center of the room, but overall sound quality is good everywhere (even outside the room).
I think full-range main speakers (at least the ones I tried) interfere with a sub as a result of different phase behavior at low frequencies. Having this sorted is essential IMO and a proper crossover (analogue or digital) will do the job.
Also note that audible bass problems may be caused by distortion from jitter and/or bad power supplies and/or equipment grounding issues etc..
My listening space is about 5m x 8m x 2.5m (16ft x 26ft x 8ft). LF room modes are not a problem. There's a variable amount of bass (and mids and highs) in different locations, like close to a wall versus the geometrical center of the room, but overall sound quality is good everywhere (even outside the room).
I think full-range main speakers (at least the ones I tried) interfere with a sub as a result of different phase behavior at low frequencies. Having this sorted is essential IMO and a proper crossover (analogue or digital) will do the job.
Also note that audible bass problems may be caused by distortion from jitter and/or bad power supplies and/or equipment grounding issues etc..