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In comparison my graph scaled to your CLIO graph:
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Doesn't look too shabby for two single subs (the graph shows also the left speaker crossed over at 120Hz). How many drivers and amps do you use?
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stigerik, in your decay comparison the monopole decay is better than the dipole below 200hz. This is surely the most important area in a sub? The hash above 200hz in the monopole isnt very relevant is it? Below 70hz amplitude is similar, but decay time is slightly worse in the dipole. Between 70 and 200hz the monopole is better. Longer decay envelope scale would resolve the data better i believe, so the true extent of the decay below 70hz can be seen.
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Then you have misinterpreted the graphs. The decay "tail" for the dipole is clearly lower in level.
i read waterfalls daily so nope. Sorry erik. The amplitude is similar, not much between both plots. The dipole is very good at exactly 80hz, but isnt that your xo point? Realistically, there isnt much to pick out between them. The monopole has lower decay but again, not much. The resonant 'ridges' of room mode excitation are very clear in dipole plot. Granted that the monopole is worse below 50hz, but i would expect that. At most theres maybe 3dB between them, when averaged out. There are easier ways to lose 3dB of room excitation, in my opinion. The stuff above 200hz isnt relevant for a sub. One looks like a near full range plot and the dipole, a sub plot. Increasing the decay scale would prove me wrong, or not. All im saying is there are areas in both plots where one is better than the other.
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well, you will be surprised to hear I live in a bunker!
Then maybe you should do the measurements
Is this a single monopole? With my two subs I also see a significant reduction in modal decay.
Just stumbled upon this Genelec paper:
http://accucalhd.com/documents/audio/Merdiean EQ Design Research.pdf
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Im looking...
I dont quite see what you mean.
The starting amplitudes in both plots arent equal, at t=0.
how can a valid comparison of decays be certain with what should be direct radiated sound only, measured at differing starting amplitudes?
I dont know much about dipoles, but from what I do know I would actually agree with yourself and Stigerik. I dont measure my own speakers, but I have measured ONCE, when I was making my 1st speaker, at school. So I dont believe it to be easy. To do it well is not easy. I cant do it well, I need practise.
Perhaps if the initial levels were equal, it would be clearer that the dipole is better.
the decay of the transient is unknown in both plots too, simply because the scale is bad.
I also miss the point about the monopole exciting room modes from an earlier point. what advantage is a delayed excitation?
As a result the whole delay envelope is offset, perhaps far enough for a longer room mode 'hangover', I would imagine.
Am I really talking garbage?
Hi,
I think the decay is not the most perceptually important parameter for bass in small room acoustics spaces. Instead, you may like to look into modulation transfer capabilities of monopole vs dipole to better describe the perceptual differences on music listening.
- Elias
How does a multiple subwoofer configuration perform in terms of modulation transfer capabilities?
The problem is that Elias' comparison is biased towards the dipole - the dipole speaker was equalized but the monopole wasn't and only a single placement was tested...
Interesting, but just because measurements show that one speaker performs better than another in this particular metric, doesn't mean it sounds any better.
Where is the research to prove that the modulation transfer ability of a speaker/room is a valid predictor of sound quality at bass frequencies, and beginning at what threshold ?
Until we have that information all we have is pretty graphs of possibly academic interest.
In fact I have seen papers that suggest that below 100Hz we are very insensitive to long decay resonances and extremely insensitive to them below 50Hz, on any normal music material. We simply don't have good temporal resolution at low frequencies, with all the timing information in low bass notes coming from the overtones.
(I don't have time to dig the paper up just now but it was discussed and linked to in another thread you were party to
)Distributed sub modal smoothing tends to fix a large part of the decay response anyway, by virtual of providing a nearly flat response, and done properly, making the bass response mostly minimum phase.
(Notches produced by boundary interference tend to be non minimum phase due to sudden phase reversals, but this is avoided with sufficiently distributed subs)
I would suggest that a better indicator of bass quality is plain old frequency response flatness, coupled together with excess group delay to identify (and eliminate, by multiple sub positioning) any sudden phase reversals or extreme group delay spikes that are due to boundary cancellation issues.
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