You can definitely feel the air flow coming out of the vents. I placed the tower speakers so they stay on top of the vent covers otherwise the covers would rattle.
I measured the THD with the vent covers in place. Surprisingly the pressure drop around the vents did not create significant distortion.
No chaffing sound is coming from the vent covers for those test levels.
I did not measure the excursion of the drivers but it seemed around 0.8 Xmax. The subs are capable of around 6-8dB more before hitting the Xmech. The sound quality remains almost the same until it hits the Xmech.
The main strengths of that system are:
1. VERY VERY LOW THD - around 1% from 8Hz - 37Hz.
2. The subs are totally out of view and wife really happy about that.
OMG, I still can't believe those numbers given whatever the average mass market subs THD measurements are (10% and up).
I did the readings few times over just to make sure. Than I pulled out the RatShack meter and its SPL reading was +/-1dB from the REW readings - so the UMIC was OK.
The bass sound is Clean and Detailed - no matter if the music is playing at 100dB or 70dB - you can always hear the bass standing out especially when the sub sound starts/stops.
It sounds effortless, quick, clean, with authority, no lingering after the sound is gone.
I measured the THD with the vent covers in place. Surprisingly the pressure drop around the vents did not create significant distortion.
No chaffing sound is coming from the vent covers for those test levels.
I did not measure the excursion of the drivers but it seemed around 0.8 Xmax. The subs are capable of around 6-8dB more before hitting the Xmech. The sound quality remains almost the same until it hits the Xmech.
The main strengths of that system are:
1. VERY VERY LOW THD - around 1% from 8Hz - 37Hz.
2. The subs are totally out of view and wife really happy about that.
OMG, I still can't believe those numbers given whatever the average mass market subs THD measurements are (10% and up).
I did the readings few times over just to make sure. Than I pulled out the RatShack meter and its SPL reading was +/-1dB from the REW readings - so the UMIC was OK.
The bass sound is Clean and Detailed - no matter if the music is playing at 100dB or 70dB - you can always hear the bass standing out especially when the sub sound starts/stops.
It sounds effortless, quick, clean, with authority, no lingering after the sound is gone.
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"http://www.linkwitzlab.com/phs-dist.htm" :
Quote: "The waveforms of A, B and C above are quite different and it would not be unreasonable to expect that they sound different. Yet, I have not found a signal for which I can hear a difference. This seems to confirm Ohm's acoustic law that we do not hear waveform distortion. At least it seems to apply to the phase distortion generated by typical allpass crossovers."
So it's all good
OTOH the sharp cutoff is needed for:
1. Removing as much of the Main towers resonant port sound - it gradually does phase shifting the lower it goes towards port frequency.
2. Staying away from the subwoofer box resonant frequency Fb which is around 60Hz
I'm still doubting, you add a LR48 at 40 Hz on loudspeakers that are already equipped with a passive crossover, the signal distortion should be huge but i don't know if it is audible.
No choice there.
There are (2) bad entities here: Main towers Port resonance and Subwoofers Box resonance - 25Hz apart.
They should be kept out.
..and it sounds really really good
You can perform a test with no filters by closing the loudspeakers ports only ?
Leaving subs with xover and running the mains full range would mess up the phases below xover when both channels phase relation would start shifting
Leaving subs with xover and running the mains full range would mess up the phases below xover when both channels phase relation would start shifting
It should depend of the slope of the alignment of your main loudspeakers, IMHO there no phase problem with -12dB at the point source.
... Unless you use FIR processing.
FIR can get you a system-wide delay but no phase wraps. For stereo playback, that can be very useful.
Chris
Each hand is a loss of signal fidelity, the more your loudspakers are accurate and the more your hear them but you are in the case of a listening of a reverbrant room in the far field and it should be absolutely impossible to hear them.
Yes. I plan on using all FIR filters for my Open Baffle line array.
Last year I tried FIR and wanted to see if I could hear artifacts of that process.
I set up (2) of the line array 4" drivers - RS 100T-8 - one in each channel. Than I did 96dB/oct Hanning window FIR at 400Hz (as far as I remember) in "rephase" and loaded it in MiniDSP.
On freq sweep I couldn't tell when the sound jumped from one driver to the other. No change in sound timber, etc. It worked great.
Even better - you can use "rephase" to straighten up the phase response of ANY existing speaker (multi-way with xovers, passive speaker, active speaker, etc) to 0 deg in the audio range as long as you know what your current phase curve is or you can "play it by the ear" while adjusting it.
The only penalty here is time delay - it's needed for signal spectrum evaluation and is proportional to the time period of the lowest frequency evaluated.
As far as I remember for a xover at 40Hz the time delay was around 60msec.
FIR and "rephase" are great tools for getting the max out of you system. I love it.
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