I am about to create an excel tool that optimizes port geometry, based on enclosure volume, tuning frequency and max desired (port) spl. I hope to be ready with a very first "beta"-version in about one week.
If you have some time you could read through my port geometry thread:
Generally flaring ports is always useful to avoid chuffing noise (and port resonance) excited by sharp edges. At least both port ends should have some flange and roundover.
Thanks; that was helpful. I managed to find a copy of the user's manual for the amplifier. It appears that the high-pass filters available on this amplifier introduce a peaking bass boost of a few dB, which is handy to know. The following frequency response chart was taken from the user's manual.
Best not to try to reproduce any meaningful output level below 20Hz with a 12" driver!
When I saw the above frequency analysis plot, it piqued my interest as a result of the relatively high signal content at around 11Hz or so.
When I undertook my own frequency analysis, that very broad low-frequency energy peak at 11Hz went away entirely. See the plot below for my results. I'm not sure what's happening at your end, but something seems to be injecting copious quantities of infrasonic energy into the signal chain. I wonder where it might be coming from?
The highest peak occurs at 65Hz (−14.5dB). There is another significant peak at 41Hz (−17.2dB), which is about 3dB lower. The two peaks at 23Hz (−30.5dB) and 21Hz (−41.2dB) are quite a bit lower again. If we treat the 41-Hz peak as a reference, then the peaks at 23Hz and 21Hz are 13.3dB and 24.0dB lower. As a result, even at 21Hz the subwoofer excursion shouldn't be too extreme to pose any major worry, as long as the system is really cranked up as loud as it can go. However, a reasonable level of caution would still be warranted, gradually checking to see how the woofer's excursion is going when higher listening levels are being used.
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Maybe he got the input from a turnable playing vinyl with RIAA pre-amp that goes down to some Hz without low-cut.
I remember when I was a child back in 70's and my father had a very good RIAA preamp/amp that produced a lot of few Hz signal to the speakers with no HPF at all. I loved to see the 15" inch speakers slowly moving back and forth. I've got passioned by speakers since then.🙂
I remember when I was a child back in 70's and my father had a very good RIAA preamp/amp that produced a lot of few Hz signal to the speakers with no HPF at all. I loved to see the 15" inch speakers slowly moving back and forth. I've got passioned by speakers since then.🙂