I'm toying with a ported design in WinISD, and in an effort to get the port length down to something even close to reasonable my port velocity is going up well beyond the rule of thumb I've heard of ~ 5% of sound speed. However, my input power into the system is the peak rating of the woofers. I'm seeing about 33 m/sec in the low bass near the tuning frequency, or almost 10% of sound speed.
Am I worrying for no good reason? Under what conditions would I see peak power into the box, playing real world music? In this case peak is 2X the drivers' RMS power rating. Would such a velocity actually lead to audible noise on a quick transient? Would the ear likely pick up on it? Would it be better to characterize port velocity at the RMS rating of the drivers?
Thanks in advance for any advice.
Am I worrying for no good reason? Under what conditions would I see peak power into the box, playing real world music? In this case peak is 2X the drivers' RMS power rating. Would such a velocity actually lead to audible noise on a quick transient? Would the ear likely pick up on it? Would it be better to characterize port velocity at the RMS rating of the drivers?
Thanks in advance for any advice.
Depends a lot on what you'll be listening to on the speakers.
In lots of genres of music, the extreme LF around tuning frequency is definitely not the loudest part of the tracks, so with such music you'd likely get away with the kind of airspeed modelling you describe.
You could try putting a few tracks through a spectrum analyzer to see what LF content they have - the free software Audacity has a perfectly useable module for that, for example.
In lots of genres of music, the extreme LF around tuning frequency is definitely not the loudest part of the tracks, so with such music you'd likely get away with the kind of airspeed modelling you describe.
You could try putting a few tracks through a spectrum analyzer to see what LF content they have - the free software Audacity has a perfectly useable module for that, for example.
That makes sense. I have Audacity -- I can do that.
To get a feel for worst-case scenario, do you have any suggestions as to what types of music would actually have a fair amount of sub-40 Hz content? Pipe organ? EDM? I'm pretty sure most standard rock 'n roll is above that, since a low E on a bass guitar is 41 Hz, and kick drums don't tend to go real deep.
To get a feel for worst-case scenario, do you have any suggestions as to what types of music would actually have a fair amount of sub-40 Hz content? Pipe organ? EDM? I'm pretty sure most standard rock 'n roll is above that, since a low E on a bass guitar is 41 Hz, and kick drums don't tend to go real deep.
Evanescence - Bring Me To Life, full orchestra plus organ. Sheffield Labs sound disk, AV files of locomotives starting up etc....
Interesting - have had that Evanescence album for ages, never thought to check it - looks like 30Hz is only 7dB down from the peak, which is pretty high for pop/rock.
Haven't checked out too many of these myself, but there have been various threads on various fora discussing the topic over time, herewith a couple from one forum I hang out at a lot:
Songs that are strong below 35Hz
dB Technologies S30N vs RCF SUB 8006-AS Comparison
Attachments
Yes, I'm open to a PR. So far I've struggled to find products that either don't sacrifice F3 or don't force a bigger box to get the same F3 (and sometimes I can't even get there).
That said, the volume of the port tube itself isn't zero, and for a very small speaker, it can represent a 25% bump or more in external volume. So, I probably shouldn't be so critical of the PR designs.
That said, the volume of the port tube itself isn't zero, and for a very small speaker, it can represent a 25% bump or more in external volume. So, I probably shouldn't be so critical of the PR designs.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.