Hello guys. I getting conflicting info on max port velocity. Is it 16m/s max or 30m/s max.. I think the confusion comes from some people measuring in feet per second..
Also do any of you guys have any info on max group delay? Any help would be much appreciated..
Also do any of you guys have any info on max group delay? Any help would be much appreciated..
Greets!
Historically, ~17 m/s and have yet to see a max, but based on HR's math it increases ~exponentially = ~ 34 m/s it's a 4x greater compression (presume pretty much choked), so ~1.4142x = ~24 m/s seems a reasonable upper limit, but leave it to the higher math and/or actual measurement folks to fine tune it.
There was a long discussion on the long gone BassList that distilled down to this: group delay
Do a search for more recent discussions, though it's so dependent on the app, one's hearing combined with the fact that the lower the tuning the quicker it decays combined with critically damping the vent renders it moot IME.
Historically, ~17 m/s and have yet to see a max, but based on HR's math it increases ~exponentially = ~ 34 m/s it's a 4x greater compression (presume pretty much choked), so ~1.4142x = ~24 m/s seems a reasonable upper limit, but leave it to the higher math and/or actual measurement folks to fine tune it.
There was a long discussion on the long gone BassList that distilled down to this: group delay
Do a search for more recent discussions, though it's so dependent on the app, one's hearing combined with the fact that the lower the tuning the quicker it decays combined with critically damping the vent renders it moot IME.
Thank you very much my friend you guys are fantastic. I always thought it was 17 but youtube hobby guys say 30.. I'm running a dayton 1000w rms amp and a dayton um18inch also 1000w rms.
If I set the signal on winisd at 1000w am I right to assume that I should aim for 24m/s as the speaker volume will cover chuff. And as I come down 600w I am around 19m/s.. or should I be at 17m/s at 1000w signal?
Don't hesitate to correct me if I am wrong.
I am tuning for music at 22hz as I don't watch TV or movies most of the time.
If I set the signal on winisd at 1000w am I right to assume that I should aim for 24m/s as the speaker volume will cover chuff. And as I come down 600w I am around 19m/s.. or should I be at 17m/s at 1000w signal?
Don't hesitate to correct me if I am wrong.
I am tuning for music at 22hz as I don't watch TV or movies most of the time.
1000W continuous is very unrealistic as music is a dynamic signal.
I think you will be fine with the port size you simulated and won't hear any chuffing. But be sure to flare your port as that makes a huge difference.
I think you will be fine with the port size you simulated and won't hear any chuffing. But be sure to flare your port as that makes a huge difference.
It depends on your listening level. What SPL are you looking at with your listening position at 1000 watts from what distance? That's what matters. Do you listen to music at 105db? More? Less? Model your port based on a port velocity that won't exceed a tolerance based on this. And then go a bit more over so that you are covered if you turn it up at all or find yourself farther from the sub when you listen.
I goal around 18 meters per second as a peak in my usable frequency range. If it goes way up down below a frequency not in my range, I don't worry about that, as my highpass filter will nuke that.
How about posting your model?
Very best,
BB,
Noise is one issue, but port compression, distortion, and tuning frequency increase start around 7m/s, at 16m/s both will be worse, though generally acceptable. Avoid over 17m/s if you want the best possible, though the port is going to be big for a speaker with so much displacement and such a low Fb (port tuning frequency).
The UM18-22 is rated at 22mm Xmax, whatever "power" (voltage) simulated to reach that excursion in the region around 1/3 octave above Fb should be used to keep the port velocity in check.
Depending on box size, reaching Xmax may require more or less than the rated RMS power handling rating, a 1000w RMS rating implies 4000 watt peaks are possible without mechanical or thermal failure.
Art
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I'm running dsp also so I boost or cut where needed. I'm considering building a tube sub 350litres 600mm diameter and approximately 2000mm tall with 8inch port approximately 1000mm long. I have the equipment and space to build two of these as I have two dayton audio 1000w rack amps.. I am going to put pictures of the room up after work.. I need to get this system completed as its been two years and its driving me mad
I'm going to post everything this evening. System/ room/ design as I'm really struggling. I'm over 6grand in now! 3rd amp and two bk monolith subs also that don't cut it.. its a victorian house out plan over 4000cuft. I have it about 105db for an hour or so but then I turn down to about 80db
At what velocity a port starts to chuff and when it no longer acts as a port, can be estimated with this software:
https://www.subwoofer-builder.com/flare-it.htm
https://www.subwoofer-builder.com/flare-it.htm
