Originally Posted by basshead81
Normally subs tuned higher especially in the audible frequency range(30hz>) tend to sound boomy….not always but more then not.
I don't believe what folks "Think" they are hearing is the port tune difference...imo it's a difference in frequency response and harmonics.
Originally Posted by Marc Alexander
How do you attribute this to the port tune? That is not my experience, that the port tune explains boominess.
Originally Posted by basshead81
Because subs that are tuned low( <20hz) output is not influenced by the port above 30hz where the frequencies are audible...you are hearing primarily the driver. If you tune a sub above 30hz, then the port is contributing to the output in the audible frequency range...so you can hear the port per say. Take a box store Klipsch sub12 and play some bass oriented music, place your head equidistant from the driver and port, you can hear the output switch between the port and driver. Now perform the same test with a sub tuned below 20hz and you wont hear the bass output switch between port and driver. On the Klipsch sub when the output switches to the port in the 35hz area the tonal balance of the sub changes.
I think the association of higher port tunes and boomier subs has lead you to a conclusion which may not accurate. Port tune is not what makes a sub boomy or not IMO (it can be a factor in the whole design). I believe you unintentionally made a case for lower-tuned subs. I am not a sub designer by any means but here is my understanding:
The port in a bass-reflex system is contributing to the output closer to a full octave (than half) above tune and maybe ⅓ octave below. Above this range the system operates as an acoustic suspension (sealed). No air should escape the port. Lowering the tuning frequency not only increases the ULF efficiency (sacrificing some efficiency 1-2 octaves above). It also increases the range in which the driver is operating in "sealed mode". I find this desireable as I prefer sealed designs in most cases.
I.E. if we choose 20Hz as the lower threshold of audibility, then a 10Hz tune makes perfect sense. 25Hz is actually much more audible than 20Hz (16Hz is barely audible to me). 12.5Hz is a tune which Rythmik has been offering for almost 10 years now. I don't find it a stretch to say that the FV15HP has been the standard of 15" ported subs and still is. Their recent port improvement has mitigating the chuffing issue in single port mode.
In regards to boominess I have been using Energy S8.3 (same as the Mirage Omni S8) subwoofers for years (office, exercise room, etc.). The tune is ~30Hz and they are far from boomy. I have dual Acoustic Research FPS-10's under the bed in our master BR. Their tune is ~40Hz and they aren't boomy (by my standards at least). I have a few TurboSound PA subs tuned closer to 50Hz. They are fairly boomy inside. However they are designed for large open spaces, not small rooms.
Maybe not to your satisfaction, but I believe we have proven that there is more to it than amplitude response and compression sweeps. The PSA V1801s (and likely the V36xx) was far more suitable in
's room than the JTR Caps 1400 & 2400ULF (which he documented very well).
what first-hand experience do you have with low-tuned subs? Are you willing to host a GTG (the more ears the better)? We can arrange for a couple of low-tuned subs to test. The JTR 2400 and Rythmik FV15 or FV18 are quite manageable in size. You would then be able to control all of the variables and test your hypotheses. I'd be very interested to participate and see what differences are actually detected blind (I do believe that psychoacoustics often affects our perceptions). What do you say? (No rush, anytime in 2019 would do)