Originally Posted by bear123
Concerning accuracy, articulation, speed, overhang, etc, some of these are somewhat "made-up" adjectives regarding subs. If you are after good sound quality, the answer is any well designed sub, ported or sealed, and properly integrating two of them into ones room with ones system. In the end, that is what determines sound quality.(Assuming you are starting with a decent quality sub). Overhang, by which I assume you mean ringing, is an actual and measurable trait. This will not be an issue in any well designed sub. However, interaction with the room is what will greatly determine ringing, even in a sub that has no ringing issues when measured in a field. Ported subs normally(always?) have some ringing around port tune, but you don't "hear" ringing at 17 Hz, especially since music doesn't realistically have much if any content that low.
Originally Posted by Rythmik
Hey bear, the speed (phase delay) is a real issue. If you look at the Databass JTR cap 1400 measurement specifically on spectrogram, it measures the energy "dispersion" (very similar to the optical dispersion) of bass signal. The red color represents the highest density/concentration of the energy. The y axis represents delay. Ideally, we want to see the red bar to be perfectly horizontal. But you can see the plot for cap 1400 almost looks like a caterpillar. The lower end is off the other frequency range by as much as 100ms? How much is 100ms, that is about tthe time that I need to adjust my set top box so that the voice and video match (or lip sync'ed). It is not insignificant. In addition, you will only see lower bass being delayed. You will not see lower bass being ahead of other frequencies. It is mathematically impossible. So our hearing hunch is correct. You will never hear someone says this bass is just too fast. Of course, this is just one reason some ported subs sound slower. Other reasons include the memory effect. But more importantly, the low bass delay shown in spectrogram is directly related to "overhang". This can be mathematically proved. So two of the four terms you mentioned indeed exist. The other two are more subjective. But again, some people understand and others take longer to learn.
A lot members here only focus on "rumbles". But rumble is static, meaning the signal is a steady state signal. But startling effect, which is another real fun of movies, is about dynamic characteristics of movie sound effects. I think what Bruce has described is exactly about this.
Originally Posted by Rythmik
What you observed is correct. The decay time of ringing is related to Q value. The effect becomes more prominent above Q=0.9. It is also peceived as boomy bass (or more full body bass) because the ringing lasts longer. But why do we put in Q value of 1.1 there in low damping? Because that is the Q value required to make the frequency response look more like a step. Lower Q will look like it has less bass extension on the frequency reponse curve.
Originally Posted by PlasmaPZ80U
that explains why mid/Q of 0.9 is preferable to me... it has just the right amount of ringing to work for both movies and music
In the 2.5 years that I have known about Rythmik subwoofers I have been learning all I can about them. Though I am far from an expert, I have to admit that the flexibility of the control options is very appealing to the engineer and tinkerer in me. I stumbled onto this interesting exchange in a recent search.
I took a look the data-bass reviews for the FV15HP, JTR Cap 1400, and PSA XV30SE (long out of production, BASH). It is amazing that the FV15HP is likely still the top production ported 15" (surpassed only by the 15.5" SVS PB16? I digress). A lifetime achievement award may be in order. Amidst releases of new subs by SVS, PSA, and JTR, while I am impatient I am still enthusiastic about the upcoming Rythmik models. I believe they will be well worth the wait and the price tag. I will not be surprised if Brian can deliver more for your buck than even JTR! This is a great day and age to be in the market for subwoofers. Rythmik, JTR, PSA, DSS, Seaton Sound, and Funk all seem to be hitting their strides!
Based on Brian's comments about caterpillar shaped spectrograms, overhang, and damping/Q I have developed several hypotheses. That 1-port mode should be the mode of choice for most FV15HP users. Does anyone use 2-port mode? Is port noise an issue in either mode? Does anyone go through the trouble of changing modes for movies vs music? That low damping/high Q may restore some movie impact that may appear to be lean in a head-to-head comprison, like @Cain
's F25s vs PSA S3000s. And, that the ported Rythmiks are likely the best compromise (from any vendor) for both movie and music. I can't wait for the FV18 and FV25 sightings to start trickling in!
I am hoping you can experiment with the F25 amplifier settings and report back. I'd like to add one more sealed sub to my room and it will likely be the F25 or another S3000i if at all possible (bass traps and treatments come first, scheduled to get our taxes done next week). I am also anxiously awaiting @wakeoftheflood
's comparison of dual F25s to dual S3000s
The great news is that I connected with @kyzer soze
and will have a chance to hear his FV15HP soon! I will finally be able experience Rythmik in the wild.