This isn't a question about velocity.
I've noticed that speakers with larger port volumes produce more woolly, loose bass when compared to their counterparts.
e.g. a cabinet tuned to 50hz using a 50mm port sounds better than one tuned to the same frequency using a 75mm port.
How does the volume of resonator affect performance?
nb: The port frequency remains the same regardless of diameter, length is adjusted to maintain frequency.
I've noticed that speakers with larger port volumes produce more woolly, loose bass when compared to their counterparts.
e.g. a cabinet tuned to 50hz using a 50mm port sounds better than one tuned to the same frequency using a 75mm port.
How does the volume of resonator affect performance?
nb: The port frequency remains the same regardless of diameter, length is adjusted to maintain frequency.
You first need to define what is not woolly, not loose bass.
Then maybe someone can tell what is better/correct, woolly or not woolly.
Actually nearly every one had is own preference and nothing is 100% best for every one.
I prefer OB bass, without any port or cabinet.
Technically there is difference in Q of the resonators (box volume and port defined Helmholtz resonator), but there are also driver parameters involved and for some drivers 75 mm is better for some 50 mm.
Then maybe someone can tell what is better/correct, woolly or not woolly.
Actually nearly every one had is own preference and nothing is 100% best for every one.
I prefer OB bass, without any port or cabinet.
Technically there is difference in Q of the resonators (box volume and port defined Helmholtz resonator), but there are also driver parameters involved and for some drivers 75 mm is better for some 50 mm.
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I can only explain in non-technical terms.
A driver will produce direct, authentic bass.
A port will produce indirect bass enhancement within a narrow frequency band.
Driver: Air - Ear.
Port: Driver - Air - Port - Air - Ear.
The second-hand nature of port bass renders it a delayed, poor quality analogue copy.
When the efficiency of the port bass approaches that of direct driver bass the sound becomes one-note-ish and the overlap creates a sound reduced in decay.
Does that make sense to anybody?
A driver will produce direct, authentic bass.
A port will produce indirect bass enhancement within a narrow frequency band.
Driver: Air - Ear.
Port: Driver - Air - Port - Air - Ear.
The second-hand nature of port bass renders it a delayed, poor quality analogue copy.
When the efficiency of the port bass approaches that of direct driver bass the sound becomes one-note-ish and the overlap creates a sound reduced in decay.
Does that make sense to anybody?
In theory the port is not delayed, it is a minimum phase device even though it's not in phase.
A larger diameter port has a larger cross section as well as needs to be longer for the same tuning frequency. Did you compensate for that? If not, and you just put a larger port in the same volume box, since the larger port itself takes up more volume you're now operating at a smaller net volume.
How did you determine the tuning frequency?
How did you determine the tuning frequency?
At port frequencies, how the speaker is placed in the room will probably play a large part in the outcome, unless your room is anechoic.
Don’t know if this has a bearing, but the long, very high aspect ratio vebts used in our miniOnkens subjectively gives elegant, very well behaved bass response. The shape of the vebnts pushges the box towards aperiodic making them less sensitive to the dynamic changes in T/S parameters meaning the boxes don’t go out of tune as easily with any adjustment in the amount of wick you are giving them.
To use them i have had to come up with my own alignment, modelers do not take the extra vebnt R into consideration. They only go as low as they go.
dave
To use them i have had to come up with my own alignment, modelers do not take the extra vebnt R into consideration. They only go as low as they go.
dave
Probably 2 factors:
The tuning frequency might be the same, but the Q will be different when changing vent dia. and length.
The ports will have different behaviour in how they resonate at higher unwanted frequencies and how they leak out internal cabinet resonances.
The tuning frequency might be the same, but the Q will be different when changing vent dia. and length.
The ports will have different behaviour in how they resonate at higher unwanted frequencies and how they leak out internal cabinet resonances.
There is one parameter that does change with a larger port diameter, that is the port length increases. The increase in length pushes the fundamental port resonance lower. Likely the this is the "Woolly" sound your are hearing. In addition, the Larger port is likely to allow more mid-range frequencies to escape form the inside of the enclosure. These mid-range frequencies include reflections and standing waves from the box interior.