Quote:
mrstampe wrote:
 Assuming both port ends are flared, is there a port velocity below which churfing can be avoided? I've seen this addressed in different ways and with different answers in several threads. |
Different people try to keep air velocity through the port below certain speeds to minimize chances of port chuffing. Depending who you ask you will get different answers, but in general lower is better. I generally try to keep max airspeed below 25m/s, but depending on application can allow for it to go higher.
Quote:
mrstampe wrote:
On a related question, how far above the low pass freq is it safe to have the first port resonance in order to avoid turning your sub into a trumpet? |
This depends on a couple factors mainly crossover order and crossover point. The lower frequency first resonance starts at the higher order crossover you will need to use to avoid reaching this band. I have heard and am currently building a pair of subwoofers whose first port resonance is about 120Hz. Due to this resonance happening at a pretty low frequency I will be using an extremely steep crossover (8th Order - 48dB/octave) and crossing the subwoofers over around 60-80Hz.