How can monitors with holes not be out of phase?
Posted: Mon May 01, 2017 2:14 am
How can the phase component of frequency response graphs for monitors that have holes in them be correct?
The wikipedia page on frequency response graphs defines frequency response as: "a measure of magnitude and phase of the output as a function of frequency, in comparison to the input"
With sealed speakers that have no holes, it's easy to understand to see how both the phase and magnitude of the output can match the input.
However, with speakers that have holes in them, especially in the back, a significant portion of the sound is necessarily going to be out of phase in comparison from the sound coming directly off the speaker face since the distances are so different.
For instance, suppose you have a monitor with holes in the back and it's placed 5 feet from a wall. At 1.12533 ms/foot, the sound coming off the wall is going to be about 11 ms delayed which will make it quite hard to hear what a kick is actually doing since you'll get an overlay of the initial attack and middle "formant" section of the kick sample.
For a monitor with holes in the front, the sound from the hole will be out of phase by about double the depth of the monitor, if it's internally 1 foot deep it should have an out of phase component of about 2 ms or so.
I've noticed that in many pro studios, the monitors are set inside the walls to minimize the sound coming off the other faces of the speaker. I've also found that wrapping the sides and back of my monitors with acoustical blankets significantly clears up the low mid ranges.
So my question is, are unsealed monitors always going to have the out of phase component and therefore be avoided, or am I making a mistake somewhere and that it really is possible for the two paths the sound takes to end up back in phase?
The wikipedia page on frequency response graphs defines frequency response as: "a measure of magnitude and phase of the output as a function of frequency, in comparison to the input"
With sealed speakers that have no holes, it's easy to understand to see how both the phase and magnitude of the output can match the input.
However, with speakers that have holes in them, especially in the back, a significant portion of the sound is necessarily going to be out of phase in comparison from the sound coming directly off the speaker face since the distances are so different.
For instance, suppose you have a monitor with holes in the back and it's placed 5 feet from a wall. At 1.12533 ms/foot, the sound coming off the wall is going to be about 11 ms delayed which will make it quite hard to hear what a kick is actually doing since you'll get an overlay of the initial attack and middle "formant" section of the kick sample.
For a monitor with holes in the front, the sound from the hole will be out of phase by about double the depth of the monitor, if it's internally 1 foot deep it should have an out of phase component of about 2 ms or so.
I've noticed that in many pro studios, the monitors are set inside the walls to minimize the sound coming off the other faces of the speaker. I've also found that wrapping the sides and back of my monitors with acoustical blankets significantly clears up the low mid ranges.
So my question is, are unsealed monitors always going to have the out of phase component and therefore be avoided, or am I making a mistake somewhere and that it really is possible for the two paths the sound takes to end up back in phase?