Hi guys
I have been reading recently that the woofer on some models of ML are wired out of phase with the panels.
This was in a comment regarding 'Absolute Phase'. Is it just matter of reversing the polarity on the woofer connections? I have them biwired so this would be easy to do.
What is likely to be the effect of carrying this out, better or worse. Also what is the idea of doing this as surely there must be some detrimental effect of doing this?
I do not have a circuit diagram so I can't check if this correct.
Regards to all
I have been reading recently that the woofer on some models of ML are wired out of phase with the panels.
This was in a comment regarding 'Absolute Phase'. Is it just matter of reversing the polarity on the woofer connections? I have them biwired so this would be easy to do.
What is likely to be the effect of carrying this out, better or worse. Also what is the idea of doing this as surely there must be some detrimental effect of doing this?
I do not have a circuit diagram so I can't check if this correct.
Regards to all
You can't damage the speaker by swapping its woofer leads. Assuming that the relative phasing would be either 0 degrees (in phase) or 180 degrees (exactly opposite phase), depending on which way you connect the woofer leads, you can verify the phasing by ear using a test tone that approximately matches the speaker's crossover frequency (so that about half the tone would play thru the panel and the other half thru the woofer).
First play the test tone thru the speaker at a comfortable volume level. Then, without changing the volume setting on your preamp, power off the amp, swap the woofer leads, power the amp back up and play the test tone again. Whichever woofer connection gives the loudest volume will be correctly phased. That is; when the panel and woofer are in phase their separate sounds combine constructively to give the highest relative volume. Conversely, if the woofer and panel are out of phase their separate sounds combine destructively, giving reduced volume.
First play the test tone thru the speaker at a comfortable volume level. Then, without changing the volume setting on your preamp, power off the amp, swap the woofer leads, power the amp back up and play the test tone again. Whichever woofer connection gives the loudest volume will be correctly phased. That is; when the panel and woofer are in phase their separate sounds combine constructively to give the highest relative volume. Conversely, if the woofer and panel are out of phase their separate sounds combine destructively, giving reduced volume.
Last edited:
See the attached plot set for a visual of the description CharlieM gave.
Basically whenever a woofers reponse is rolled off with a low-pass filter there is an accompanying phase shift.
Similarly, phase shift also is involved when rolling off the ESL response with a high-pass filter.
Sure it would be nice if both woofer and ESL were wired with the same absolute phase. But, it is much more important that they have the same phase thru the crossover region where they both are contributing significantly to the sound output. If they aren't in phase there, they cancel each other's output and you get a null in the response as shown in the left hand side of the plot set.
The plot set is for a 2nd order filter(12dB/oct slopes), and as you can see the summation thru the crossover region is best when the woofer and tweeter are wired out of phase. I'm not sure what type of crossover slope ML used, but if they wired the woofer out of phase with the ESL it was probably to achieve the best acoustic summation thru the crossover region.
As CharlieM mentioned, no harm in experimenting with the woofer phase.
The specified crossover frequency is 450Hz, so you you might start your listening experiment there.
Basically whenever a woofers reponse is rolled off with a low-pass filter there is an accompanying phase shift.
Similarly, phase shift also is involved when rolling off the ESL response with a high-pass filter.
Sure it would be nice if both woofer and ESL were wired with the same absolute phase. But, it is much more important that they have the same phase thru the crossover region where they both are contributing significantly to the sound output. If they aren't in phase there, they cancel each other's output and you get a null in the response as shown in the left hand side of the plot set.
The plot set is for a 2nd order filter(12dB/oct slopes), and as you can see the summation thru the crossover region is best when the woofer and tweeter are wired out of phase. I'm not sure what type of crossover slope ML used, but if they wired the woofer out of phase with the ESL it was probably to achieve the best acoustic summation thru the crossover region.
As CharlieM mentioned, no harm in experimenting with the woofer phase.
The specified crossover frequency is 450Hz, so you you might start your listening experiment there.
Attachments
Hi guys
Thanks for the replies. I'm travelling at the moment but when I get home I will give your suggestions a try.
Many thanks for your help
Best regards
Thanks for the replies. I'm travelling at the moment but when I get home I will give your suggestions a try.
Many thanks for your help
Best regards
Hi,
If you have a correctly designed pair of speakers, which implies
2nd order x/o acoustic slopes and the drivers wired out of phase,
then the only consequence of reversing one driver will be a huge
dip at the the x/o point, which is in fact a great test that the x/o
is phase correct and often shown in tests as the "reverse null".
The worse the null the better the x/o phase matches.
If anything it illustrates the utter nonsense of absolute phase,
however if your interested you need to compare reversing
both connections to normal, not changing one of them.
rgds, sreten.
If you have a correctly designed pair of speakers, which implies
2nd order x/o acoustic slopes and the drivers wired out of phase,
then the only consequence of reversing one driver will be a huge
dip at the the x/o point, which is in fact a great test that the x/o
is phase correct and often shown in tests as the "reverse null".
The worse the null the better the x/o phase matches.
If anything it illustrates the utter nonsense of absolute phase,
however if your interested you need to compare reversing
both connections to normal, not changing one of them.
rgds, sreten.
Last edited:
- Status
- Not open for further replies.