In theory, a second-order filter requires to reverse the polarity of one driver to let the sound wave in-phase at a region near the crossover point. But in practice, many designs have no reversing performed on the driver and the system's frequency response can still be flat.
In the case of both flat frequency responses, which one is better between reverse and non-reverse polarity, assume performing on the tweeter of a 2-way system? Please share your opinion. Thank you in advance
In the case of both flat frequency responses, which one is better between reverse and non-reverse polarity, assume performing on the tweeter of a 2-way system? Please share your opinion. Thank you in advance
If we are talking about 2nd order Linkwitz-Riley (LR2) filtering, then a reversed polarity between the drivers is needed for a textbook-like phase and frequency response.
If you have flat frequency response with non-reversed polarity, then the followings are possible:
1. the drivers acoustical responses doesn't follows enough the LR2 slopes
2. The acoustical distances from the drivers to the listening (or measuring) spot is not equal
So which is better? I don't know, but usually i try to follow textbook responses as much as possible.
If you have flat frequency response with non-reversed polarity, then the followings are possible:
1. the drivers acoustical responses doesn't follows enough the LR2 slopes
2. The acoustical distances from the drivers to the listening (or measuring) spot is not equal
So which is better? I don't know, but usually i try to follow textbook responses as much as possible.
The reverse-polarity thing only applies if the acoustic centres are aligned. This may not be the case.
Chris
Chris
I tend to find it goes either way? Regardless, neither polarity is necessarily better.
In addition, second order filters are often used to achieve higher order rolloffs which may change the expected polarity.
To answer the question, there is a metric by which you can judge this - group delay.
In addition, second order filters are often used to achieve higher order rolloffs which may change the expected polarity.
To answer the question, there is a metric by which you can judge this - group delay.
If we were to modify the speaker whose frequency response is not flat,
A) Without tweeter reversed polarity, its default setting from the factory, the sound is slightly reduced in mid-range. The frequency response curve is estimated as a slight "V" shape.
B) With tweeter reversed polarity, the mid-range is greatly boosted. The frequency response curve is a slight "^" shape. It seems to be good since the detail is more produced. But, it causes fatigue when listening for a long period.
To improve this speaker, we have to flatten the response curve. But there's a question that should we increase the mid-range from condition A) or decrease mid-range from condition B)?
What do you think? Thanks in advance
A) Without tweeter reversed polarity, its default setting from the factory, the sound is slightly reduced in mid-range. The frequency response curve is estimated as a slight "V" shape.
B) With tweeter reversed polarity, the mid-range is greatly boosted. The frequency response curve is a slight "^" shape. It seems to be good since the detail is more produced. But, it causes fatigue when listening for a long period.
To improve this speaker, we have to flatten the response curve. But there's a question that should we increase the mid-range from condition A) or decrease mid-range from condition B)?
What do you think? Thanks in advance
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This is so generic it's basically meaningless in practice, although the short answer is that there is likely to be little practical difference if you modify each leg of the filter in the same way. 'Reversed polarity' and 'without reversed polarity' in themselves have almost zero meaning without proper context.
You're also riddling it with further assumptions, e.g. that to 'improve' things, you need to flatten the response curve in all times and places. To which I would point out that what is optimal in fact will also depend on the exact frequencies in question, the power response & distortion performance, to say nothing of the room, speaker & listening positions in that space.
You're also riddling it with further assumptions, e.g. that to 'improve' things, you need to flatten the response curve in all times and places. To which I would point out that what is optimal in fact will also depend on the exact frequencies in question, the power response & distortion performance, to say nothing of the room, speaker & listening positions in that space.
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In addition to the frequency graph, you must also watch the phase-frequency characteristic, and necessarily in a comparative measurement with angles of 0, 15, 30 degrees.
Speakers in common mode can give beautiful measurements at 0 degrees, but at an angle of 30 degrees they will all be sad.