Hello, I have a question that runs in my mind about crossover freq, we have the usual passive crossovers low pass/high pass 2.5khz , 3, 3.5 ,4 etc, and active with a knob from 250 to 100hz for low pass on car amps for example.
Let's say we need a high pass filter for our tweeters let's say at 3khz ( active or passive doesn't matter ) , now if we look at the musical notes frequencies , closest to 3khz we have :
if we look for 3.5khz we have:
3520hz which is closer to 3500, we use 3500 instead of 3520 for "easier manufacturing" component values ? or why.
Is there a difference if we cross over at 3khz or cross over on the " exact note freq " at 2959hz ?.
, Bruno.
Let's say we need a high pass filter for our tweeters let's say at 3khz ( active or passive doesn't matter ) , now if we look at the musical notes frequencies , closest to 3khz we have :
F#7/Gb7 | 2959.96 |
G7 | 3135.96 |
A7 | 3520.00 |
Is there a difference if we cross over at 3khz or cross over on the " exact note freq " at 2959hz ?.
, Bruno.
Crossovers are not generally designed based on the frequency of a musical note (although I imagine some have done so). They're usually selected for reasons of on & off-axis frequency response, distortion performance, power-handling and when relevant cost (so in those cases they may be working with a natural rolloff etc.).
Perhaps the following is another way of looking at it?
The summed response of a 2-way crossover would ideally be flat and would not distinguish between frequencies such as 3000 Hz and 2959 Hz.
The summed response of a 2-way crossover would ideally be flat and would not distinguish between frequencies such as 3000 Hz and 2959 Hz.
Even if it was a good idea to align crossover frequencies to specific notes, you couldn't rely on those frequencies being constant. For instance if you use the speakers to watch films here in the UK, they are likely to have been resampled from 24fps to 25fps, which means a 3520Hz A would actually be played at 3667Hz.
Not only is the crossover frequency not related to musical frequencies, you're unlikely to have components to distinguish (using your example) 3500Hz and 3520Hz - that's a less than 1 percent frequency change, you'll have to spend extra for 1% tolerance components or buy many to measure them to match within 1%.
It may be worth doing to make sure the speakers match, but you would also want to measure driver impedance, sensitivity and such.
It may be worth doing to make sure the speakers match, but you would also want to measure driver impedance, sensitivity and such.
No, its unimportant. What is important is that the transition band (here from say 1kHz to 10kHz very roughly speaking) is well behaved, smooth and the two drivers complement each other across the transition band. Whether the nominal cross over freq is 2.9kHz, 3.2kHz or whatever is the least of your concern - cross over is not something that happens at one frequency (if it were, it would be very noticable as a note slides across that frequency and jumps from one driver to another with much phase variation).