Guys are you not worried with a 65 hz Fs and a sealed at 100 hz XO ? Not fear to have a distorsion generator with all its harmonics there ?
Not only concerned with harmonics. Normally harmonics alone below 200Hz are normal and not a big concern.
Long slow normally woofer frequencies in the mid driver will force large voice coil displacements. Force factor will modulate and amplitude modulation will cause cause IMD's well up into the upper mid-range frequencies.
Hopefully the XO frequency is adjustable.
Long slow normally woofer frequencies in the mid driver will force large voice coil displacements. Force factor will modulate and amplitude modulation will cause cause IMD's well up into the upper mid-range frequencies.
Hopefully the XO frequency is adjustable.
Hi AllenB,
Highly curious with your input.
Say you have for illustration of ths thread a 60 hz mid Fs. You can cross it within the first octave say 100 hz for the op, without much problem. Not sure I understand what you illusrate. Much above my head, could you illustrate, please ? Is it to say it is possible with some care because in this bass area it is less important ? Does it means that disto because near cone Fs (break ups?) limits will not be distributed in the harmonic in the mid area with high spl : H2, H3, H4, H5 and so on, supersiding on mid fundamentals that could have less spl (especially above 800 hz) ?
I am trying to understand what you say, why do you feel cone breakup is a problem? Why do you say there is harmonic distortion? Do you say they are connected?
I believed there was an acoustic short cut near the Fs which is creating too much cone exursion.
So eventually creating high THD and all its harmonics polluting the rest of the driver frequency range.
In my simple view there is more THD when the frequencies are near the Fs. I eventually believed it was good for midrange to cross over at least one octave above to avoid those higher thd near the Fs to be distributed in its harmonics higher in the band. Break ups...my not acurate vocabulary. Perhaps cone modes or higher thd cause nearer to the xmax limit ?
when the amp is seing the higher ohms of the Fs ?
So eventually creating high THD and all its harmonics polluting the rest of the driver frequency range.
In my simple view there is more THD when the frequencies are near the Fs. I eventually believed it was good for midrange to cross over at least one octave above to avoid those higher thd near the Fs to be distributed in its harmonics higher in the band. Break ups...my not acurate vocabulary. Perhaps cone modes or higher thd cause nearer to the xmax limit ?
when the amp is seing the higher ohms of the Fs ?
So my asking is how one can manage to cross over near the Fs or in the Fs diving curve after the impedance peak ? Steep cut off ? LCR trap
I like to use compression tweeters across and below their resonance frequency(s). It's no problem playing at fs with the right driver and situation.
Dome tweeters are special for the way we decide to cross them higher than fs. In some ways it is because of their rolloff, and traditionally passive systems treat that as the end. Also, some avoid the impedance peak when crossing passively without measurement because it's easier that way. In addition, some people try to avoid the HD there, but it's not too bad with smaller amounts of lower order distortion.
Dome tweeters are special for the way we decide to cross them higher than fs. In some ways it is because of their rolloff, and traditionally passive systems treat that as the end. Also, some avoid the impedance peak when crossing passively without measurement because it's easier that way. In addition, some people try to avoid the HD there, but it's not too bad with smaller amounts of lower order distortion.
You should not be seeing cone modes at fs.
It is easy when you simulate. You can deal with the impedance peak and the response variation and you can get any result you want. I do the same checks with passive or active systems.
If you're going with sealed for this driver, the enclosure specs as simmed are 7.2 liter interior volume, with the Qtc of 0.5...which is noted as "transient perfect". The low end performance comes in at -3 Db @ 157.8 hertz.
-----------------------------------------------------------------------------------------------------------------------------------Rick...
-----------------------------------------------------------------------------------------------------------------------------------Rick...