by kbakken » Thu Nov 29, 2007 8:20 am
solacedagony wrote:Only there IS content over the "cutoff limit" or crossover point. Say you're using a 2nd order LR. Your signal is -3db at 80hz and -15db at 160hz. When you apply the second one, it's cascading on that last crossover. Now you're -6db at 80hz and -30db at 160hz.
The device doesn't "see" anything. It's like saying if you EQ your tweeter to -5db @ 80hz, it's not actually happening. Even if the signal at 160hz was down to -100db, it'd now be -112db. Just because you can't hear it doesn't mean it's not there. :happy055:
I'd hate to be so blunt, but you are wrong :) . Makes no sense. If you apply a rule with one device, and the same rule with another, it makes no sense that it would compound. "Just because you can't hear it doesn't mean it's not there"; if the HU cuts the signal (say low pass at 80Hz), then the amp doesn't "see" anything below 80Hz. The resulting music signal is now everything above 80Hz.
Also, try to understand that a frequency is a frequency. 80Hz is in the low-mid bass range (like part of a kick drum in a band). You mean to tell me that if you kept applying filters to it (of the same 80Hz cutoff), that you would eventually cut into the high sound of the guitars (around 500Hz and higher)? There's no way. Impossible. 80Hz is just that, 80Hz.
If you wanted to cutoff at 160Hz, then you would apply that rule to one of the devices. If you did it to the second one in line, this would effectively (what we hear) null the first one which is at 80Hz. But in terms of the audio signal, the first one cuts it at 80Hz, then the second one only sees the altered audio signal as everything above 80Hz, then cuts it at 160Hz. If you reverse the two where 160Hz is the first one and 80Hz is the second one: the first one cuts it at 160Hz, and the second one sees the altered music signal at everything above 160Hz. Therefore, the rule at the second one of 80Hz cutoff, would not effectively do anything to the audio signal since there is no 80Hz in the signal passed to it.
The same can be said for rolloff (slope). It does not add up in the end. It is what it is. If one rolls of at 3db/oct and the other at 12db/oct, the more extreme will be cut from the signal, and therefore be heard.
Graph out a frequency curve and overlap the two filters to see a graphical representation.
I like talking this kind of stuff. :)
[quote="solacedagony"]Only there IS content over the "cutoff limit" or crossover point. Say you're using a 2nd order LR. Your signal is -3db at 80hz and -15db at 160hz. When you apply the second one, it's cascading on that last crossover. Now you're -6db at 80hz and -30db at 160hz.
The device doesn't "see" anything. It's like saying if you EQ your tweeter to -5db @ 80hz, it's not actually happening. Even if the signal at 160hz was down to -100db, it'd now be -112db. Just because you can't hear it doesn't mean it's not there. :happy055: [/quote]
I'd hate to be so blunt, but you are wrong :) . Makes no sense. If you apply a rule with one device, and the same rule with another, it makes no sense that it would compound. "Just because you can't hear it doesn't mean it's not there"; if the HU cuts the signal (say low pass at 80Hz), then the amp doesn't "see" anything below 80Hz. The resulting music signal is now everything above 80Hz.
Also, try to understand that a frequency is a frequency. 80Hz is in the low-mid bass range (like part of a kick drum in a band). You mean to tell me that if you kept applying filters to it (of the same 80Hz cutoff), that you would eventually cut into the high sound of the guitars (around 500Hz and higher)? There's no way. Impossible. 80Hz is just that, 80Hz.
If you wanted to cutoff at 160Hz, then you would apply that rule to one of the devices. If you did it to the second one in line, this would effectively (what we hear) null the first one which is at 80Hz. But in terms of the audio signal, the first one cuts it at 80Hz, then the second one only sees the altered audio signal as everything above 80Hz, then cuts it at 160Hz. If you reverse the two where 160Hz is the first one and 80Hz is the second one: the first one cuts it at 160Hz, and the second one sees the altered music signal at everything above 160Hz. Therefore, the rule at the second one of 80Hz cutoff, would not effectively do anything to the audio signal since there is no 80Hz in the signal passed to it.
The same can be said for rolloff (slope). It does not add up in the end. It is what it is. If one rolls of at 3db/oct and the other at 12db/oct, the more extreme will be cut from the signal, and therefore be heard.
Graph out a frequency curve and overlap the two filters to see a graphical representation.
I like talking this kind of stuff. :)