The logic behind using a HPF on a crossover and not just pulling the EQ sliders down.

[Rezrover]

I know I read it on here somewhere, can't find it though.

[lifeloverwg]

There used to be a great set of EQ measurement files over on PSW that included the "death to 100hz" measurements, but I can't find them anymore.

 

Here's a good concise explanation for why a HPF is better that I did find though......

 

"When you push down all the faders on a graphic EQ below 100 Hz, you don't get a cut-off like you expect from a proper high-pass filter. Rather, you get the center frequencies for each band cut only 15 dB, with some ripple of less attenuation between each band.

 

So a proper 24 dB/octave high-pass at 100 Hz, like one would use with a crossover, is down 3 dB at 100 Hz, 27 dB at 50 Hz and down 51 dB at 25 Hz.

 

By contrast, the "death-to-100" is only down 15 dB at 25 Hz. That is a significant difference.

 

The whole phase discussion is beside the point when you realize that the amplitude in the Death Case is not what you think it is."

 

Winston

[agedhorse]

A proper crossover (24dB/octave LR) is 6dB down at 100Hz not 3dB. Important distinction since the error sums to give a hump (electrical) w/ other alignments like BW.

 

The problems with using an eq as a crossover is that the slope is between 6 and 12dB/octave (depending on type) and since it's a bandpass filter there is a finite cut amount (12-15dB), and between adjacent bands there will be a signioficant (3-6dB) response ripple. This is why some eq's have shelving HPF's built in.

[Rezrover]

Thank you!

[Gordon Sound]

My eq ( rane mojo) crossover ( rane mojo) and amps (Crown MA2400's) dont have a hi-pass what can I do?

[TimmyP]

 

My eq ( rane mojo) crossover ( rane mojo) and amps (Crown MA2400's) dont have a hi-pass what can I do?

 

 

Sounds like a good excuse to sell the Ranes and get a DSP.

[Scodiddly]

Another reason not to use the sliders is that often each slider has a tap at the center, such that the filter is essentially out of the circuit when left at 0dB. Each slider away from 0dB ends up adding a bit more noise to the output.

[agedhorse]

 

My eq ( rane mojo) crossover ( rane mojo) and amps (Crown MA2400's) dont have a hi-pass what can I do?

 

 

Your crossover has a HPF, sadly it's -3dB at 15Hz and 18dB/octave but it is a BW filter. In your case, dropping the bottom band is probably the least of the evils IMO.