Questions about low cut filter on DBX 231 EQ?

[papejazzer]

Hello hope all of You had a good Memorial day weekend.

 

First let me list some equipment I am using. AH Mixwiz, DBX 231 EQ, DBX 223XL crossover, Peavey CS 2000, Peavey SP 118 (New style, Peavey Black Widow speaker, 8 ohms, rated 600/1200/2400).

 

I am running only one sub (mono summed) out of the DBX 231 crossover into one channel of the newer style Peavey CS 2000 power amp.

 

The DBX 231 EQ manual gives two different specs for the LOW CUT SWITCH.

 

Page 6. of the manual states 12 db per octave 50 Hz low cut filter.

 

Page 7. states Low Cut Enable Switch inserts or removes the 18dB/ octave 40 Hz low cut filter from the signal path.

 

Page10. under Specifications, FUNCTION SWITCHES, it states Low Cut: Activates the 50 Hz 12 dB/ octave high-pass filter.

 

Is the low cut filter 50 Hz 12 dB/ octave or 40 Hz 18dB/ octave?

 

Can I assume, if it is 50 Hz 12 dB, that it would be better to use the low cut on the EQ rather than the 40 Hz 12 dB on the DBX 223XL crossover?

 

Is it OK to have them both engaged at the same time?

 

I have the crossover set, stereo, using only one side, mono Low Sum, at approx. 100 Hz.

 

For tops I may use (according to need) one Powered Peavey Impulse 12 D, Two Peavey passive 115 EU's or Two JBL passive MRX 512's.

 

I also have a Peavey PV 3800 and a Peavey IPR 3000.

 

Thanks, Michael

[agedhorse]

I have a 131 on the bench and it appears to be a 12dB/octave HPF, though I can't test for cutoff frequency as it's waiting for parts.

 

I think that with a second order filter, you would be fine with either 40Hz or 50Hz but not both together as that would increase the cutoff to >60Hz.

[papejazzer]

Thanks agedhorse!!! Your knowledge and Your willingness to share it with others is invaluable to this Forum and the People who come here. Thank You again. Have a GREAT week. Michael

[agedhorse]

You are most welcome.

[TimmyP]

I hope it's better than the filter on their analog crossovers, which is actually a shelving filter.

[RoadRanger]

I hope it's better than the filter on their analog crossovers, which is actually a shelving filter.

Are you talking about the 40Hz filter? How do you know?

[agedhorse]

I hope it's better than the filter on their analog crossovers, which is actually a shelving filter.

 

Good grief, I sure as hell hope the HPF is a shelving filter, that's what it's SUPPOSED to be. (clarification of terminology... being conventional HPF rather than peak/dip type, and not a Baxandall type)

[Rezrover]

[RoadRanger]

Out here a shelving filter looks like this:

and a HPF like this:

 

Note the -12db "shelf" on the former that limits the maximum "cut".

[agedhorse]

The difference is in the terminology, and who is using the terminology. Colloquial use of a filter type in context is that a HPF is a shelving type as opposed to a bandpass or peak/dip. In audio terms, shelving can mean 2 different things unfortunately, a Baxandall type of shelving filter, for example, has ultimate plateaus, whereas a state variable or infinate feedback type filter generally does not... but it can be configured to if that's desired. This is a case of my assuming that you were following the context of the filters being discussed colloquially.

 

I happen to have a DBX-231 eq on the bench right now so I ran it through the analyzer and it's response is a standard second order Butterworth high pass filter and not a peak/dip filter (which can be useful in certain applications, specifically when used as a cascaded or compound asymmetrical filter but not here).

 

I don't know what terminology Timmy was using, but I am positive that the eq filter uses a traditional HPF (in the non-plateauing sense) and I have 99% confidence that the same is true for the crossover though I do not have one to verify here.