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[Jeffrey l jones]

In my opinion, the wrong terminology is 'low-cut', which some mixers use to refer to the HPF on the mic inputs. The accepted standard is HPF and LPF, so mixer manufacturers are just creating confusion when calling HPF filters 'low cut'


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No understanding how allowing high frequencies in my subs helps.

[Debbie Dunkley]

Inside a powered subwoofer, frequencies HIGHer than ~25Hz are passed to the driver. Frequencies LOWer than ~100Hz are passed to the driver. It contains both a low- and high-pass filter used by itself, internally.

Some subwoofers are meant to be used with tops that don't have a high-pass filter at the sub/top crossover region (~100Hz). Those subs will have a high-pass output for the top. Those tops still have high pass filters on every driver whether being used with a previously high-passed signal or not.

Debbie, I know you know how all this works, I'm just trying to put words to why high-pass is the correct terminology for both cases.

I appreciate all the responses Corey because I realize everyone is trying to clarify for me so I'm probably not explaining myself well - sorry... I have a rotten cold and feel like like poop so not a clear head I'm afraid...

Ok so - yes I suppose I wasn't even considering the high pass above 25-30hz. It is more the output term that is confusing to me. I use it all the time but I just started questioning whether it is correct or not.....

So .....
JBL PRX718xlf. Has high pass (output) which only sends everything above 120hz to the tops. This seems to me to be correct terminology- passing high frequencies.
QSC KW181. Has high pass but sends the whole range of frequencies through to the tops. So how can they both  be called the same thing?
How does one distinguish between 2 different subs if both are described this way yet one passes all freq and the other only high frequencies?

[Corey Scogin]

JBL PRX718xlf. Has high pass (output) which only sends everything above 120hz to the tops. This seems to me to be correct terminology- passing high frequencies.
QSC KW181. Has high pass but sends the whole range of frequencies through to the tops. So how can they both  be called the same thing?
How does one distinguish between 2 different subs if both are described this way yet one passes all freq and the other only high frequencies?

The JBL has a HIGH-pass OUTPUT.
The QSC has a FULL-range OUTPUT.

[Debbie Dunkley]

Sorry Jeffrey- didn't mean to derail too much.

[Debbie Dunkley]

The JBL has a HIGH-pass OUTPUT.
The QSC has a FULL-range OUTPUT.

OK so i should be using the term HP output when referring to this function. Thanks Corey..... I know this sounds trivial but it threw me when it was pointed out that all subs have HP.  I suppose I assumed the meaning was HP output.

As you were ... Thanks all!

[TJ (Tom) Cornish]

I appreciate all the responses Corey because I realize everyone is trying to clarify for me so I'm probably not explaining myself well - sorry... I have a rotten cold and feel like like poop so not a clear head I'm afraid...

Ok so - yes I suppose I wasn't even considering the high pass above 25-30hz. It is more the output term that is confusing to me. I use it all the time but I just started questioning whether it is correct or not.....

So .....
JBL PRX718xlf. Has high pass (output) which only sends everything above 120hz to the tops. This seems to me to be correct terminology- passing high frequencies.
QSC KW181. Has high pass but sends the whole range of frequencies through to the tops. So how can they both  be called the same thing?
How does one distinguish between 2 different subs if both are described this way yet one passes all freq and the other only high frequencies?

Subwoofers use a low-pass filter to prevent high frequencies from being reproduced in the sub.  More important than that, subwoofers need a high-pass filter to prevent them from trying to reproduce frequencies lower than they can handle, which will quickly cause speaker damage.  This high-pass filter will be somewhere between 25Hz and 40Hz.  All self-powered subwoofers will have this high-pass filter built-in, but it needs to be manually added for passive subwoofers.

[Tim Tyler]

Deb -

High pass does NOT mean high frequencies.  It means passing frequencies ABOVE (higher than) a given frequency.

Ex.   A given frequency:   40 Hz   
-  frequencies allowed above 40 Hz are HIGH PASSED frequencies - a high pass of 40
-  frequencies allowed below 40 Hz are LOW PASSED frequencies - a low pass of 40
-  or pick any frequency...

-Hope this helps...

-Tim T

[Debbie Dunkley]

Subwoofers use a low-pass filter to prevent high frequencies from being reproduced in the sub.  More important than that, subwoofers need a high-pass filter to prevent them from trying to reproduce frequencies lower than they can handle, which will quickly cause speaker damage.  This high-pass filter will be somewhere between 25Hz and 40Hz.  All self-powered subwoofers will have this high-pass filter built-in, but it needs to be manually added for passive subwoofers.

So if a passive speaker just uses a resistor and this is what was missing from the sub in question, then it wasn't suitably protected from frequencies below what the driver is designed to produce?

[Alex Rigodanzo]

In my opinion, the wrong terminology is 'low-cut', which some mixers use to refer to the HPF on the mic inputs. The accepted standard is HPF and LPF, so mixer manufacturers are just creating confusion when calling HPF filters 'low cut'


Sent from my iPhone using Tapatalk

Not confusing at all if you came from older home audio where most receivers and pre or integrated amps had a low cut (or rumble) filter to reduce turntable feedback.  Low cut describes what's happening just the same as high pass.

[Debbie Dunkley]

Deb -

High pass does NOT mean high frequencies.  It means passing frequencies ABOVE (higher than) a given frequency.

Ex.   A given frequency:   40 Hz   
-  frequencies allowed above 40 Hz are HIGH PASSED frequencies - a high pass of 40
-  frequencies allowed below 40 Hz are LOW PASSED frequencies - a low pass of 40
-  or pick any frequency...

-Hope this helps...

-Tim T

I realize that Tim - I just wasn't considering the HP used at the low end range in the sub - my head was totally into the HP OUTPUT..
Like I said - I have a cold ....LOL ( it's a Basil Fawlty thing - the Brits and any Fawlty Towers fans will get it)

[ProSoundWeb Community]