My dumb question of the day: What does roll off mean

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tonyoci

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OK so I get the general idea that "roll off" the bass means reduce the bass, but what is "roll off" is that reduce something in particuar, a gradual decrease down the frequencies or just another word for reduce.

Thanks, I have many more of these dumb questions :)
 
Ok imagine you're looking at a graphical eq plug in. Now assuming you know what kind of eq i'm talking about a roll off is simple its exactly what it says. you roll off the frequencies gradually to nothing. I usually start my roll off around 30 to 40 hz. It looks just like a slope from 40hz down to nothing. You can also do this on the highs. This probably didn't help at all, I'm terrible at describing things.
 
No that did help, it was what I had guessed, a slope down towards either end depending on whether you're rolling off highs or lows,

thanks

Tony
 
tonyoci said:
is that reduce something in particuar, a gradual decrease down the frequencies
Click to expand...

yeah, that one.
a gradual decrease or slope set to a certain degree that is usually adjustable. some roll offs such as microphones that have this function are not adjustable.
 
a typical "roll off" on a mic is -12 db up to 80 hz.
 
Roll off has to do with the slope of the cut. Yes, it means a reduction, but it also implies a gradual reduction spread out over a range of frequencies.

Bass "cut" rather than "roll off" implies a much sharper slope. More reduction in less frequency width.


sl
 
I bet the terminology comes from either the curve, or the fact that there used to be no faders, only knobs, and rolling or turning the knob made the desired changes.

Kind of like hanging up a phone, from the old days when all phones had an earpiece that you hung on the phone after you were done.

Who knows.
 
As I understand it

Roll off does look like the curve - - -

The curve being the graph of the equations for the phase reactivity to the circuit capacitance or inductance VS frequency.
 
A Bass roll off switch on a mic is just a high pass filter. Filters can come in high pass, low pass and band pass. A high pass filter does exactly what it says, it pass the highs through while cutting the lows on a slope. The start of the slope is measured at what's known as the "3 dB down point" It's eaiser to measure a signal after it's dropped 3 dB rather than trying to measure exactly where it starts to roll off. With that said, it's important to remember that if you set a high pass filter to 80Hz, you're still cutting a few frequencies above 80Hz. The rate at which the filter rolls off the frequencies is measured in dB per octave (usually written as dB/8v) So, if you have a high pass filter centered at 80Hz with a 6dB/8v filter, your basicly dropping the signal 6dB from 80-40 and another 6dB from 40-20, giving you 12dB of loss from 80-20. Some filters can be as sharp as 24dB/8v. The sharper the slope, the more the frequencies get cut. Microphones like the Shure SM81 have slope switches like this. Some folks will use the term roll off with turning down frequencies on a parametric or shelving EQ, but this is usually refered to as a cut.

M. Tristan
 
RedFrogAudio said:
A Bass roll off switch on a mic is just a high pass filter. Filters can come in high pass, low pass and band pass. A high pass filter does exactly what it says, it pass the highs through while cutting the lows on a slope. The start of the slope is measured at what's known as the "3 dB down point" It's eaiser to measure a signal after it's dropped 3 dB rather than trying to measure exactly where it starts to roll off. With that said, it's important to remember that if you set a high pass filter to 80Hz, you're still cutting a few frequencies above 80Hz. The rate at which the filter rolls off the frequencies is measured in dB per octave (usually written as dB/8v) So, if you have a high pass filter centered at 80Hz with a 6dB/8v filter, your basicly dropping the signal 6dB from 80-40 and another 6dB from 40-20, giving you 12dB of loss from 80-20. Some filters can be as sharp as 24dB/8v. The sharper the slope, the more the frequencies get cut. Microphones like the Shure SM81 have slope switches like this. Some folks will use the term roll off with turning down frequencies on a parametric or shelving EQ, but this is usually refered to as a cut.

M. Tristan
Click to expand...

Damn you sound like my teacher...

Wait I think you ARE my teacher....

Mike?
 
Well, if you go to HCC in Houston and are in my class, then yes I am your teacher... where's your homework???
 
Dammit now I have to find somewhere else to get the answers to your take home tests...

And why are you just giving away the info that I'm paying for at school? :p :D
 
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