Parametric EQ Basics

  • Thread starter Thread starter HRmusic90
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HRmusic90

HRmusic90

21st Century Digital Boy
Hello, I'm having fun playing with the parametric EQ plugin with my Sound Forge software, but I'm trying to figure out something.
I get the basic idea of parametric EQ - it lets you hone in on a specific frequency. But after looking up units online, I notice they often have a symbol that looks like a wishbone opening either to the left or to the right. What does this symbol mean? What does that tell me about what my EQ is doing?
 
That is the shelving of the low end or high end roll off. Most can be switched to a bell curve.
 
I guess I'm more ignorant to this stuff than I thought. What is "shelving"? What is a "shelf" with respect to audio engineering?
 
Say you set the top end at, for instance, at 8K it will shelve down from there (8K) giving you the roll off of the higher frequencies.
The same can be said for the low end roll off where as if you set it at 100 everything below that will be rolled off.
 
Actually a shelving EQ isn't really a roll off as it can also be used to boost the highs or lows as well, the high pass/low pass filters are cut only, they are the symbols that look bent down to the right or left.
 
Here's what shelf eqs look like, showing a low shelf cut with a steep roll off and a high shelf boost with a shallow roll off:

shelving.jpg
 
Strryder said:
Actually a shelving EQ isn't really a roll off as it can also be used to boost the highs or lows as well, the high pass/low pass filters are cut only, they are the symbols that look bent down to the right or left.
Click to expand...

Right you are Strryder.
I always refer to it as a roll off for I don't think that I have ever used the shelving to boost. Yet you can if you want/need to. Sorry HRmusic90, My bad.
 
bouldersoundguy said:
Here's what shelf eqs look like, showing a low shelf cut with a steep roll off and a high shelf boost with a shallow roll off:

shelving.jpg
Click to expand...



There you go. A picture is always worth a thousand words.
 
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Thank you for the picture. That actually does help me get the hang of the "shelf" idea. And thanks for all the replies.
 
Oh I'm sure I'm not :p When I get some more free time I'll have to play around with it some more.
 
HRmusic90 when you said wishbone I was thinking more Q size then bell curves. if its a wish bone its the actual size of the band narrow or wide. Moresound is right tho
 
Here's a picture I found where I highlighted the symbols I was confused about:
ParamEQ.webp

I'm still not 100% clear on what that symbol is telling me. Is it one thing branching off into two things or two things converging into one thing?
 
The reason it looks like a wishbone is because it's one branching off into two, displaying that you can either boost the frequency (the top of the wishbone), or cut it (the bottom of the wishbone).

If that doesn't really make sense, look at your picture where the yellow dot is boosted. That's called a "bell-curve." If you look at the where you have circled, next to the wishbone is a sort of circle. The circle just shows that with a bell curve, you can either increase the level (the top of the circle), or decrease the level (the bottom of the circle).

I see you're running Pro Tools. I'm not sure if you're aware of this (and I mean no offense to you by saying this), but when the wishbone is light blue like that, it means it's not selected, so your High Frequency knob (The dark blue) and the Low Frequency knob (dark red) are set to use the same kind of "bell-curve" as the Yellow circle. Clicking on the blue wishbone makes it grey, and it means that your High Frequency or Low Frequency is now acting as a "shelving" instead of a "bell" EQ.
 
Ahh. Thank you! That's a lot clearer.

I'm actually not running Pro Tools :o I just did a Google image search for "parametric EQ" to find what I was looking for.
 
I'm using Sound Forge Pro 10. I usually mix the individual tracks in ACID and finish with Sound Forge. It's what I'm familiar with. I used to use these products back when they were still owned by Sonic Foundry!
 
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