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Help Understanding Parametric EQ

G

Gladowsky

Apr 30, 2007
241
46
Iowa
#1
I've been using a Demeter HBP-1 preamp and am asking for clarity on a few items -- hopefully in layman's terms (am a bit embarrased at my lack of understanding this feature).

See attached image: the EQ has a frequency control for low and mid areas. What are the two stacked knobs for? Do you turn them to change the span between wide and narrow to select the frequency (that is my hunch)? Which knob, the small outward one or the one close to the panel controls the width vsl narrow settings or does it matter?

I would also like to better understand the terms "peaking" and "shelving".

If there is a website or manual that anyone could recommend that would be appreciated.

Thanks.
 

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#2
Gladowsky said:
I've been using a Demeter HBP-1 preamp and am asking for clarity on a few items -- hopefully in layman's terms (am a bit embarrased at my lack of understanding this feature).

See attached image: the EQ has a frequency control for low and mid areas. What are the two stacked knobs for? Do you turn them to change the span between wide and narrow to select the frequency (that is my hunch)? Which knob, the small outward one or the one close to the panel controls the width vsl narrow settings or does it matter?

I would also like to better understand the terms "peaking" and "shelving".

If there is a website or manual that anyone could recommend that would be appreciated.

Thanks.
Click to expand...

The little diagram under the pots shows that the inside knobs control bandwidth and the outer part controls the selected frequency center.

Rane, Symetrix, and Ashly all do a great job on their manuals and have made nice parametric EQs. This TB thread is a good start as well.
 
#3
Passinwind said:
The little diagram under the pots shows that the inside knobs control bandwidth and the outer part controls the selected frequency center.

Rane, Symetrix, and Ashly all do a great job on their manuals and have made nice parametric EQs. This TB thread is a good start as well.
Click to expand...

Of course. Thank you very much. The light bulb has just been turned on ... no longer in the dark.

Thanks for the links too.

Now to make that appointment with the brain surgeon.
 
#7
Passive boost is an oxymoron, dunno what they mean to say exactly.

Shelving is a filter that cuts off below or above the frequency with the slope. Again, their wording might be less than accurately describing it.

You should link the attachment with your church amp thread.
 
#9
This is a poor description but it's essentially a variable para EQ freq with a fixed Q...my Presonus is set at 0.7. From my perspective, I've found this to be more sonically pleasing than conventional shelving when dialing in lows or low-mids, particularly when light boosting is required. The option gives you greater flexibility finding the sweet spot without creating unwanted "bumps" in adjacent freq's. IMO, some shelving controls paint with too wide of a brush.

Riis
 
#11
Downunderwonder said:
Okay then. Your James EQ bass knob is a max 10db boost/cut all the way down to flaptown starting from 120hz.

It's generally considered a bad idea to cut and boost adjacent frequencies but to solve your church far boundary problem I would try a little crazy.

Cut the bass about half and boost PEQ, centered at 100 to 120, width 1.5 octaves, boost big. Go with the flat settings for everything else at the start but be trimming mids and highs as you bring up master volume to get the booty. Just don't kill your cabs please.
Click to expand...

Thanks for the tip. I adjusted it the best I know how - according to your recommendations - and it definitely brought in the "booty" more. Still would like to reduce the boxiness I'm hearing however I'm finding that what I dislike in the sound up close is actually a good thing as it cuts through much better. My pointman said it sounded great. He could hear the note definitions clearly.

Speaking of "know how". I'm trying to get a grasp on how the term "octave" is used in these adjustments. I know what an octave is as a musical interval but when you are saying 1.5 octaves for a parametric adjustment what do you mean? There are no markings indicating this on the width/narrow adjustment. Since the span is 4 octaves I put the pointer a little less than half way as a guess at 1.5 octaves.

Thanks much - especially for being patient with this high-end-gear novice.
 
#12
Good guess. Without asking Demeter one can only guess and tweak by ear.

An octave spread starts at frequency 'X' hz and finishes at 2x 'X' hz.

One could guess that the audio taper on the bandwidth pot might coincide well with log scale of frequency rising turning it into a linear scale of octaves.

Now you know why bass boosted guitars obscure the bass so effectively. That's our mids they are stomping on with a mess of distortion.
 
#14
Downunderwonder said:
Good guess. Without asking Demeter one can only guess and tweak by ear.

An octave spread starts at frequency 'X' hz and finishes at 2x 'X' hz.

One could guess that the audio taper on the bandwidth pot might coincide well with log scale of frequency rising turning it into a linear scale of octaves.

Now you know why bass boosted guitars obscure the bass so effectively. That's our mids they are stomping on with a mess of distortion.
Click to expand...

Terrific. Thanks for the information.
 
#15
You're welcome, I forgot to mention, the "centre" frequency of the parametric is numerically way closer to the low end than the high end of whatever width setting you set. That makes the actual "centre" selection in the 100 to 120hz region extremely sensitive to small adjustments.
 
#16
Gladowsky said:
Speaking of "know how". I'm trying to get a grasp on how the term "octave" is used in these adjustments. I know what an octave is as a musical interval but when you are saying 1.5 octaves for a parametric adjustment what do you mean?
Click to expand...

[Invalid or Expired Link Removed]

As you can see, "it depends" is often the real answer. ;)
 
#17
Downunderwonder said:
...I forgot to mention, the "centre" frequency of the parametric is numerically way closer to the low end than the high end of whatever width setting you set. That makes the actual "centre" selection in the 100 to 120hz region extremely sensitive to small adjustments.
Click to expand...
took me a minute to figure out what you meant by that :confused:

the frequencies are doubling as you go across, so yeah, a center frequency of 400Hz is equally "far" from 200Hz on one side and 800Hz on the other side.
 

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