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Fromel Shape EQ "Q" question

Blue-moon

Gold Supporting Member
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3,688
For those Fromel Shape EQ experts out there....what does the "Q" control do?
 
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1,185
Q means "quality factor" and refers to the bandwidth affected by a filter. It's the ratio of the center frequency to the bandwidth.

Say you have a bandpass filter set to 83 Hz (low E string). A Q factor of 0.1 means 83/830, so the bandwidth is +/- 415 Hz. A Q factor of 10 means the bandwidth is +/- 4.15 Hz.

In musical terms a higher Q filter selects a smaller range of notes.
 

Blue-moon

Gold Supporting Member
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3,688
Q means "quality factor" and refers to the bandwidth affected by a filter. It's the ratio of the center frequency to the bandwidth.

Say you have a bandpass filter set to 83 Hz (low E string). A Q factor of 0.1 means 83/830, so the bandwidth is +/- 415 Hz. A Q factor of 10 means the bandwidth is +/- 4.15 Hz.

In musical terms a higher Q filter selects a smaller range of notes.
So, in layman's terms....what's going on when I move the knob?
 

Heady Jam Fan

Member
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9,009
Q generally is the kurtosis or curvature of the peak created by that knob. In other words, what range of frequency is effected by the know - a smaller ranger would be a more acute peak in specific frequencies, a wider range would be a softer effect spanning more frequencies and would be more flat than peaked.

However, I thought the Q knob on the Fromel actually selected which midrange frequency was the center of the midrange peak rather than the width of the peak. I could be wrong, but I have a Fromel and turning the knob clockwise seemed to brighten the mids rather than actually change the Q value (such as adjust the Q on a wah), so I assumed it was a misnomer.
 

drbob1

Gold Supporting Member
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29,052
Yeah, the Fromel is semi-parametric. You have control over frequency and gain/cut but not really Q (just like the PQ401 it's based on). So, in that case the Q knob is controlling the mid frequency that you're cutting or boosting at.
 

Whalestone

Member
Messages
1,018
The Fromel Shape EQ does not feature a knob controlling Q;
Controls from left to right.

Bass - cut/boost - center dent at zero
Mid Freq
Switch under Mid Freq changes from shelf to parametric sweep (last 60 or so)
Mid - Cut/boost - center dent at zero
Treble - cut/boost - center dent at zero
Switch under Treble changes from buffered bypass or true bypass
 

Heady Jam Fan

Member
Messages
9,009
The Fromel Shape EQ does not feature a knob controlling Q;
Yea - this is what I thought and was describing in my post. I actually had just looked up this very same post! IIRC it matches the manual, but that is at home.

So the knob in question selects the specific peak of the mid frequency to boost rather than the width of the peak.
 

Blue-moon

Gold Supporting Member
Messages
3,688
Yea - this is what I thought and was describing in my post. I actually had just looked up this very same post! IIRC it matches the manual, but that is at home.

So the knob in question selects the specific peak of the mid frequency to boost rather than the width of the peak.
Ok...that makes sense. I think in my manual he refers to as Q. I might be mistaken, though.
 

Blue-moon

Gold Supporting Member
Messages
3,688
Just go this from John in an email...

They Q control changes the frequency that is cut or boost by the mid control, when the switch below the Q control is up, Q acts as a shelf taking the selected frequency and everything below that as cut or boost. When the switch is down the Q acts as a normal parametric which selects the frequency mor the mid control.
 






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