Four controls and one switch per band. Turn the knobs on the front panel here and watch what each one does to the curve. Press play to hear it on raw tracks from a Nashville session. Then play the five moves that make this a different kind of three-band EQ.
Dial a classic
Level (dB)Phase (degrees)
Run it on
Start with a plain bell: Shape and Q fully down, a few dB of boost. Turn Shape up and the bell lifts into a shelf: the high side on the High and Mid · Hi bands, the low side on Mid · Low and Low.
Selected band
Drag a knob to turn it. On the black knob the outer ring is Gain and the cap is Shape. On the blue knob the outer ring is Frequency and the cap is Q. Click a switch to flip it, including EQ IN/OUT beside the Low band. Each band keeps its own settings, and all three are in the signal path.
Gain
Shape
Freq
Q
Play the five moves
Each one is a short animation of a single control.
What each control does, and why it is there
Boost / Cut / Notch
3-position toggle, one per band
Does
Decides what the gain knob means. Boost adds the filtered band back in phase. Cut adds it back flipped. Notch keeps flipping until it cancels.
Why
Cut and notch are the same circuit at different strengths. That design choice is what made Notch and Vari-Phase possible.
Gain
Black knob, outer ring · 0 to 10
Does
Up to 15 dB of boost or cut. In Notch mode, 5 is the full null and 10 is the phase flip.
Why
It is constant-Q. The width you set stays put as you add gain.
Shape
Black knob, inner cap
Does
Fully down is a bell. At 12 o'clock it is a conventional shelf. Past that it changes the slope of the shelf, ending at the slow vintage rise with a small dip before it.
Why
Every other EQ ships with one shelf its designer picked. This started as a trim pot inside the prototype for making that pick, and moved to the front panel.
Frequency
Blue knob, outer ring · continuous
Does
High 1.4 to 22 kHz. Mid 90 Hz to 1.4 kHz or 390 Hz to 6 kHz, switched. Low 20 to 340 Hz.
Why
A pot, not a switch, so a classic shelf shape can sit at any frequency instead of the three or four its original offered.
Q
Blue knob, inner cap · 0.3 to 10
Does
Sets width on a bell, from a broad tilt to a surgical spike. On a shelf it adds a peak at the corner, then an undershoot.
Why
It never switches off. One band can make a curve that takes three bands elsewhere, with less phase shift piling up.
Pad and EQ In
Two toggles, whole module
Does
Pad drops the input 10 dB. EQ In/Out bypasses the whole equalizer.
Why
Shelf plus high Q can add more than 30 dB at one frequency. The pad buys the headroom for drum buses, mix buses and hot preamps.
How they work together
Shape × QShape picks the kind of shelf. Q sharpens its corner. Together they reach curves no fixed shelf has.
Shape × FrequencyWith Shape fully up the rise is slow, so set the frequency about a tenth of where you want the boost to land.
Notch × Gain0 to 5 deepens the notch to a full null. 5 to 10 brings the band back, now flipped in phase with the level flat.
Notch × ShapeAt 12 o'clock in Notch mode the band becomes a filter: high-pass on the low band, low-pass on the high band.
The curves and the sound on this page come from a simplified model of a parallel EQ band, built to behave the way the UTEQ500 manual describes. They are an illustration running in your browser, not a measurement or a recording of the hardware. Audio from “Shortcut”: Anthony Da Costa and Russell Durham, with Mark Raudabaugh on drums and Rhees Williams on bass, recorded by Bobby Holland at Pentavirate Studios, Nashville. API, Neve, SSL and Pultec are trademarks of their respective owners. Undertone Audio is not affiliated with or endorsed by any of them.
