Using the EQP-WA

This guide will provide a brief overview of Warm Audio's EQP-WA, a recreation of the world renowned tube EQ, the Pultec EQP-1A.

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EQP-WA Controls:

1. The unit has two stepped, semi para­met­ric bands which share a band­width (Q) con­trol. Also fea­tures a Low pass Fil­ter (Cut High Frequency).

2. The far left con­trol is the boost (ampli­fi­ca­tion) for the fre­quency of the first band.

3. The boost & cut low fre­quency pot con­trols what cen­tre fre­quency the band is set to. This pot is stepped so only the named fre­quen­cies on the unit can be selected. This ranges from 20Hz — 800Hz.

4. The cut (atten­u­a­tion) pot con­trols how much you atten­u­ate the cen­tre fre­quency by.

It is pos­si­ble to boost and cut the same cen­tre fre­quency, because both con­trols share the same fre­quency control.

This causes a dip before the cen­tre fre­quency, then a boost slightly after­wards, this is known as a res­o­nant curve.

This helps to empha­sise the boost and can be used in very cre­ative ways.

5. The fourth pot con­trols the band­width (Q value). It ranges from sharp to broad, 0 — 10. How­ever in Q value terms sharp would be a high num­ber >10 Q to cre­ate a nar­row band­width. While broad would be a low num­ber <0.2 Q to cre­ate a slight curve.

6. The next three con­trols are the same as the first three, how­ever the High fre­quency pot steps from 3kHz — 16kHz.

7. The final con­trol to the far right is the Cut High Fre­quency pot. This con­trol is a stepped Low pass Fil­ter,3kHz —20kHz.

8. This unit is a clone of the famous Pul­tec EQP-​1A, and fea­tures Pre­mium grade input and out­put Cin­eMag USA Tran­sform­ers. It is pow­ered by two high volt­age tubes, the 12AX7 and the 12AU7.

A trick with the orig­i­nal Pul­tec was to bypass the EQ (using the bypass switch on the far left) and run the sig­nal through the unit purely for the tube and trans­former coloura­tion. This is believed by many to add analogue warmth.

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Troubleshooting:

1. Make sure the EQP-​WA is on, check the switch to bot­tom right of the unit. The light should be on.

2. Sig­nal com­ing through but the con­trols aren’t work­ing? The EQ can be bypassed, the switch to the bot­tom left needs to be up for the con­trols to affect the signal.