The Barber Tone Pump is an overdrive pedal from Barber, the maker behind pedals like the Direct Drive and Gain Changer. Its distinguishing feature is the depth of its tone shaping: alongside the usual gain and level controls, it carries Presence, Bass and Mids knobs, six controls in all, giving a player far more EQ reach than a typical three-knob overdrive1.
What it does
The Tone Pump is an overdrive design built around a dual opamp, the LM4558n. Where many overdrives hide their tone shaping behind internal trimmers, the Tone Pump puts Presence, Bass and Mids on the front panel as external knobs, so the player can dial the EQ from the top of the pedal rather than opening it up1.
For players exploring Barber's range, the Tone Pump sits among the maker's other overdrive designs, including the Compact Direct Drive, the Gain Changer SR and the B.U.S.S Five Watt World edition. An introduction to the wider category is on the Overdrive Pedals page.
The DIY stripboard layout
The Tone Pump is documented here largely through a stripboard (vero) layout published on Guitar FX Layouts in February 2014, a site where independent builders share verified layouts for home construction. The layout was based on the schematic for the original Tone Pump as per Dave Barber's schematic, and its author, IvIark, modified it slightly so all six knobs are external instead of the Presence, Bass and Mids being internal trimmers1.
A few practical points from the layout are worth knowing before building:
- The Presence pot is used as a variable resistor, so it only needs two of its lugs connected1.
- The layout calls for an LM4558n opamp, but the author notes you could try any of the common dual opamps used with these effects, listing the NE5532, LM1458, LM358, NJM072, OP275, OPA2107, OPA2134, OPA2604, RC4558P, TLC272 and AD712 as candidates1.
- A builder verified the layout in March 2014, reporting that they had to use a B50 pot for the Mids but that it seemed to work okay1.
This layout is for the original Tone Pump. It changes the circuit from the factory design by moving the Presence, Bass and Mids controls from internal trimmers to external knobs, so a build will not match the stock pedal's control layout exactly1.
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Questions
Can I build a Barber Tone Pump myself?
A stripboard (vero) layout for the original Tone Pump was published on Guitar FX Layouts in February 2014, based on Dave Barber's schematic of the pedal. The layout modifies the original design so that all six controls, including Presence, Bass and Mids, are external knobs rather than internal trimmers. A builder verified the layout, using a B50 pot for the Mids control.
What opamp does the Tone Pump use?
The layout calls for an LM4558n dual opamp. The layout's author notes that any of the common dual opamps used in these effects could be tried instead, listing substitutes including the NE5532, LM1458, LM358, NJM072, OP275, OPA2107, OPA2134, OPA2604, RC4558P, TLC272 and AD712.
Sources (1)
- Guitar FX Layouts: Barber Tone Pump, Guitar FX Layouts (tagboardeffects.blogspot.com), 2014-02-09
