The Pete Cornish NBM-2 Duplex is a boost pedal that combines four functions in one box: line driver, linear boost, isolated tuner feed and system mute. Pete Cornish describes the linear boost as a volume lift "without any tonal alteration, to lift a player's solo above the background" sound level, so it is about clean level rather than color12. The pedal was originally designed as an integral part of each Pete Cornish Custom Pedalboard and Rack System before being offered on its own1.
Because the boost is linear, the pedal is best placed for maximum effect at a specific point in the chain. Pete Cornish advises that for maximum linear boosting the unit should be connected just before the input of a clean amplifier and after any effects units2.
What it does to your sound
The core of the pedal is a linear boost with unity gain buffering. With the boost off, the buffer can drive long cables without tonal loss, which is the line driver half of its job1. Press the BOOST footswitch and your pre-selected amount of boost, up to +27dB, is available at the output1. Pete Cornish states there is no tonal change or phase shift to the boosted signal1.
The isolated tuner feed runs independently of the main controls: the setting of the Boost control and the position of the Boost and Mute switches do not alter the signal sent to the tuner output1. That means you can mute the main output for silent tuning while the tuner feed keeps working.
Controls and switches
| Control or switch | What it does |
|---|---|
| Boost control | Sets the pre-selected amount of boost, up to +27dB1 |
| BOOST footswitch | Engages the boost; not a bypass switch1 |
| MUTE switch | Totally shuts down the audio path to the main output, with or without boost engaged1 |
| Tuner feed output | Sends an isolated signal to a tuner, unaffected by the boost and mute settings1 |
The footswitches are heavy duty all-metal types with Hi-Brite LEDs, so the boost and mute states are visible on a dark stage1.
Not a bypass pedal
The BOOST footswitch on this unit is not a bypass switch. When the indicator light is off, the unit acts as a unity gain buffer amplifier, so the signal always passes through the pedal's electronics rather than being switched around them1. For a player comparing this with true bypass boost pedals, that is the key difference: the NBM-2 Duplex is always in the circuit, buffering the line whether boosted or not.
Power: 9V DC or 24V DC
The NBM-2 Duplex runs on a 9V DC adapter that should be noise free and fully stabilized and capable of supplying 20mA. The coax connector is 5.5/2.1mm with the center pin negative, matching standard center negative pedal power supplies1.
The unit was upgraded to dual voltage with a 24V DC maximum1. The supply voltage changes the headroom:
The earlier NBM-2 page specifies a fully stabilized 9.6V supply, or up to 18V DC maximum after the dual voltage upgrade, with an M2.1 connector, tip negative2. The Duplex page gives 9V DC with a 24V DC maximum and a 5.5/2.1mm connector1. The two pages disagree on the exact figures, so check your own unit's labeling before choosing a supply.
The pedal also has an INPUT / PWR ON jack arrangement in which the battery is switched on when you insert the input jack2.
Who builds it
Each unit is housed in a rugged die-cast box and is hand built, wired and tested by Pete, Lynda and Mingus Cornish1. The warranty runs twelve months from date of purchase against original manufacturing faults, with normal wear, misuse, unauthorized modifications and accidental damage excepted; it is non-transferable and does not apply to the customer's own equipment connected to the unit1.
Questions
Is the Pete Cornish NBM-2 Duplex a bypass pedal?
No. The BOOST footswitch is not a bypass switch. When the indicator light is off, the unit acts as a unity gain buffer amplifier, so your signal always passes through the pedal's circuitry rather than being switched around it1.
How much boost does the NBM-2 Duplex give?
The gain range is 0dB to +27dB. You set the amount with the Boost control, and that pre-selected boost is available at the output whenever you press the BOOST footswitch1.
What polarity does the NBM-2 Duplex power supply need?
The power input uses a 5.5/2.1mm coax connector with the center pin negative, so a standard center negative 9V DC pedal power supply fits. The adapter should be noise free and fully stabilized1.
Can the NBM-2 Duplex run on 24V?
Yes. The unit was upgraded to dual voltage with a 24V DC maximum. On a 24V supply the maximum output rises to +16 dBm/5Vrms/14v peak to peak, compared with +10 dBm/2.4 Vrms/6.8v peak to peak on the lower supply1.
Who builds Pete Cornish pedals?
Pete Cornish pedals are hand built, wired and tested by Pete, Lynda and Mingus Cornish. The NBM-2 Duplex was originally designed as an integral part of each Pete Cornish Custom Pedalboard and Rack System1.
What does the mute switch do on the NBM-2 Duplex?
The MUTE function totally shuts down the audio path to the main output. It can be activated at any time, whether or not the boost is engaged, which makes it useful for tuning silently or silencing the rig between songs1.
Sources (2)
- Pete Cornish NBM-2 Duplex, Pete Cornish, 2016
- Pete Cornish NBM Duplex, Pete Cornish, 2014
