The Amptweaker Big Rock Pro II is a high-gain preamp in a stomp box, built for recording or live performance. Amptweaker describes its sound as bringing back "the glory of the So-Cal, Plexi modded, tone loved and desired by millions," the classic "Big Gain Tone" in pedal form1. It is all analog, with what the maker calls none of the latency associated with digital technology, and it can be used either as a preamp or as an effect pedal1. For players weighing it against other options, it sits alongside Amptweaker's other high-gain preamps such as the Tight Metal Pro II and Fat Metal Pro II, and belongs to the wider family of preamp pedals.
Controls and routing
The pedal carries Gain, Tight and Volume controls1. What sets the Big Rock Pro II apart from a straightforward distortion or overdrive pedal is its routing: three loops that let it sit at the center of a rig rather than just in front of the amp.
| Loop | When it works | What Amptweaker suggests it for |
|---|---|---|
| Global Loop | Whenever the pedal is on | EQ, reverb and similar effects1 |
| Boost Loop | Whenever the Boost switch is activated | Placing delay, reverb or other effects to build a lead tone1 |
| Side Track | When the pedal is not active | An A/B switcher between amps (clean and dirty, for example), or an ancillary loop for additional effects1 |
The Big Rock Pro II keeps the same control set as its predecessor: Gain, Tight and Volume controls, with Amptweaker describing them as "Gain, Tight & Volume Controls"1. The pedal measures 5.63" W x 5" D x 2.13" H, weighs 3 lbs., and carries a 5 Year Limited Warranty1.
Power and running voltage
The Big Rock Pro II runs at 9V or 18V. Amptweaker's guidance is to run it at 18V for more headroom, or at 9V for more drive and compression1. Current draw is listed at 39mA with a 9V adapter, and the power supply is not included1.
At 39mA, the Big Rock Pro II draws more current than many standard pedals, so a shared power supply or daisy chain needs enough spare current to run it. Amptweaker lists the supply as not included.
Size and specifications
Amptweaker publishes an owner's manual for the Big Rock Pro II on its site1.
Videos
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Questions
Is the Amptweaker Big Rock Pro II analog?
Yes. Amptweaker describes the Big Rock Pro II as having all analog circuitry, with none of the latency associated with digital technology. It can be used as a preamp or as an effect pedal, and it is aimed at recording or live performance.
What do the Global Loop, Boost Loop and Side Track do?
The Global Loop works whenever the pedal is on, which Amptweaker suggests is great for EQ or reverb. The Boost Loop works whenever the Boost switch is activated, so you can place delay, reverb or other solo effects there. Side Track works when the pedal is not active: it can act as an A/B switcher between amps, such as clean and dirty, or as an ancillary loop for additional effects.
How much current does the Big Rock Pro II draw?
Amptweaker lists the current draw as 39mA with a 9V adapter. The power supply is not included, and the pedal can also run at 18V for more headroom.
Who designed the Amptweaker Big Rock Pro II?
Amptweaker says the Big Rock Pro II was designed by iconic high-gain amp guru James Brown. The pedal is made in the USA.
Where is the Big Rock Pro II made?
The Big Rock Pro II is made in the USA, according to Amptweaker's product page.
Sources (2)
- Big Rock Pro II, amptweaker.com, 2023-04-28
- Tight Rock, amptweaker.com, 2025-12-08
