Keeley Electronics GC-2 Limiting Amplifier Review – Best Limiter Pedal?

Review of: Keeley Electronics GC-2 Limiting Amplifier

Reviewed by: Rating:5On May 13, 2015Last modified:October 8, 2016



Keeley Electronics is perhaps the most well-known name in stompbox compression. After all, Robert Keeley’s classic 4-Knob and (recently discontinued) 2-knob Compressors have been going strong for over a decade, surpassing well over 40,000 guitar pedals sold. So when Keeley Electronics finally released their “Guitar Compressor #2”, or GC-2 as it’s called, it raised more than a few eyebrows. But the GC-2 Limiting Amplifier isn’t to be mistaken as a replacement for the legendary 4-Knob Compressor. As the name implies, this pedal’s focus is more so limiting as opposed to general compression. What’s the difference? Glad you asked…

Compression Vs. Limiting

Compression and limiting are essentially variations of the same thing: dynamic control that reduces volume peaks in audio. Basically, these effects make loud sounds quieter. A useful side effect of this is that quiet sounds will appear louder as your peaks are reduced in volume, essentially evening out your overall volume level a bit. This can also result in clean sustain which is very sought after among guitarists. Of course an unwanted side effect of compression/limiting can be that low level noise gets louder as well, making it important to use such effects with restraint and with understanding of how their parameters work.

Essentially, guitar compressors are typically used on the front-end of your effects signal chain. Compression helps even out your playing dynamics for a consistent signal that can be louder, punchier, smoother, and generally more flattering depending on what you’re going for. As limiting guitar pedals like the GC-2 are pretty uncommon, it’s important to understand how limiting is typically used in the studio to figure out how to best make use of such a pedal.

Limiting is one of the most important effects used on mixes and final masters of audio recordings. A limiter is typically the last effect used in an audio path on the master mix bus to put the final touches on the overall dynamics of a recording. Also, the technique of “brickwall” limiting is often used to put an aggressive ceiling on dynamics that prevents any volume peaks from crossing the selected threshold. Being a limiter in pedal form, the idea of using the Keeley GC-2 Limiting Amplifier as an end-of-signal-chain pedal opens up a few possibilities that typical stompbox compressors lack. All of that will be mentioned soon in our review.

The Legendary dbx 160A Compressor/Limiter… at your feet!

Keeley-Electronics-GC-2-Limiting-Amplifier-dbx-160-01The GC-2 packs another surprise under the hood: its “extreme high-fidelity THAT Corp. 4320” chip. These chips were conceived and created by former dbx engineers and deliver performance and response that rival the legendary dbx 160A, widely considered one of the best compressors of all time. The diminutive GC-2 Limiting Amplifier even sports a similar 3-knob control set and hard-kneed compression style as its dbx predecessor. Thanks to this chip and other ultra-high quality components, the GC-2 has a frequency response that extends far outside the typical range of guitar, making this truly a studio-grade pedal. This means two things: your tone will not be compromised and you can potentially use this pedal with other instruments and line signals for a style of compression/limiting that’s reminiscent of that dbx 160 sound. Very cool.

Now let’s run down the features and find out if this is the best limiter pedal around in our Keeley Electronics GC-2 Limiting Amplifier review.


  • Studio-grade compression in a pedal
  • User-friendly controls so you can find your perfect sound
  • Contains THAT Corp. 4320 chip
  • Controls for Ratio, Threshold, & Level
  • Attack Time: typically 15ms for 10dB, 5ms for 20dB, 3ms for 30dB
  • Release Time: typically 8ms for 1dB, 40ms for 5dB, 80ms for 10dB, 160ms for 20dB, 240ms for 30dB
  • Powered by batter or 9VDC power adapter (current draw: 15mA)

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Sound & Performance:

First, I’m going to evaluate the merits of using the GC-2 Limiting Amplifier as a front-of-signal-chain compression effect. The GC-2 is actually a modified version of Keeley’s Bassist Limiting Amplifier, a pedal designed for extremely smooth and even compression response, essential for consistent bass signals. The GC-2 differs from the Bassist in that it is designed to be less responsive to those ultra-low bass frequencies, instead responding within a range more suitable to guitar. It also has a “snappier” response and a quicker Attack & Release than Keeley’s Bassist Limiting Amplifier. But the idea is that it can really give you a level of compression that’s more even and consistent than what you may have experienced with other compression pedals.

When setting the Threshold and Gain knobs at around noon, you’ll typically achieve a setting th