The AIRCHILD Six Sixty Compressor is a sonic interpretation of the famous vintage 660 studio compressor. We've been using the original 660 and 670 (stereo) compressors in our studio for years, consistently rated as some of the best compressors available. The classic guitar compressor has produced some very recognizable tones, especially throughout the history of country music. However, we felt there were already too many clones of the legendary circuit, and very few other variations. While traditional compressor circuits tend to squash the sound like a limiter, this effect is often valued in certain genres of music. We wanted to create a compressor that functions like a studio compressor, enhancing harmonic richness and evening out the tonal range without squashing it. The AIRCHILD Six Sixty simply makes you want to play more, increasing sustain without squashing output, enriching the overall tone and adding feel to your playing. We aimed for the slide tone of Lowell George and the singing lead/rhythm tone of Mark Knopfler. ■Controls OUTPUT: It may sound simple, but output is a key feature in properly setting up a compressor. If you want the compressor to have the most effect, keep the output below unity (it interacts with the threshold control, so raising the threshold will make it louder). Turning the output up to push the input to the amp harder will increase the gain and you'll lose compression. You'll gain sustain and harmonic richness, but the compression effect will be less audible). Tone: One of the biggest complaints about compressors is the effect they have on EQ. Typical compressors introduce noise and distort the top end. AIRCHILD's EQ helps mitigate these typical issues and achieve a natural balance in the overall EQ. Turning the knob counterclockwise increases the bottom and reduces the top, while turning it clockwise increases the top and reduces the bottom. This allows you to balance the EQ to suit different setups for each amp. Blend: Blend blends the dry and compressed signals, allowing for fine tuning. THRESHOLD: The threshold controls how much compression is applied. Counterclockwise is off, clockwise is full compression. The blend control allows you to find the balance you like. Experiment with the threshold control, paying attention to how it interacts with the output control. The higher the output, the higher the gain, so the lower the effect. Adjust the compression to your liking. power supply: Use only 9V/DC center negative. Power consumption 20mA. (No built-in battery option)Power Supply: 9VDC (sold separately, center negative) Current consumption: 20mA