The EAR 660 Fairchild-type valve limiter-compressor is designed to limit or compress the signal with the barest minimum of interference below threshold, and give the most subjectively satisfying operation on high-level signals.
The unit has the standard range of attack and release times, making it easy to use. Considerable effort has been spent optimizing the behavior around the "knee" of the attack/decay envelope and it is this that greatly contributes to the outstanding transparency and transient response that has made the EAR 660 the first choice of so many top audio professionals.
The audio circuit conforms to the EAR principles of simplicity and subjective “transparency”, with low distortion at all normal signal levels. The onset of limiting is sufficiently gentle not to call attention to itself, although in fact the unit will react very rapidly to overload conditions when required.
The EAR 660 is very versatile and lends itself to both mastering and tracking use. When tracking, it will give excellent results with any instrument, but is especially effective on vocal applications. It is also ideally suited for use as a buss limiter.
Input and output impedance: 600 ohms nominal, balanced and floating
Gain (maximum): 20 dB
Input and output normal operating level: +4dBm
Maximum output level (@1% distortion): +16dB linear, +10dB @ 10dB compression
Attack time: 0.2 to 0.8 ms variable
Release time: 0.3 to 5s variable
Release time ("classical music" setting): up to 25s for sustained high levels
Compression ratio: 1:1 to 10:1 adjustable
Circuit: all-tube audio path: solid-state DC sidechain control path
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