6386 & ES-8 Remote Cutoff Tube Limiters

A Modern Approach to Classic Tube Compression

The 6386 and ES-8 are modern two channel limiters designed to have the compression characteristics of a vintage unit, but with a higher level of sonic accuracy. Rather than trying to recreate the past, we've taken an entirely different approach. The 6386 uses the gain control tube (remote cutoff triode) found in the vintage Fairchild limiters to provide the classic feedback response unique to the characteristics of this class of tubes. The ES-8 uses a different remote-cutoff triode with the same dynamic characteristics. Subsequent amplification is accomplished with a Class A, balanced transformerless line amp, rather than the push-pull transformer output stage used on vintage variable-mu units. The result is a new class of limiters that possess the 'dynamic signature' of a classic tube compressor, but with a more accurate, less colored signal path. The two units are identical, except for the tube used for gain reduction.

The soft-knee design used in the 6386 and ES-8 offer effortless dynamic control with a smooth transition from compression to limiting. In addition, both channels can be operated independently, or linked with the flip of a switch. When linked, the threshold and attack/release parameters are controlled entirely by channel 1, assuring precise stereo balance over the entire range of gain reduction.

For maximum versatility, the 6386 and ES-8 incorporate a solid-state sidechain to provide a wide range of control with three modes of processing: In the FAST mode, the limiter works extremely fast (less than 0.5ms attack time), and is remarkably free of the 'pumping' artifacts normally encountered with slow variable-mu compressors. It's the ideal choice for invisible dynamics processing, either for tracking or tight program compression. The PRESET mode consists of six classic attack/release time settings (identical to the Fairchild 670) that are optimized for program compression, including two settings with program-dependent release times. The MANUAL mode offers total control over the attack and release times, which is particularly useful for creative compression effects or for processing bass guitar.

Most important, the hard bypass switches on the front panel conveniently allow a quick determination of exactly what the 6386 or ES-8 is, or in most cases, isn't doing to your signal.

Specifications

Circuit Type: Remote cutoff gain control tube with balanced class A solid-state line stage and transformerless output
Input Sensitivity: +4dBu
Input Impedance:  10Kohm
Frequency Response:  -1.0dB 15Hz and 75kHz with 600Kohm output load
Noise: less than -85dB below +4dBu output level with output control at unity gain (12:00)
Distortion: less than 0.08% THD+N, 20Hz to 10kHz
Output: +27dBu balanced into 600ohm load
Max. Gain Reduction: 12dB
Threshold: up to 12dB of gain reduction at -8dBu input level
Ratio: 1:1 to limiting, program-dependent
Output: off to +15dB
Modes: fast (peak-averaged), preset or manual operation
Presets:  1ms/0.1s, 1ms/0.3s, 2ms/1.0s, 4ms/2s, 2ms/1 to 4s and 1ms/0.5 to 20s (program dependent)
Manual: attack time variable from 1.0ms to 100ms, release time variable from 0.1s to 2s
Meter: selection of input level, gain reduction, or output level, referenced to +4dBu = 0VU
In/Bypass: hard bypass of input signal to output connector
Link/Split: links channel 1 and channel 2 for stereo operation
Polarity: input and output XLR connectors are pin 2 hot
Vacuum Tubes: 6386: (2) 6386, GE five star. ES-8: (2) 6ES8 (US) or ECC189 (European)
Power: 120Vac, 30W (240Vac optional)
Power Supplies: +250Vdc, +12.6Vdc and ±18Vdc, fully regulated with soft-start warm-up and output bypass

Dimensions

2U Enclosure: 19" x 3.5" x 12.5" (48.2 x 8.8 x 31.8 cm)
Weight: 14lbs (6.4kg)

Fast Features

Classic feedback compression with the same compression profile as the Fairchild 660 and 670 · The 6386 uses the same gain control tube (remote cutoff triode) as the Fairchild 660 and 670 · The ES-8 uses a more readily available (and less expensive) tube with the same compression characteristics as the 6386 · In all other aspects, the two units are identical · Modern class A, solid-state gain make-up stage for wide bandwidth and low distortion · Soft-knee design with smooth transition from compression to limiting · Fast attack (0.5ms) and release times ideal for tight program compression or tracking · Low noise and superior transient response · Three sidechain operating modes: Fast, Presets and Manual · Two completely independent channels with stereo linking · Tubes calibrated for precise stereo balance · Hard bypass switches for each channel · Sidechain inserts for frequency-dependent compression and de-essing · Transformerless balanced output stage capable of delivering +27dBu · Soft-start warm-up with outputs bypassed until all voltages are stabilized · Gold-plated relay contacts, I/O connectors and tube sockets · Fully regulated high voltage (250V), filament and bipolar power supplies · Custom toroidal power transformer with shield for minimum hum · Polypropylene capacitors and metal film resistors · Limited production · Handcrafted in the USA

Notes:
0dBu = 0.775 Vrms
All noise measurements are unweighted, 20 - 20,000 Hz bandwidth
All Specifications are subject to change without notice