Symetrix 304 4 Channel Headphone Amplifier, 1 february 2000, made in USA

Link: symetrix [Owner's manual] | Owner's Manual [PDF, Ru]

Specifications

INPUT/OUTPUT
Input Type: Bridging, Balanced or Unbalanced
Maximum Input Level: +18 dBu Balanced Maximum
Output Level: 21 dBm, 600 Ohm load, >6 VRMS, 200 Ohm load
Input Impedance:  20k Ohms Balanced, 10k Ohms Unbalanced
Output Impedance: 100 Ohms

Performance Data
Frequency Response: 20 Hz to 20 kHz, +0, -1 dB
THD+Noise: 01% (1kHz, 0 dBm, 600 Ohms) .02% (1kHz, +20 dBm, 600 Ohms)
Signal-to-Noise Ratio: 95 dB
Maximum Gain: 25 dB

CONNECTIONS
Input: 1/4" TRS
Output: 1/4" TRS
Power In: 7-pin DIN

PHYSICAL
Size (hwd): 1⁄2 rack unit 1.75 x 8.5 x 6.5 in., 4.445 x 21.59 x 15.875 cm.
Shipping Weight: 4.5 lbs

ELECTRICAL
Power Requirements115 VAC nominal, 95 to 130 VAC, 50 to 60 Hz 230 VAC nominal, 207 to 253 VAC, 50 Hz

Symetrix A-220 Stereo Amplifier, 1981-1994, made in USA

The Model A-220 Stereo Amplifier is a compact, high performance power amplifier configured for use in professional and commercial audio systems. The A-220 may be operated as a two channel amplifier with 20 watts per-channel, or as a single channel amplifier capable of 40 watts (in bridged mode). The amplifier is intended for use with near field monitors, small speakers used for 'radio reference', audio or video, and with headphones. In stereo mode the minimum load is 4-ohms, in mono-bridged mode the minimum load is 8-ohms.

For convenience, the A-220 is equipped with both 1/4' and XLR-3 input connectors, which will accept either balanced or imbalanced input signals. Full power output can be produced with an unbalanced .5 volt (-6dBv) input signal, or 1 volt (0dBv) balanced input signal. Since the A-220 can be used as a true stereo amplifier, as a 2-channel amplifier, or as a single-channel mono-bridged amplifier, the input level control configuration may be switched to reflect the usage. For stereo, use the DUAL TRACKING position, for 2-channel use the INDEPENDENT position.



Model: A-220
Manufacturer: Symetrix, Inc.
Type: Power Amplifier - Pro
Year: 1981-1994
# of Channels 2 (Stereo)
RMS Power (Watts Per Channel) 20 x 2 @ 4
Amplifier Features Bridgeable
I/O Interfaces 1/4", TRS
Weight (lb) 9

Link: symetrix [Operating Manual, PDF]

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