ISA Two Classic Dual Mono Transformer-Based Microphone Preamplifier Specifications:

• 1/4" Instrument input
• Variable input impedance: Low, ISA 110, Medium, High
• Input selection: Mic, Line, Instrument
• 0-30dB/30-60dB gain switch
• Phantom power switch
• Phase invert switch
• 0-60dB gain in 10dB steps
• 0-+20dB continuously variable trim
• Variable high-pass filter with on/off switch
• Insert point on/off switch
• Eight-LED user-calibrated level meters
• Single power switch

• XLR-F mic inputs
• 1/4" TRS line inputs
• 1/4" TRS Sends
• 1/4" TRS Returns
• XLR-M line output
• Single peak meter calibration dial
• Single IEC power socket

• Maximum Output Level: +24 dBu with a THD+N < 0.01% at 1kHz measured with 150 ohm source impedance and 22Hz/22kHz band-pass filter
• Maximum Microphone Transformer Input Level: +7 dBu with a THD+N < 0.7% at 1kHz measured at 0dB of gain with 150 ohm source impedance and 22Hz/22kHz band-pass filter

• Gain range: 0dB to +60dB in 10dB steps, plus 0dB to +20dB continuously variable trim
• Input Impedance: Switched Impedance setting/Equivalent Input Impedance at 1kHz
• Low = 600 ohm
• ISA 110 = 1.4 kohm
• Med = 2.4 kohm
• High = 6.8 kohm
• EIN (Equivalent Input Noise): Measured at 60dB of gain with 150 ohm source impedance and 22Hz–22kHz band pass filter = -127dB
• Noise: Noise at output with unity gain (0dB) and 22Hz–22kHz band pass filter = -97 dBu
• Signal-to-Noise Ratio: Measured with 150 Ohm source impedance and 22Hz–22kHz band pass filter = 121dB relative to max output +24 dBu
• Total Harmonic Distortion + Noise: Measured with a -20 dBu input signal at +30dB of gain and with a 22Hz–22kHz band pass filter = < 0.0007% at 1kHz

• At minimum gain (0dB)
• -0.5dB at 10Hz, -1dB at 135kHz, relative to 1kHz
• At +60dB gain
• -6 dB at 10 Hz, -1dB at 115kHz, relative to 1kHz

• -94dB for mic input at 60Hz for max. output = +24dBu
• -91dB for mic input at 10kHz for max. output = +24dBu
• Crosstalk Channel to Channel: Mic input, with I/P = 0dBu, gain = 0dB @ 1kHz input to channel A, channel B output = -85dB

• Gain Range: -20dB to +10dB in 10dB steps, plus 0dB to +20dB continuously variable trim
• Input Impedance: 10 kohm from 10Hz to 200kHz
• Noise: Noise at main output with gain at unity (0dB) measured with 50 ohm source impedance and a 22Hz–22kHz band pass filter = -97 dBu
• Signal-to-Noise Ratio: Measured with 50 ohm source impedance and a 22Hz–22kHz band pass filter = 121dB relative to max output +24 dBu
• Total Harmonic Distortion + Noise: Measured with a 0 dBu input signal, +10dB of gain and a 22Hz–22kHz band pass filter = < 0.002% at 1kHz

• At unity gain (0dB) -0.3dB at 10Hz, -1dB at 80kHz, relative to 1kHz
• Crosstalk Channel to Channel: Line input, with I/P = 0 dBu, gain = 0dB @ 1kHz input to channel A
• Channel B output = -91dB

• Gain Range: +10dB to +40dB continuously variable trim
• Input Impedance: > 2 mohm
• Noise: >Measured with 22Hz–22kHz band pass filter = Minimum gain (+10dB) = -95 dBu

• At minimum gain (+10dB)
• -0.1dB at 10Hz
• -1dB at 115kHz, relative to 1kHz
• At maximum gain (+40dB)
• -2.5dB at 10Hz
• -1dB at 110kHz, relative to 1kHz

• Roll-Off: 18dB per octave (3-pole filter)
• Frequency Range: Continuously variable from 16Hz to 420Hz (-3dB)

• Dimensions (WxHxD): 18.90" x 1.73" x 11.02" (480 mm x 44 mm x 280 mm)
• Weight: 8.16 lb.