• Circuitry designed by legendary John Curl
• Ultra-high bias Class A/AB operation
• Stable with speaker impedance dips below 1Ω
• Bybee Music Rails™ - active high frequency filters for input stage
• New John Curl driver stage employs a cascode circuit for greater open loop bandwidth & superior linearity
• Gain switch to select 29 dB or 23 dB gain for optimum compatibility with high gain preamps or extremely efficient speakers
• R-core transformer for input stage suppresses noise on power line
• 6 massive 33,000 uF Nichicon Gold Tune filter capacitors for output stage
• 22,400 uF input stage power supply filter capacitors, independent of the main power supply
• CHK Infinium, custom 5-way speaker binding posts for easy bi-wiring
• Neutrik locking XLR balanced input & loop output jacks
• Vampire 24k gold-plated RCA input & loop output jacks
• Direct-coupled signal path, no capacitors or inductors in the audio path
• JFET input stage, MOSFET driver stage
• 24 beta-matched 15 ampere, 230V, 60 MHz bipolar output transistors
• Independent power supplies for input stage, driver stage & output stage
• Full power is rated all the way down to 2Hz for unrestricted low-end bass
• Harris hyper-fast soft-recovery bridge diode rectifiers
• REL & Nichicon Muse capacitors
• DC servo & relay protection circuits
• AC turn-on inrush surge protection with relay bypass
• Automatic turn-on by 12 V trigger or audio sensing
• 2 rack space chassis with rear carry handles
• Available in black

Power Output

• 250 watts@8 Ω
• 450 watts@4 Ω
• 800 watts @2 Ω
• Power measurements are with 120 VAC: 0.15% THD, RMS continuous power, full audio band (20 Hz - 20 kHz)

Class A Power Output

• 8 Watts, bias set to high
• 4 Watts, bias set to low

Current Capacity 100 amps, peak

Slew Rate > 130 volts per microsecond

Frequency Response

• 2 Hz - 110 kHz, +0/-2 dB
• 20 Hz - 20 kHz, +0/-0.25 dB

Total Harmonic Distortion (THD)

• < 0.15 % at full power
• < 0.02 % at typical listening levels

IM Distortion < 0.03 %

TIM Unmeasurable

Input Impedance

• Unbalanced: 50 kΩ
• Balanced: 100 kΩ, (50 kΩ per leg)

S/N Ratio,inputs shorted

• >120 dB, IHF A-weighted, bias set to Low
• >118 dB, IHF A-weighted, bias set to High
• >110 dB, Unweighted, bias set to Low
• >108 dB, Unweighted, bias set to High

Total Gain

• 29 dB (Gain switch set to normal)
• 23 dB (Gain switch set to low)

Input Sensitivity for 28.28 V into 8Ω (Gain switch set to normal)

• Unbalanced: 1V
• Balanced: 1V per leg

DC Trigger Requirements +9 Vdc to +12 Vdc, 5 mA

Audio Trigger Requirement 2.5 mV - 10 mV

XLR Pin Identification

• 1 = Ground (Shield)
• 2 = Positive
• 3 = Negative (Return)

Dimensions

• Width: 17.25" (437 mm)
• Height without feet: 3.5" (89 mm), 2U
• Height with feet: 4.125" (105 mm)
• Depth: 20" (508 mm)
• Depth with cables: 21.5" (546 mm)

Net Weight 42 lbs (19.1 kg)

ShippingWeight 50 lbs (22.6 kg)

PowerRequirement

• Standby:<1 Watt
• Idle (bias set to low): 125 Watts
• Idle (bias set to high): 240 Watts
• Typical Listening levels: 300 Watts
• Maximum: 800 Watts

The Absolute Sound, Robert Taylor

Just Audio, July 2024

JCM250 Manual