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Aphex 124B


The Aphex Model 124B Audio Level Interface is designed to allow use of -10dBV consumer hi-fi equipment with +4 or +8dBm professional/industrial/broadcast audio systems.

SKU: Model 124B Categories: , ,
Brands: Aphex


A Clean and Reliable Solution for Bidirectional Level and Impedance Matching

The Aphex Model 124B Audio Level Interface is designed to allow use of -10dBV consumer hi-fi equipment with +4 or +8dBm professional/industrial/broadcast audio systems. It provides an extremely clean, reliable two-way buffer so both systems can operate at maximum performance levels, matching impedances and operating levels.


Servo-balancing means that high common mode voltages, such as induced hum from a nearby AC line, are compensated for, preserving headroom. The input impedance of 100K Ohms allows bridging over a 600 Ohm balanced or unbalanced line with negligible loading effects. Front panel switchable 600 Ohm load allows for input line termination when required.


Servo-balancing allows the outputs may be used balanced or unbalanced (single-ended) at any time by simply grounding either unused pin. The servo compensates for the voltage loss on one side so there is no 6dB loss of level. The outputs are also protected against short-circuits, so nothing is damaged if the wrong pins are grounded. A front panel indicator will flash red when the balanced output level is 5dB below clipping.

Rackmount Kit for 120B, 124B and 141B

Allows for the rack mounting of one or two “B” series products in one rack space. The new front panel design of the “B” series products and the new rack mount kit design makes installation 100% faster!

Additional information

Weight 1.6 kg

Allows use of consumer (–10dBv) gear with pro (+4 or +8dBm) systems
Two-way buffer so consumer and pro systems can operate properly
Acts as a signal splitter, providing two high quality balanced outs from an unbalanced "Y" connector



5Hz – 100 kHz (+0, -0.5dB)

Dynamic Range
99 dB


Channel Isolation
> 70dB

CMRR (typical)
> 45 dB


IHF Input Connectors
RCA Jacks

IHF Input Impedance
18 k Ohms

IHF Input Level
-10 dBV; peak +15dBV (ref. 1V)

Balanced Input Connectors
XLR 3-pin Female

Balanced Input Impedance
100k Ohms with front panel 600 ohm termination switch

Balanced Input Level
+4 dBm (+8dBm via internal jumpers); peak +30 dBm


IHF Output Connectors
RCA Jacks

IHF Output Impedance
150 Ohms

IHF Output Level
-10 dBV, peak +18dBV (ref. 1V)

Balanced Output Connectors
XLR 3-pin Male

Balanced Output Impedance
65 ohms

Balanced Output Level
+4dBm Front panel adjustable ± 6dB, peak +25dBm


Power Requirements
100, 120, 220, OR 240 VAC, 50-60Hz

1.75″H x 8.25″W x 7.25″ D (44.5mm x 209.5mm x 184.2mm)

Net Weight
3.5 lbs (1.6 kg)

Ship Separately


Product can be split into multiple boxes





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STUDIO General Interfaces Mixers and Source Selectors Aphex 124B