1. GAIN (stepped, 12-position switch): clockwise rotation yields an increase in input signal amplitude, counterclockwise rotation yields a decrease in input signal amplitude
  2. 48V: engage to turn phantom power on, disengage to turn phantom power off
  3. PHASE (Ø): engage to adjust input signal polarity by 180°, disengage to leave input signal polarity unchanged
  4. OUT LEVEL: clockwise rotation yields less attenuation, counterclockwise rotation yields more attenuation (for beginners, it’s best to leave the output level fully clockwise and increase Gain as needed so as not to saturate the input transformer)
  5. Hi-Z: engage to select faceplate TS jack as input source, disengage to select XLR input jack on 500 series rack as input source (GAIN does not adjust signal level, however, OUT LEVEL does attenuate the signal)

Black Lion Audio B173 500

£0.00 £449.00 inc. VAT
£374.17 exc. VAT

B173 500 Mic Pre

The B173 is one of the most “bang for your buck” preamps in existence, and is now available in the 500 series format. The B173 500 not only delivers the beefy lows, buttery mids, and polished highs of a classic 1073 preamp, but does so at a fraction of the price!

The preamp and line amp circuitry found in the B173 500 is identical to the original B173. Not a single component or design feature was compromised while converting it to a smaller package. As a result, the circuit boards are jam packed with all sorts of delicious components, including a brawny Cinemag input transformer!
The power supply is the backbone of any preamp design, and can make a huge impact on the overall sound and performance of the preamp. The +24V rail needed to power the B173 500 is painstakingly converted from the +/- 16V rails of a 500 series rack using a custom DC-DC converter circuit specially designed to keep any unwanted noise or modulations out of the signal path. Complete isolation is then achieved through the use of inductors, ferrite beads, decoupling capacitors, power regulation, and a custom enclosure surrounding the entire circuit.

The B173 500’s “Class A”, discrete circuitry combined with high-end components provide a fresh approach to a classic sound that won’t disappoint!

  • 500 Series format (500 series rack required for use)
  • Cinemag Input Transformer
  • Edcor Output Transformer
  • 80dB Gain
  • Hi-Z Input (passive, unbalanced)
  • Phantom Power
  • Phase Switch
  • Output Attenuator
Max Microphone Input Level
+1 dBu
Input Impedance
+12dB to +80dB
Equivalent Input Noise (noise floor)
THD+N (@ +4dBu output)
.072% @ +8 dBu Gain .074% @ +29 dBu Gain .082% @ +44 dBu Gain .152% @ +60 dBu Gain .709% @ +76 dBu Gain
Bandwidth (1kHz, 150Ω source, unweighted)
10Hz to 30kHz
THD+N (@ +4dBu output)
.0045% @ +10 dBu .0076% @ +15 dBu
Max Output Level
.0045% @ +10 dBu .0076% @ +15 dBu
Max Output Level
Output Impedance
Power Supply
+24V provided by ultra low noise, custom power supply (500 series rack required)
Product Dimensions
1 .5” x 6.5” x 5.25”
Product Weight
1.2 lbs
Shipping Dimensions
13” x 13” x 5”
Shipping Weight
3 lbs