LHZ vs. HazLabs vs. KHaz

We had the opportunity to compare the circuitry, components, EQ response, and audio artifacts between our LHZ-01 and LHZ-02 preamps and a vintage HazLabs preamp (serial number 2029). We also had a KHaz clone and ran the same comparisons as well.


S/N 2029
Circuit WiringCompare schematic against PCB traces. Passing grade indicates all components are connected in the same manner.PASSPASS
Component MarkingCompare component marking. Passing grade indicates stated values and types match or are functional equivalent.PASSPARTIAL
Component ValuesCompare component values to marking. Passing indicates components match marked values.PASSFAIL
EQ ResponseVisualize EQ when fully boosted and fully cut. Passing grade indicates unit exhibits the same EQ response.PASSFAIL
Audio ArtifactsVisualize audio artifacts. Passing grade indicates unit exhibits the same audio artifacts when preamp is driven hard.PASSFAIL

We are happy to report the the LHZ is a component-level clone of the HazLabs preamp and exhibited the same EQ response and audio artifacts. The only variance was that the LHZ uses a 100uF power capacitor where the HazLabs uses a 33uF. This capacitor is strictly for the power supply and does not impact the audio performance.

The KHaz unit we tested had a several discrepancies in the circuity and operation:

  • Used 1M voltage divider resistors instead of the 100k used in the Haz & LHZ preamps.
  • An output resistor measured 6.8k but was marked as 100k. The resistor did not appear to be damaged. The low resistance significantly reduced the preamp output volume lower than the Haz &LHZ preamps.
  • The KHaz used an 072D op-amp instead of the LF442CN used in the Haz & LHZ.
  • EQ response was different. (This is likely due to mis-labeled capacitors as the wiring match the Haz.)
    • Treble control was shelf to 20kHz instead of bell curve.
    • Bass boost was approximately 3dB lower, and slightly lower range.
      (This is likely due to mis-labeled capacitors as the wiring match the Haz.)
  • Audio artifacts were different (likely due to op-amp used).

The differences in the EQ response of the KHaz is likely due to mis-labeled or failed capacitors as the wiring correctly matches the HazLabs preamp. The difference in audio artifacts is related to the use of the 072D op-amp instead of the LF442CN as used in the HazLabs as each op-amp responds differently when driven hard.

IMPORTANT: The observations about the KHaz performance is specific to the single unit we tested, and is not intended to be a blanket statement about all KHaz preamps. We are confident that if the KHaz were repaired using the same components found in the HazLabs, it would offer identical performance.