Monoprice Cavalli Liquid Platinum technical measurements

Discussion in 'Headphone Amplifier Measurements' started by atomicbob, Nov 14, 2018.

  1. atomicbob

    atomicbob dScope Yoda

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    SMPS - NoiseNuke - LPS comparison part 3 of 3

    20181112-40 36V 56R residual noise 200mV 10uS div 20MHz - SMPS.png
    20181112-40 36V 56R residual noise 200mV 10uS div 20MHz - SMPS.png

    20181112-41 36V 56R residual noise 200mV 10uS div 20MHz - NoiseNuke.png
    20181112-41 36V 56R residual noise 200mV 10uS div 20MHz - NoiseNuke.png

    20181112-42 36V 56R residual noise 200mV 10uS div 20MHz - LPS .png
    20181112-42 36V 56R residual noise 200mV 10uS div 20MHz - LPS .png

    20181112-45 36V 56R residual noise 200mV FFT 10Hz - 50KHz - SMPS.png
    20181112-45 36V 56R residual noise 200mV FFT 10Hz - 50KHz - SMPS.png

    20181112-47 36V 56R residual noise 200mV FFT 10Hz - 50KHz - LPS.png
    20181112-46 36V 56R residual noise 200mV FFT 10Hz - 50KHz - NoiseNuke.png

    20181112-46 36V 56R residual noise 200mV FFT 10Hz - 50KHz - NoiseNuke.png
    20181112-47 36V 56R residual noise 200mV FFT 10Hz - 50KHz - LPS.png

    20181112-48 36V 56R residual noise 200mV FFT 10KHz - 15MHz - SMPS.png
    20181112-48 36V 56R residual noise 200mV FFT 10KHz - 15MHz - SMPS.png

    20181112-49 36V 56R residual noise 200mV FFT 10KHz - 15MHz - NoiseNuke.png
    20181112-49 36V 56R residual noise 200mV FFT 10KHz - 15MHz - NoiseNuke.png

    20181112-50 36V 56R residual noise 200mV FFT 10KHz - 15MHz - LPS.png
    20181112-50 36V 56R residual noise 200mV FFT 10KHz - 15MHz - LPS.png

    Power supply noise differences input to Liquid Platinum are measurably different. SMPS+NoiseNuke and LPS offer lowest noise presented to Liquid Platinum.
     
    Last edited: Nov 14, 2018
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  2. atomicbob

    atomicbob dScope Yoda

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    reserved 22/23.
     
  3. atomicbob

    atomicbob dScope Yoda

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  4. Ice-man

    Ice-man Friend

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    Told ya that this sound a whole lot like a Crimson. :p Thanks for the write up AB!
     
  5. dBel84

    dBel84 Friend

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    I know it sounds good but am amazed how good it looks on "paper" - I have been of the mindset that, in general, perfect measurements imply soul sucking waste of space .... this defies my bias ..... gladly so ;)

    ..dB
     
  6. nickwin

    nickwin Facebook Friend

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    @atomicbob, do you have any opinion on whether the differences in residual noise with the different PSs is audible?

    Edit: @atomicbob does negligible = inaudible in this case? Thanks!
     
    Last edited: Nov 22, 2018
  7. atomicbob

    atomicbob dScope Yoda

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    Please read the last line in this post
     
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  8. johnjen

    johnjen Doesn’t want to be here but keeps posting anyways

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    DAMN Bob, that is a WHOLE bunch of work for all those measurements.

    That's like over a day worth of time spent (according to my handy dandy napkin math) measuring that little amp and the Noise Nuke®™©.
    Not to mention all the work spent posting all this data (keeping it all straight and labeled properly etc.).

    Much appreciated and I especially liked the spectral analysis of the SMPS vs SMPS & Noise Nuke®™© vs the LPS.

    It is amazing how the entry level gear has lowered in price AND risen in SQ, and to such an extent that the gap between it and SotA gear is so much closer these days.

    A Win-Win-Win all the way around.

    JJ
     
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  9. atomicbob

    atomicbob dScope Yoda

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    @johnjen - the actual amount of time required is documented in the first post in the section labeled Test Data.
    Thank-you for observing that it was a LOT of time and effort to measure and post such detailed level of information.
     
  10. atomicbob

    atomicbob dScope Yoda

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    Questions like this are easy to ask but difficult to answer correctly. At least three very important data inputs required:

    1. Headphone sensitivity (dB/mW for example)
    2. Listener hearing acuity
    3. Environment ambient residual noise SPL

    Without all three of those inputs nobody can answer this question accurately.

    Some considerations:

    1. headphone sensitivity
    115 dB/mW 10R Campfire Audio Solaris
    102 dB/mW 55R Focal Clear
    98 dB/mW 300R Sennheiser HD6x0 and HD800

    2. Listener hearing acuity - ears tested by an audiologist

    3. Ambient residual noise:
    See this post about my threshold of audibility, in my acoustic lab, using Sennheiser HD800 for ZDT Jr residual hum at -75 dBu: here

    In that post are graphs depicting accurate actual sound levels for some common noises.

    Now consider that the Liquid Platinum has a residual noise of approximately -90 dBu. That is 24.5 uV of noise. 24.5 millionths of a volt. Computing the math required for each of the headphone sensitivities listed above will results in the following SPL produced by this residual noise level:
    43 dB SPL Campfire Audio Solaris
    22 dB SPL Focal Clear
    11 dB SPL Sennheiser HD6x0 and HD800

    I could venture a guess that only the Campfire Audio Solaris might present a slight hiss to the listener but audibility to the specific listener would also require good hearing acuity and the ambient environment must be very quiet.
     
  11. atomicbob

    atomicbob dScope Yoda

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    Liquid Platinum LPS power supply warning!!
    (also applies to use of NoiseNuke with Monoprice supplied SMPS)

    Use of any power supply other than that supplied by a vendor, or exact replacement, is not guaranteed to work nor covered by manufacturer warranty. Proceed at your own risk.

    Liquid Platinum is a high performance amplifier with many sound quality optimizations while maintaining DC coupling from input to output. To avoid stressing amplifier components or headphones during power on / off transitions, a combination of mosfet inrush current power management and high voltage (HV) delay timer are used. It is necessary for tubes to reach sufficient electron conduction temperature before applying HV and enabling amplifier outputs.

    In the off position Liquid Platinum's front panel power switch resets timing circuits. If an external power supply equipped with a power switch is used while the Liquid Platinum front panel power switch is engaged potential for excessive component stress and possibly damage exists. This can happen at either power On or power Off cycle.

    During one late night measurement session while fairly tired I neglected to follow standard lab procedure of powering off Unit Under Test (UUT) before switching the lab linear power supply off. I realized my lapse in procedure immediately. Upon following correct power up procedure, UUT off, then Lab supply on, I noted the tubes were glowing without engaging Liquid Platinum's power switch. Once engaged, timing circuits behaved correctly and the amp was verified to perform as expected. Unfortunately the power management mosfet had shorted Source to Drain.

    Since that event using the proper power up procedure I have not experienced any issues with my Liquid Platinum other than tube heaters are on whenever the external power supply is powered. Listening evaluations still result in auditory delight.

    Here is a power off discharge measurement comparing the supplied SMPS with a Zero Zone 65W LPS. The SMPS stores very little energy and is down to zero volts in approximately 100mS. Zero Zone LPS has big capacitors, as expected and requires approximately 4 seconds to discharge; 40x longer. Liquid Platinum power management has been designed to work optimally with the supplied SMPS. During the 40x extra time unpredictable circuit behavior may occur, such as mosfet S-D melting into a short.
    30 20181130 SMPS vs ZeroZone 36V 56R load - power off - 500mS 10V div.png

    Proper procedure for power on:
    1. verify both external power supply and Liquid Platinum power switches are in OFF position
    2. switch ON power supply
    3. switch ON Liquid Platinum

    Proper procedure to power off:
    1. switch OFF Liquid Platinum
    2. wait for a few seconds
    3. switch OFF power supply

    NEVER switch power ON or OFF to external power supply while Liquid Platinum front panel power switch is in the ON position.

    Once the mosfet is damaged, the unit is likely to operate as expected. However, even if the mosfet becomes damaged, continue to follow proper power On / Off procedure described above. This is very important for proper operation of HV timing circuits.
     
    Last edited: Nov 30, 2018
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  12. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Would utilizing the Noise Nuke with stock PSU cause similar concerns?
     
  13. atomicbob

    atomicbob dScope Yoda

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    Yes!

    Good point. Warning post has been edited appropriately.
    The Noise Nuke has very large electrolytic capacitors with high energy storage capability.
     
    Last edited: Nov 30, 2018
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  14. rtaylor76

    rtaylor76 Can't wipe his tag

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    I also assume similar type circuits in the Liquid Spark and MCTH?
     
  15. atomicbob

    atomicbob dScope Yoda

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    Never assume. You know the saying.
    My lab procedures are ingrained so I have not (yet) had a lapse in power cycle procedure using lab supplies or Noise Nuke with either MCTH or Liquid Spark. Thus no opportunity to blow them up or open to see what damage I incurred.
     
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  16. rtaylor76

    rtaylor76 Can't wipe his tag

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    I just know I assume to use an LPS the same way I would the stock power supply - make sure lead is hot and unit is off, then use the power button as normal. Any other way might incur damage like you say.
     
  17. GanGreinke

    GanGreinke Wow, I made it this far without being a friend?

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    This must have been what happened to my amp. I'd like to tag @runeight to let him know as he was helping me with the troubleshooting in the other Liquid Platinum thread.
     
  18. gepardcv

    gepardcv Wow, I made it this far without being a friend?

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    Does this imply that a power outage can damage this amplifier, even with the included default SMPS? Also, this amplifier cannot be safely plugged into a power strip with a separate switch? And cannot be safely unplugged from a wall socket without first being turned off on the front panel?
     
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  19. dBel84

    dBel84 Friend

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    Alex will respond in greater detail, but initial lab testing did not suggest that the stock psu would cause issues with power outages..dB
     
  20. atomicbob

    atomicbob dScope Yoda

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    Power up / power down sequences have been with us since the beginning of separate components for stereo and pro audio:
    Power up
    1. Source on
    2. Preamp or Mix console on
    3. Outboards (processers) on
    4. Amps on

    Power down
    1. Amps off
    2. Outboards off
    3. Mix console (preamp) off
    4. Source off

    Failure to follow sequence may result in unpleasant loud noises and damage.

    It is enough of an issue that pro audio types have rack sequencers when allowing less knowledgeable users operate complex racks. See this Furman product as an example:
    https://www.furmanpower.com/product/15a-standard-power-conditioner-sequencer-M-8S

    If using a switched power distribution or conditioner, I would still practice turning off amps first and on last as per procedure.

    The Liquid Platinum has been designed to work with the provided SMPS. Consider the following data:
    31 20181130 SMPS vs ZeroZone 36V 56R load - power off.png
    During power interruption the SMPS discharges rapidly (green line.) The amp is designed to work at 36Vdc. When the voltage is lower than operational design point, stability of operation cannot be guaranteed, true of any electronic component during power interruption and why UPS exist. So consider the time spent between say 34Vdc and 1Vdc. With the SMPS there are 100mS of potentially unstable behavior and the violet line depicts possible energy delivered. It is a tiny amount in the graph's lower left corner.

    Now consider the LPS discharge (red line) which requires 4000 mS to discharge. The blue line depicts amount of potential energy delivered during power interruption. Clearly there is more time for the circuit to be potentially unstable and far more energy available. This is not desirable. So I would recommend only using any LPS or Noise Nuke if willing to either follow the power sequence procedures, use a UPS if worried about power outages or willing to take risks. This applies to all amps, not just the Liquid Platinum.
     
    Last edited: Dec 3, 2018
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