Monoprice Monolith Liquid Platinum Headphone Amplifier by Alex Cavalli

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Vtory, Apr 4, 2018.

  1. GanGreinke

    GanGreinke Almost "Made"

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    Before @atomicbob published his measurements for the LP, I purchased this linear power supply: https://www.ebay.com/itm/Custom-make-Linear-power-supply-for-pro-ject-Phono-Box-RS/122866202627?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649. It was custom made for 36V and 1.5A. It arrived a few days ago and worked with no problems for the first day.

    Now, though, I find that the amp will power up when I turn on the linear power supply, even when the amp power button is in the off position. The tubes light up and the led light will turn from red to green, though there isn't the click that usually comes when the light changes color. I also notice that the amp gives up a soft whining sound when the power button isn't pushed in. The amp still works normally when powered on, but it just won't turn off. Does anyone know what could be the issue?
     
  2. runeight

    runeight MOT: Alex Cavalli

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    You're welcome. Thanks for buying a Platinum. :)

    I have been in this community for a long time and know many. I have had the great privilege of seeing the technology advance by leaps and have known many of the folks who were part of that. It's been great.

    And, really, headphones are way more fun than speakers. And a helluva lot cheaper (well mostly). :)
     
  3. runeight

    runeight MOT: Alex Cavalli

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    Yes. It would appear that the power circuit has been damaged.
     
  4. jmpsmash

    jmpsmash Rando

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    what happens when you plug in the stock power supply?
     
  5. GanGreinke

    GanGreinke Almost "Made"

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    @runeight Thank you Dr. Cavalli for the response. That makes sense. I just hope that Monoprice would be willing to service the amp (and I would be willing to pay since I'm pretty sure I voided the warranty using a non-stock power supply) rather than just telling me that I am SOL.

    The problem still persists even when the stock power supply is used.
     
  6. runeight

    runeight MOT: Alex Cavalli

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    I cannot say without having more data what exactly has happened, but let me strongly suggest a power sequence.

    Plug in and turn on the LPS first. Make sure the Platinum power switch is off.

    Then engage the Platinum power switch.

    Do the reverse when turning off.

    Don't cycle using the LPS power switch with the Platinum switch engaged.
     
  7. runeight

    runeight MOT: Alex Cavalli

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    Please contact MP and if they need to talk to me I am aware of what is going on. At least so far. :)
     
  8. svperstar

    svperstar Rando

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    Anyone have an Asgard 2 and can compare it to the LP?
     
  9. Pillars

    Pillars Embarrassment to Colorado crew

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    There is a pretty big well of info on the differences of SS and tube hybrid around here. However, it comes down to your preference. I can't comment on the SQ of the liquid platinum however I can say that I prefer many amps I've had over the Asgard 2.
     
  10. earnmyturns

    earnmyturns Friend

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    Not quite, but here's my headamp ranking from everything I've owned, mostly with Ether C Flow headphones and a range of mutibit DACs:

    Solid state:

    Asgard 2 < Liquid Carbon < Jotunheim < Neurochrome HP-1

    Hybrid relative to solid-state (and this is a bit more preference and music choice rather than fundamentals):

    Jotunheim < Lyr 3 < Apex Peak (with a range of well-tested NOS and some new 6SN7 tubes)

    I've not spent time tying to place the HP-1 with respect to the hybrids, as I have a good use for the HP-1 where I don't want to have a tube amp.

    From memory, the main weakness of the Asgard 2 relative to the other amps listed above is a slight harshness, lack of refinement in the mid range, especially for solo piano. Not a huge thing, but enough to make me move up the ladder.

    From everything I've read, the LP might sit somewhere at or above the Lyr 3. I've actually been tempted to get one, except that I can't quite find the reason and time to play with yet another headamp.
     
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  11. songmic

    songmic Gear cycler East Asia edition

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    For a split second I thought Psalm came back lurking with a new account after being banned. I must be getting paranoid...

    I preferred the CTH to Asgard 2 with virtually any headphone I threw at, so I don't think it will be much of a contest, really. Unless you're him.
     
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  12. James Paschini

    James Paschini Rando

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    Alright, So I have been playing around with my new Cavalli amp this weekend.
    I am stunned by the amount of detail and resolution i'm hearing with the 800s's
    I was reading everywhere that the 800s could really show if a recording is not done correctly, this weekend I really understood the meaning of this.
    I had a blast.
    I paired the Liquid Platinum with the RME ADI-2 Dac and the pairing is wonderful. So customizable and fun.
    I just am enjoying this setup. I don't see myself changing anything is the near future (maybe a pair of closed cans...? who knows)
    I was impressed by the packaging and quality of the unit.
    Having ordered from Monoprice in the past, I was honestly expecting less.
    The feel is super premium.
    A+++ for me on the shear simplicity of the unit.
    I will give more feedback in the weeks to come, but so far..... I think i'm in love...:)
     
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  13. GanGreinke

    GanGreinke Almost "Made"

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    Just a heads up, to follow up on my issue with the power circuit (which, to be clear, was almost certainly my fault), I just got a response from Monoprice regarding a possible repair, and they responded that they do not have a repair service in place. I was advised to try and find a local repair center.

    Someone in the thread had asked about repairs, and it looks like Monoprice doesn't have anything set up. If something goes wrong under warranty, it'll probably just be a straight up replacement.

    @runeight, if I did want to get my amp repaired, do you have a recommendation for a company? Would Avenson Audio be willing to work on it?
     
  14. svperstar

    svperstar Rando

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    Naw I'm not Psalm, shame he got banned cuz he sounds like a cool dude.

    It came down to the LP or the Gilmore Lite MK2 and I picked the Gilmore because I have always regretted selling my old Gilmore Lite back in the day.
     
  15. runeight

    runeight MOT: Alex Cavalli

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    Hey guys, time for a follow up on using various LPSs.

    First, if you haven't read this please go here and read AtomicBob's investigations (and many thanks to AB for taking all his time and expertise to create all of this data):

    https://superbestaudiofriends.org/i...echnical-measurements.7105/page-2#post-235287

    I have been thinking on the use of LPSs.

    Keep in mind that the Platinum was carefully engineered to reduce a really good single ended Liquid Crimson amp to a fully balanced Liquid Crimson (Platinum) in a much smaller size and at a much more affordable cost. What of this is important here is that all aspects of the Platinum design, including the SMPS power supply, all work together to accomplish this. The characteristics of the SMPS are part of the design.

    Part of its behavior is its current limiting when over loaded. This overloading happens at turn on for a very brief period of time and the SMPS does its thing by limiting the current. The power circuit in the Platinum is expecting this to happen.

    Using an LPS that does not current limit or has huge capacitors at its output or can otherwise dump a lot of current into the DC jack is definitely a RISK. It is likely out of the design envelope of the power management portion of the amp.

    Though I am not Monoprice I have to recommend that you don't use LPSs with this amp and that you do stick with the supplied SMPS.

    It is designed to perform extremely well with this supply. :)
     
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  16. runeight

    runeight MOT: Alex Cavalli

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    They might. I will ask them tomorrow. If my guess as to what was damaged is correct, the fix is very easy.
     
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  17. runeight

    runeight MOT: Alex Cavalli

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    Yes, they said they would. Please contact them through the CA website.
     
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  18. purr1n

    purr1n Finding his inner redneck

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    Not the same class. I don't think anyone really here likes the Asgard 2 all that much. It's OK. Better than any medium or small form factor Audio-GD amp I've heard so far though - although the latest Audio-GD stuff is supposed to be better - but I'm not about to waste SBAF war chest funds on them.
     
  19. svperstar

    svperstar Rando

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    I just went with the Gilmore Lite mk2 because I have always wanted another Gilmore Lite.
     
  20. songmic

    songmic Gear cycler East Asia edition

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    Then it would've been better if you had asked for a comparison between LP and GLmk2 in the first place. You're just repeating yourself after people are answering your question now that it doesn't matter to you anymore.

    Although I haven't had firsthand experience with Kevin Gilmore's dynamic amps (e.g. Dynahi, Dynalo, GS-1, GS-X mk2/mini, etc.), not many folks here seem to be a big fan of his designs, for more of tonality rather than technicality reasons. On the other hand, they are lauded as arguably the best dynamic headamps at Head-Case.

    I would like to give them the benefit of the doubt, since I recently bought the KGSSHV Carbon and it has greatly surpassed my expectations as an electrostatic amp. However, given the dynamic headphone I'm using (Code-X) and my experience with the slightly warm and wet nature of Cavalli amps, choosing the LP was no-brainer.

    I have a feeling the Gilmore amps would be a better match with HD650/Clear/PMx2/Audezes than they are with, say, Utopia/HD800.
     
    Last edited: Dec 6, 2018
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