Liquid Gold X Balanced Headphone Amplifier from Monoprice by Alex Cavalli

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by jexby, Sep 10, 2019.

  1. Pancakes

    Pancakes Friend

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    Pretty sure lol.
     
  2. ilikebananafudge_

    ilikebananafudge_ Rando

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    In all seriousness, I don't own the LAuX, but I've never seen a spark when plugging in any of my audio gear. That doesn't sound normal to me. Perhaps try various outlets to make sure it's not outlet dependent?
     
  3. Pancakes

    Pancakes Friend

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    Plugging directly into LP's PSU (which has been working without issues for close to a year) to confirm and I get the same thing. Just to clarify, this isn't a spark when plugging PSU into outlet but rather when plugging PSU into back of amp.
     
  4. Beefy

    Beefy Almost "Made"

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    Ooooh, I don't think you should do that. Potentially big inrush currents to charge the uncoupling capacitors. Bad for the connector, bad for the power supply.

    Generally, you should plug the power supply into the amp, then plug the power supply into the wall, then power up. Most power supplies will pseudo soft-start (even without a dedicated soft start) to reduce this, simply by the time taken to energise the toroid and bring up the voltage rails.

    [EDIT] Just checked the user manual, and it seems there is a whole heap of protection circuitry to avoid problems. Yet they do still say make no electrical connections while power is on. So yeah, don't do what you're doing. Power switch off. Power supply unplugged. Make the connection power supply to amp, make the connection power supply to wall, power on at front panel.
     
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    Last edited: Oct 13, 2021
  5. loadexfa

    loadexfa Friend

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    Same thing happened with mine. I thought it was odd but the amp worked so I ignored it.
     
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  6. CEE TEE

    CEE TEE Free Agent

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    ^This!! Always best to plug the wall wart (or inline power brick) into the amp, then plug the wall wart/inline brick into the wall/power strip.

    Because of the momentary jump through the wall wart and across the plug into the back of the amp, large safety parts have to be placed at the amp's power supply input section to protect against frying the power supply section. But best not to subject the back of your amp to this. o_O
     
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  7. Pancakes

    Pancakes Friend

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    I suspected that it's the inrush current. I assumed that the power switch on the amp exists for that very reason - no power connection until it's clicked "on" but apparently that's not the case. So yeah....wall socket last. Almost makes me wonder what the power button does - just running through the startup sequence I guess?
     
  8. atomicbob

    atomicbob dScope Yoda

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    The amp power switch on the latest cavalli designs does two things:
    1) change state of series power FET to the ON state
    2) begin the power up protection sequence

    This power supply system was designed expecting a soft source from SMPS type power supplies. LPS and SMPS + NoiseNuke™ combination represent hard sources with potential for enormous inrush currents at power on. It would be best to incorporate a small series inductor limiting the inrush current. Otherwise the series power FET may fail. If it fails Source - Drain short then it is still important to use the amp power switch to properly sequence power up protection.
     
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  9. Pancakes

    Pancakes Friend

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    @atomicbob I guess this implies that there is a set of PSU caps sitting right behind the power plug (before the actual "turn on" circuit)?
     
  10. atomicbob

    atomicbob dScope Yoda

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    It depends on the Linear Power Supply circuit topology. Here are some links to different design topologies and some reference information:

    https://www.eleccircuit.com/simple-designing-12v-5a-linear-power-supply/
    https://www.amb.org/audio/sigma11/
    https://mcitransformer.com/about-mci/power-supply-design-notes/

    In answering questions about Cavalli amps with external SMPS it is best to assume the entire spectrum of LPS may be considered by a given user. Some LPS topologies use brute force similar to the NoiseNuke™ and some use a regulator with a small cap.

    Personally, I don't find use of LPS with Liquid Gold or Liquid Platinum to offer any advantage and certainly not enough, if any, to offset risks of damaging the power control FET.
     
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  11. Rob the Comic

    Rob the Comic Almost "Made"

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    Well congratulations! I am 61 and have had slight constipation for a few days, but I read your first sentence and shit myself!! I am not even a ‘made man’ yet and I thought WTF have I done now; I have inadvertently pissed off the gearmeister.
    Seriously, I would dig your impressions of the XE. I also have a Heed Audio Canalot III Q-PSU which is a great amp as well. It has no balanced output but I keep it hanging around because it has 2 SE outputs for shared listening - which would be very handy if I had friends. :)
     
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  12. rhythmdevils

    rhythmdevils Best SBAF member of all time

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    you should be a made man let’s see what we can do there. ;)
     
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  13. Pancakes

    Pancakes Friend

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    Actually my question is precisely because these particular amps use an SMPS. I understand how an LPS works (a very simple circuit) and the best way to do it with an outboard PSU (for an amplifier) is to have the last C in the filter be separate and sitting in the amp chassis.

    I'm not familiar with SMPS outboard designs so was wondering if that's the case as well. Because otherwise (no PSU filtering caps in the amp chassis), I don't understand what's causing the current inrush and therefore the spark. Something's causing current to flow in an amp that's supposedly "off".

    If this is going too far off topic, my apologies.

    Edit*
    Never mind, I'll just open up the amp when I get around to it and find out how it's done.
     
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    Last edited: Oct 13, 2021
  14. CEE TEE

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    ^I'm trying to remember from CTH development but I believe the SMPS wall warts and inline bricks don't shut down the initial rush/discharge fast enough when the spark jumps from the plug to the back of the amp because you are plugging into the amp last. This surge from SMPS can overload the MOSFET and demands a really beefy one in order to keep the power supply section operating correctly. If the SMPS overloads and blows the back MOSFET, amp exhibits as being "always on" and you have to unplug the amp to power it down.
     
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  15. atomicbob

    atomicbob dScope Yoda

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    I misunderstood your question. I thought you were asking about energy storage from power sources external to the Liquid Gold or Liquid Platinum. I see now you are asking about energy storage internal to the amps. Internal there are multiple power supply systems for necessary low and high voltages. Those supply systems consist of multiple capacitor -> regulator -> capacitor topologies.

    So in aggregate it looks like this:
    external PS -> FET switch -> subsystem supplies.

    The inrush current is a function of the internal energy storage drawing from the external energy storage system. FET switch is rated for 120 Amps. However there is a safe operating area during power on which must be observed.
    IPB120P04 safe operating area.png

    When there are too many joules of energy storage available from the external power supply at a very low impedance this safe operating area can be exceeded. With the extreme stiffness of some supplies such as SMPS + NoiseNuke™ the following condition may be produced:
    Mosfet inrush current at power on with stiff power source.png
    For approximately 10 to 20 uS the inrush current exceeds 310A at approximately 36V. That is outside the safe operating area for this specific case. When used with power supplies intended, the LAuX and LP are far inside the safe operating area and there is no issue.
     
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    Last edited: Oct 14, 2021
  16. Pancakes

    Pancakes Friend

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    This is exactly what I was looking for. You da man.
     
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  17. Rob the Comic

    Rob the Comic Almost "Made"

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    Agree with @CEE TEE original cautions. I ensure everything is good to go, even including the headphones in; only then do I turn on the power followed by the device and do the same when switching off.
    The Phonitors are notorious for actually blowing up if inserting or removing a Single End plug when the unit is on.
     
    Last edited: Oct 14, 2021
  18. Pancakes

    Pancakes Friend

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    Super duper short initial impression.

    It's been on for ~ 1 week so initial burn-in weirdness should be mostly gone.

    Audirvana -> Pi2AES -> *internal DAC* -> HD600

    One word - polite.

    When I get a chance I'll plug it into Yggdrasil and do a more thoughtful "analysis".
     
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  19. Pancakes

    Pancakes Friend

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    I haven't done a review of any audio gear before nor do I consider myself to have golden or trained ears nor do I have any special wordsmithing skills. With that out of the way, a few notes about my preferences:


    I'm a detail, staging and, imaging whore. Haven't listened to much acoustic live music so timbre is not something I can comment on with any competency. Tonally, I'm not too bothered by sins of omission and anything that is warm or neutral or a slight v is fine. Different flavors and all can be enjoyable. I'm particularly sensitive/bothered/annoyed by bright or nasally presentations.


    I listen to Electronic, 80s, Rap, Rock, Metal.


    This review was done under duress. I received the amp and had to send it back for a replacement due to a power fault. Once I got a working unit, I casually listened to it for a week to let it break-in. It normally takes me a couple of weeks of listening after break-in to get a complete idea of what an amp sounds like but my window for a return left me with only 3 days so everything got rushed.


    Chain:

    Audirvana using ALAC or streaming Quobuz -> Pi2AES -> AES -> Yggdrasil A2/OG -> balanced -> LAuX high gain -> Focal Eligia. All headphones are 4 pin XLR terminated and run off balanced out.

    If you read my post above, it was one word - polite. Macrodynamics/slam was missing. I figured this would change with time and with the use of Yggdrasil instead of the built-in DAC. There was a very small improvement but I ended chasing it during my entire time with the unit. Switching from the HD600 to the Diana V2 didn't improve the situation (I didn't actually expect it to but figured I'd try anyway). So, I ended up doing all my listening with the (arguably least competent) easiest to drive, darkest and, slammiest headphone I own, the Eligia in what proved to be an almost obsessive yet fruitless chase for dynamics, fun, PRaT, excitement.


    The following are all relative to SW51+ with stock tubes and Low Z out.


    DMX's Ruff Ryders' Anthem and AC/DC's Thunderstruck are songs that should be kicking your ass. But there is none of that. Limp dick. SW51+ wipes the floor with the LAuX on this track. No other attributes matter if these tracks can't get you to headbang or want to punch somebody in the face.


    In general, across all the tracks I used, bass amount is lacking in comparison to SW51+...it almost sounds rolled off. Definition is there but it's not satisfying.


    Highs are an improvement over SW51+. High-hats, cymbals and various other high frequency instruments and sounds are better defined and more present. Never fatiguing or rough or sibilant. This is one of the amp's highlights for me.


    Microdetail and blackground are an improvement over SW51. In the very beginning of Whitney Houston's I Will Always Love You, for the first time I can hear the space she's in in the very beginning of the song (literally the very first part where it's just her voice). Up until now, all I've heard was her voice on a black background. With the LAuX, it was a revelation - there's a well defined space she's in and I can see it. All the reverb off the walls is there and it's amazing.


    Separation/imaging is the best I've heard from any of the amps I've tried. SW51+, WHAMMY (in various flavors), LP, cap modded LP, Liquid Spark, Magni 3, highly modded BHC. The song Diamond Veins by French 79 has the singer's (female) voice layered at various parts of the song and I always find myself trying to hear how many tracks of that voice there are on top of each other. I'm still not sure if there are just 3 or 4 (or more?) but the 3 I hear are *much* easier to pick out than with other amps.


    Finally, my torture test track for unpleasantness in the mids is The Great Gig in the Sky (Pink Floyd). Clare Torry's voice is a regular agitator easily sounding shrill, congested, compressed. LAuX is the first I've heard that handles this well and doesn't require me to turn down the volume.


    I'm in love with the things it does well and can see why others may as well. Except that I can't live with the lack of dynamics and measly bass. It's just boring for me. I don't need fireworks but there's gotta be some life. I've packed it and it's ready to be returned (I figure there's no point in posting it FS here since there's already one listed since Tuesday).

    However! I owned the Liquid Spark for a while and while I liked how it sounded, I ended up selling it because it lacked punch/slam/macrodynamics. The LP is just better enough in this department (but only after I swapped caps) for me to keep. So long story short, it's probably not the LAuX per say that's the problem. The Cavalli house sound itself is apparently not for me. Or at least the Monopriced versions - never heard the originals.

    Off topic - I can't believe how long it takes to write a semi-competent review. Kudos to all of you who do it regularly (and competently).


    2FB6E187-A454-4D0F-AB3F-94C658CA39B1.jpeg
     
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    Last edited: Oct 24, 2021 at 10:28 PM
  20. rhythmdevils

    rhythmdevils Best SBAF member of all time

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    Great review @Pancakes you should write more reviews/impressions.

    The impressions of lack of bass are puzzling to me. Not just because I don't have the same impression, but because comparing to multiple other amps I don't hear a lack of bass or bass slam. It has the same ass quantity as my Liquid Glass, SOHA1, First Watt Aleph J, Jottenheim 2, BHA-1, Magni 3+, etc. I wonder if there is a synergy issue at play. Curious. But great write up!
     
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    Last edited: Oct 23, 2021 at 3:22 AM

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