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. ecline56

    ecline56 Almost "Made"

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    Well 7 weeks since my last post and I still am completely enamored with this amp. The LP is excellent+ with my M1060 and M1070 planar's. The LP sounds very, very good with my modded Sennheiser HD599 using the single ended headphone output.

    Speaking of single ended, after much listening I find I like the single ended outputs of my DAC's to the LP's single ended inputs best. But all my balanced digital sources have D/S chips and my single ended DAC's are RTR/ NOS designs. I thought the reason was probably that I much prefer RTR designs. But, with more listening I determined I like the single ended outputs from the D/S DAC's better too. Single ended is richer sounding and I like the treble presentation better.

    Balanced out to the headphone is the best by far with my planar's no question. The Sennheiser HD58x sounds like ass balanced on the LP.

    I like this amp so much I just bought a used Liquid Gold from Adam/ Ilikebananafudge for a great price. Can't wait to try the Gold!
     
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    Last edited: May 21, 2023
  2. Azimuth

    Azimuth FKA rtaylor76, Friend

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    What DAC are you using to feed it? Any unbalanced source is converted to balanced with the splitter. And the balanced out is then summed to unbalanced.

    I have always found the sound of the unbalanced output pretty bland no matter what headphone used. I only use balanced output out of the LP when I use pretty much any headphone, including HP650, HP600, JAR560. Now the HP58x from Massdrop has a pretty high treble presentation and very sensitive, so I can see how the more cloudy output of the SE out can sound better with that headphone.

    The LG is even better with planars than the LP as it can bring out more low level detail, although it might not sound quite as organic and lush as the LP.
     
  3. ecline56

    ecline56 Almost "Made"

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    MMB1, MMB2, Modded BF1 OG, Modded Zhalou 4398 dac with a class A output stage circa 2007. I have a Chinese 1865 NOS dac single ended only but I have not tried that one. The Zhaou has a SE/ balanced output. I have a Sony 9100 ES with a SE/ balanced Class A output stage and an old modded Eastsound E5 cd player circa 2009 with a SE /balanced Class A output stage. I use the Monoprice XLR and RCA cables for hookup.

    I know everyone seems to say go balanced from dac to headphone output. But this thins the timbre of the headphones and the treble sounds almost to detailed and draws attention to itself .... which I do not like. All the balanced dac's are D/S. I always think D/S dac's I have heard or own have to much treble (as in the amount) which covers other areas of the sound spectrum up. Balanced makes that treble issue worse to my ears.

    I use balanced output for all the headphone I have except the Senn 599SE/ 598Cs. The senns sound really good out of the LP single ended. But, I do like these headphones best out of my M^3 or Whammy.
     
    Last edited: May 22, 2023
  4. Azimuth

    Azimuth FKA rtaylor76, Friend

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    Sounds like the issue is the DACs you have, not really if the input of the LP is balanced or unbalanced. I run balanced into my LP from my Freya N, and have used it just direct from the Theta, and it sounds so much fuller and cleaner, but certainly not more etchy or more treble.
     
  5. ecline56

    ecline56 Almost "Made"

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    I like RTR better most of the time. But, I don't really care which way I run the input to the amp the sound is A- to A+ no matter which input I use. Just like single ended a little better. The modded BF1 OG I have is single ended and really good.
     
  6. ecline56

    ecline56 Almost "Made"

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    OK another two and half months later and I still am very, very pleased with this amp. I like the amp best with my planar headphones which is the consensus around SBAF. I have found some tubes that really make the amp sing with my balanced source .... Jan Sylvania 6922's. Very spacious and open with tremendous natural sounding resolution and enough body to avoid sounding thin. But, still the amp sounds fantastic with my MMB2 in NOS mode which is SE only and then balanced output from the amp to the headphone; usually modded MP M1070.

    Lots of tubes work well with the single ended MMB2 source. I have 1974 6N23 Reflectors and 1971/72 6N23 Voskhods and the above mentioned Sylvania 6922's. The Sylvania's are the best. Hard to beat good NOS USA tubes. However, the difference while noticeable is not night and day single ended. The big difference with the Sylvania tubes is when I use the balanced souce where they scale much more than the Russian tubes.

    The amp with its best SE or Balanced source/ tube combination is equally musical, equally satisfying and a mind numbing deal when on sale.

    Now while I am clearly thrilled with the performance of the LP I bought a used LG. I did not expect the LG to be so good. The LG is definitely more resolving but in a good way. Never pushing detail in your face, never emphasizing sibilance/ treble detail and just making the music more real sounding. Micro dynamics across the spectrum reveal every little nuance with the LG. The bass is slightly more present and has more slam with the LG. But ultimately, the LG is just so musical you can listen for hours. There is such good resolution and dynamics you do not need much volume for a satisfying listen.

    I listened to the Derek and the Dominoes Filmore Outtakes, the D&D In Concert 2 cd release and the first three cd's of the Allman Brother Filmore concerts box set straight before posting this update.... about six hours or so. No fatigue, just totally engaging, great sounding music.

    Onkyo DX-390 changer as transport >MMB2 in NOS mode> Liquid Gold> modded MP M1070 planar headphones with Hart balanced cable.
     
  7. Wilewarer

    Wilewarer Almost "Made"

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    I've had this for a few months now. Can't imagine it's leaving my desk anytime soon. This gets to use the balanced outputs on BF2/64 and that might be no small thing, so keep in mind that could be responsible for some of the good stuff. Specifically with Eikon though at least (which gets almost all my listening time), I'd rather use this than Lyr 3 or Piety.

    This is a very clean-sounding amp, in that I don't hear any weird traits that distract me from music. Which is what I wanted out of Lyr 3, but this has some advantages over that (I was surprised that the noise floor on Lyr 3's high gain was ever an issue with ZMF and Senn, but it was). No obvious weird flavors, very clean background, never feel like I'm missing any texture/nuance/etc. A counterpoint to Piety, which to me has some shortcomings in that respect and also definitely does very nice commissive flavor stuff (some of which is weird in comparison - I feel sometimes as though the Piety is throwing soundstage that should not be there, like checking between OS and NOS DAC modes).

    A 2/64 specific note: The sibilant traits from it are dispersed into the background better than with other amps I've tried. Could be an output thing, who knows. I'm not one of the people overly bothered by it (I hear it as better than original BF2, not worse), so maybe this would not be helpful enough to the people it does bother.

    I would say tubes don't change the sound all that much, least not with what I tried. The stock new EH tubes seem perfectly fine. I tried some old Soviet EVs too, those seemed more relaxed, less forward. Which is more what what I want, but, same amp basically, it's not a transformative effect. If anything the real preference for the Soviet stuff would be that it's cheaper, but nothing's cheaper than the stuff they just give you with the amp.

    The legend of the Liquid Crimson meant I was probably always going to end up with one of these; whether this gets anywhere close to that, it's good enough that doing much better in a way that actually matters to me is hard to imagine. I wouldn't have bought it at the undiscounted price, but at the ~300 bucks I got it at, I don't know what else you'd get that's better. Could pay a few hundred bucks more and still be happy. There are other good options, but this at least holds its own among them.
     
  8. thekorsen

    thekorsen Acquaintance

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    PSA if you lost the original power supply, don't try using this one:
    https://www.amazon.com/dp/B08HZ13L18?psc=1&ref=ppx_yo2ov_dt_b_product_details

    Monoprice refused to send or sell me a replacement since I wasn't the original owner, and the equivalent Fuyuang FY3601500 isn't sold on ebay anymore. I was aware of the power supply issues highlighted by @atomicbob in his measurements thread so I made sure I got a switching power supply that didn't look too cheap. Maybe its because it has a current limit of 3A instead of 1.5A (figured that wasn't too big of a jump and circuits usually only source the current they need). Plugged it into my LP (power switch off) and saw a big spark. Tubes now heat regardless of if the power button is on, which sounds similar to atomicbob's experience using a linear supply.

    I actually have another LP also without a power supply...I still need a replacement power supply for that one. Can someone who successfully found a replacement point me in the right direction? Otherwise I have 2 LPs that are paperweights. :(
     
    Last edited: Jul 8, 2023
  9. ecline56

    ecline56 Almost "Made"

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    Did you plug the power supply into the amp before you plugged in the power supply to the wall.? That is what the manual tells you to do ..... or you get arching just like you described that damages the amp.
     
  10. thekorsen

    thekorsen Acquaintance

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    Yeah I did start the amp with the power supply plugged in first, which is kinda natural my natural instinct TBH (sort out wires under table first then plug wire into amp). If this is a huge failure mode, there really should be a warning on the amp and not tucked away in the manual no one probably reads.

    After re-reading over the design fault and thinking I have a better grasp of it, I pluged the 2nd liquid platinum I had in the accepted order and it seemed to boot normally (tubes don't power on unexpectly, red LED turned white after some time) but I'm not getting any audio through the amp. Maybe its still the power supply triggering a failsafe, and maybe the first one could still be usable even though the tubes always stay on (mosfet failed on? think that's what atomicbob mentioned could happen). I'll order some new supplies that are rated for exactly 1.5A (if I can find some) and try again.
     
    Last edited: Jul 9, 2023
  11. ecline56

    ecline56 Almost "Made"

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    Do you have the correct input selected? If the power supply is 36 volts the higher ( 3 amp) amperage would not be used and the amp should work OK. You didn't hook up this second LP the wrong way at some point to did you?
     
  12. thekorsen

    thekorsen Acquaintance

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    Yeah I was really careful not to power the supply before connecting it to the amp. The order was:
    • Amp switched off, power supply unplugged, power supply barrel connected to amp
    • Power supply powered on
    • Amp switched on
    I only had a single ended dac to test with, but I tried every combination of RCA in ports in the rear, bal/se mode switch in the front, and bal/se outputs to headphones. No luck. I also verified the source was playing music during the test by connecting the dac to another amp before and after this test.

    Edit: I just realized I can hear music faintly out of the amp when the knob is turned to max. Probably not a great sign.
     
    Last edited: Jul 9, 2023
  13. ecline56

    ecline56 Almost "Made"

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    Looking at the back of the amp the left most RCA pair is the SE input. The other RCA pair is a pass through. I would hook the amp up again and give it a try. Those selector buttons do not always engage when you switch inputs.
     
  14. thekorsen

    thekorsen Acquaintance

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    Pretty sure I tested that combo earlier, but just in case it was a power thing I re-tested that as follows:
    • Amp off, I / O button clicked out, DAC off connected through leftmost RCA, PSU off connected to amp
    • Power supply on
    • Dac on
    • Amp on
    I repeated the above for the I/O button clicked in as well. Same low volume at max knob turn behavior, also confirmed the dac is functioning normally through the other amp I have directly after.

    Kinda glad that didn't work, if the amp startup was that finicky I'd probably throw it out the window at this point.
     
  15. hifiandrun

    hifiandrun Almost "Made"

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    [QUOTE=".... Monoprice refused to send or sell me a replacement since I wasn't the original owner, and the equivalent Fuyuang FY3601500 isn't sold on ebay anymore. I was aware of the power supply issues highlighted by @atomicbob in his measurements thread so I made sure I got a switching power supply that didn't look too cheap. Maybe its because it has a current limit of 3A instead of 1.5A (figured that wasn't too big of a jump and circuits usually only source the current they need). Plugged it into my LP (power switch off) and saw a big spark. Tubes now heat regardless of if the power button is on, which sounds similar to atomicbob's experience using a linear supply.

    I actually have another LP also without a power supply...I still need a replacement power supply for that one. Can someone who successfully found a replacement point me in the right direction? Otherwise I have 2 LPs that are paperweights. :([/QUOTE]

    @thekorsen, I bought this power supply from Digikey for my Liquid Gold, not Liquid Platinum. If my memory serve, I thought they were the same. The only difference I noticed was the plug was "L" shaped instead of straight. This link:
    TRH50A360-01E03 VI
    (https://www.digikey.com/en/products...3Jfh9Sw2tkfp3Lu-6kvcHhI-D0q0qfGs4HPqc1GxN8w8e)
     
  16. thekorsen

    thekorsen Acquaintance

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  17. Poimandres

    Poimandres Acquaintance

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    I have had my LP Amp and LP DAC for over a year and just got it set up a few days ago.

    My manual appears to only mention plugging into the back of the amp before turning the power button on. It doesn’t state (unless I have missed it or misread) the sequence to plug the power supply in.

    That being said I can’t remember when I plugged my ps into the wall however there was no arc. I’m curious if the polarity on the plug was inverted?
     
  18. Pancakes

    Pancakes Friend

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    Plug into amp. Plug into wall.
     
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  19. Poimandres

    Poimandres Acquaintance

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    I appreciate that is how you and most others plug it in, and is likely a best practice.

    The manual makes no mention of when to plug the power supply into the wall unless I am missing something.
     
  20. dasman66

    dasman66 Self proclaimed lazy ass - friend

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    That is best practice for anything electrically powered. Plug into the device first, and then into the wall. Any arc is between the plug and the wall instead of into your device.
     
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