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Monoprice Monolith Liquid Platinum - By Alex Cavalli

Discussion in 'Headphone Amps (full-size)' started by ufospls2, Apr 4, 2018.
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  1. runeight
    Give the tubes at least 50 hrs to clear out. Should come to sound signature around 100 hrs. Should be recognizable change about 25 hrs. Don't rush this process. Most importantly have a good time. I'll be back in Texas morning.
    Eagle13, Wes S, PaganDL and 6 others like this.
  2. Rattle
    @runeight can you give any impression on which headphones have great synergy with the platinum? I bought a spark and really liked it with HD600 and HD6xx which are my back and forth headphones.
  3. runeight
    I would like to, but I really don't know. There have been so many new headphones introduced in the last several years that it is impossible to keep up. In addition, headphone technology is getting better and better.

    I also think that synergy is partly in the ear of the beholder. My guess is that the current group of owners will have things to say about this over the next month or so and I will learn along with everyone else.
    PaganDL, cardeli22 and Rattle like this.
  4. rockytopwiz
    I'm hoping to hear of some impressions with the he1000. I had read in the liquid crimson thread that it was an excellent match, but reading the Platinum has a more rolled off bass has left me perplexed. I like bass
    alphanumerix1 likes this.
  5. alphanumerix1
    How's the elex pairing?
    displayname and Panimation like this.
  6. zfisch1
    I own the massdrop cavalli (mcth). Interested to hear from @runeight and others how you would compare the two. Especially what are the areas that the platinum outperforms the mcth. (running auteurs balanced with modi multibit). Thanks!
  7. runeight
    The CTH is a really fine amp. There are several places where the Platinum is different:

    1. Balanced vs. SE
    1. Power output - 1W CTH, 3.6W (Bal) Platinum
    2. Cap coupled hybrid CTH , DC coupled embedded hybrid Platinum
    4. Totally different amp topologies.
  8. jinxy245
    Sounds like the Platinum is the logical upgrade...I hope they'll be able to keep it in stock long enough for me to save up.
  9. runeight
    Liquid Crimson --> Liquid Platinum II

    If you haven't seen this, please go here:

    To squeeze a balanced Crimson into the Platinum sized box at 1/4 the price requires several engineering changes.

    1. Power output - Today's headphones are, in general, more efficient than when the Crimson was designed. While back then 4-5W might have been a necessity, today it is not. Most (but not all) headphones will run happily to ear-splitting levels at much less power. Thus, the first engineering change is to reduce the power output. Not by than much, but by enough to be practical. This includes going to a balanced topology which reduces the rail voltages considerably.

    2. Power supplies - there simply isn't enough room for a big transformer and linear supplies in the box and on the board. The only possible solution is an outboard supply, in this case for efficiency an SMPS. Then, this SMPS is used to create all of the needed supplies - LV rails, Housekeeping, HV and Heater.

    The HV and Heater supplies are made with small DC-DC converters. These are efficient, small, and perfectly suitable for the constant low current requirements of the tube portion of the circuit. Some would claim that linear supplies would be better here even if they provided less voltage. I would disagree. The Platinum HV supply makes over 100V to place the 6922 at a very good operating point. The CTH, to note, also has a 100V HV supply instead of a lower voltage linear one.

    Thus, the very big Crimson linear supplies are replaced with very small and/or outboard supplies which are all super efficient. This reduces the power demands of the amp a lot and the power dissipated by the non-audio components.

    3. Power Dissipation - the confines of the new box and lack of external heatsinks demands much lower power dissipation. This is partly accomplished with the new supplies. It is also accomplished by reducing the idle currents in the output devices significantly. Whereas the Crimson's output devices burnt almost 5W each at idle the Platinum's output devices burn less than 1/2 per device. The Platinum's outputs are cooled through the board making it possible to get it all in this small enclosure.

    4. SMD vs Through Hole - the Crimson was nearly entirely hand-assembled through hole components (expensive). The biggest change in the footprint of the Platinum is its use of SMD components. They are vastly smaller, don't compromise the performance, and are auto assembled dramatically reducing the manufacturing cost.

    All of these 4 engineering changes working together are what makes it possible to offer the Platinum in its small box at the current price point.
    Last edited: Nov 3, 2018
    Eagle13, jasonho, CoFire and 25 others like this.
  10. llcook51
    Same for me in Florida minus the state taxes.
  11. llcook51
    Thanks so much. Your insight would be greatly appreciated.
  12. Jim N
    Positive after last night's session. Had about 16 hours burn-in on the LP and 140 on the Elex (balanced) at the time. Right now my standard of comparison is an Auralic Taurus Mk II. I listened for about 3 hours. Bass is quite solid and highs are just a touch recessed right now. It seems like it is taking shape so to speak. Nice tonality on very forward piano and aggressive tenor sax and they also have nice weight to them. It is evolving from initial quick listens earlier and I am sure it will continue to do so. Not night and day (as the amp sounds quite nice right now) but more in the way of refinement.

    By slightly recessed highs I am using a track by Flim & The BB's titled "Room With A View of You" off their "Tunnel" album as an example. There is a glockenspiel part that repeats after the chorus and it's a bit more prominent on the Taurus. This was one of the first CD's I bought and has been in regular rotation for me since the mid 80's. That part was one of the first things that sold me on CD's.

    After having the thermal protection circuit kick in once while running a very challenging burn in disk with Fostex TH-X00 connected via TRS it has not happened again but I have had balanced Elex connected. Volume was set at between 9 and 10 o'clock when running the burn in and listening. I do not crank the volume.

    By way of full disclosure I am in my 60's and have very mild tinnitus. The latter is variable so it can impact each listening session differently. I won't be doing a back and forth comparo between amps. I'll run my HD600 balanced tonight.

    I am enjoying the amp. I did not buy it hoping it would exceed the Taurus in all areas but rather to have two different perspectives and synergy. No regrets so far.

    I noted Alex's comment on the SMPS providing more than adequate power but I am curious about added noise versus an LPS. It would appear that any LPS efforts are being left to aftermarket vendors. I completely understand the sacrifices needed to achieve the price point. I could never afford a Liquid Crimson. Also understand the point about dissipation as this is a very small enclosure and the top in front of the tubes is quite warm when running as it is. This is a very carefully thought out design that required some serious tightrope walking and balancing of conflicting needs. I am glad Alex made this effort.

    Any thoughts on tube rolling? The tube socket requires a lot of pressure to seat the tubes and wonder if the unit is voiced with the included Electro Harmonix 6922, which is not a bad tube at all.
  13. spyder1

    When using the Liquid Platinum (SE output to powered speakers, AMP {pass through}), does the Liquid Platinum vacuum tube stage have a "tube buffer effect" on the SE [Pass Through] output?
    displayname likes this.
  14. runeight
    The socket will be tight at the beginning until the tangs relax a little. The amp isn't really made for a lot of tube rolling, though as you guys know from my previous comments, I knew that some folks would do some tube rolling in any case.

    The amp is not voiced to the EHs. I don't actually voice amps in any way. I generally have a set of goals and then let the amp sound the way it will. :o2smile:
    Eagle13, displayname and Jim N like this.
  15. runeight
    Not in this design. The loop out on the RCA input is directly wired to the input jacks. Nothing in between.
    displayname likes this.
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