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. Ruined

    Ruined HD700 ruined my ear holes

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    Yeah just the fact that it followed the headphone R cup when reversed made me think it was something in the chain, but it very well may be a sensitivity of mine. Just wish I had the equipment to confirm. There are a few ppl in HF forum mentioning experiencing distortion in 2020 built units.

    Re build quality its really not bad, but was a bit turned off with my first unit having a really messed up front headphone jack. My last HPA was built like a tank so was a bit of a downgrade in that regard.
     
    Last edited: Sep 8, 2020
  2. Skyline

    Skyline Double-blindly done with this hobby

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    That's fair. Mine is from the original run of amps, so who knows if something has changed in production since then.

    Mine has been problem-free from day 1 *knock on wood*
     
  3. HotRatSalad

    HotRatSalad Friend

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    I got my LP right at launch, never had that issue with 3 or 4 different tube sets and as many dacs. I've heard people say they have this same issue on head fi. Maybe it's a newer run issue ? Could it be something else ? Any noise or interference I got with SE gear was always killed and completely silent in LP.
     
  4. Inoculator

    Inoculator Friend

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    A friend of mine made some interesting findings in regards to the different versions of the LP when he was experimenting with cap modding. I have an original first-run LP, and he also had a 2020 model that he purchased after liking the cap mod on mine. Both of us were big fans of the elna cap mod, but were both pretty unsatisfied with the bass performance after the mod. He found that the cap for the XLR jack makes a surprisingly big difference in the bass performance. (Granted only testing balanced). Keeping the original cap in there had better performance than the elna cap, but switching to a KZ series nichicon cap yielded the best bass performance of the three configurations. This experiment started to highlight some pretty major differences between an original model LP and the 2020.

    First off, the channel/pot imbalance is horrible on the new 2020 model until you get to 11 o'clock or so, which seems to be a common issue. Bad enough that is is not worth purchasing if you don't have a preamp in front of it and just set the amp itself at unity gain. The biggest sonic difference between the amps after modding them though is the original model is airier, a bit more analytical, and pretty neutral. The 2020 model on the other hand has a noticeable mid-bass bump, and a much thicker tonality. My buddy said he has never heard the HD 600 slam as hard as on the 2020 LP cap modded with that KZ front/xlr cap, while the original model LP is still pretty bass light even after experimenting with that cap.

    Interesting that just in the process of changing the gain/tube sockets that the tonality of the amp has changed so much. (Maybe I missed some other major changes that were made?) Maybe overall the channel imbalance issues and the variations in tonality just point to really poor quality control for the LP and I need to avoid any newer models? If willing to change the volume pot and caps though on a 2020 model you might be getting a really solid amp though if you want to preserve a more lush presentation.
     
  5. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Unless the pots are different parts, I wouldn't bank on newer units being necessarily different. Pot variance can, well, vary wildly. But running component changes aren't out of the norm either, whether due to cost, sourcing, ease of use, reliability, availability, etc.
     
  6. Ksorota

    Ksorota Friend

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    I was finally able to track down some KZ caps for the XLR location and have to say, yes, I totally agree. I am running with the HD600 and like your friend think that bass impact is improved and overall tonality sounds a bit more pleasing. I would not say the Elna's really take away from the stock sound at that location, but the KZ's do sound better.

    I have gone through the process of swapping out the stock volume pot for an Alps RK27 and although not an easy swap requiring some modifications to the front panel as well as the internals, to me it was worth it. Channel balance is now spot on down to zero volume. Having been involved in swapping caps on some dozen units already I can say that channel matching is a mixed bag. Some older units are better, and some newer units are fine as well. I am sure it comes down to the cheap pot that monoprice is sourcing (and more importantly not testing) to put into this great amp

    Disclaimer: I always like SS amps more than tubes

    I did not love the LP prior to the mod...it was thick, too thick for my tastes. The Elna swap removes some of that and as a side affect makes tube swapping more effective in changing the overall signature. The upgraded LP forced me to sell off my GSX mini...so that is saying something.

    Best analogy I can think of right now is that, To me, the swap removes some of the syrup and adds in some caffeine into the audio chain. The KZ caps in the mix are like adding a drop or two of syrup into your coffee...and its delightful.
     
  7. penguins

    penguins Friend, formerly known as fp627

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    So when LP came out I and I think others had asked how similar it was to the LC it was given that the Platinum is based off (but obviously not a clone of) the Crimson. Now that I actually have and have been listening to the LC for more than a session or two here/there, I can definitely say no, the two do not sound the same or almost the same. I am not knocking the LP - I still think it's a pretty good amp for the under $600 new price (it went on sale for under $500 new not long ago) and it's especially good on a good used deal.

    The main reason I made the post - for those who have seen or taken apart both, why do you suspect the two sound so different? Are the designs actually that different? Is it just the sum of differences in components adding up? Etc. FWIW I never took the LP apart when I had it and I won't be taking the LC apart anytime soon (if ever). Wondering b/c I may one day in the distant future consider building a similar sounding amp to LC.

    As an example, a lot of amps are similar to BH Crack yet they don't necessarily sound "that similar". Even with a BH crack, adding speedball (or a similar CSS circuit/section) changes the sound a lot IMO but you can still tell it's the same amp. Lastly, component upgrades all add up but in this case the sound signature doesn't change so much as it does "improve".
     
    Last edited: Sep 26, 2020
  8. lcmusiclover

    lcmusiclover Friend

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    Commenting on post from deals thread:
    As someone who has owned 3 of these, and has a fourth inbound, I feel qualified to comment here.

    My first LP, purchased within a month of introduction, died -- I suspect it was the power supply which failed, but don't really know. Sent it back to Monoprice and they sent me a brand new unit -- this was 6 - 7 months after purchase. This first amp had the worst imbalance of the three I've had. Without attenuation between my balanced DACs and LP, Utopia was close to unusable. Nice, relatively quiet listening level was 7:00 - 8:30ish (9:30 absolute max for my ears) and there was imbalance up to 8:15ish, so I couldn't listen 'quietly' without the imbalance being pretty bad. Since I have a balanced passive preamp, the issue didn't matter as much to me, but without attenuation it would have been a deal-breaker.

    My second LP, purchased just after my first died (since I feared that Monoprice might just refund me and LP had just come down to $600 on Amazon) had much less imbalance. Really almost un-noticeable. I ended up selling it once Monoprice shipped me a brand-new, replacement for the first one. I sold the 'second amp' when the third, warranty replacement, unit came in.

    My third one (the warranty replacement) was essentially identical to the second one. I say 'was' because it is now cap-modded. But it has barely noticeable channel imbalance with my most sensitive cans/IEMs, even when I crank the preamp all the way up to take me to the lowest volume level on the LP. Just a teeny bit of imbalance from Andromeda, which plays at like 7:02, where somewhere between 6:30 & 7:00 is 'all the way down'.

    My fourth LP will be the one I just purchased from @Inoculator and I'm hoping for the best :)

    Bottom line, I think the channel imbalance is really bad on some units, but I'm not sure that it is better or worse depending on when you purchased. It's clear that recent purchases have had some differences, and there's probably a different volume pot being used now. But at least some of the 'first run' units had very bad imbalance, apparently way worse than my first unit based on comments in the LP thread over on Head-fi.

    Caveat, I believe that all three of my units (and my incoming unit) have been 'version 1' so I don't know, maybe things are worse now.
     
  9. mk801

    mk801 Almost "Made"

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    I bought mine brand new from Monoprice during their earlier $484 run about a month to two months ago. That first unit had a big gain jump at 11 o'clock and, most of the time, pretty bad channel imbalance below that gain boundary, so I sent it back for a replacement. My second unit thankfully does not have that channel imbalance below that gain boundary. Also, the jump in gain seems to be less steep with the second unit than the first unit. I just shake my head when looking at the cheap pot used for this amp, especially one that retails for $800 MSRP.
     
  10. lcmusiclover

    lcmusiclover Friend

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    Thanks for adding experiences with recent builds.

    As far as 'cheap pot' in $800 amp, you have to wonder if a good pot and a gain switch would have allowed them to actually sell some units @ $799. My recollection was that they bumped the price from 7 to 800, but pretty quickly started dropping the price and have continued to do so.

    I will say that none of the three units I've owned had a 'big gain jump'. Again, 'version 1' vs 'version 2'?
     
  11. lcmusiclover

    lcmusiclover Friend

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    Discussion over this amp’s QC is getting heated up.

    Disclaimer: I’ll most likely be putting my cap-modded LP up for sale once it spends time with @Inoculator ’s which I bought to get the KZ cap mod w/out sending my LP out again. Then again, maybe I’ll send mine out to be modded now and hold it for insurance :)

    But I wouldn’t want my input to be taken as a criticism per se. Obviously, since I’m going on my 4th unit, I have some affection for the LP. But I also think it’s not so surprising that, given the price LP is selling for, there are QC issues. Disappointing? Yes. Surprising? No. Low cost suppliers + cursory validation of parts received = low and/or inconsistent quality.

    Of course it’s VERY disappointing if they made a running change that lowered quality. Is there a definitive external differentiator? I searched this thread (and the one over on HF) but didn’t catch a post about. Specifically looked at @Ksorota ’s posts — maybe I missed it, but it would be good to know if it does exist.

    The good news is that they’ve handled warranty issues quickly & cleanly by all reports I’ve seen (clearly a precise measure of anecdotal data). Of course all bets are off once you cap-mod :rolleyes:
     
  12. HotRatSalad

    HotRatSalad Friend

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    I guess there was some internal differences I believe were pointed out with pics. Over at the other place. I have about 700 hours on mine I bought 2 years ago. No issues still enjoy it but looking to move up a bit myself.
     
  13. Hammy

    Hammy Friend

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    The Liquid Gold X is now available. :D
    The LauX is more transparent (in the sense that you can better hear through the amp and the headphones disappear more) and has more musical nuance, but the midrange is more laid-back and midrange and bass don't hit as hard. The LauX is more finesse while the Liquid Platinum is a little more brute. Still both are very Cavalli. The LauX has a neat SS style of sonic holography.
     
  14. HotRatSalad

    HotRatSalad Friend

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    I think the LP is kind of my "laid back" threshold, while I do love the amp I paid $600 for I don't know if I want to shell out $1000 for the same build quality. Plus I'll be able to hear something a wonderful shade of blue soon :)
     
  15. Ksorota

    Ksorota Friend

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    The only way to differentiate from the outside is by looking at the tube sockets. Here are some photos which show the old versus new. Sorry about the quality of the new, looks like the image is a bit washed out.

    old top side.jpeg
    Early version of LP

    New_Topside.JPG
    Newer version of LP - notice the gold ring inside the center of the tube socket.
     
  16. lcmusiclover

    lcmusiclover Friend

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    Can someone please take a pic of a 'new version' amp with the cover on (without tubes in obviously), focusing on the tube sockets? If you'll PM to me I'll take a shot of my 'old version' amp with my tubes (and adapters) removed and make a post with both so we have a good pair of comparison shots with the covers on.

    My a.nervosa has led me to wonder if I must mod my LP some more, replacing the pot as described elsewhere. Since I use a preamp to attenuate input to my LP, the channel imbalance doesn't affect me. But does the low-quality pot still affect sound quality? Aaaah!
     
  17. Ksorota

    Ksorota Friend

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    image.jpg

    Couldn’t figure out how to send a photo in pm. So for the benefit of all!
     
  18. lcmusiclover

    lcmusiclover Friend

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    Doesn't look like you can, only image links. Sorry, my bad!

    Thanks for the pic -- exactly what I was looking for.
     
  19. Jer925

    Jer925 New

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    I currently have both liquid platinum and a MP thx 887 amp. I tried these amps one at a time both have the same problem in my system below.


    My source is Yamaha SACD player. It works fine going to the headphone amp. But when I hook up RCA from the pass thru of the HP amp to a Yamaha receiver. The sound is distorted in the headphones. Strangely the sound quality is restored when I turn the receiver on.


    I tried 3 different receivers I had and they distort the headphone to some degree when it is left passively hooked up the a receiver downstream (when off).


    Does anyone know why this is happening. Although these 2 products is from monoprice they are designed by different people.


    My solution is not to hook up both headphones and speaker system at the same time. But it seems like a very basic function that should have worked?


    I tried the Schitt sys after the headphone amp and it does work in some degree but due to the ground being shared I feel the sound may be contaminated. Maybe it’s in my head.


    Still I am thinking of putting Schitt sys in reverse right at the source and redirect the source to either the speaker or the headphone amp.

    Do you think using the volume knob of the SYS to cut the signal will let me put the LP at a higher knob position and have less channel imbalance. But would SYS introduce some imbalance as well? I feel there is some imbalance until at least 11 o clock. But most of my CDs I can listen at 12 or even 1 o clock. But it would be nice to keep it at 1 o clock for most music.

    Thanks
     
  20. Azimuth

    Azimuth FKA rtaylor76, Friend

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    It sounds like the pass through of your Yamaha is an active circuit not a passive one. It likely is a buffer circuit, like a Tape or Aux out, but those need those op-amp buffers. If you want to use it, leave it on. Or something like a Sys would be a good option as well. Note, you are not getting the best out of this amp with an unbalanced source.

    The channel imbalance on these Monoprice and Drop amps are due to the cheap volume control. With the LP, it is even worse because it is a 4-gang pot not just a stereo 2-gang pot because it is a balanced amp. The best way to deal with this is set the volume up to the unity point or electronically bypass and then use an external high-end attenuator of your choice.

    It seems like there is room in this amp for a better potentiometer. Such as a TKP 4CP601C-A10K. Seems it would be a worthy upgrade. Although might be hard to find. The only one I found was on a Japanese website for about $50, and they may not even ship to the US and who knows what the tariff would be on something like that.
     

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