Pass Labs X0.2 still has issues....

nooshinjohn
nooshinjohn Posts: 25,034
edited January 2019 in 2 Channel Audio
I have a new(to me) Pass Labs X1, that was just serviced and given a clean bill of health at the Lab just this past week. It was sent in because it had a loud and very audible "pop" between steps on the volume, and an audible "hiss" similar to what you would hear on a cassette tape back in the day. This hiss gets louder with each step up in volume and once an increment of 10 is achieved, the hiss steps back down again.

A large shift away from factory settings for DC offset were found and corrected, as well as a handful of capacitors found to be out of spec and replaced. The popping sound has been diminished by about 50 percent, but I find that the hissing noise is still there and very much a distraction to listening.

I sit 10 feet away from my speakers, and use Polk Audio SDA-SRS 1.2TL's, which have crossovers that have been recapped. The speakers are 91db sufficient. Driving them are my tube amplifiers. All connections to source components are made through XLR cables made by Audioquest.

My previous preamp was a Pass Labs X1, which exhibited none of the noise issues I have described. I do understand the pop sound is a function of the volume control and is a characteristic of it's design, and I am more than ok with that.

All functions of the pre work as intended and it sounds great otherwise. The only issue that really concerns me is that hissing sound. It is present regardless of source selected and can be heard some 20 feet away from the speaker even if nothing is playing. Is there something that can be done to reduce or eliminate this noise?
The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
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Comments

  • audioluvr
    audioluvr Posts: 5,420
    And swapping out the pre with another eliminated this?
    Gustard X26 Pro DAC
    Belles 21A Pre modded with Mundorf Supreme caps
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
    Wireworld Silver Eclipse IC's and speaker cables
    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)


    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
  • pitdogg2
    pitdogg2 Posts: 24,474
    Man i was hoping this would be a giant game changer for you John.

    Bummed
  • nooshinjohn
    nooshinjohn Posts: 25,034
    audioluvr wrote: »
    And swapping out the pre with another eliminated this?

    X1 and no noise at all. Swapping in the X0.2 and the noise is quite prevalent. All cables are the same. The only change was swapping the preamps. I have triple checked everything, swapped cables, disconnected the sda, everything I can think of. I think the troubles are within the volume control itself. I cannot fathom why they did not change it when it was there.

    On the plus side.... holy crap this thing produces the largest soundstage I have ever heard come from my speakers. Everything was great before but now it is on an entirely different level. I hope a solution can be found, because I would hate to be on the prowl for a different preamp.
    I am listening at low level right now and the nuance and micro detail is astonishing.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • BlueFox
    BlueFox Posts: 15,251
    Good luck with it. I wonder if they do a listen test, or just measure the specs. I'm still waiting to get my XP-22 back.
    Lumin X1 file player, Westminster Labs interconnect cable
    Sony XA-5400ES SACD; Pass XP-22 pre; X600.5 amps
    Magico S5 MKII Mcast Rose speakers; SPOD spikes

    Shunyata Triton v3/Typhon QR on source, Denali 2000 (2) on amps
    Shunyata Sigma XLR analog ICs, Sigma speaker cables
    Shunyata Sigma HC (2), Sigma Analog, Sigma Digital, Z Anaconda (3) power cables

    Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
    Three 20 amp circuits.
  • nooshinjohn
    nooshinjohn Posts: 25,034
    edited January 2019
    They did an amazing job, including all new packaging and boxes, cleaned the crap out of it inside and out. AMAZING service all the way around, just can't live with that hissing.

    They say it takes 48 hours to warm up and settle in. Maybe I am being too hard on things right now, but something tells me this is just the character of this unit. I can't imagine Nelson Pass would accept this noise coming from a flagship preamp.

    The detail this beast is capable of is astonishing. Bud... you had an XP30 before, correct? did you have a similar issue, or way it stone quiet? I might look to acquire an XP20 if I can't get this one sorted out.
    Post edited by nooshinjohn on
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • BlueFox
    BlueFox Posts: 15,251
    I had an XP-20, and it was dead quiet. Plus it never broke. :)
    Lumin X1 file player, Westminster Labs interconnect cable
    Sony XA-5400ES SACD; Pass XP-22 pre; X600.5 amps
    Magico S5 MKII Mcast Rose speakers; SPOD spikes

    Shunyata Triton v3/Typhon QR on source, Denali 2000 (2) on amps
    Shunyata Sigma XLR analog ICs, Sigma speaker cables
    Shunyata Sigma HC (2), Sigma Analog, Sigma Digital, Z Anaconda (3) power cables

    Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
    Three 20 amp circuits.
  • Clipdat
    Clipdat Posts: 12,558
    Send it back, since it hasn't been serviced to your expectations.
  • nooshinjohn
    nooshinjohn Posts: 25,034
    edited January 2019
    It costs money to do that. My gut just tells me that it may not like my tube amps, which is a very real possibility. What I need is a solid-state amp to test that hypothesis.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • Clipdat
    Clipdat Posts: 12,558
    Why does the preamp care if the amp it's outputting to is tube or SS?
  • nooshinjohn
    nooshinjohn Posts: 25,034
    Might just be a bad fit for them is all. I don’t have all the knowledge, but I am thinking a gain mismatch.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • Clipdat
    Clipdat Posts: 12,558
    I'm getting my read on: https://www.passlabs.com/sites/default/files/x0.2_om.pdf

    Could it be some weird configuration issue or setting that has been overlooked? It does seem strange that Pass wouldn't give it a listening test before sending it back.
  • monepolk
    monepolk Posts: 1,140
    Do you have another system that you can try the pre in?
  • audioluvr
    audioluvr Posts: 5,420
    Maybe reposition it so its isolated to see if it's some weird RF thing.
    Gustard X26 Pro DAC
    Belles 21A Pre modded with Mundorf Supreme caps
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
    Wireworld Silver Eclipse IC's and speaker cables
    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)


    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
  • tonyb
    tonyb Posts: 32,902
    John,

    Your not the only one. I have a hiss too in the upper frequencies after changing things back to what they were. Only thing that changed was the addition of a new older amp, same cables same everything same way everything was hooked up.

    Had the amp looked at, it's fine. Changed tubes in the pre, fine, still there. Nothing is more aggravating in this hobby of ours than chasing down an errant sound that appears that wasn't there before. Nothing bothers me more, than an errant sound I can't locate from where it's coming from. So much so...that I'm ready to rip it all apart and start from scratch.
    HT SYSTEM-
    Sony 850c 4k
    Pioneer elite vhx 21
    Sony 4k BRP
    SVS SB-2000
    Polk Sig. 20's
    Polk FX500 surrounds

    Cables-
    Acoustic zen Satori speaker cables
    Acoustic zen Matrix 2 IC's
    Wireworld eclipse 7 ic's
    Audio metallurgy ga-o digital cable

    Kitchen

    Sonos zp90
    Grant Fidelity tube dac
    B&k 1420
    lsi 9's
  • txcoastal1
    txcoastal1 Posts: 13,124
    Might just be a bad fit for them is all. I don’t have all the knowledge, but I am thinking a gain/impedance mismatch.

    This can very much be the cause. Do you have the specs on the amp?

    When I was speaking with Dan (Modwright) while pairing up a preamp with the Thresholds he asked for the specs. He tweaked the LS100 slightly to better match up the impedance pairing

    https://forum.audiogon.com/discussions/how-to-match-preamp-and-power-amp

    http://av2day.com/question/how-do-you-match-a-pre-amp-to-a-power-amp/

    and many more on the web
    2-channel: Modwright KWI-200 Integrated, Dynaudio C1-II Signatures
    Desktop rig: LSi7, Polk 110sub, Dayens Ampino amp, W4S DAC/pre, Sonos, JRiver
    Gear on standby: Melody 101 tube pre, Unison Research Simply Italy Integrated
    Gone to new homes: (Matt Polk's)Threshold Stasis SA12e monoblocks, Pass XA30.5 amp, Usher MD2 speakers, Dynaudio C4 platinum speakers, Modwright LS100 (voltz), Simaudio 780D DAC

    erat interfectorem cesar et **** dictatorem dicere a
  • tonyb
    tonyb Posts: 32,902
    Good point Ron, a very important point too because sometimes we lay all the blame on a certain piece without considering it's just a bad match-up impedance wise.
    HT SYSTEM-
    Sony 850c 4k
    Pioneer elite vhx 21
    Sony 4k BRP
    SVS SB-2000
    Polk Sig. 20's
    Polk FX500 surrounds

    Cables-
    Acoustic zen Satori speaker cables
    Acoustic zen Matrix 2 IC's
    Wireworld eclipse 7 ic's
    Audio metallurgy ga-o digital cable

    Kitchen

    Sonos zp90
    Grant Fidelity tube dac
    B&k 1420
    lsi 9's
  • heiney9
    heiney9 Posts: 25,053
    Clipdat wrote: »
    Why does the preamp care if the amp it's outputting to is tube or SS?

    Not all gear plays well together and tube amps can be a bit more touchy.

    John,

    Knowing the caliber of the "lab", I am more inclined to think it's a gear mismatch more than a bad pre. Have you called and talked to Desmond or anyone else at Pass to bend their ear about your issue? You know how willing and helpful they can be. They would know more than anyone here what the issue might be.

    It would be nice if someone close to test it on a SS amp just to see what shakes out.

    Good luck and I'm sure you know Pass will bend over backwards to help you.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
  • tonyb
    tonyb Posts: 32,902
    Maybe someone in the area can lend you a SS amp to test this theory.
    HT SYSTEM-
    Sony 850c 4k
    Pioneer elite vhx 21
    Sony 4k BRP
    SVS SB-2000
    Polk Sig. 20's
    Polk FX500 surrounds

    Cables-
    Acoustic zen Satori speaker cables
    Acoustic zen Matrix 2 IC's
    Wireworld eclipse 7 ic's
    Audio metallurgy ga-o digital cable

    Kitchen

    Sonos zp90
    Grant Fidelity tube dac
    B&k 1420
    lsi 9's
  • dromunds
    dromunds Posts: 9,969
    I agree with Heiney, I'd call them and have an in-depth talk about your issue.
  • marvda1
    marvda1 Posts: 4,862
    edited January 2019
    It costs money to do that. My gut just tells me that it may not like my tube amps, which is a very real possibility. What I need is a solid-state amp to test that hypothesis.

    input/output impedance need to match.
    Amplifiers: Norma IPA 140, MasterSound Compact 845, Ayre v6xe, Consonance Cyber 800
    Preamp: deHavilland Ultraverve 3
    Dac: Sonnet Morpheus 2, Musical Paradise mp-d2 mkIII
    Transport: Jay's Audio CDT2 mk2, Lumin U1 mini
    Speakers: Rosso Fiorentino Volterra II
    Speaker Cables: Organic Audio Organic Reference 2
    Interconnects: Argento Organic Reference 2, Argento Organic 2
    Power Cables: Argento Organic Reference, Synergistic Research Foundation 10 and 12 ga.
    Puritan PSM156
  • mhardy6647
    mhardy6647 Posts: 32,926
    edited January 2019
    The ol' rule of thumb (which is no more, nor less, than just that): Input impedance of the load (power amp, in this case) should be at least ten times the output impedance of the source (preamp, in this case).
    https://electronics.stackexchange.com/questions/46948/the-10x-rule-for-impedance-bridging

    The nominal input impedance of the amp and output impedance of the preamp should be available from their manufacturers' specifications.

    FWIW. The most telling symptom, I think, is this (from the first post of the thread:
    ...This hiss gets louder with each step up in volume and once an increment of 10 is achieved, the hiss steps back down again...

    I am assuming that this preamp uses a resistive attenuator, which is not a constant impedance device. The maximum impedance of a resistive type volume control is, I have been told, maximum at an intermediate level of attenuation somewhere in the middle of its adjustment range, and it is not uncommon for a component (preamp, integrated amp, or receiver) to display a maximum level of hum at an intermediate setting of the "volume control".

    Now, hum is not hiss*, and perhaps the attenuator in the component in question is a constant impedance network rather than simply adjustable resistance, but I am guessing that the symptom arises from an impedance issue of some sort.

    Just a cluster of SWAGs, though.

    ______________
    * FWIW: "hiss", in my experience, is usually thermionic noise (tubes) or "shot noise" (transistors), and is also usually most audible at minimum attenuation ("high volume" settings).


  • nooshinjohn
    nooshinjohn Posts: 25,034
    edited January 2019
    The amplifier specs...

    2 Hz to 85 kHz (–3 dB)
    Distortion: Less than 0.5%
    Power Bandwidth: 24 Hz to 28 kHz without filters
    Line Inputs: 1RCA
    Input Impedance: 100 K ohms (RCA)
    Gain: 30 dB (8 ohms)
    Tube Complement: One 12AX7, one 12AT7, one 6AL5, six KT120
    Hum and Noise: Better than 120 dB, referred to 350 watts, A-weighted

    Preamp specs for the X0.2

    Gain 14dB or 20dB
    Gain adjustment Internal
    Number of volume control steps 72
    Freq. Response -3dB @ 2Hz, -3dB @ 100kHz
    Distortion @ 1KHz <0.1% THD typ, 0.003% @ 2V
    Output Voltage 20 Balanced, 7 Single-ended
    Output Impedance 750 Balanced, 150 Single-ended
    Input Impedance 20K Balanced, 10K Single-ended
    Number of gain paths 4
    Separate analog channels Yes
    Remote control Yes
    Input voltage before overload 11
    CMRR 80db 20-20kHz
    Output noise floor -110dBV ref to 20V output
    Crosstalk typ. -90dB 20 - 20kHz
    External amp turn on
    Single-ended only inputs 5
    Balanced / single ended inputs 6
    Mono operation setting Yes
    Unity gain setting Yes
    Power Supply External
    Power consumption 30 watts
    Number of chassis Dimensions 3
    Weight 72
    Post edited by nooshinjohn on
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • mhardy6647
    mhardy6647 Posts: 32,926
    edited January 2019
    amp input impedance: 100,000 ohms (unbalanced) -- no spec for balanced*
    preamp output impedance: 150 ohm (unbalanced), 750 ohm (balanced)

    Certainly no mismatch between the two for an unbalanced connection.
    Are you running balanced or unbalanced?

    ___________
    * Presumably also high -- does the amp have balance inputs?

  • nooshinjohn
    nooshinjohn Posts: 25,034
    Unbalanced between amp and pre. The amp does not have balanced input.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • heiney9
    heiney9 Posts: 25,053
    The "X" gear is really designed to be run balanced. It can run unbalanced, but perhaps this is part or all of your issue?

    If your read closely between the lines in the owner's manuals of most, if not all, X gear, it's suggested to run balanced for best results and performance.

    Just throwing that out there.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
  • mhardy6647
    mhardy6647 Posts: 32,926
    edited January 2019
    Integrating the content of the two posts above :)
    If I were @nooshinjohn, I'd try a different set of cables 'twixt preamp and power amplifier. Couldn't hoit ;)

    Oh, I assume it does this independent of source input, yes? In other words, if (for example) the preamp has no inputs at all connected, it will still manifest the hiss at some intermediate attenuation (volume) levels, yes?



  • nooshinjohn
    nooshinjohn Posts: 25,034
    I did H9... The X0.2 also runs at full output at all times, using a unique resistive attenuator to adjust the volume. The X1 does not, and I think that may be what the speakers are picking up.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • bikerboy
    bikerboy Posts: 1,205
    Preamp output impedance is 150 ohms and the amp input is 100k ohms. Thats the problem. Unless I am reading it wrong.
    Main system: Lyngdorf TDAI 2170 w/ Pioneer 42" plazma-> Polk LSiM 703 w/Tivo, Marantz tuner, BRPTT: Nothingham Spacedeck-> Pioneer PL L1000 linear arm-> Soundsmith DL 103R-> SUT->Bottlehead ErosDigital: I3 PC w/ Jriver playing flac -> Sonore Ultrarendu -> Twisted Pair Audio ESS 9028 w/ Mercury IVY Vinyl rips: ESI Juli@24/192-> i3 PC server
  • nooshinjohn
    nooshinjohn Posts: 25,034
    mhardy6647 wrote: »
    Integrating the content of the two posts above :)
    If I were @nooshinjohn, I'd try a different set of cables 'twixt preamp and power amplifier. Couldn't hoit ;)

    Oh, I assume it does this independent of source input, yes? In other words, if (for example) the preamp has no inputs at all connected, it will still manifest the hiss at some intermediate attenuation (volume) levels, yes?



    Yes, it does this independent of source selected and is still present even with no source connected to the preamp. The hiss is present even if the attenuation is set to zero. It is also present in both left and right channels, with or without the SDA connection. In my mind, that eliminates cables or source components from being an issue.

    It would appear to be exclusive to the preamp itself, or in the match between amps and preamp.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • heiney9
    heiney9 Posts: 25,053
    edited January 2019
    I am also thinking if they at Pass Labs can isolate your issue, maybe they could offer something or a suggestion to lessen the effects. They're pretty good that way. Have you looked in the Pass Labs forum on DIY audio to see if anyone else with similar gear has experienced this? That's an amazing resource and Papa interacts a lot in the DIY forum.

    Might want to have a look see over there

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!