Neurochrome HP-1

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Cspirou, Oct 26, 2016.

  1. tomchr

    tomchr MOT - Neurochrome

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    It's been a busy few days of soldering here. Testing will take place tonight and tomorrow then two of these will ship on Monday morning.
    [​IMG]

    Tom
     
    Last edited: Jul 8, 2017
  2. cskippy

    cskippy Creamy warmpoo

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    Pic broken :(
     
  3. tomchr

    tomchr MOT - Neurochrome

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    Should work now. You might have to hit reload in your browser.
     
  4. earnmyturns

    earnmyturns Smartest friend

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    Really nice, almost making me regret my blue HP-1 ;)
     
  5. tomchr

    tomchr MOT - Neurochrome

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    You can always buy the grey chassis by itself. Change clothes on your HP-1 whenever you're in the mood. ;)

    Tom
     
  6. The Alchemist

    The Alchemist MOT: Schiit - Here to help!

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  7. MrTeaRex

    MrTeaRex His head's not fat, he's my brother!

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    One of the graphite HP-1s in Tom’s last picture is mine. I received it several weeks ago and have been able to form some impressions in a desktop setup. The new steel top plate is sturdy and devoid of any noticeable flex when plugging or unplugging headphones.

    While working on the computer, I often listen to genres that don’t require much focus like hip-hop, electronica, new wave, and 70s-80s pop. Over time, I’ve discovered a preference for planars with these genres. I dislike planars for progressive, hard rock, blues, etc. and avoid headphones in general for metal as speakers keep the tracks from sounding overwhelmingly claustrophobic and congested. I already have a Torpedo III at my desk for rock and blues with dynamic headphones, so I went looking for something to drive planars with these other genres.

    Based on my use case, I wanted an amp to feature:
    • A small-ish form factor that fit in my little desktop rack next to the T3 (with space for both amps to breathe)
    • Balanced XLR inputs, the SE RCA outputs of the DAC are used by the T3 (couldn’t care less if the amp topology is actually balanced)
    • Very little, if any, warm up time (pretty much rules out tubes)
    • Low output impedance and several watts of power suitable for planars

    After some research, the short list of candidates included the iFi Pro iCAN, Schiit Jotunheim, and Neurochrome HP-1. The components upstream and downstream of the amp would be a PMx2 / HE-500 and Holo Spring KTE.

    I auditioned the Jot first as it was the cheapest and a personal friend had one he was willing to ship (in exchange for some undefined future favor, not my brightest negotiation). I haven’t particularly liked the thin character of any of the Schiit amps I’ve tried (Mjolnir 1, Asgard 1, Valhalla 2). Although, if I was on a strict budget, I could definitely see the appeal. The Jot was different. It sounded more cohesive, with additional body, and the low end was improved. However, the PMx2 is an unusually accurate headphone and was unforgiving of the Jot’s treble glare and grain, so it ended up being a less than ideal match.

    The Pro iCAN was next as it’s readily available from online retailers with return policies. I liked the overall sound and my issue with this amp is completely irrational and personal. There are too damn many buttons, knobs, and gimmicky options for an amplifier. Initially the options were kind of fun to play with, but in the end I think they simply changed the sound (more than improved the sound) and prefer not to pay for features I don’t plan to use. iFi’s marketing of these features is also annoying, using terms like “luxurious” to describe the Tube+ option and “out of head placement” to describe the 3D Holographic feature.

    If the HP-1 could perform well and allow me to use the ~$400 price difference versus the Pro iCAN to rent more time with select women (those of you with higher moral standards can interpret this as a nice dinner and entertainment), it would be the best option. If not, the Pro iCAN was a very viable option.

    Ultimately, the HP-1 ended up being the best fit based on my use case. The combination of the PMx2 and HP-1 did not expose any unnatural upper-mid or treble nastiness on tracks such as Orbital - Spare Parts Express or Jackson 5 - ABC. The bass extended low and exhibited exceptional control on tracks like Run the Jewels - Call Ticketron and Black Star - Definition. The vocals and mids were smooth with sufficient body on JT’s Fire and Rain and Billy Joel’s Only the Good Die Young. Additionally, the HP-1 proved to be very clear and resolving. When debating a purchase, I feel that considering the soundstage of headphone gear is like considering the 0-60 times of minivans. It’s possible, but they all suck and it’s not a reason to buy one.

    Just because the HP-1 is a good fit for my requirements does not mean it’s a match for everyone in all situations. At high volumes, macrodynamics sounded compressed by the combination of the HE-500 and HP-1. Further evaluation of macrodynamics when including a HD650 and T3 resulted in the following hierarchy: HD650/T3 > HD650/HP-1 > HE-500/HP-1. The observation that the HD650/HP-1 was arguably better than the HE-500/HP-1 leads me to believe that the compression inherent in most planars has more impact than the compression of the HP-1. If you’re not overly bothered by planar compression, it’s possible you won’t be bothered by the HP-1.

    I wouldn’t normally audition a headphone amplifier with metal tracks, since I have yet to find a headphone setup enjoyable with metal, but comments earlier in this thread regarding picking and decay piqued my interest. Most of my metal is thrash or doom. Neither genre has anywhere near the amount of tremolo picking as black metal, but I own very little black metal and don’t like what I do own, so thrash and doom it was. I was unable to identify the decay issue described by several others, but that could be due to any number of reasons: a) my ears aren’t that good, b) my source material didn’t contain enough clear examples, c) I’ve never heard it rendered correctly in the first place, or d) I have too many other issues with metal originating inside my head instead of in front and around me to focus on specific decay issues.

    TLDR: The HP-1 pairs very well with planars and heavily processed music (hip-hop, electronica, new wave, pop, etc.). It would not be my first choice with dynamic headphones and music that is more raw (rock, blues, metal, etc.). However, solid-state amps in general would not be my first choice for those headphones and genres. Overall, the HP-1 compares favorably to the solid-state amps I have owned or heard recently (Bryston BHA-1, Schiit Mjolnir 1 / Asgard 1 / Jotunheim, iFi Pro iCAN, HeadAmp GS-X2 / GS-1, and Apex Arete).
     
    Last edited: Sep 3, 2017
  8. tomchr

    tomchr MOT - Neurochrome

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    Very cool. Thank you for your in-depth review. I appreciate it.

    Tom
     
  9. Mithrandir41

    Mithrandir41 Friend

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    That whole decay issue was brought up by @Psalmanazar, and was always BS. He wrongly applied the precedent (haas) effect to tremolo picking.
     
  10. kiss m

    kiss m Dill weed - acquaintance

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    psal cannot defend himself because of the unjust ban, he has this to say: "he is just f'ing deaf if he can't hear Iommi's sustain being fucked up by the Neurochrome."
     
  11. Mithrandir41

    Mithrandir41 Friend

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    "The unjust ban". Don't be a fanboy @kiss m, no one's interested.
     
  12. strangecargo

    strangecargo Acquaintance

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    I'm a little surprised by your conclusion. In my own experience, I have yet to find a dynamic headphone that the HP-1 doesn't drive superbly, but I've had it sound somewhat flat and lacking in dynamics with hungrier planars, namely the HE-6. I find blues/rock a ton of fun to listen to on the HP-1 because it has so much speed and transducer control; it feels like I can hear every buzzing edge and all the harmonic overtones that comprise guitar distortion, without hearing any character imparted by the amp itself.
     
  13. MrTeaRex

    MrTeaRex His head's not fat, he's my brother!

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    I didn't find the HP-1 to have any issues adequately driving dynamic headphones and agree that it exhibits exceptional control and clarity. In general, solid state amps wouldn't be my first choice for blues/rock and the HP-1 didn't end up being an exception. With well mastered tracks at high volumes, the T3 sitting next to the HP-1 sounds livelier and hits harder. Appropriate impact is more important for me to connect with those genres than it is with compressed hip-hop, electronica, and pop. If I had to live with only solid state amps, it would be a tough choice between the HP-1 and BHA-1.

    The HE-6 is OOP and driven with speaker amps by several people here. While it's arguably the best planar, I wouldn't consider it the best example of the average planar. The HP-1 didn't have any issues driving the PMx2 or HE-500 and I'd be surprised if it had issues driving any members of the current HiFiMAN or Audeze lineups.
     
  14. tomchr

    tomchr MOT - Neurochrome

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    I took the HP-1 to a Head-Fi meet last year where it was used to drive a pair of HE-560. No issues there. Some seemed a bit surprised by that as the HE-560 is supposedly a hard phone to drive.

    The HE-6 seems to be troubling many amps. I know some have built my Modulus-86 to drive the HE-6.

    Tom
     
  15. Armaegis

    Armaegis Friend

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    Those with HE-6's ought to be tossed in the loony bin for pushing the headphone amp market into dangerous and unnecessarily high places...
     
  16. frenchbat

    frenchbat Almost "Made"

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    Or simply bringing back headphones where they belong, behind a power amp in a speaker system
     
  17. tomchr

    tomchr MOT - Neurochrome

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    The HE-6 is specified at 83.5 dB efficient. Sadly, this figure is given without any qualifiers so it isn't of much use. Does anyone know if it's at 1 mW, 1 V, or something else?

    The EF-6 is the amp Hifiman intend you to use with the HE-6. It claims 5 W into 50 Ω. That should be possible to reproduce with an amp running on ±24 V supply rails. 50 Ω is an easy load. The issue is that many amps, including the HP-1, can't deliver the output voltage swing needed for 5 W into 50 Ω as they run from ±18 V or lower rails. This combined with the exceptionally low efficiency of the HE-6 is the issue. The HP-1 will deliver 2 W into 50 Ω. That's 4 dB below 5 W. 4 dB is noticeable but not a huge difference, which leaves me wondering if even the EF-6 is a tad under-powered.

    Anyway... Another day, another design. :)

    Tom
     
  18. ultrabike

    ultrabike Measurbator - Admin

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    According to @Tyll Hertsens (which is usually right on target on these things), the HE-6 needs 19.69 mW / 1.018 Vrms to reach 90 dBSPL (impedance is 53 ohms):

    https://www.innerfidelity.com/images/HiFiMANHE6.pdf

    I think that comes down to 77 dB/mW or 107 dB/W. Dunno what butt hole the 83.5 dB number came from, unless there is product variability.

    Other brands, as measured by @Tyll Hertsens (and sometimes me), tend to be closer to their sensitivity specs.
     
    Last edited: Aug 8, 2017
  19. frenchbat

    frenchbat Almost "Made"

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    Tom, the ef6 is not recognized as being the most adequate amp for the he6, eventhough it was meant to. So your hunch is absolutely justified.
     
  20. tomchr

    tomchr MOT - Neurochrome

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    Awesome. Thanks. 19.69 mW to get 90 dB SPL -> 77 dB SPL at 1 mW. Wow. That's rather inefficient.

    5 W would "only" result in 101 dB SPL according to the sensitivity measurement quoted above. Yeah. That's probably a bit quiet for some. I'll keep that in mind.

    Tom
     

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