Neurochrome HP-1

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

  1. ultrabike

    ultrabike Measurbator - Admin

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    The HE-6 is probably the most inefficient planar I know. But similar generation HifiMan's tend to be very inefficient. On dynamics you have the AKG 7xx family as somewhat inefficient cans. But the HE-6 is something else.

    BTW, 90 dBSPL is very loud IMO (specially if listening for long sessions). Protect your hearing guys.
     
  2. tomchr

    tomchr MOT - Neurochrome

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    I wholeheartedly agree. Those hair cells in the cochlea don't grow back. Once they're gone, they're gone.

    Tom
     
  3. frenchbat

    frenchbat Almost "Made"

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    For sustained level it is nuts. For dynamic range it's a different story. Plenty of amps can drive the he6 loud, few can drive it properly.
     
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  4. tomchr

    tomchr MOT - Neurochrome

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    Yeah. I'm thinking that slight clipping on the peaks of the signal is one of the things people perceive as "harsh" or "compressed" sound.

    As far as I understand human perception, we're mostly perceiving the average SPL as "loudness". So for the HE-6 to be driven to, say, 80 dB average SPL for critical listening, you'd need 100 dB SPL on the peaks for a good recording (20 dB crest factor). That requires 10 W on the peaks for the HE-6...

    Tom
     
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  5. Kattefjaes

    Kattefjaes Mostly Harmless

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    Is it? I'm surprised by that. I have a pair of second gen HE-560 somewhere (after they changed to more sensible connectors, not sure there were any actual driver changes), and always found them relatively easy to drive.. I can never remember what the orthodoxy is, whether planars are supposed to need a lot of voltage swing, or a lot of current (etc.). I assume whichever it is can be a problem for some common topologies?
     
  6. ultrabike

    ultrabike Measurbator - Admin

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    The HE-560 are listed as 2.53 mW for 90 dBSPL:

    https://www.innerfidelity.com/images/HiFiMANHE5602014.pdf

    That is 85dB/mW which is still a bit inefficient. Not HE-6 inefficient, but still relatively inefficient.

    In contrast, the HE-400 family seems to be about 0.34 to 0.59 mW for 90 dBSPL:

    https://www.innerfidelity.com/images/HiFiMANHE4002014.pdf
    https://www.innerfidelity.com/images/HiFiMANHE400.pdf
    https://www.innerfidelity.com/images/HiFiMANHE400S.pdf

    That is 92.3 to 94.7dB/mW, which IMO is relatively efficient. Not HD6x0 efficient, but not bad.

    In general I think planars consume relatively a bit more current than dynamic cans due to their typically low efficiency and low impedance. That said, I don't think the HE-400 would need that much juice (maybe 4 mA @ 90dBSPL). HE-560 might need a little more juice, but proly not that difficult (maybe 8 mA @ 90dBSPL).
     
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    Last edited: Aug 8, 2017
  7. tomchr

    tomchr MOT - Neurochrome

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    And something like the Sennheiser HD-650 which is ~100 dB SPL @ 1 mW as I recall.

    Tom
     
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  8. ultrabike

    ultrabike Measurbator - Admin

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    If the Sennheiser's were inefficient, the voltage requirements would go through the roof. But since they are efficient, they are not as bad as an HE-6 or something crazy like that.

    They do probably benefit from more voltage swing in order to preserve some headroom for high dynamic range material.
     
  9. ultrabike

    ultrabike Measurbator - Admin

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    <start of Innerfidelity shilling>

    One of the many many things that Innerfidelity, run by @Tyll Hertsens, brings to the table are all those headphone sheets that not only provide consumers some guidance, but may also help headphone amplifier manufacturers by giving an idea about product requirements.

    The impressions, discussion, and material selection is pretty awesome as well.

    <end of Innerfidelity shilling>

    Anyhow. Yes, HifiMan planars, specially the first generations, are pretty hard to drive. For most random everyday headphones, I think the HP-1 has plenty of juice. It boils down to costumer preferences IMO.
     
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    Last edited: Aug 8, 2017
  10. Kattefjaes

    Kattefjaes Mostly Harmless

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    Thanks both :)
     
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  11. tomchr

    tomchr MOT - Neurochrome

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    I share the measurements on my products for similar reasons. For the HP-1 the availability of measurements for the HE-6 doesn't change anything, though. I'm running the parts at their specified supply voltage limit, so I'm up against physics there. I'll keep the care and feeding of the HP-1 in mind for a future design if/when that happens.

    Tom
     
  12. tomchr

    tomchr MOT - Neurochrome

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    Black Friday and Cyber Monday are coming up. I am gearing up to have a pretty tall stack of HP-1s manufactured, so I will be partaking in the Black Friday, Cyber Monday madness. Don't worry. You don't have to skip the Thanksgiving turkey to line up outside my door. All you have to do is to apply the discount code SBAF17 when you place your backorder of your fully assembled HP-1.

    Is there a catch? Yes! There is a catch. The finished HP-1s cannot ship until just before Christmas. Due to the power supply modules being out of stock, manufacturing cannot start until early December, which drives this delivery schedule. Sorry... Then again, getting an HP-1 for under $1k is pretty sweet. I hope it's worth the wait.

    The discount code is active now and expires by 23.59 (Mountain time; GMT-6) on Monday Nov. 27th.

    Happy Thanksgiving.

    Tom
     
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  13. fishski13

    fishski13 Friend

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    I had two unopened boxes from Mouser and Digikey since March - components for my HP-1. I busted them open last evening to double check against the BOM, and started soldering tonight. It's been a crazy year with my wife finishing grad school, finding a new job, living up to my title as 'Mr. Awesome' in the neighborhood, and raising kids.

    I haven't done SMD in awhile. I'm pretty rusty. It took me a dozen resistors or so to find my groove. I'm also using different solder, wick, and flux than what I've used in previous SMD adventures. Really pleased thus far. I haven't built anything for myself in quite a long time.
     
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  14. Armaegis

    Armaegis Friend

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    I know the feeling. I've been working 65+hr weeks since summer. My workbench has barely seen any action except for fixing household things.
     
  15. tomchr

    tomchr MOT - Neurochrome

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    My project work has been at a standstill as well. Midterm exams started in mid-October and I've been working 12-15 hour days since then trying to keep up with assignments. It's been a crazy semester. Four days to go! In return, the exam season will be easy.

    Tom
     
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  16. fishski13

    fishski13 Friend

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    Finally finished my HP-1. What a super best awesome soldering project. I had a lot of fun building this and took my sweet time. I went with a deep orange/amber LED to partner with my favorite cocktail, the Old Fashioned. I'm loving the pairing with the HD600 and Gung as source.
    https://solderworksaudio.wordpress.com/neurochrome-hp-1/
     
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  17. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    Amber leds, ftw. The closest an SS-lover will get to tube sound!
     
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  18. tomchr

    tomchr MOT - Neurochrome

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    I'm old school too. I for some reason really enjoy the HeNe red LEDs, such as the HLMP-D101. They're just pretty.

    Tom
     
  19. zhouharvey

    zhouharvey PayPal’s $2 Sensible Enforcer

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    Quick question: anyone of you know if the Neurochrome HP-1 is a fully balanced design with two channels separated from input to output?

    The specs seem like the power from 4-XLR and 1/4'' SE is the same, which make me not sure whether it is fully balanced design or not.

    My question is based on whether a balanced DAC would be beneficial or a SE DAC would suffice, and whether the 4-XLR balanced output will be beneficial for connection to balanced headphones or they are actually the same to SE.
     
  20. Cspirou

    Cspirou They call me Sparky

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    A lot of this has already been answered in the thread. The amp is not balanced however it does benefit from using the balanced connections. The output is the same whether you use 6.25mm or the 4-pin xlr, but the separate grounds in the XLR jack still helps with noise so its not just there for convenience. Balanced interconnects are typically better too because you aren't using the ground as a signal reference and DAC chips will have better specs when used in mono mode.
     
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