Where's the portable DSP headphone amp?

Discussion in 'General Audio Discussion' started by jhaider, Mar 25, 2017.

  1. jhaider

    jhaider Acquaintance

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    I've been looking for a new portable headphone amp to replace the HeadRoom Total BitHead I've had for over 15 years, and there's a lacuna in the headphone market that really surprises me: I can't think of a single portable DSP headphone amp!

    Wouldn't anyone else like to see something with the core features of the Oppo HA-2SE or Peachtree Audio Shift (standard size USB input that's plug-and-play with iOS/macOS/others, battery bank, nice build quality, travel-friendly form factor) and an app controlled DSP front end that could handle crossfeed and parametric EQ, maybe with a few presets for different headphones or different listening moods?

    I'm really surprised there's nothing like that on the market right now. It just seems so obvious.
     
  2. BenjaminBore

    BenjaminBore Friend

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    I bloody well would. EQ is a pain in the portable behind. The only thing there is is the Audeze Cypher cable, app for it only has a graphic equalizer but it saves your adjustments to the dac/amp. Of course it's already correcting for whichever Audeze headphone it came with. Would be difficult to get ahold of one and would probably need to re-terminate the cable.

    iOS PEQs are not system-wide, but I expect there would be system-wide solutions for Android.

    For the MAC you can use the TDR Nova plugin with Audio Hijack, works wonderfully.
     
  3. jhaider

    jhaider Acquaintance

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  4. Kattefjaes

    Kattefjaes Mostly Harmless

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    I don't know, I'm quite happy choosing headphones that sound good plugged into my DAP, which also sounds good. I feel like I've outgrown huge wads of banded-together audiospooge, and value a reliable, predictable and pocketable experience these days- without having to deal with tons of flimsy cables, charging loads of different items etc..

    It sounds better than a lot of desktop setups, and is very liberating to use. I don't even use the onboard EQ, keeping it all source direct. When carrying a separate DAP is too much hassle, I just use different IEMs, directly from my phone.
     
    Last edited: May 30, 2017
  5. BenjaminBore

    BenjaminBore Friend

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    This looks really interesting. I wish it had a proper line out, and user replaceable batteries. The amp section doesn't look like it'll do well with anything particularly demanding.
    https://www.minidsp.com/images/documents/Product Brief - HA-DSP.pdf
    • ten fully programmable parametric EQ bands per channel
    • ESS Sabre ES9018K2M / Up to 127DNR @ 32-bit
    • Headphone amplifier chip: High-fidelity Texas Instruments TPA6120A2 / Up to 120 dB SNR
    • Maximum output: 100 mW + 100 mW (32 Ω, 1 kHz, digital in 0 dB)
    Anyone had any experience with TPA6120A2 based amplifiers?
    http://www.ti.com/lit/ds/symlink/tpa6120a2.pdf
    • The TPA6120A2's current-feedback AB amplifier architecture delivers high bandwidth, extremely low noise, and up to 128dB of dynamic range.
    • 1300V/μs Slew Rate
     
    Last edited: May 19, 2017
  6. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    They look good on paper, can't vouch for real world use. I'm half sure that Oppo HA-2 used them and a friend of mine built a Sjostrom amp based on these chips.

    Actually the best thing about this device is the SHARC DSP core. It can do really interesting things if one is eager to tweak. Heck you can do linear, minimum or hybrid phase calibration. We're most likely ordering one of these headamps to see what we can do with them.
     
  7. BenjaminBore

    BenjaminBore Friend

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    Yes, absolutely. I gather this can be potentially done with some DAC chips internally, but based on my experience with the DEQ2496 I suspect that a dedicated DSP would do a much better job.

    I expect it will need a PC/MAC software interface. I've never been fond of depending on, often shaky, proprietary software that will eventually be abandoned.
     
    Last edited: May 19, 2017
  8. ButtUglyJeff

    ButtUglyJeff Stunningly beautiful IRL

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    It sounds like you're describing the voodoo inside the Audeze Cypher cable. I was "meh" with the closed Sine, but it seems everyone who uses it with Cypher cable is in love with it...
     
  9. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    There aren't really any DAC chips with enough power to do complex real time FIR operations. That's why SHARC is the industry choice to do this. I remember that Soekris DAC boards have configurable filters, but they have very little taps.

    The problem with portable units like these is that your smartphone is way more powerful than any DSP chip out there, so it would make more sense to do processing there.
     
  10. BenjaminBore

    BenjaminBore Friend

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    Theoretically, yes. But system-wide EQ isn't possible on iOS, so you're limited to EQ apps that can only access a local library of music. If I recall correctly the last time I looked into Android the available options looked poor, and required rooting.

    The CPU utilisation for PEQ is going to hit the battery hard, and if you're using a CCK and a battery-less DAC the drain is more than you want already. I've not tested EQu or Equalizer's effect on my iPhone's battery life, but for example I can see the TDRNova plugin using 20% CPU on a 1.4ghz i5 Haswell Dual Core at 44.1khz sample rate. Though I'm sure they all differ.
     
    Last edited: May 19, 2017
  11. Armaegis

    Armaegis Friend

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    This is interesting stuff. So now they just need to partner with the THX AAA headphone amp which uses the same tech as the Benchmark AHB2 amplifier. Get all your dsp wizardry in the first half, with ultra low distortion amp in the second half.
     
  12. macro

    macro Rando

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    I'm sure this isn't exactly what you had in mind, but Jaybird now makes a Bluetooth MMCX cable for Ultimate Ears with some built-in equalization functionality. I think it's the same cable the Jaybird Freedom uses including the built-in equalizer that you set via the Jaybird smartphone app. It appears to support 5 parametric bands, but the app doesn't show you the exact decibels, frequency, or Q factor; you have to just eyeball it. The signal processing is built into the cable, though, so the equalizer will work with all apps and even carry over to other devices. I doubt the sound quality or battery life will compare to something like the miniDSP, but it could still be a convenient option for some use cases.
     
    Last edited: Oct 3, 2017
  13. gixxerwimp

    gixxerwimp Professional tricycle rider

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    I think the definition of parametric EQ is being able to set frequency, and Q factor. So that app would support graphic EQ and only 3 bands it would seem.

    [​IMG]
     
  14. macro

    macro Rando

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    Each of those 5 circles represents an equalizer band. You can set the frequency or level of a band by dragging the circle side to side or up and down respectively. If you tap one of the circles, the app will display two vertical lines equidistant from the circle. You can then dag the lines closer to or farther from the circle to adjust the Q factor of that band. I believe that constitutes a 5 band parametric EQ albeit not the most intuitive or precise.

    The app is free to download and you can adjust the equalizer without connecting a Bluetooth device if you just want to see how it works.
     
    Last edited: Oct 4, 2017

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