Schiit IEMagni Measurements

Discussion in 'Schiit' started by purr1n, May 12, 2021.

  1. purr1n

    purr1n Super Friend

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    Impresions thread here: https://www.superbestaudiofriends.org/index.php?threads/schiit-iemagni-discussions-and-impressions.10991

    Let's take a look at IEMagni measurements. First off, let's do 1kHz steady-state sine waves. This is the one that rules them all and of the SINAD is derived from. Note that the voltages I use are lower than that of another site. I run the output -3dBU which is ~0.550mVrms.

    First, obligatory photo:
    PXL_20210512_155515254.NIGHT.jpg

    Schiit IEMagni
    High Gain
    1kHz Steady-State Sine Wave
    -3dbU output into 300-ohms, normalized to 0dbC upload_2021-5-12_10-45-30.png

    Schiit IEMagni
    High Gain
    1kHz Steady-State Sine Wave
    -3dbU output into 30-ohms, normalized to 0dbC
    upload_2021-5-12_10-47-3.png

    Note: Harmonic pattern has successively lower harmonics as we go up. Some consider this ideal. Triodes have exhibit this kind of behavior.
     
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    Last edited: May 15, 2021
  2. purr1n

    purr1n Super Friend

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    Let's check out medium gain.

    IEMagni
    Medium Gain
    1kHz Steady-State Sine Wave
    -3dbU output into 300-ohms, normalized to 0dbC
    upload_2021-5-12_10-51-17.png

    IEMagni
    Medium Gain
    1kHz Steady-State Sine Wave
    -3dbU output into 30-ohms, normalized to 0dbC
    upload_2021-5-12_10-52-48.png
     
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  3. purr1n

    purr1n Super Friend

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    IEMagni
    Low Gain
    1kHz Steady-State Sine Wave
    -3dbU output into 300-ohms, normalized to 0dbC
    upload_2021-5-12_11-1-54.png

    IEMagni
    Low Gain
    1kHz Steady-State Sine Wave
    -3dbU output into 300-ohms, normalized to 0dbC
    upload_2021-5-12_11-2-57.png

    Note: At lower gains, we start to see the distortion pattern squaring up where the second and third harmonics are more equal.
     
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    Last edited: May 12, 2021
  4. M3NTAL

    M3NTAL Friend

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    Hey Purrin - I'm pretty sure you had a small hand in letting them know there was some interest in this. I appreciate it big time! Can't believe it has taken this long for someone to put "IEM" in the name of a wall powered head amp. I remember the ALO / RWA amps were all battery powered for the same reasons, but they couldn't push all the popular big headphones at the time.

    Thank you @schiit - I am still interested in the IEM only buffer that you propose. My wallet has a 1K limit on this hobby/equipment though - unless something radical comes along and changes my mind.
     
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  5. purr1n

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    Here are the gains:
    upload_2021-5-12_11-9-35.png

    Low gain: -10.82db
    Medium gain: -1db (Unity gain more or less, there will always be some minor losses)
    High gain: 14.36db

    Gain is adjusted via a three position switch in the back. The prior Magni amps had two position switches.
     
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    Last edited: May 12, 2021
  6. purr1n

    purr1n Super Friend

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    Yes. I've been bugging Jason about this since way back last year when I was still in CA. The more options for desktop amps where we can use our super duper high sensitivity Campfire IEMs (or whatever), the better. The IEMagni is based on the Heresy, but with upgrades. Some are less obvious where I don't want to say anything, but will let Jason say if he wants do. Others are more obvious, like the fantastic OPA1656 (x7), which probably explains the cost increase. The IEMagni is affordable enough so I'll refrain from any subjective comments and let you guys decide if this sounds better than the Heresy.

    opa1656.png

    PXL_20210512_162348789.NIGHT.jpg
     
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  7. purr1n

    purr1n Super Friend

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    BTW, OK to post here or ask questions despite this being a measurement thread. It will be a day or two until impressions come in.
     
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  8. purr1n

    purr1n Super Friend

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    Here are the 2Vrms output! Note that 2Vrms will probably explode most IEMs.

    IEMagni
    Low Gain
    1kHz Steady-State Sine Wave
    8.23dbU or 2Vrms output into 300-ohms, normalized to 0dbC
    upload_2021-5-12_11-44-9.png
     
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  9. bboris77

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    1. Does it sound any different than Heresy subjectively?
    2. Have you experienced even one instance of DC-sensing circuit being overzealous and shutting things down while listening?
    3. How warm does it run especially when using high current, low-impedance planars? While the Heresy has not had any reports of catastrophic failures, there have been a few reports of Magni 3+ units going up in smoke. Why exactly that happened is anyone's guess.
     
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  10. Biodegraded

    Biodegraded Friend

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    I wanna see 2V into 16 Ohms. Then I want you to listen to it at that volume and tell me about the distortion :D
     
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  11. purr1n

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    1. Yes.
    2. Not overzealous, but during testing, I accidentally fed the input an 18dbU signal while the unit was on high gain resulting in a severely clipped signal. I heard an audible click. Upon stopping the signal generator, I heard another click. It happened so quickly that I am not sure what happened. I did see the analyzer FFT light up sky high at every harmonic just momentarily. The unit still performs normally.
    3. I am charging my FLIR right now.
     
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  12. purr1n

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    That would be Mortal Kombat meets Pink Panther.
     
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  13. purr1n

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    Here is low gain THDN vs input amplitude (dBu). To arrive at the output level, subtract about 11db.
    upload_2021-5-12_12-3-13.png

    My generator can't go above 20dBu, hence we never see the IEMagni. Note the wide sweet spot - better than 100 SINAD for output levels from -18dBu to 10dBu++, which is 0.098Vrms to 2.45Vrms.

    Here is unity gain THDN vs input amplitude (dBu). To arrive at the output level, subtract about 1db.
    upload_2021-5-12_12-7-17.png
     
  14. purr1n

    purr1n Super Friend

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    Here is high gain THDN vs input amplitude (dBu).
    To arrive at the output level, add a bit more than 14db. Load is 300-ohms.
    upload_2021-5-12_12-9-44.png

    Here we start to clip at about 20dBu or 7.7Vrms.

    Note: Here we see a characteristic common to many chip amp designs. A steady low THDN with the sudden onset of clipping for low current loads. The shit hits the fan. Discrete designs can and usually degrade more gracefully, that is we get signs that the shit is going to hit the fan before it does.

    Same thing here, but with a more difficult 30-ohm load!
    upload_2021-5-12_12-18-15.png
     
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    Last edited: May 12, 2021
  15. purr1n

    purr1n Super Friend

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    Finally, a low-gain THDN vs input amplitude (dBu) sweep. Again, to get output level, subtract 11db.
    upload_2021-5-12_12-20-35.png
     
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  16. M3NTAL

    M3NTAL Friend

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    Would be interesting to see the distortion characteristic differences between the Heresy and the IEMagni in their 0db setting. Most users would probably stick in that gain level I would think.

    Schiit - where is the ValIEM (Tube buffer) :EVIL GRIN:
     
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  17. yotacowboy

    yotacowboy McRibs Kind of Guy

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    Since it wasn't mentioned in Purrin's posts, and for those who have no self control, like me, these are live on schiit.com.
     
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  18. HotRatSalad

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    Available in black ? I might have to buy one for 3DT. Would it be better than JoT 2 low gain balanced though?
     
  19. yotacowboy

    yotacowboy McRibs Kind of Guy

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    I'll be trying it out from BF2, comparing directly to Jot2, through 2019 Andro and Solaris OG.
     
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  20. YMO

    YMO it's not drinking alone if you're on Zoom

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    Keep your IEMatch handy.
     

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