KTE Spring2 technical measurements

Discussion in 'Source Measurements' started by atomicbob, May 3, 2020.

  1. atomicbob

    atomicbob dScope Yoda

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    Holo Audio KTE Spring2 technical measurements

    Standard Prologue
    If you are unfamiliar with audio measurements please use a search engine with the query:
    "audio measurements" or "audio measurement handbook"
    Look for publications by Richard C. Cabot and also by Bob Metzler, both from Audio Precision. There are other useful publications as well. These will provide basic knowledge.
    Interpretation of the following measurements is beyond the scope of technical measurements posts.

    The data presented were collected as follows:

    1. PrismSound dScope III, picoscope 5243B, Cal Test CT2593-2 balanced probe
    2. Tecnec 75R spdif cable
    3. Balanced XLR cables Belden 1800F with Neutrik 110R AES connectors
    4. Single Ended cables Mogami 2964 1 meter with Amphenol RCA connectors
    5. 100 Kohm load used for measurements
    6. dScope analyzer sample rate 48 KHz unless otherwise noted
    7. DAC 44.1 KHz sample rate, 24 bit depth unless otherwise noted
    9. Audioquest Forest and Schiit Pyst USB cables
    9. Vaunix Lab Brick USB hub
    10. Shielded 14AWG and 16AWG power cables
    11. NOS filter mode unless otherwise noted

    Measurements are made in accordance with AES17:2015

    Holo Audio KTE Spring2
    Measurements for record commenced after warmup of at least 168 hours.
    Measurements were performed over a period of several days.
    Balanced measurements were performed twice, one month apart for consistency verification.

    Index
    Post 1 - measurement setup description, highlights
    Post 2 - spdif input - Bal XLR outputs part A
    Post 3 - spdif input - SE RCA outputs part B
    Post 4 - USB ASIO input - Bal XLR outputs part C
    Post 5 - USB ASIO input - SE RCA outputs part D
    Post 6 - Filter response
    Post 7 - reserved for additional data and corrections
    Post 8 - reserved

    Notable highlights:
    While the KTE May is Holo Audio's statement DAC, KTE Spring2 is very close and even exceeds KTE May performance in residual noise spectrum.
    Ultra low distortion
    Power supply noise spectrum are at or below -160 dBFS in balanced output
    The power supply spectrum residual noise was so low it was necessary to reconfigure y-axis scale low enough to see the noise floor.
    Balanced output Dynamic Range of 135 dB
    Balanced output Cross-talk is dual mono with > 145 dB isolation
    Balanced output Gain Linearity is nearly perfect to -110 dBFS, less than +/- 2 dB to -130 dBFS
    Exceptionally low jitter
    NOS square wave is near perfect with fast slew rate and, of course, no filter ringing
    Single Ended performance is somewhat less than Balanced output, as is typical
    Single Ended performance is still exceptional compared to other DAC SE outputs

    Well done Jeff Zhu!

    Commentary:
    Power supply is at least 50% of any audio component's design. The higher the level of performance the more the power supply matters. Holo Audio recognizes this and has gone to heroic lengths enhancing KTE Spring2's power supply, keeping noise to 100s of nanovolt levels while supplying 10s of volts throughout the system. Make no mistake, this is an incredible achievement. Every aspect of performance has been scrutinized and optimized. The result is an equally impressive natural presentation, allowing one to observe amplifer character with ease. I have my pairing favorites, based on my personal preferences.

    For more descriptive narration see @Torq's comment:

    https://www.superbestaudiofriends.o...tsune-tuned-edition-impressions-reviews.3172/

    The Spring Level 3 has much in common with the KTE Spring2 where the latter is the former performance enhanced.

    Measurement setup picture example:
    20200502 KTE Spring2 test setup example small.jpg

    Listening pictures
    Way more than usual listening session hours disappeared while evaluating KTE Spring2 with a variety of headphone amps. KTE Spring2 has received 400+ listening hours. I have enjoyed this DAC so much as to buy one for myself. Here are a few of my favorites DAC - Headamp combinations:
    20200502 KTE Spring2 + SW51+ HD800-Jmod small.jpg

    20200502 KTE Spring2 + DSHA-3F + HD800-Jmod small.jpg

    20200502 KTE Spring2 + T4 + HD800-Jmod small.jpg
     
    Last edited: May 3, 2020
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  2. atomicbob

    atomicbob dScope Yoda

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    spdif input Bal output measurements part A

    KTE Spring2 Dynamic Range spdif input Bal output
    20200501 KTE Spring2 dynamic range FFT spdif Bal.png
    Excellent performance, as is most of the following data presented

    Dynamic range, in simplified terms
    1. find maximum output voltage at 0 dBFS
    2. find residual noise with a -60 dBFS 1 KHz stimulus, removed from analysis by window notch
    3. Dynamic Range is the difference between maximum output and residual noise
    Specifics are in AES17 section 9.3 (measurebators do your homework please)
    Example here:
    https://www.maximintegrated.com/en/design/blog/spec-dynamic-range.html

    Why we have a -60 dBFS stimulus
    Some clever codec designers include an output gate that shuts off when there is no signal present. This has the dual benefit of lowering output idle noise while also gaming the measurements. AES became wise requiring a -60 dBFS stimulus so any such gates are open during measurement and true Dynamic Range performance measured.

    KTE Spring2 -120dBFS sine spdif input Bal output
    FFT_0_L1T18_1.png
    Wow! -120 dBFS sine representation on an R2R design. Impressive.

    KTE Spring2 A04 THD+N THD nth-HD FFT spdif input Bal output
    20200501 KTE Spring2 A04 THD+N THD nth-HD 4+HD+N 60Hz FFT Bal 0dBFS - spdif.png

    KTE Spring2 50 + 7000 Hz spdif input Bal output - Left Channel
    FFT_2_L1T13_1_A.png

    KTE Spring2 Gain Linearity spdif input Bal output - Left Channel
    G2_L1T3_1_A.png

    KTE Spring2 THD+N vs Frequency spdif input Bal output - Left Channel
    G2_L1T5_1_A.png

    KTE Spring2 Residual Noise Bal spdif input Bal output - Left Channel
    FFT_2_L1T16_1_A.png
    Note the y-axis extends down to -180 dBFS rather than the usual -160 dBFS!!!
    KTE Spring2 DAC residual noise is the lowest I've ever measured and exceptional considering R2R design.

    Complete spdif input Bal output analysis report pdf attached
     

    Attached Files:

    Last edited: May 3, 2020
  3. atomicbob

    atomicbob dScope Yoda

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    spdif input SE output measurements part B

    KTE Spring2 A04 THD+N THD nth-HD FFT spdif input SE output
    20200403 KTE Spring2 A04 THD+N THD nth-HD 4+HD+N 60Hz FFT SE 0dBFS - spdif.png

    KTE Spring2 50 + 7000 Hz spdif input SE output - Left Channel
    FFT_2_L1T13_1_A.png

    KTE Spring2 Gain Linearity spdif input SE output - Left Channel
    G2_L1T5_1_A.png

    KTE Spring2 THD+N vs Frequency spdif input SE output - Left Channel
    G2_L1T5_1_A.png

    KTE Spring2 Residual Noise spdif input SE output - Left Channel
    FFT_2_L1T16_1_A.png

    Complete spdif input SE output analysis report pdf attached
     

    Attached Files:

    Last edited: May 3, 2020
  4. atomicbob

    atomicbob dScope Yoda

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    USB ASIO input Bal output measurements part C

    KTE Spring2 Dynamic Range USB input Bal output
    20200501 KTE Spring2 dynamic range FFT ASIO Bal.png

    KTE Spring2 -120dBFS sine USB input Bal output
    FFT_0_L1T18_1.png

    KTE Spring2 A04 THD+N THD nth-HD FFT USB input Bal output
    20200501 KTE Spring2 A04 THD+N THD nth-HD 4+HD+N 60Hz FFT Bal 0dBFS - ASIO.png

    KTE Spring2 50 + 7000 Hz USB input Bal output - Left Channel
    FFT_2_L1T13_1_A.png

    KTE Spring2 Gain Linearity USB input Bal output - Left Channel
    G2_L1T3_1_A.png

    KTE Spring2 THD+N vs Frequency USB input Bal output - Left Channel
    G2_L1T5_1_A.png

    KTE Spring2 Residual Noise Bal USB input Bal output - Left Channel
    FFT_2_L1T16_1_A.png

    Complete USB input Bal output analysis report pdf attached
     

    Attached Files:

    Last edited: May 3, 2020
  5. atomicbob

    atomicbob dScope Yoda

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    USB ASIO input SE output measurements part D

    KTE Spring2 A04 THD+N THD nth-HD FFT USB input SE output
    20200501 KTE Spring2 A04 THD+N THD nth-HD 4+HD+N 60Hz FFT SE 0dBFS - ASIO.png

    KTE Spring2 50 + 7000 Hz USB input SE output - Left Channel
    FFT_2_L1T13_1_A.png

    KTE Spring2 Gain Linearity USB input SE output - Left Channel
    G2_L1T3_1_A.png

    KTE Spring2 THD+N vs Frequency USB input SE output - Left Channel
    G2_L1T5_1_A.png

    KTE Spring2 Residual Noise USB input SE output - Left Channel
    FFT_2_L1T16_1_A.png

    Complete USB input SE output analysis report pdf attached
     

    Attached Files:

    Last edited: May 3, 2020
  6. atomicbob

    atomicbob dScope Yoda

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    Filter Response

    Measurement conditions
    1. -4 dBFS 20Hz square wave
    2. 44.1 KHz sample rate
    3. USB ASIO input
    4. SE output to oscilloscope

    Filter response measured the same across inputs and outputs

    KTE Spring2 10mS/div NOS
    20200502-01 KTE Spring2 20 Hz sqr -4 dBFS 4 Vpp 10mS div SE - ASIO - NOS.png

    KTE Spring2 10mS/div OS
    20200502-02 KTE Spring2 20 Hz sqr -4 dBFS 4 Vpp 10mS div SE - ASIO - OS.png

    KTE Spring2 10mS/div OS PCM
    20200502-03 KTE Spring2 20 Hz sqr -4 dBFS 4 Vpp 10mS div SE - ASIO - OS PCM.png

    KTE Spring2 10mS/div OS DSD
    20200502-04 KTE Spring2 20 Hz sqr -4 dBFS 2 Vpp 10mS div SE - ASIO - OS DSD.png

    KTE Spring2 200uS/div NOS
    20200502-05 KTE Spring2 20 Hz sqr -4 dBFS 4 Vpp 200uS div SE - ASIO - NOS.png

    KTE Spring2 200uS/div OS
    20200502-06 KTE Spring2 20 Hz sqr -4 dBFS 4 Vpp 200uS div SE - ASIO - OS.png

    KTE Spring2 200uS/div OS PCM
    20200502-07 KTE Spring2 20 Hz sqr -4 dBFS 4 Vpp 200uS div SE - ASIO - OS PCM.png

    KTE Spring2 200uS/div OS DSD
    20200502-08 KTE Spring2 20 Hz sqr -4 dBFS 2 Vpp 200uS div SE - ASIO - OS DSD.png

    KTE Spring2 200uS/div NOS BW calculation
    20200502-09 KTE Spring2 20 Hz sqr -4 dBFS 4 Vpp 200uS div SE - ASIO - NOS - BW calc.png
    Bandwidth estimation: BW (MHz) = 0.35 / RT (mS)
    Where RT = 10 to 90% Rise Time
    0.35 / 9.251 uS = 37.8 KHz

    KTE Spring2 200uS/div OS BW calculation
    20200502-10 KTE Spring2 20 Hz sqr -4 dBFS 4 Vpp 200uS div SE - ASIO - OS - BW calc.png
    Bandwidth estimation: BW (MHz) = 0.35 / RT (mS)
    Where RT = 10 to 90% Rise Time
    0.35 / 33.66 uS = 10.4 KHz
     
    Last edited: May 3, 2020
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  7. atomicbob

    atomicbob dScope Yoda

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    reserved for additional data and corrections
     
  8. atomicbob

    atomicbob dScope Yoda

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