ECP Audio DSHA-3F technical measurements

Discussion in 'Headphone Amplifier Measurements' started by atomicbob, Feb 26, 2019.

  1. atomicbob

    atomicbob dScope Yoda

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    ECP Audio DSHA-3F technical measurements

    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 this post.

    The data presented were collected as follows:

    1. PrismSound dScope III, picoscope 5243B, Micsig DP10013 balanced probe, Keysight 34465A DMM
    2. 300 and 30 ohm loads used for measurements
    3. Balanced cables Canare L-4E6S starquad with Neutrik XLR connectors
    4. Vaunix Lab Brick USB hub for measurement equipment
    5. Audioquest Forest and Schiit Pyst USB cables used for measurement equipment
    6. Amplifier gain adjusted to 0 dB gain @ 0.775 Vrms 0 dBu
    7. DSHA-3F gain knob at approximately 2:30 to achieve 0 dB gain (varies a little between 30R and 300R load)
    8. 14 and 16 AWG sheilded power cables used

    Reference data for two headphones to keep in mind:
    HD 650 impedance 300R, sensitivity 98 dB/mW
    HE-500 impedance 38R, sensitivity 89 dB/mW

    SPL levels for above headphones for reference:
    +9 dBu 300R 16.00 mW - 110 dBSPL @ 98dB/mW
    0 dBu 300R 2.00 mW - 101 dBSPL @ 98dB/mW
    -10 dBu 300R 0.20 mW - 91 dBSPL @ 98dB/mW
    -20 dBu 300R 0.02 mW - 81 dBSPL @ 98dB/mW

    +9 dBu 30R 160.00 mW - 110 dBSPL @ 89dB/mW
    0 dBu 30R 20.00 mW - 102 dBSPL @ 89dB/mW
    -10 dBu 30R 2.00 mW - 92 dBSPL @ 89dB/mW
    -20 dBu 30R 0.20 mW - 82 dBSPL @ 89dB/mW

    All testing performed at 0 dBu unless otherwise noted.
    This level is consistent with listening to headphones (referenced above) at 90 dBSPL average with peaks to 100 dBSPL, if the music has 10 dB Peak to Avg ratio. That is LOUD for long listening sessions.

    Highlights
    First, well done Doug! This is an incredible headphone amplifier.
    Nearly perfect gain linearity spanning over 110 dB range!!!!!
    +/- 1 dB gain linearity over 140 dB range!!!!!
    SNR greater than 116 dB!!!!!
    Tube magic midrange yet no tubes.
    Great square wave response, with a tight ring on rising and falling edges.
    Bandwidth: DC to greater than 115 KHz

    Bottom line
    DSHA-3F has been added to the A list of headphone amplifiers in the acoustic lab inventory.

    Test Data Organization
    Post
    1 - introduction
    1 - Bal input to 4XF output 300R load part 1 of 3
    2 - Bal input to 4XF output 300R load part 2 of 3
    3 - Bal input to 4XF output 300R load part 3 of 3
    4 - Bal input to 4XF output 30R load part 1 of 3
    5 - Bal input to 4XF output 30R load part 2 of 3
    6 - Bal input to 4XF output 30R load part 3 of 3
    7 - dynamic series 30R load

    My personal preferences include listening typically at an average of 75 dB SPL. Assuming a typical Peak to Average ratio of 10 dB puts peaks at 85 dB SPL. This suggests the measurements at -20 dBu represent my experience with HD6x0 and HD800 headphones. Auditory experiences for someone listening 10 dB SPL average higher may diverge from my own experiences.

    editorial - I believe there is a tendency to focus excessively on numbers such as THD attempting to reduce a complex topic to a single number representing a sort of goodness rating. Graphs can present far more data conveying a better understanding of the measurement over a range of frequency, levels, etc. Please don't read too much into the numbers presented. Read the tutorial presented here for a good example of why.

    Picture of Audio Lab setup for DSHA-3F measurements
    DSC_0063_small.jpg


    Bal input 4XF output 300 ohm load part 1 of 3

    Output impedance measured 4.88R

    DSHA-3F THD+N THD nth harmonic distortion (A04) FFT 0dBu 300R load
    20190221 DSHA-3F A04 THD+N  THD  nth-HD FFT 300R 4XF.png

    DSHA-3F Gain vs Amplitude 300R load
    20190221 DSHA-3F 1 KHz gain linearity 300R.PNG
    Wow! Incredible gain linearity over such a large dynamic range for an amplifier!!!

    DSHA-3F THD THD+N vs Freq 0dBu 300R load
    20190221 DSHA-3F THD THD+N vs Freq 300R 4XF.png

    DSHA-3F 1 KHz spectrum Left and Right 0dBu 300R load
    20190221 DSHA-3F 1 KHz THD+N THD FFT 0dBu 300R 4XF.png

    DSHA-3F 50 Hz + 7000 Hz spectrum Left and Right 0dBu 300R load
    20190221 DSHA-3F 50+7000Hz 0dBu 300R 4XF.png
    50 Hz stimulus resulting in low level harmonic series similar to tube amps!

    DSHA-3F 600 Hz + 1700 Hz spectrum Left and Right 0dBu 300R load
    20190221 DSHA-3F 600+1700Hz 0dBu 300R 4XF.png

    DSHA-3F IMD spectrum Left and Right -16dBu 300R load
    20190221 DSHA-3F 19+20KHz -16dBu 300R 4XF.png
    Very clean IMD.

    DSHA-3F residual noise spectrum Left and Right A=0dB 300R load
    20190221 DSHA-3F residual noise A=0dB 300R 4XF.png
    Residual noise is quite low.
     
    Last edited: Feb 26, 2019
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  2. atomicbob

    atomicbob dScope Yoda

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    Bal input 4XF output 300 ohm load part 2 of 3

    DSHA-3F square wave 20 Hz 2 Vpp 10 mS / div 300R load 100 KHz BW
    20190221 SigGen DSHA-3F 20 Hz square 2000mVpp 10mS div 100KHz filter 300R.png

    DSHA-3F square wave 20 Hz 2 Vpp 10 mS / div 300R load 5 MHz BW
    20190221 SigGen DSHA-3F 20 Hz square 2000mVpp 10mS div 5MHz filter 300R.png

    DSHA-3F square wave 20 Hz 2 Vpp 10 uS / div 300R load 5 MHz BW
    20190221 SigGen DSHA-3F 20 Hz square 2000mVpp 10uS div 5MHz filter 300R.png

    DSHA-3F square wave 20 Hz 2 Vpp 1 uS / div 300R load 5 MHz BW
    20190221 SigGen DSHA-3F 20 Hz square 2000mVpp 1uS div 5MHz filter 300R - BW calc.png

    Bandwidth estimation: BW (MHz) = 0.35 / RT (mS)
    Where RT = 10 to 90% Rise Time
    0.35 / 2.857 uS = 122.5 KHz

    DSHA-3F amplitude - phase - gain (A01) 300R load
    20190221 DSHA-3F A01 amplitude - phase - gain 300R.png

    DSHA-3F signal to noise (A07) 300R load
    20190221 DSHA-3F A07 SNR 300R FFT.png
    Very impressive dynamic range!!

    DSHA-3F THD+N THD nth harmonic distortion (A04) 300R load
    20190221 DSHA-3F A04 THD+N  THD  nth-HD 300R.png

    DSHA-3F Crosstalk (A08 A09) 300R load
    20190221 DSHA-3F A08 A09 Crosstalk 300R.png
    Excellent channel separation.
     
    Last edited: Feb 26, 2019
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  3. atomicbob

    atomicbob dScope Yoda

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    Bal input 4XF output 300 ohm load part 3 of 3

    DSHA-3F Frequency Response and Interchannel Phase pg 1/2 300R load
    G2_L1T2_1_A.png

    DSHA-3F Frequency Response and Interchannel Phase pg 2/2 300R load
    G2_L1T2_1_B.png

    DSHA-3F THD+N vs Amplitude Left 300R load
    G2_L1T7_1_A.png

    DSHA-3F THD+N vs Amplitude Right 300R load
    G2_L1T7_1_B.png

    DSHA-3F Crosstalk Left to Right vs Frequency 300R load
    G1_L1T11_1.png

    DSHA-3F Crosstalk Right to Left vs Frequency 300R load
    G0_L1T12_1.png
     
    Last edited: Feb 26, 2019
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  4. atomicbob

    atomicbob dScope Yoda

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    Bal input 4XF output 30 ohm load part 1 of 3

    DSHA-3F THD+N THD nth harmonic distortion (A04) FFT 0dBu 30R load
    20190221 DSHA-3F A04 THD+N  THD  nth-HD FFT 30R 4XF.png

    DSHA-3F Gain vs Amplitude 30R load
    20190221 DSHA-3F 1 KHz gain linearity 30R.PNG

    DSHA-3F THD THD+N vs Freq 0dBu 30R
    20190221 DSHA-3F THD THD+N vs Freq 30R 4XF.png

    DSHA-3F 1 KHz spectrum Left and Right 0dBu 30R load
    20190221 DSHA-3F 1 KHz THD+N THD FFT 0dBu 30R 4XF.png

    DSHA-3F 50 Hz + 7000 Hz spectrum Left and Right 0dBu 30R load
    20190221 DSHA-3F 50+7000Hz 0dBu 30R 4XF.png

    DSHA-3F 600 Hz + 1700 Hz spectrum Left and Right 0dBu 30R load
    20190221 DSHA-3F 600+1700Hz 0dBu 30R 4XF.png

    DSHA-3F IMD spectrum Left and Right -16dBu 30R load
    20190221 DSHA-3F 19+20KHz -16dBu 30R 4XF.png

    DSHA-3F residual noise spectrum Left and Right A=0dB 30R load
    20190221 DSHA-3F residual noise A=0dB 30R 4XF.png
     
    Last edited: Feb 26, 2019
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  5. atomicbob

    atomicbob dScope Yoda

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    Bal input 4XF output 30 ohm load part 2 of 3

    DSHA-3F square wave 20 Hz 2 Vpp 10 mS / div 30R load 100 KHz BW
    20190221 SigGen DSHA-3F 20 Hz square 2000mVpp 10mS div 100KHz filter 30R.png

    DSHA-3F square wave 20 Hz 2 Vpp 10 mS / div 30R load 5 MHz BW
    20190221 SigGen DSHA-3F 20 Hz square 2000mVpp 10mS div 5MHz filter 30R.png

    DSHA-3F square wave 20 Hz 2 Vpp 10 uS / div 30R load 5 MHz BW
    20190221 SigGen DSHA-3F 20 Hz square 2000mVpp 10uS div 5MHz filter 30R.png

    DSHA-3F square wave 20 Hz 2 Vpp 1 uS / div 30R load 5 MHz BW
    20190221 SigGen DSHA-3F 20 Hz square 2000mVpp 1uS div 10MHz filter 30R - BW calc.png

    Bandwidth estimation: BW (MHz) = 0.35 / RT (mS)
    Where RT = 10 to 90% Rise Time
    0.35 / 3.037 uS = 115 KHz

    DSHA-3F amplitude - phase - gain (A01) 30R load
    20190221 DSHA-3F A01 amplitude - phase - gain 30R.png

    DSHA-3F signal to noise (A07) 30R load
    20190221 DSHA-3F A07 SNR 30R FFT.png

    DSHA-3F THD+N THD nth harmonic distortion (A04) 30R load
    20190221 DSHA-3F A04 THD+N  THD  nth-HD 30R.png

    DSHA-3F Crosstalk (A08 A09) 30R load
    20190221 DSHA-3F A08 A09 Crosstalk 30R.png
     
    Last edited: Feb 26, 2019
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  6. atomicbob

    atomicbob dScope Yoda

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    Bal input 4XF output 30 ohm load part 3 of 3

    DSHA-3F Frequency Response and Interchannel Phase pg 1/2 30R load
    G2_L1T2_1_A.png

    DSHA-3F Frequency Response and Interchannel Phase pg 2/2 30R load
    G2_L1T2_1_B.png

    DSHA-3F THD+N vs Amplitude Left 30R load
    G2_L1T7_1_A.png

    DSHA-3F THD+N vs Amplitude Right 30R load
    G2_L1T7_1_B.png

    DSHA-3F Crosstalk Left to Right vs Frequency 30R load
    G1_L1T11_1.png

    DSHA-3F Crosstalk Right to Left vs Frequency 30R load
    G0_L1T12_1.png
     
    Last edited: Feb 26, 2019
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  7. atomicbob

    atomicbob dScope Yoda

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    reserved 7/8. - will update later - long day today.
     
    Last edited: Feb 26, 2019
  8. atomicbob

    atomicbob dScope Yoda

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    reserved 8/8.
     
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    Elnrik Super Friendly

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    I'm guessing that is Tamarind, but I would love to know for sure. It's gorgeous! Thank you!
     
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    k1arg Almost "Made"

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    Is it me or are the odd-order harmonics on channel B consistently a bit higher than on A? Both are way down, but I wonder if there is anything interesting there.
     
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    dsavitsk Friend

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    Spalted maple. It is basically maple that has started rotting and has fungus growing in it - if caught at just the right moment, it is still stable enough to use and has lovely black veining through it.
     
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