CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => Amp and DAC Measurements => Topic started by: atomicbob on September 25, 2015, 10:03:13 PM
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20150926 UPDATE - last section added comparing 1 KHz -90 dBFS Balanced vs. Single Ended between Optical, SPDIF and USB inputs.
Look carefully at the jitter graphs. Gungnir MB jitter is impressively low. Balanced output has an exceptionally low noise floor. Single ended jitter measurement is a little higher in residual noise floor as expected.
Channel matching is excellent. Frequency response and square wave response left and right channels are so well matched as to overlay one another.
The 1 KHz -90 dBFS sine Single Ended measurement appears a little noisier than I would have expected and would still entertain the notion of a setup problem, though many corrective actions were attempted.
Balanced XLR measurements were at approximately 1 hr of power on time.
Single Ended RCA measurements were at approximately 3 hrs of power on time.
Balanced XLR through Radial Twin ISO (Jensen transformers) for conversion to single ended output measurements were at approximately 4 hrs of power on time.
The Gungnir MB data presented were collected as follows:
1. PrismSound dScope III, picoscope 5243B
2. DAC balanced output XLR, unbalanced output RCA
3. 100 Kohm load used for measurements
4. 44 KHz sample rate, 24 bit depth
5. USB input – Audioquest Forest
6. Balanced cable Canare L-4E6S with Neutrik XLR
7. Unbalance cable DH Labs Silver Sonic Air Matrix RCA
8. Vaunix Lab Brick USB hub
Balanced XLR output measurements part A
Frequency Response
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11107;image)
Frequency Response (y-axis zoom)
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11109;image)
Dynamic Range
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11111;image)
THD+N
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11113;image)
IMD
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11115;image)
Crosstalk
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11117;image)
Inferred Jitter
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11119;image)
Inferred Jitter (x axis zoom)
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11121;image)
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Balanced XLR output measurements part B
1kHz @ -90dBFS
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11123;image)
20 Hz square wave 0dBFS 6Vpp 10ms
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11125;image)
20 Hz square wave 0dBFS 6Vpp 500us
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11127;image)
1 kHz gain linearity
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11129;image)
Imaging
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11131;image)
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Single Ended RCA output measurements part A
Frequency Response
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11133;image)
Frequency Response (y-axis zoom)
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11135;image)
Dynamic Range
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11137;image)
THD+N
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11139;image)
IMD
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11141;image)
Crosstalk
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11143;image)
Inferred Jitter
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11145;image)
Inferred Jitter (x axis zoom)
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11147;image)
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Single Ended RCA output measurements part B
1kHz @ -90dBFS The noise has quieted somewhat after 27 hrs of power on time. See reply #6.
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11149;image)
20 Hz square wave 0dBFS 6Vpp 10ms
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11151;image)
20 Hz square wave 0dBFS 6Vpp 500us
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11153;image)
1 kHz gain linearity
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11155;image)
Imaging
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11157;image)
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Balanced XLR output through Radial Twin ISO (Jensen transformers) for single ended conversion measurements part A
Frequency Response
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11159;image)
Frequency Response (y-axis zoom)
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11161;image)
Dynamic Range
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11163;image)
THD+N
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11165;image)
IMD
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11167;image)
Crosstalk
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11169;image)
Inferred Jitter
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11171;image)
Inferred Jitter (x axis zoom)
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11173;image)
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Balanced XLR output through Radial Twin ISO (Jensen transformers) for single ended conversion measurements part B
1kHz @ -90dBFS
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11175;image)
20 Hz square wave 0dBFS 12Vpp 10ms
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11177;image)
20 Hz square wave 0dBFS 12Vpp 500us
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11179;image)
1 kHz gain linearity
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11181;image)
Imaging
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11183;image)
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In this section 1 KHz -90 dBFS comparisons between USB, Optical and SPDIF for both Balanced and Single Ended are presented.
Due to concern about the results of Single Ended measurements for 1 KHz -90dBFS and measurement setup with the dScope,
there is also a 1 KHz -90dBFS comparison using the P5243B oscilloscope.
P5243 oscilloscope measurements were consistent with those obtained by the dScope.
Gungnir MB power on time was 27 hrs at time of measurements.
Bal 1 KHz -90 dBFS optical
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11199;image)
Bal 1 KHz -90 dBFS spdif BNC
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11201;image)
Bal 1 KHz -90 dBFS USB
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11203;image)
SE 1 KHz -90 dBFS optical
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11205;image)
SE 1 KHz -90 dBFS spdif BNC
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11207;image)
SE 1 KHz -90 dBFS USB
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11209;image)
Bal 1 KHz -90 dBFS USB P5243B oscilloscope
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11211;image)
SE 1 KHz -90 dBFS USB P5243B oscilloscope
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11213;image)
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Thanks for the measurements!
The RCA results look weird, though. Why is the noise floor so high compared to XLR? :-\
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Thanks for the measurements!
The RCA results look weird, though. Why is the noise floor so high compared to XLR? :-\
I don't know. I checked the SE measurements multiple times, re-positioned equipment, cables, disconnected and reconnected cables, tried different cables, cycled power and rebooted dScope and laptop. Same results. I expect the SE output to be a little higher in noise. Maybe Jason has a suggestion. I won't have another time opportunity to repeat any measurements for another week.
However, it should be noted that I am thoroughly enjoying the sound of the Gungnir MB balanced output through the Twin ISO Jensen transformers into a Project Sunrise III and HD650 headphones. The Gungnir MB is an exceptional performer. It well deserves its position on Marv's DAC chart. Tomorrow I'll spend some more time listening to the Single Ended outputs.
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Yeah, the 1kHz sine wave at -90db looks mysterious - everything else looks good.
Note increased distortion, especially down toward the bass, with the Jenson XLR-> SE transformers. Not something to worry about, but I suspect a slightly warmer sound from them.
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Yeah, the 1kHz sine wave at -90db looks mysterious - everything else looks good.
Note increased distortion, especially down toward the bass, with the Jenson XLR-> SE transformers. Not something to worry about, but I suspect a slightly warmer sound from them.
Cool stuff Atomic. Your contribution is limited by my browser's capability.
Marv's notes are interesting. Radial markets a lot of these boxes with sound shaping abilities. I would be very interested in seeing how measurements and sound change between different DI boxes. There seem to be a wide variation in prices as well. I would love to see if it's worth spending more on these. There are passive and active DI boxes as well. How would they differ?
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Wows excellent stuff atomicbob, damn Gumby is freakishly good. Yeah the low level distortion test at -90dbFS is squaring out the little sine wave.
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Awesome stuff Bob! Thanks! :money:
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Update made concerning 1 KHz -90 dBFS measurements.
I have spent some time listening to both the single ended output and balanced to SE conversion through Jensen transformers on my ZanaDeux SE. I have a slight preference for the XFMR Bal to SE conversion in this setup. The soundstage, 3-D dimension and depth with clarity remain impressive either way. Channel matching, gain linearity and Jitter may be the measurements that most reflect the subjective auditory experience I describe. This is an important DAC development that deserves serious consideration. Everyone should audition the Gungnir MB if possible.
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thank you!
this is why I love changstar so much.
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Picture of test setup.
I should have used the hot lights but was in a hurry to finish before the next scheduled event on the list by my social program director.
Gungnir MB - dScope - picoscope 5243b
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11218;image)
Gungnir MB - dScope - MSD192 for SE measurement setup verification
(http://www.changstar.com/index.php?action=dlattach;topic=2894.0;attach=11220;image)