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Author Topic: Leckerton UHA-6S mkII measurements  (Read 2900 times)

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atomicbob

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Leckerton UHA-6S mkII measurements
« on: May 28, 2015, 02:07:18 AM »
Here are measurements for a DAC / Amp combo that provides enjoyable listening in a very portable format; Leckerton UHA-6S mkII. If you have been following my other measurement posts, you may begin to see some trends.

The data presented were collected as follows:
 
1.  PrismSound dScope III, picoscope 5243B
2.  DAC unbalanced output RCA
3.  100 Kohm load used for measurements dScope measurements
4.  50 ohm load used for square wave measurements
5.  44 KHz  sample rate, 24 bit depth
6.  USB input – Audioquest Forest
7.  S/PDIF input - Canare broadcast grade 75 ohm BNC cable
8.  TosLink - Mediabridge 0.5 meter
9.  Unbalanced cable Radio Shack nothing special 3.5mm TRS to stereo RCA
10. Vaunix Lab Brick USB hub
11. output gain switch set to low position

Tests were run at a gain consistent with my personal listening sound levels which is between 70 to 77 dBC SPL.

Frequency Response



Frequency Response (y-axis zoom)



Dynamic Range



THD+N (updated 20150530)



IMD



Crosstalk



1kHz @ -70dBFS



1kHz @ -90dBFS


« Last Edit: May 30, 2015, 10:10:22 PM by atomicbob »
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atomicbob

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Re: Leckerton UHA-6SmkII measurements
« Reply #1 on: May 28, 2015, 02:10:48 AM »
Measurements part B

inferred jitter - USB



inferred jitter - S/PDIF



inferred jitter - TosLink



gain linearity



imaging



imaging with 19 KHz tone




« Last Edit: May 28, 2015, 02:48:38 AM by atomicbob »
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atomicbob

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Re: Leckerton UHA-6SmkII measurements
« Reply #2 on: May 28, 2015, 02:12:01 AM »
Measurements part C

20 Hz sqr 0dBFS 600 mVpp 50 ohm load 10 mS/div



20 Hz sqr 0dBFS 600 mVpp 50 ohm load 500 uS/div




What happens when the mastering engineer sets the limiter very close to 0 dBFS during the final processing of the music to which you listen?
Here are four THD+N and THD measurement sets depicting the behavior at -0.1, -0.2, -0.5 and -1.0 dBFS maximum signal for the UHA-6SmkII. The closer to 0 dBFS the greater the risk of recovery filter inter-sample overs and the rise in distortion, typically below 200 ~ 500 Hz. Please note the Leckerton is not unique. All DACs exhibit this more or less as can be seen in the THD+N and THD measurements I've made at -0.1 dBFS for other DACs.

THD+N and THD with signal generator set to sweep at -0.1 dBFS



THD+N and THD with signal generator set to sweep at -0.2 dBFS



THD+N and THD with signal generator set to sweep at -0.5 dBFS



THD+N and THD with signal generator set to sweep at -1.0 dBFS



« Last Edit: May 29, 2015, 01:14:10 AM by atomicbob »
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atomicbob

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Re: Leckerton UHA-6SmkII measurements
« Reply #3 on: May 28, 2015, 02:13:13 AM »
measurements part D - amplifier section only:

dScope measurements

UHA-6SmkII amplitude - phase - gain



UHA-6SmkII signal to noise



UHA-6SmkII THD+N  THD  nth harmonic distortion


















« Last Edit: May 29, 2015, 01:56:13 AM by atomicbob »
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firev1

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Re: Leckerton UHA-6S mkII measurements
« Reply #4 on: May 28, 2015, 02:54:52 PM »
Imaging with 19khz tone, is the tone an overlay? Its supposed to be two separate test that are just superimposed on one another for easy reference. Its easy enough to see the aliasing though.

For amp testing does the dscope come with a notch filter? Just asking. :3
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atomicbob

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Re: Leckerton UHA-6S mkII measurements
« Reply #5 on: May 28, 2015, 03:07:49 PM »
Quote from: firev1 on May 28, 2015, 02:54:52 PM
Imaging with 19khz tone, is the tone an overlay? Its supposed to be two separate test that are just superimposed on one another for easy reference. Its easy enough to see the aliasing though.

For amp testing does the dscope come with a notch filter? Just asking. :3
I tried something new, I pre-mixed white noise and the 19 KHz tone for a source and then ran the dScope asynchronously to see how the imaging components changed from the white noise alone.

The dScope has a notch filter, which can be swept. It also has more configurable components than I have yet to explore in depth.

For the Leckerton, I combined measurements as the DAC / Amp combination is being measured together. I could have measured the Amp portion separately but I didn't see an easy way to get at just the DAC without opening the unit and putting a probe onto the PCB, which would no longer be representative of a typical user use model.
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firev1

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Re: Leckerton UHA-6S mkII measurements
« Reply #6 on: May 28, 2015, 03:16:46 PM »
The only problem with the pre mixed signal is that most of the aliasing components from the 19khz tone is covered by the ripple in the stopband.

Would like to have a glimpse of the Leckerton's amp only performance, which I reckon might require the notch to measure, maybe.
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Anaxilus

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Re: Leckerton UHA-6S mkII measurements
« Reply #7 on: May 28, 2015, 05:03:02 PM »
Amp measurements would be nice as many of use just that in a brick setup. No surprise about toiling and coax measuring better than USB here. Cool.
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thune

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Re: Leckerton UHA-6S mkII measurements
« Reply #8 on: May 28, 2015, 08:21:51 PM »
I'm not understanding the THD plots ( 0.1%<=100hz seems excessively large.) Also the Leckerton UHA-6S THD plot appears eerily similar to the Mousai MSD192 and Yggdrassil THD plots. I'm wondering if there is a setup/equipment issue with this test.
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atomicbob

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Re: Leckerton UHA-6S mkII measurements
« Reply #9 on: May 29, 2015, 01:32:39 AM »
Quote from: thune on May 28, 2015, 08:21:51 PM
I'm not understanding the THD plots ( 0.1%<=100hz seems excessively large.) Also the Leckerton UHA-6S THD plot appears eerily similar to the Mousai MSD192 and Yggdrassil THD plots. I'm wondering if there is a setup/equipment issue with this test.

Updated 20150530.

In this case it was a USB driver issue creating inter-sample overs due to modifying the data stream with some math operation.

But the dirty little secret of recovery filter inter-sample overs when the source approaches 0 dBFS still is a problem. As soon as we drop below -0.5 and -1.0 dBFS most DACs look a lot better. Look at the Leckerton handling it very well as soon as the signal is -0.2 dBFS or lower. Another reason this little DAC / Amp rocks.
« Last Edit: May 30, 2015, 10:13:32 PM by atomicbob »
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