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Signalyst DSC1
Signalyst DSC1
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Old 19th August 2019, 03:12 PM   #1501
brimax is offline brimax
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Quote:
Originally Posted by quanghao View Post
Hi, all ok, it is best , for last design with THD and SPL.
I see noise in new with reclock.
Thanks
Do you find differencies beetwen amanero or BBB?
thx
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Old 19th August 2019, 06:17 PM   #1502
koldby is offline koldby  Denmark
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I have almost completed the soldering of the latest DSC2 with on-board reclocker, but I cannot find any information ov orientation of the two X-tal oscillators.
Can anyone help, pls?
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Old 19th August 2019, 06:25 PM   #1503
gtose is offline gtose  United States
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Signalyst DSC1
koldby,

Dot goes to the corner created by the silkscreen lines. See my second photo via a microscope at Signalyst DSC1.
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Old 19th August 2019, 06:51 PM   #1504
nautibuoy is online now nautibuoy  United Kingdom
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Quote:
Originally Posted by gtose View Post
koldby,

Dot goes to the corner created by the silkscreen lines. See my second photo via a microscope at Signalyst DSC1.
I agree. I had the same question so checked the oscillator datasheet against the gerber files for the board to confirm.
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Old 19th August 2019, 07:09 PM   #1505
koldby is offline koldby  Denmark
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Thanks a million!
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Old 19th August 2019, 09:40 PM   #1506
audiodesignguide3 is offline audiodesignguide3
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Default CT7302 with external clock in src mode 2

Like suggest in the application note I have switch with the firmware the CT7302 in SRC mode 2 and add an external clock generator with a FOX 24.576MHz.


It can play any format, multiple frequencies of 44 and 48, without a clock switch.
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Old 19th August 2019, 10:38 PM   #1507
nautibuoy is online now nautibuoy  United Kingdom
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The second reclocker PCB has been soldered and tests OK on the bench power suppy. Unfortunately I've just realised that I've run out of PCB headers so am unable to plug onto the BBB for further testing until I get some more. Grrrrr!
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Old 20th August 2019, 05:31 AM   #1508
audiodesignguide3 is offline audiodesignguide3
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Here the thd at 1.4Vrms 0dB using the optical spdif 1 with input Optoplay set at 96KHz
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File Type: jpg DSC2_1V4rms_1KHz_thd_0dB_spdif_24576MHz_mode2.jpg (192.4 KB, 298 views)
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Old 20th August 2019, 12:24 PM   #1509
Vit123 is offline Vit123  Russian Federation
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Quote:
Originally Posted by audiodesignguide3 View Post
Here the thd at 1.4Vrms 0dB using the optical spdif 1 with input Optoplay set at 96KHz
Ok, you have 0.0069% THD. Change Y-axis scale (set from -160dB to -10dB) and you will see harmonics. Can'e be seen now as they are lower then -84dB (100 - 16).

As for DSC 2.5.2 measurements
Have a look at THD measurements with different input signals. Pay attention to significant increase in distortion with increasing input signal. This is not an ADC overload. It's DSC feature.

Measurements had been done without an output transformer (direclry from DSC). 4dBu input of RME ADI-2 Pro FS was used.
Adding output transformer adds some distortions
- very big (10/15 dB increase in harmonics) with LL1684
- very small with stock transformers. See measurements.

Both 0.0069% and 0.0024% THD are quite big and may be audible ("coloration"). So, IMO, the best way to use DSC is a small volume attenuation before DAC (HQP Volume Control).

And you can easily get 0.0003% THD/THD+N with AKM/Sable baced DAC.
Attached Images
File Type: jpg -1dBFS.jpg (84.1 KB, 263 views)
File Type: jpg -10dBFS.jpg (90.0 KB, 264 views)
File Type: jpg Trans.jpg (90.4 KB, 59 views)
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Old 20th August 2019, 06:47 PM   #1510
audiodesignguide3 is offline audiodesignguide3
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The my aim was not to prove that the distortion of ct7302 + dsc 2 is low as a traditional dac.
I am not in a position to verify this because now I have only a development environment with 10cm long I2S connection, with 10cm DSD connection and my oscillator is connected to an external pcb 10cm away from the CT7302.
In these conditions it is almost a miracle that something comes out.
I have only shown that the CT7302 in its best configuration with external reference oscillator at 24.576MHz and in SRC mode 2 works very well.
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