diyAudio

diyAudio (https://www.diyaudio.com/forums/index.php)
-   Vendor's Bazaar (https://www.diyaudio.com/forums/vendor-s-bazaar/)
-   -   Hi-end DSP based multi-channel integrated Preamp/Crossover/DAC project (https://www.diyaudio.com/forums/vendor-s-bazaar/264743-hi-dsp-based-multi-channel-integrated-preamp-crossover-dac-project.html)

labjr 4th October 2015 12:11 AM

Quote:

Originally Posted by Tranquility Bass (https://www.diyaudio.com/forums/vendor-s-bazaar/264743-hi-dsp-based-multi-channel-integrated-preamp-crossover-dac-project-post4472119.html#post4472119)
I'm kind of hoping that whatever they come out with will be a drop-in replacement for the existing ADC but failing that there are some other options from other vendors that I could consider which also offer high performance.

cheers

I say take your time and get it right.

torgeirs 4th October 2015 08:52 AM

Quote:

Originally Posted by Tranquility Bass (https://www.diyaudio.com/forums/vendor-s-bazaar/264743-hi-dsp-based-multi-channel-integrated-preamp-crossover-dac-project-post4472092.html#post4472092)
Not needed as the DSP has an inbuilt SRC and everything is referenced to a 192KHz sample rate ;)

cheers

Thats great.
As I understand the DSP uses the AD1896 SRC IP.
From the:
http://www.analog.com/media/en/techn...ets/AD1896.pdf
44.1 kHz:192 kHz –123 dB
For any other sample rate ratio, the minimum THD + N will be better than –117 dB.

Funny to see that it only matches the ADC and DAC THD+N.

But thats just numbers and has no real world implication:).

pos 4th October 2015 09:13 AM

As the analog input part is an optional board, will this delay the release of the rest of the system?
As has already been stated by some, I am sure many here would already be happy with digital in only!

torgeirs 8th October 2015 07:44 AM

Will there be a way of attunating the digital input before the SRC?
See 3.2 in the tcelectronics paper.
http://www.tcelectronic.com/media/10...les_aes121.pdf
I don't know how AD1896 or the DSP handles +0dBFS signals and if it is better handled than by those old chips mentioned in the paper.

Bitperfect is not always the best:-)
Regards Torgeir

Tranquility Bass 8th October 2015 10:57 PM

Quote:

Originally Posted by torgeirs (https://www.diyaudio.com/forums/vendor-s-bazaar/264743-hi-dsp-based-multi-channel-integrated-preamp-crossover-dac-project-post4476464.html#post4476464)
Will there be a way of attunating the digital input before the SRC?
See 3.2 in the tcelectronics paper.
http://www.tcelectronic.com/media/10...les_aes121.pdf
I don't know how AD1896 or the DSP handles +0dBFS signals and if it is better handled than by those old chips mentioned in the paper.

Bitperfect is not always the best:-)
Regards Torgeir

I assume the SRC in the SHARC is built the same way that fixed point FIR filters are handled in the SHARC where extended precision handles the overflow situation so there should be no issue with clipping.

cheers

torgeirs 9th October 2015 09:40 AM

1 Attachment(s)
I made a zipped 44.1 fs, 5512.5 Hz sin stereo wav file that has 22.5 degree phase change and 1.08 (linear) amplitude in left channel. The right channel is normalised to -2dBFS and should be under 1 (linear) in amplitude. The output should be clean but in a audacity the left channel looks clipped.
This can be used to check if such overload is taken care of.
Regards Torgeir

torgeirs 9th October 2015 11:40 AM

2 Attachment(s)
I made the file again this time left 1.08 and right -3dB or 1.08 / sqr(2) = about 0.76 linear. 1.08 linear is about +0.67dBFS so the rigth is about -2.33dBFS.

Asumes that +/-1 top linear corresponds to 0dBFS

Tranquility Bass 10th October 2015 04:55 AM

1 Attachment(s)
Quote:

Originally Posted by torgeirs (https://www.diyaudio.com/forums/vendor-s-bazaar/264743-hi-dsp-based-multi-channel-integrated-preamp-crossover-dac-project-post4477771.html#post4477771)
I made a zipped 44.1 fs, 5512.5 Hz sin stereo wav file that has 22.5 degree phase change and 1.08 (linear) amplitude in left channel. The right channel is normalised to -2dBFS and should be under 1 (linear) in amplitude. The output should be clean but in a audacity the left channel looks clipped.
This can be used to check if such overload is taken care of.
Regards Torgeir

OK this is the output I get when I feed this waveform via a direct S/PDIF stream from the output of my soundblaster into the SRC/DSP. Top waveform is left channel and bottom waveform is the right channel. Output from S/PDIF is at FS.

Tranquility Bass 10th October 2015 04:56 AM

1 Attachment(s)
Quote:

Originally Posted by torgeirs (https://www.diyaudio.com/forums/vendor-s-bazaar/264743-hi-dsp-based-multi-channel-integrated-preamp-crossover-dac-project-post4477859.html#post4477859)
I made the file again this time left 1.08 and right -3dB or 1.08 / sqr(2) = about 0.76 linear. 1.08 linear is about +0.67dBFS so the rigth is about -2.33dBFS.

Asumes that +/-1 top linear corresponds to 0dBFS

And this is the output I get when I feed this waveform via a direct S/PDIF stream from the output of my soundblaster into the SRC/DSP. Top waveform is left channel and bottom waveform is the right channel. Output from S/PDIF is at FS.

torgeirs 12th October 2015 07:01 AM

Is it the analog output or the digital output?
For analog it should be two clean sinuses.
Or will the 44.1 -> 192 convertion interpolate the +0dbFS sinus to a clipped signal instead of a clean sinus?
Thank you for the testresults.
Kind regards Torgeir


All times are GMT. The time now is 09:28 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 17.65%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio

Wiki