Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Master clock and isolator for the MiniDSP USBStreamer
Master clock and isolator for the MiniDSP USBStreamer
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st November 2013, 07:39 PM   #11
alexmi is offline alexmi  United States
diyAudio Member
 
Join Date: Jul 2003
Location: Portland, OR, USA
Default clock?

Dumb question from a novice...I thought one of the goals for your board was a "better" clock...if the new board doesn't have on board oscillator how will it get the "better" clock ??

Thanks, alex
  Reply With Quote
Old 1st November 2013, 07:45 PM   #12
alexmi is offline alexmi  United States
diyAudio Member
 
Join Date: Jul 2003
Location: Portland, OR, USA
Default digital crossover

My interest in the USBstreamer is to build a computer music system, do the digital crossover inside the computer (BruteFIR) and have it output six channels (low/mid/high R + L ) over USB into the USBstreamer, and from there connect either to a DAC + amp or to the new Full Digital Amp (those take I2S input).
So, a "better" clock in USBstreamer would be nice.

Thanks, alex
  Reply With Quote
Old 1st November 2013, 11:56 PM   #13
JensH is offline JensH  Denmark
diyAudio Member
 
Join Date: Jul 2009
Master clock and isolator for the MiniDSP USBStreamer
Hi Alex,

I will try to explain it with a bit more details.

On the first version i did include two crystal oscillators. The ones I used were fairly standard types, with OK, but not exceptional jitter levels. I could mount some better oscillators in the design and get even better jitter performance.
But there is a risk of getting added jitter due to buffers and the cable connection when feeding the clock from the USBStreamer Interface to the converter board.

Ideally the oscillators should be placed very close to the converters to avoid added jitter from buffers and cables etc. That is why I decided to make the V3 board without oscillators. It does require that the converter board contains two oscillators. And it must change frequency on command (logic signal) from the USBStreamer Interface.

The converter board can then use the best oscillators you can find (or afford). So good oscillators like the Crystek CCHD-957, Tent Labs or NDK's NZ2520SD series can be used.
If it was possible to find an absolutely perfect crystal oscillator (which does not exist of course) it would be possible to use it with no degradation from the PC interface (USBStreamer + USBStreamer Interface). The clock fed back to the USBStreamer Interface may have some added jitter, but this is not critical, as long as the converters get the clean clock and use it as the master clock. Even a jitter (in the clock going to the USBStreamer Interface) in the order of 1ns (or even more) would not be a problem.

If the converter boards are existing boards, without the oscillators needed for the USBStreamer Interface V3, I guess we are back to the USBStreamer Interface V2 (or even V1 if only playback is needed). I have not built and tested the V2, but basically it should work like the V1, only with faster isolators. I am sure that, with very good oscillators like the NDK's, this will also work very well, with much lower jitter levels than the USBStreamer on its own (and with the added benefit of the isolation).

I have some NDK oscillators on order, but I won't receive them until sometime in December. I will probably use a couple of them for a PCM1794A based DAC design I expect to mount and test within the next couple of weeks.

The digital crossover you mention should certainly be possible as long as you need 8 channels or less. If you need 10 channels it would be necessary to use also the Toslink output. This can also be done synchronous to the master clock, but I have not made a dedicated design for this. I have tested the principle with a couple of SPDIF/Toslink receivers in a similar setup, so it definitely can be done.
  Reply With Quote
Old 2nd November 2013, 01:02 AM   #14
alexmi is offline alexmi  United States
diyAudio Member
 
Join Date: Jul 2003
Location: Portland, OR, USA
ahhh...I think I understand (I think...;-)) I will need only 6 channels out (possibly 8 out in the future, but I doubt it), and I don't have yet the converters. I was thinking to use the "new" Full Digital Amplifiers that take I2S input and generate
power....there is no DAC so to speak. Still early in the project, and very probably well over my head, I'm a software guy.

Thanks a lot, I appreciate the explanation. Alex
  Reply With Quote
Old 2nd November 2013, 07:06 PM   #15
JensH is offline JensH  Denmark
diyAudio Member
 
Join Date: Jul 2009
Master clock and isolator for the MiniDSP USBStreamer
My explanation got a bit long, so I made a couple of block diagrams, which may be easier to understand.
Attached Files
File Type: pdf Visio-USBStreamer Interface 2 V1_V2_V3 Block Diagrams.pdf (17.2 KB, 415 views)
  Reply With Quote
Old 2nd November 2013, 07:49 PM   #16
alexmi is offline alexmi  United States
diyAudio Member
 
Join Date: Jul 2003
Location: Portland, OR, USA
Ahhhh, yes, now it is very clear. When there are 6 channels out (so 3 DAC's) it will be a single DAC (the master) that generates the "clean" MCLK and feeds the other two DAC's and the USBStreamer, correct ??

Found this very inexpensive DAC with ES9023 (supposedly a good one) it has a I2S input, and space for a clock...but I think it has space for just a single clock
(and it is 27MHz) not for a dual 22.57 + 24.57...what do you think, could it be
forced into working with Version 3 of your Interface ?

Hifimediy ES9023 DAC, I2S and left justified input, 192Khz/24bit

Thanks again, I appreciate your time.

alex
  Reply With Quote
Old 2nd November 2013, 09:27 PM   #17
JensH is offline JensH  Denmark
diyAudio Member
 
Join Date: Jul 2009
Master clock and isolator for the MiniDSP USBStreamer
Yes, if there are 3 DAC's, one could feed the clock to the other ones, as long as the clocks are transferred without adding too much noise. The 3 DAC's could also be implemented on one PCB together with the oscillators. This could give better control over the clock quality.

The V3 will not work with e.g. a 27MHz clock. Best case the playback speed will be much faster than normal (about 10 to 20%), which of course isn't acceptable. If it works at all. I haven't tried it. With the ESS converters the V1 or V2 could be used. But the clean clocks may not really bring anything unless the SCLK, LRCK and data are resynchronized by the MCLK. And I don't know if it actually helps much in this case, since the ESS DAC's supposedly should be good at eliminating jitter due to the ASRC. The ESS DAC ASRC will do sample rate conversion internally.

Another way to use ESS DAC's, e.g. ES9018 is to run it without sample rate conversion. For the ES9018 this will require the 49.152/45.1584MHz clocks mentioned in the first post. These clocks should then be divided by two and fed to the USBStreamer Interface. It is something I would like to try one day, but it may still take some time before I get to that. Unlike you Alex, I'm a hardware guy and not a software guy. And the ES9018 requires some SW setup.
But the ES9018 could actually give you the 6 channels you need. But it is of course in a different league (also cost wise) than the ES9023 or e.g. the TI PCM5102A. I have actually worked with the PCM5102A recently and got good results.
  Reply With Quote
Old 3rd November 2013, 03:54 PM   #18
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
Now it is more clear.
But what is the USB interface You draw?
Some of the existing, Amanero, Hiface or something else?
__________________
###
  Reply With Quote
Old 3rd November 2013, 04:48 PM   #19
JensH is offline JensH  Denmark
diyAudio Member
 
Join Date: Jul 2009
Master clock and isolator for the MiniDSP USBStreamer
If you read the thread title it should be relatively clear
  Reply With Quote
Old 3rd November 2013, 04:49 PM   #20
alexmi is offline alexmi  United States
diyAudio Member
 
Join Date: Jul 2003
Location: Portland, OR, USA
ohhh, I wasn't even aware that there is a ES 8 channel DAC. Sure, even if it is a bit more expensive, this is the proper solution. Found already a project on diyaudio and a board on ebay. I'll keep on looking.

Thanks, this is very useful, Alex
  Reply With Quote

Reply


Master clock and isolator for the MiniDSP USBStreamerHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
ES9023 DAC design for MiniDSP USBStreamer Neil_J Digital Source 27 27th February 2015 08:20 AM
WTB:Universal 1ppm CDCD clock + SPDIF isolator Sergelisses Swap Meet 2 17th September 2013 04:37 PM
clock + SPDIF isolator Bassivus Digital Source 6 14th July 2012 05:31 PM
Universal 1ppm CD clock + SPDIF isolator low jitter dublin78 Digital Line Level 10 30th April 2012 01:24 PM
clock, master/slave no clock? pforeman Digital Source 0 29th January 2011 07:17 PM


New To Site? Need Help?

All times are GMT. The time now is 04:05 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki