Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 241 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

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 16th February 2013, 05:20 PM   #2401
diyAudio Member
 
andrea_mori's Avatar
 
Join Date: Jan 2005
Location: Italy
Quote:
Originally Posted by qusp View Post
did I say it couldnt be done? you should read more carefully
I read very carefully instead, you said "EVERYONE has trouble ...", that's not true.
Those who own the proper instrument had no problem measuring at this level.
Take a look at Agilent manual and then take a look at post #2344. As you can see is very easy measuring -95dBc@1Hz and -135dBc@10Hz, WITH THE PROPER EQUIPMENT
And now convert that measurements in the time domain.
  Reply With Quote
Old 16th February 2013, 06:21 PM   #2402
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
yes, everyone DOES have trouble, measuring 1ps phase noise is troublesome, no matter what equipment you have.

you are utterly discounting the time to set up, the time to build and set up the power supply, the time to build the buffer to avoid loading the clock with the probes, shielding the whole thing

easy....

you need to study how to read context

Last edited by qusp; 16th February 2013 at 06:24 PM.
  Reply With Quote
Old 16th February 2013, 08:04 PM   #2403
diyAudio Member
 
iancanada's Avatar
 
Join Date: Dec 2009
Location: Toronto
Quote:
Originally Posted by Fridrik View Post
Same feeling here Ian, my own FIFO project two years ago set me back for 100$ worth of parts from Digikey. Parts still in my electronic cabinet nicely going toward obsolescence. On my own this FIFO project (all boards) could have cost me easily a 2K-3K$ in R&D. Equivalent performing devices on the market cost from 400$ to 1500$. Ok they are final products but you don't get the flexibility and tweaking possibility given by Ian FIFO.

I think their is also a confusion about DIY projects and open source projects. Back in the 80s Heatkit was a commercial endenvor and a DIY provider...

Jitter measurements are a important guide to make development decision but they required costly and very well calibrated equipment operated by skillfully technicians. And even then the results could be challenged.

Like some one said not so long ago :

If you believe you can make a difference, not just in politics, in public ... prepared to accept that you are not going to get 100 percent approval
Thanks Fridrik, 100% agree with you.

Ian
__________________
Ian GBV - I2S to PCM converter board & FIFO KIT
http://www.diyaudio.com/forums/group...ml#post3662743
  Reply With Quote
Old 16th February 2013, 08:19 PM   #2404
diyAudio Member
 
iancanada's Avatar
 
Join Date: Dec 2009
Location: Toronto
Quote:
Originally Posted by regal View Post
Well first of all there is no such thing as a 3.2V LiPFE04 battery, batteries don't have regulation their voltage changes as they are used, from 3.6V down to 3.2V.

Second what do you think, do you want to mess around with batteries or use a LDO regulator that you never have to worry about charging or installing backwards and frying your pcb. Batteries are for OCD types like qusp

Basically if you have to ask go with the regulator.
Thanks regal

Quote:
Originally Posted by Fridrik View Post
Ian
From the Si570 Clock Board guide:

>This LDO board has been determined to be one of the best ways so far to power the Si570 Clock Board.<

Do you implying that powering up the clock with the LDO board give subjectively (in your setup) a better sound then directly powering the clock from Lipefo4 3.2V Bat or simply that the LDO powering is a best solution overall, if we take convenience in account?

Great manual by the way, thanks for all the info in the tips sections
Hi Fridrik

regal gives very good point.

Battery has some disadvantages:
1, Voltage is not stable, decreasing along the discharge, so there are always some sweet point, another secret.
2, Internal resistor is not keeping constant also
3. Sensitive to the load
4, Over-charge and over-discharge can damage the battery easily.

However the battery is the easiest way letting your touch the low noise power supply.

Ian
__________________
Ian GBV - I2S to PCM converter board & FIFO KIT
http://www.diyaudio.com/forums/group...ml#post3662743

Last edited by iancanada; 16th February 2013 at 08:25 PM.
  Reply With Quote
Old 16th February 2013, 08:24 PM   #2405
diyAudio Member
 
iancanada's Avatar
 
Join Date: Dec 2009
Location: Toronto
Quote:
Originally Posted by qusp View Post
yeah its as easy as buying the equipment....

Demian, who has much experience with such things, has already commented on the difficulty of such measurements, if you think its easy just because you have the right equipment, you are fooling yourself. did I say it couldnt be done? you should read more carefully
Yes, both of the two things are very diffcult:
1, Measure the phase noise of a low jitter clock
2, Measure the noise of a low noise power supply.

Demian also suggested measuring them from the output of the audio signal, that is kind of finial solution for audiophiles, you just need a AP

Ian
__________________
Ian GBV - I2S to PCM converter board & FIFO KIT
http://www.diyaudio.com/forums/group...ml#post3662743
  Reply With Quote
Old 16th February 2013, 09:59 PM   #2406
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 3
Quote:
Originally Posted by iancanada View Post
Yes, both of the two things are very diffcult:
1, Measure the phase noise of a low jitter clock
2, Measure the noise of a low noise power supply.

Demian also suggested measuring them from the output of the audio signal, that is kind of finial solution for audiophiles, you just need a AP

Ian
Both are difficult, especially when approaching the state of the art.

However I did get close to a very useful tool using an FM tuner to look at phase noise. Start with a very low noise tuner. I used a Yamaha TX-950 which is one of the lowest noise tuners ever made. Mod it by taking a direct output from the detector (no low pass filter or eq.) Output to FFT. Input from clock will actually be a harmonic, 2X 4X etc and it works. The noise is multiplied by the harmonic multiple. The input is AC coupled so it won't screw things up. Adding an isolation transformer on the input can help remove ground loops and noise coupling into the DUT. It can be a useful troubleshooting tool. Calibrating it in absolute terms proved to be too much for me. Too many steps from SSB carrier noise to FM deviation in Hz to work through so its a relative tool.

If you can measure the power supply noise with a normal instrument its not that low. Its possible to get close to 1 nV/rtHz, which is below what you can measure with an AP directly. I built a transformer coupled preamp to get the equivalent noise down, I think it was about 5 Ohms. Huge PITA as well.

You don't need an AP to get the jitter at the output. You need a decent sound card (Juli@, EMU 0404, EMU 0202 for example) and some suitable FFT software like ARTA or this WaveSpectra and a J-Test file like the two attached.
Attached Files
File Type: zip 24-44 JTest.zip (106.2 KB, 14 views)
File Type: zip 24-48-JTest.zip (102.5 KB, 9 views)
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 17th February 2013, 01:23 AM   #2407
tubo is offline tubo  Philippines
diyAudio Member
 
Join Date: Apr 2007
Location: Mundelein, Illinois
Hi guys,

I finally got my cchd957 for dual xo working and it sounds wonderful. It improved my shigaclone transport to another level that i didnt knew was possible.

Since groupbuy 4 is on going, im planning on getting the si570 board but need clarification first.
My dac is a nos ad1865 and im mostly playing 16/44.1 through my shigaclone or sq touch.
My question is, do i need the si570 clock to further improve sound quality or just stick with cchd957 since i mostly play 44.1?

Please any suggestions

Thanks guys
  Reply With Quote
Old 17th February 2013, 01:28 AM   #2408
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
no, you should just stick with the cchd957 if you are playing mainly 44.1 with a non ESS dac
  Reply With Quote
Old 17th February 2013, 01:42 AM   #2409
tubo is offline tubo  Philippines
diyAudio Member
 
Join Date: Apr 2007
Location: Mundelein, Illinois
Thanks qusp
  Reply With Quote
Old 17th February 2013, 03:16 AM   #2410
diyAudio Member
 
Join Date: Jun 2010
Ian and others hello,

some questions from me please, regarding TPS7A4700 low noise regulator board V2.5:

- from what I understand, you recommend the reg over a LiFePo4 battery for the Si570 clock board based on sonic attributes, correct? You've mentioned some disadvantages before, are there any advantages?
- I've recently connected two LiFePo4s instead of the AVCC tridents on Buffalo II and it was a great improvement. Would the regs be suited at this place as well then?
- how about a possible benefit of replacing the other two tridents: DVCC and Core 1.2V (in case it goes close enough to 1.2V)?

- You suggest battery-based 4V-6V DC power for the regs. Is 6V really the upper maximum input for the regs, because then 2S LiFePos and 6V gels fall out, only some NiMh combination would work, or maybe 4V gel?

Thanks,
Abel
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
XMOS-based Asynchronous USB to I2S interface Lorien Digital Source 2129 28th August 2014 03:59 PM
exaU2I - Multi-Channel Asynchronous USB to I2S Interface exa065 exaDevices 1357 3rd March 2014 08:51 PM
DAC chip selection + I2S jitter questions drwho9437 Digital Line Level 2 26th July 2010 12:50 PM
Simple FIFO to I2S CPLD, for MCU players / reclocking KOON3876 Digital Line Level 21 19th September 2008 04:00 PM
asynchronous reclocking and low jitter clocks ash_dac Digital Source 3 8th February 2005 09:22 AM


New To Site? Need Help?

All times are GMT. The time now is 04:58 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2