Home Computer Audio Asylum

Music servers and other computer based digital audio technologies.

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Computer Audio Asylum ]
[ Alert Moderator ]

A few things...

Steve,

First you cannot measure audio related jitter with a 7G scope. Again for the 1 millionth time... the jitter we are looking for is in the low audio band like from 0.5Hz to 100Hz. These scopes would require terabytes of memory to look at this. You are only looking at jitter above 100KHz which is useless for audio. All that stuff gets averaged out and therefore is not worth looking at.

Second to get low jitter from an oscillator you need to throw away 3 terminal regulators. You need to start designing some discrete ones and have a spectrum analyzer which can test them down to the 1nVrms range below 100Hz. This will tell you more than your scope will. Like on my Crimson I have a battery supply then a local regulator and then a discrete regulator and at 1Hz the noise is 5nVrms and goes down from there.

Tony is correct in that the local oscillator will be effected by other aspects and oscillators being that they are X,Y or Z and non-related to the audio oscillator. The big problem on many of these extra oscillators is that a PLL is used to generate some high oscillator property.

High Speed USB does not work at 1KHz, instead it works at 125uS or 8000 times a second. Still in the audio band but would average out a lot easier.

But the real way to deal with USB is put these extra oscillators on a separate board with an optical barrier between them. Feed the audio oscillator into this board and to the DAC chips and therefore you don't have this contamination from the USB section because they are running on separate supplies and totally optically isolated.

But even then the USB cable still has an effect. Hey so does analog cables.

Thanks
Gordon
J. Gordon Rankin

This post is made possible by the generous support of people like you and our sponsors:
  Western Glow Tube Service  

Follow Ups Full Thread
Follow Ups
FAQ

Post a Message!

 Forgot Password?
Moniker (Username):
Password (Optional):
  Remember my Moniker & Password  (What's this?)    Eat Me
E-Mail (Optional):
Subject:
Message:   (Posts are subject to Content Rules)
Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:  Automagically notify you when someone responds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]