USB dac issues AD712 buffer/LPF - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, 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 5th January 2010, 09:23 AM   #1
diyAudio Member
 
Join Date: Jan 2010
Default USB dac issues AD712 buffer/LPF

Hi all ,
I am working on a output LPF of a PCM 2702.
Using AD712 as buffer.

The power supply is as shown :
Click the image to open in full size.

But there is hum noise from the buffer stage ,i can hear clearly although it is doing the LPF work and a buffered sound coming with the noise.
The connection is shown below...
Click the image to open in full size.

Help me with this one , could it be due to 2 different grounds?

i saw KECES dac schematic the are using a floating line from PCM2702.

Or , is it due to the cheap transformer i am using (for testing,later will add a toroidal).
  Reply With Quote
Old 5th January 2010, 11:24 AM   #2
R.I.P.
 
Join Date: Dec 2001
Location: Schaffhausen Switzerland
More likely the opamp/buffer is oscillating at some high frequency, which always sounds like hum. Can you post a schematic for it?

Regards, Allen
  Reply With Quote
Old 5th January 2010, 01:18 PM   #3
diyAudio Member
 
Join Date: Jan 2010
here is the LPF for one side:Allen Can you commentClick the image to open in full size.Click the image to open in full size.
  Reply With Quote
Old 6th January 2010, 01:19 PM   #4
diyAudio Member
 
Join Date: Jan 2010
yesterday i have checked Power supply with dropper of 4.7k in series from +15v ,

tried to drive a fiio e3 ,there is some problem,it cant drive!
normally supply shows voltage checked with LED.

is 9-0-9v, 500 miliamp secondary supply transformer too less?
__________________
Lets find the truth..inside!
  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
HIFIDIY.net PCM1798 USB DAC with Tube Buffer bongoman Digital Source 24 9th May 2014 02:16 PM
Modified USB DAC board, DDDAC with triode buffer wa2ise Tubes / Valves 6 22nd September 2008 12:57 AM
USB powered NOS USB DAC with built-in headphone amp dsavitsk Digital Source 15 10th August 2006 07:11 AM
Generalized LPF for DAC tiroth Digital Source 0 3rd January 2002 02:16 PM


New To Site? Need Help?

All times are GMT. The time now is 04:35 PM.


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