DC Offset in Oppo DV-981HD - 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 23rd September 2010, 01:19 AM   #1
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
Default DC Offset in Oppo DV-981HD

I've been toying around with an op-amp based head amp that I've put together and hooked it up to my Oppo player. I measured 16 mV DC offset at full volume from the analog audio outputs...yow...and followed it upstream to the Oppo player. On one channel I have 12.5 mV DC and on the other, 12.8 mV DC. Doesn't this seem awfully high for a modern disc player???

Anyone else with an Oppo have the same amount of offset?
  Reply With Quote
Old 23rd September 2010, 02:07 AM   #2
sandyK is offline sandyK  Australia
diyAudio Member
 
Join Date: Apr 2007
Location: Sydney
Quote:
Originally Posted by sonidos View Post
I've been toying around with an op-amp based head amp that I've put together and hooked it up to my Oppo player. I measured 16 mV DC offset at full volume from the analog audio outputs...yow...and followed it upstream to the Oppo player. On one channel I have 12.5 mV DC and on the other, 12.8 mV DC. Doesn't this seem awfully high for a modern disc player???

Anyone else with an Oppo have the same amount of offset?
Sonidos
Are you using "Mixed L and R" ?

I normally don't use Analogue Out from mine, as after sound deadening material combined with replacement of the SMPS bridge rectifier diodes with BYV26C, and a 100nF 630V across the main electro , it sounds noticeably better via SPDIF. In fact, even Video via HDMI to a friend's 1280 projector was then also markedly improved. (glossier looking picture)
My friend then did the same with his 981HD.
I just tried mine, and although it started off at several mV, it dropped to
0mV after several seconds, indicating that it is via electrolytic capacitors.
SandyK
  Reply With Quote
Old 23rd September 2010, 02:45 AM   #3
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
SandyK,

I'll have to check my settings with regards to Mixed L & R, but the offset is constant...it doesn't go to 0.

Thanks for the tips on the mods and checking your Oppo. I don't normally use the Oppo in the way that I mentioned but I was surprised to see that much offset on both outputs, so something is not right.
  Reply With Quote
Old 23rd September 2010, 02:56 AM   #4
sandyK is offline sandyK  Australia
diyAudio Member
 
Join Date: Apr 2007
Location: Sydney
Sonidos
Did you realise that you have digital volume control via SPDIF if HDMI is not enabled?
SandyK

P.S.
A quick look seems to suggest that there are 3 dual I.C.s followed by 6 x 47uF16V electros, then a muting transistor for each output.

Last edited by sandyK; 23rd September 2010 at 03:20 AM.
  Reply With Quote
Old 23rd September 2010, 04:27 AM   #5
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
sandyK,

No, but I do now! I don't have a DAC and it is used primarily via HDMI to my flat screen. I don't use it for audio purposes, but I've heard it is great if you have a DAC...so definitely on my list to build one.
  Reply With Quote
Old 23rd September 2010, 04:34 AM   #6
sandyK is offline sandyK  Australia
diyAudio Member
 
Join Date: Apr 2007
Location: Sydney
Sonidos
It is best not to use much more than 10dB of digital attenuation for best results with 16 bit files.
SandyK.
  Reply With Quote
Old 23rd September 2010, 07:08 AM   #7
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
There may be HF hash causing an incorrect DVM reading... if using a DVM rather than 'scope then try an RC filter network on the audio output (say 47k and 0.1uf) and remeasure voltage across the cap only.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 23rd September 2010, 01:27 PM   #8
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
Good stuff, guys! Mooly, I'll give that a try and see if that is indeed HF hash.
  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
OPPO DV-980H Service Manual volturnofelix Digital Source 2 14th November 2009 09:21 PM
DC Offset JannaCassandra Chip Amps 3 26th July 2008 03:20 PM
Oppo DV-981HD output impedance vizion Digital Source 4 23rd May 2008 11:23 AM
Zero DC Offset nitin Solid State 3 6th January 2005 05:28 PM
Help With DC Offset Sybex23 Chip Amps 8 15th November 2004 07:11 PM


New To Site? Need Help?

All times are GMT. The time now is 03:17 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