DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 10 Dec 2017, 21:10

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 3 posts ] 
Author Message
PostPosted: 04 Oct 2015, 17:06 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 3476
Location: Arizona, USA
Hi Everyone. A situation today has me stumped. Here is the way it played out. I started to listen to my stereo this morning .... a common occurrence. I was going to listen to a CD. I put it in the OPPO 83SE and set my preamp to the right input (#2). When the disk started it played at a medium volume level when the preamp was set for -80 db (actually it has no output there). The volume control would not work and the volume control on the OPPO would not work either. Worse it didn't matter what input I selected it was playing through all of them. Mute on the OPPO and preamp did work though. The phono played fine through the built in preamp and the controls worked. I figured that some sort of odd malfunction occurred with the PIC in the preamp or a short in the input/output relay board. I spent hours hunting for the problem. Everything on the bench checked out. Finally I tried a second similar preamp (digitally controlled with the same front end) it did the same thing. I started to disconnect things. When I pulled the HDMI cable out of the OPPO everything returned to normal. I found that the flat screen TV (is always covered by a heavy rug when not in use to cut down on sound reflections) was on. Turning it off restored all the system functions. I can see how the OPPO volume control might not work on the stereo side when HDMI is engaged at the same time.....but I can not figure out how the sound from the OPPO was able to bypass the volume and input selectors in the preamp. The only thing that makes sense is that the audio is inverted in the HDMI and a path was found through the AC mains / chassis grounds. There is no other connections between the OPPO, TV and stereo....just the AC and HDMI. Anyone have thoughts on this?

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
PostPosted: 04 Oct 2015, 17:20 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2111
Location: Chilliwack, BC
I've had a few oddidies with digital equipment, even brand new out of the box for display. Not quite your issue since we don't touch video, but I've heard customers relay the same about various brands, including Yamaha and Rotel.

My guess is there's a common chipset or software routine in them all that glitches up every now and again.

Cheers!

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


Top
 Profile  
 
PostPosted: 05 Oct 2015, 18:18 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 3476
Location: Arizona, USA
Still has me bugged...how does a signal get to the power amp inputs from the DVD player when the only thing it has are audio outputs that are grounded in the preamp by a relay when that input is not selected. Everything has a common three wire ground but nothing else. I figure that some how the arrangement is putting the audio on the gound side and "grounding" the what would be RCA connectors to the preamp. Very odd.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
cron
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy