High THD, Poor RCA Connections - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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
Thread Tools Search this Thread
Old 13th March 2006, 09:13 AM   #1
goeat is offline goeat  United States
diyAudio Member
Join Date: Mar 2006
Location: Berkeley
Send a message via AIM to goeat
Default High THD, Poor RCA Connections

I can imagine that this is a popular problem, but I couldn't for the life of my find a related thread using the search, so...

This is for equipment that I've bought, mainly a NAD 1130 Preamp and an Adcom GFA-555 MKI. I'm having a lot of problems getting a good connection between the preamp and the amp with any RCA cable (high or low quality), being especially twitchy at the preamp side of things, often resulting in loud pops and emormous amounts of distortion (~90%) should the cable be jostled. The connection at the amplifier is solid.

Some things that have been recommended to me as problems:
-Ground loop problem between the amp and the preamp's wall connection.
-Ground loop problem within the preamp.
-Poor RCA connections on the preamp.
-Faulty RCA wiring on the preamp.
Are these in the right direction?

I plan on taking apart the preamp tomorrow, mostly to see what's up in there. If anyone can provide any insight as to the RCA issue, thank you in advance. I can provide more information on how these are wired together/to wall power if anyone cares to know.

  Reply With Quote
Old 13th March 2006, 09:16 AM   #2
Did it Himself
diyAudio Member
richie00boy's Avatar
Join Date: Nov 2003
Location: Gloucestershire, England, UK
It's nothing to do with ground loops. Simply the RCA connection - probably the springy part that forms the centre contact, or the ground contact - is a bit loose somewhere.
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, modules and more.
  Reply With Quote
Old 13th March 2006, 03:50 PM   #3
Eva is offline Eva  Spain
diyAudio Member
Eva's Avatar
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
It looks like an oxidized contact or a bad solder joint in the female RCA connector.
  Reply With Quote
Old 14th March 2006, 01:43 AM   #4
anatech is offline anatech  Canada
diyAudio Moderator
anatech's Avatar
Join Date: Jun 2004
Location: Georgetown, On
I think Eva's on track. Many newer products have RCA connectors that get cracked solder joints on the PCB. Once you get in there, resolder the lot.

Also, Adcom amps have a resistor between ground and signal ground on the order of 100 ohms. You should measure 200 ohms between the RCA grounds (with the amp turned off!!).

  Reply With Quote
Old 14th March 2006, 02:57 AM   #5
diyAudio Member
myhrrhleine's Avatar
Join Date: Jan 2006
Location: Avalon Island
> Post #3
It looks like an oxidized contact or a bad solder joint in the female RCA connector.

Or similar problem with the RCA jack.
  Reply With Quote


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
Poor Man's Strad peace brainerd Multi-Way 76 20th July 2015 07:09 PM
Help a poor noob pls! jw2k_fr Multi-Way 20 9th February 2010 09:29 PM
my poor power amp... :-( timfishy Solid State 23 31st August 2004 12:55 AM
Plate amps- high vs low ohm connections? amt Solid State 1 30th January 2004 10:24 PM

New To Site? Need Help?

All times are GMT. The time now is 05:48 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2