Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site olivee.UUCP Path: utzoo!watmath!clyde!burl!mgnetp!ihnp4!zehntel!hplabs!oliveb!olivee!gnome From: gnome@olivee.UUCP (Gary Traveis) Newsgroups: net.audio Subject: Re: Installing a Varistor Message-ID: <182@olivee.UUCP> Date: Wed, 15-Aug-84 18:07:13 EDT Article-I.D.: olivee.182 Posted: Wed Aug 15 18:07:13 1984 Date-Received: Sat, 18-Aug-84 00:14:51 EDT References: <1691@inmet.UUCP> <465@houxt.UUCP> Organization: Olivetti ATC, Cupertino, Ca Lines: 45 There are a few different types of power-line related noises that can pop up in an audio system. 1) Hum - a 60hz hum that is sitting in the background and stays mostly the same amplitude over time. :This could be caused by the following circumstances. a) A ground loop caused by too little or improper grounding. AC neutral is NOT the same as ground! b) A transformer nearby a sensitve area of the system. Namely a power transformer or video device too close to preamp or pickup. c) A bad power supply with ripple in preamp or power amp. 2) Buzz - A constant buzz (low freq) that comes and goes. a) Flourescent light or ballast near audio system. b) A light dimmer being used on the same or nearby AC power line. c) Bad or dying rectifier in amp(s). 3) Whine- A variable or intermittant whine/buzz that comes and goes. Often in bursts. a) A blender, variable speed drill, vacuum cleaner or other AC/DC motor that uses brushes internal to the motor or unit itself. 4) Pops - A loud or moderate pop heard from time to time. (sometimes random crackling) a) Any capacitive or inductive load being turned on or off. Flourescent lights that use starters will flicker and cause popping on power-up. b) Non-positive switches. Bad wall switches, or aquarium heater thermostats can induce noise on both audio and TV/video systems. That covers most cases -- oops! I forgot HAM and CB interference! Well, once the cause of a problem is discovered, then the proper fix can be sought. A power line filter (a good one) can get rid of most of the above problems, but not all! Gary (hplabs,ios,fortune,allegra)oliveb!olivee!gnome - with no more time today...