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Thread: Sierra RAAL Towers/Horizon with Outlaw Audio 5000X Amp

  1. #11
    Join Date
    Mar 2019
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    NJ
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    69

    Default Re: Sierra RAAL Towers/Horizon with Outlaw Audio 5000X Amp

    Quote Originally Posted by davef View Post
    Ground loops usually present themselves as a 60Hz hum, not a hiss. What you are describing here sounds a bit more like some type of RF interference or similar.

    First step:

    if you have any cordless phones in the house, turn them off completely.
    Turn off all wifi
    Basically, turn off anything that broadcasts a wireless signal in your home (including all cell phones)

    Give that a try and report back...

    I should have mentioned to power them down completely (unplug from power)
    Yea, I agree that in the "music" case it's RF interference. I've never had a ground loop before, but have seen them discussed in audio circles fairly frequently and sort of assumed I was dealing with one. After going through some various tests and better understanding the audibility and general sound of a 60Hz hum I've ruled that out as well.

    The other thing that I've learned from this whole situation is that if you listen with your ear up to a normally sensitive speakers tweeter that passive speakers connected to power amplifiers will make noise when powered. I have an Emotiva miniX a-100 in my office room hooked up to a pair of Elac B6 bookshelf speakers which when powered also have a slight noise when I listen at a close ear level to the tweeter. The noise is there even with no input and the volume knob on that amp turned all the way down. I guess I've never actually tested the audibility of the noise floor by listening very close to my speakers tweeters before in any of my setups and thought it was a new phenomena with my recently acquired Outlaw amplifier. It turns out that it's always been there and I only assumed it was silent due to how close you have to be to actually hear anything from the speakers.

    So, from experimentation with my Oulaw, AVR, and Emotiva amplifiers along with 3 different speakers (4 if you count the Horizon as separate from the the Sierra Towers) I've learned that this is expected behavior if you stick your ear nearly up against the tweeter and listen when they're powered. Possibly some of the newer Class D amplifiers with Hypex modules, or something similar, with very high SINAD might not exhibit this noise floor behavior. I don't have an amplifier with that high of a measured SNR to test out as a comparison though.

    The only thing that isn't exactly normal is the brief RF interference that I heard the one time during testing, but it was transient, lasting less than a minute. I could try to troubleshoot that if it happens again, but it was at the approximate dB level as the noise floor that I've been hearing so it probably isn't worth the effort of acquiring ferrites, investing in fully balanced equipment, or trying to filter it out in some other way with electrical components. From reading some other peoples investigations who experienced RF interference that was actually audible at the listening position, unlike in my case, it seems to be a very tricky thing to entirely troubleshoot and eliminate.

    Thanks for your guys help in suggesting ideas as to what could be going on. I definitely learned something regarding the audibility of SNR!
    Last edited by Shazb0t; 12-28-2021 at 02:24 PM.

  2. #12
    Join Date
    Aug 2003
    Location
    Manhattan Beach, California
    Posts
    7,032

    Default Re: Sierra RAAL Towers/Horizon with Outlaw Audio 5000X Amp

    Quote Originally Posted by Shazb0t View Post

    The only thing that isn't exactly normal is the brief RF interference that I heard the one time during testing, but it was transient, lasting less than a minute. I could try to troubleshoot that if it happens again, but it was at the approximate dB level as the noise floor that I've been hearing so it probably isn't worth the effort of acquiring ferrites, investing in fully balanced equipment, or trying to filter it out in some other way with electrical components. From reading some other peoples investigations who experienced RF interference that was actually audible at the listening position, unlike in my case, it seems to be a very tricky thing to entirely troubleshoot and eliminate.
    You may want to try moving your cables around and make sure they are of the well shielded variety.

    I had a friend with the similar issue and it seemed like it was isolated to a certain power outlet.
    -curtis

  3. #13
    Join Date
    Mar 2019
    Location
    NJ
    Posts
    69

    Default Re: Sierra RAAL Towers/Horizon with Outlaw Audio 5000X Amp

    Quote Originally Posted by curtis View Post
    You may want to try moving your cables around and make sure they are of the well shielded variety.

    I had a friend with the similar issue and it seemed like it was isolated to a certain power outlet.
    For sure that could help! My understanding about RF interference is that a major contributing factor is the length and orientation of the cables relative to the location of the radio transmission tower. Crazy stuff!
    Last edited by Shazb0t; 12-29-2021 at 12:58 PM.

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