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Thread: RF (radio frequency) tests performed on my system.

  1. #1
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 6,089
    I'm Alan.

    Default RF (radio frequency) tests performed on my system.

    This testing is with Grounding boxes in mind, just to see what the background RF levels and emissions are from stereo kit.

    Radio Frequencies cover a very wide frequency range, the test equipment I have goes right up to 1GHz.
    That is 1000 MHz or to put another way 50000 times the audio bandwidth.

    RF energy is very pervasive, it is all around us and is induced into anything metallic. Even a screened lead will pick up RF on its outer braid.

    The test kit is known as a spectrum analyser and shows the frequency along its X axis with the logarithmic amplitude on the Y axis.
    The X axis is linear so shows frequencies from Zero to 1GHz, so each graticule line is 100MHz.

    The Y axis shows signals above the noise floor mush at the bottom of the screen, at about 20uV. This is ten times lower than a low output moving coil cartridge to give a context.

    Test 1.
    A 1 metre whip antenna connected to show the background RF level.



    Test 2.
    A probable ground box lead connected, made from some RG58 coaxial cable.




    A test lead was made to connect to only the outer shell of an RCA socket and used for subsequent tests.
    Test 3.
    Test lead connected a CD transport output. Transport mains OFF.



    Test 4.
    As test 3 but CD transport mains ON.



    See the slightly raised mush up to about 430MHz.

    Test 5.
    Test lead connected to a SPDIF input of Bel Canto DAC3, mains OFF.



    Test 6.
    As test 5 but DAC3 mains ON.



    Look at all those clock harmonics

    Test 7.
    Test lead connected to XLR output of DAC3, mains ON.




    Test 8.
    Test lead connected to spare input of KIN preamp, mains ON.

    I love Hendrix for so many reasons. He was so much more than just a blues guitarist - he played damn well any kind of guitar he wanted. In fact I'm not sure if he even played the guitar - he played music. - Stevie Ray Vaughan

  2. #2
    Bigman80 Guest

    Default

    What does all that mean?!!!! Lol

  3. #3
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 6,089
    I'm Alan.

    Default

    It is the amount of RF that is picked up with various connections to bits of kit.

    You are never free of it. All the spikes coming from the Bel Canto surprised me.

  4. #4
    Bigman80 Guest

    Default

    Quote Originally Posted by Firebottle View Post
    It is the amount of RF that is picked up with various connections to bits of kit.

    You are never free of it. All the spikes coming from the Bel Canto surprised me.
    Ah I see.

    Yes, RF everywhere!

  5. #5
    Join Date: Feb 2008

    Location: Down South

    Posts: 2,413
    I'm Neal.

    Default

    ....and that’s only up to 1Ghz, mobile phones at 1.9Ghz, 2.4Ghz and 5Ghz WiFi etc etc.
    Listening in a Foo free Zone...

    Only a Sith deals in absolutes.

  6. #6
    Join Date: Mar 2017

    Location: West Sūþsēaxe

    Posts: 2,015
    I'm Edward.

    Default

    Very interesting Alan. Would your test equipment and methodology be useful in proving (or not) the improvement in SQ we both heard (separately) when trying out Tony's RTZ boxes at his place? I'd imagine that you would be able to show the RF reduction. But perhaps I'm being too simplistic?
    Current: [P20] Roon/Tidal > Custom PC> Chevron Paradox NDF16 > Phast Pre > Neuro. 686 > Tannoy Berkley (RFC tweaks)


  7. #7
    Join Date: Sep 2010

    Location: West Midlands, UK

    Posts: 646
    I'm Lee.

    Default

    I popped into Alans house last night whilst he was doing these experiments with the spectrum analyser and it was quite interesting to see how much RFI is actually present within the room, I guess that all rooms would be similar? What effect this RFI has upon the sound is way above my electrical knowledge of putting a 3 pin plug on but Im interested all the same.

    If by reducing the amount of RFI present within the room does have a desired effect on the sound then this will be something that I will definitely be looking at myself
    Vinyl rig 1 - NAS Spacedeck / FR64s / Lab 12 Melto / Denon SUT / Ortofon GM SPU. Vinyl rig 2 Mono Set Up - Lenco GL75 c/w Jelco 750D / AT33 Mono / EAR 834P Modded. Amplifiers - Audio Note Empress Silver / Hattor Passive Pre. Digital - Fanless Mini PC / Lampizator TRP / Linear PSU / Hummingboard Network audio adaptor. Speakers - Horns.pl Mummy's. Cables are Audio Note / Albedo / Furutech Speaker wire. Power conditioner is a Gigawatt PC2 EVO

  8. #8
    Join Date: Jan 2008

    Location: gone

    Posts: 11,519
    I'm gone.

    Default

    Now if only you had a Grounding Box to plug in - RF up, down or the same?
    .

  9. #9
    Bigman80 Guest

    Default

    Quote Originally Posted by jandl100 View Post
    Now if only you had a Grounding Box to plug in - RF up, down or the same?
    indeed!

  10. #10
    Join Date: Nov 2011

    Location: Seaton, Devon, UK

    Posts: 13,242
    I'm Adrian.

    Default

    Quote Originally Posted by Bigman80 View Post
    indeed!
    Perhaps Mr C.would lend you one so you could repeat the test with a grounding box connected. Very interesting
    Listening is the act of aural discrimination and dissemination of sound, and accepting you get it wrong sometimes.

    Analog Inputs: Pro-Ject Signature 10 TT & arm, Benz Micro LP-S, Michel Cusis MC, Goldring 2500 and Ortofon Rondo Blue cartridges, Hitachi FT5500 mk2 Tuner

    Digital:- Marantz SA-KI Pearl CD player, RaspberryPi/HifiBerry Digi+ Pro, Buffalo NAS Drive

    Amplification:- AudioValve Sunilda phono stage, Krell KSP-7B pre-amp, Krell KSA-80 power amp

    Output: Wilson Benesch Vector speakers, KLH Ultimate One Headphones

    Cables: Tellurium Q Ultra Black II RCA & Chord Epic 2 RCA, various speaker leads, & links


    I think I am nearing audio nirvana, but don’t tell anyone.

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