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Sony F419R Amplifier: Fixing Noise & Humming Issue Above 3/10 Volume While Playing Music

Trustcio 18273 25
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Why does my Sony F419R amplifier start humming more and more above about 3/10 volume when playing from a computer, and how can I fix it?

The hum is most likely coming from the computer/input side, not from the amplifier itself, and the thread points to a ground loop and/or poorly shielded cables. Short the amplifier inputs first: if the hum stays low or disappears, the amp is probably OK; if it rises, the fault is in the amp or its wiring [#16848559] Since the noise is much smaller with a laptop/phone and much worse with the PC sound cards, the problem follows the computer/audio path; one reply explicitly identifies a ground loop in the described setup and recommends a galvanically isolated USB interface or a switch that disconnects the unused device including ground [#16848827] [#16851273] Also try using better shielded RCA/jack cables and keep the computer volume near maximum while controlling loudness with the amplifier, so the cable picks up less noise [#16848755] [#16849138] If possible, test the setup with only two blocks — one sound source and the amplifier — to isolate the bad link [#16852075]
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  • #1 16848434
    Trustcio
    Level 5  
    Hello! I have a Sony f419r amplifier. In the amplifier I replaced the loudspeaker switching relays, I set the quiescent current and it has been working well since then. Previously, I did not pay attention, but today I noticed that without the music turned on, the amplifier hums, up to 3/10 of the volume, the noise is not heard at all, but after exceeding this value it is getting bigger and bigger. I know there will always be some noise but after exceeding 4/10 it gets annoying. It's hard for me to say how it was before because I didn't pay attention, but since I didn't pay attention, it's probably smaller. NOISE IS ALSO WHILE LISTENING TO MUSIC and when I set the volume to 1/100 on the computer, you can hear it. In addition, he adds a video because you can hear this conscience enough there, I gradually increased the volume there. [movie: 20fc060092] https://filmy.elektroda.pl/47_1511629027.mp4 [/ movie: 20fc060092]
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  • #2 16848556
    pisiek47
    Level 2  
    Perhaps the cables are picking up noise
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  • #3 16848559
    Anonymous
    Level 1  
  • #4 16848723
    Trustcio
    Level 5  
    Well, I wouldn't think of it, but it looks like wires, because after unplugging or connecting another such short one, for example to a phone (because it will not get to the computer), the noise subsides, above 7/10 there is such a characteristic buzzing, but probably every amplifier has it. If I remove the wires from the cd input and even give the volume 10/10, I can not hear anything. So how does it disappear after replacing the cables, then I have to invest in a better quality cable? Honestly, I bought the cheapest one from the market for PLN 6, I think :)
  • #5 16848755
    kazikszach
    Level 39  
    In the computer, set the volume to the maximum or a little lower, and control the volume with the amplifier, then the cable will catch the noise less.
  • #6 16848763
    Trustcio
    Level 5  
    I have cables for 3 inputs connected, one short, about 10cm + adapter, but at 10/10 the volume without music, it hardly hums, the second chinch-chinch is also the cheapest but the noise is 2 times less audible than on the third jack-chinch. So it is worth investing in a better cable anyway? I also connected the short one to other entrances to check if it was not the fault of the entrance
  • #7 16848781
    kazikszach
    Level 39  
    There are two options:
    1 cable catches noise
    2 hums the output on the computer.
    Please check with another computer or cable.
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  • #8 16848827
    Trustcio
    Level 5  
    I checked this input on my laptop and phone, there is almost no noise at all and when they are of a different type and really very quiet, you have to listen to them. When I check on the computer card (I have an integre and Xfi Gamer), it hums terribly on both of them. I also have a dj controller connected to the same computer, it also makes noise, but it's 1/3 of the volume compared to sound cards. And what can I be wrong with that everything connected to the computer is humming?
  • #9 16849020
    398216 Usunięty
    Level 43  
    Trustcio wrote:
    And what can I be wrong with that everything connected to the computer is humming?
    kazikszach wrote:
    humming output on the computer.
    Either try on a different computer, or a different sound card, or ... change the power supply. (best in that order).
  • #10 16849084
    Trustcio
    Level 5  
    I tried it on a different computer and the noise is also of a different type and is also much smaller. I have two sound cards in my computer and both sound the same. So only the power supply remains? And how to check relatively easily if it is really a power supply? It is a pity to mention it, because it may be something else.
  • #11 16849138
    yogi009
    Level 43  
    And branded cables or total "china"? Use those that just have a solid screen.
  • #12 16849152
    Trustcio
    Level 5  
    As for the chinch-jack that I have connected to the computer, I wrote above that the cheapest for PLN 6 from Auchan :) But on a laptop, phone, the noise is barely audible, on the second computer it is a bit worse, but what is on this is an exaggeration :) What is the power supply, I have this: Be Quiet System Power 7 500W
  • #13 16849181
    yogi009
    Level 43  
    For PLN 6 in this store, buy eight rolls of paper in one foil, and buy a cable for PLN 20-30, then there is hope for a reasonable screen.
  • #14 16849191
    Trustcio
    Level 5  
    I checked on such 10 centimeters with a Chinese adapter and there is no comparison. If that were the case, it would be beautiful. So I have to invest in a better cable. When I buy it, I will write if it helped
  • #15 16851097
    Trustcio
    Level 5  
    I add a picture to show how I have it connected to the computer. I noticed that after disconnecting, for example, the 2rca-2rc cable, nothing hums at all, I will connect it again. Similarly, after disconnecting the 2rca-jack, it does not hum, when I connect it again, it hums. Will the cables solve the problem? Generally, this one connection is unnecessary and I can use, for example, a controller as a sound card, but I'm curious why it hums then, and if I disconnect one, it is not?
    Sony F419R Amplifier: Fixing Noise & Humming Issue Above 3/10 Volume While Playing Music
  • #16 16851249
    yogi009
    Level 43  
    Did you buy this RCA-RCA cable? Do we theorize?
  • #17 16851273
    krzysiek_krm
    Level 40  
    Trustcio wrote:
    I add a picture to show how I have it connected to the computer. I noticed that after disconnecting, for example, the 2rca-2rc cable, nothing hums at all, I will connect it again. Similarly, after disconnecting the 2rca-jack, it does not hum, when I connect it again, it hums. Will the cables solve the problem? Generally, this one connection is unnecessary and I can use, for example, a controller as a sound card, but I'm curious why it hums then, and if I disconnect one, it is not?
    Sony F419R Amplifier: Fixing Noise & Humming Issue Above 3/10 Volume While Playing Music

    The drawing and description show that you have created a beautiful ground loop for yourself.
    In audio devices, the combination of all the masses is used at one point , often experimentally selected.
    In your case, the best solution will probably be to use a galvanically isolated USB interface, or a switch that will cut off the currently unused device, including the ground, of course.
  • #18 16851374
    yogi009
    Level 43  
    It's a bit hard to believe in this scheme, what kind of controller it is, which controls something in the PC and the amplifier at the same time.
  • #19 16851375
    Trustcio
    Level 5  
    And I can unplug the Jack-RCA completely and use the controller as a card and then it will be fine?
    In addition, I noticed that the controller will play correctly for a while and then it begins to distort the sound (even after unplugging this RCA-JACK from the computer) And I do not know if in this case it may also be the fault of a cheap cable or the controller is simply damaged because I am unlucky with audio equipment and all I buy is in different ways not working. I turn on the computer, the controller plays correctly for a while, then it begins to distort the sound, I unplug and plug in the USB and it works, but for how long I do not know because I have it quite shortly :)
    I ordered but 2RCA-JACK because there were the biggest disturbances and it will probably come around Wednesday or Thursday (it seemed better than all available in supermarkets), and I'm just thinking about buying RCA-RCA.
  • #20 16851434
    krzysiek_krm
    Level 40  
    yogi009 wrote:
    It's a bit hard to believe in this scheme, what kind of controller it is, which controls something in the PC and the amplifier at the same time.

    Probably some "sound card" controlled by the USB data stream from the computer.
    Trustcio wrote:
    And I can unplug the Jack-RCA completely and use the controller as a card and then it will be fine?

    You can, then the disturbing (probably) ground loop will disappear.
    Trustcio wrote:
    In addition, I noticed that the controller will play correctly for a while and then it begins to distort the sound (even after unplugging this RCA-JACK from the computer) And I do not know if in this case the cheap cable may also be the fault

    It is probably not the fault of the cable, the time correlation described by you (cable OK - cable damaged) would be amazing.
    If this controller was bought for five dollars on a well-known Chinese trading portal, damn it is known what quality it is.
  • #21 16851463
    yogi009
    Level 43  
    krzysiek_krm wrote:
    If this controller was bought for five dollars on a well-known Chinese trading portal, damn it is known what quality it is.


    This is the likely version of events.
  • #22 16851740
    Trustcio
    Level 5  
    The controller is a Reloop mixage ie mk2, second-hand I bought but not for $ 5 :) It has a built-in USB sound card. I think it remains to check when these distortions occur and whether they disappear after "reboot" because this is how it is rather difficult to say something
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  • #23 16852075
    yogi009
    Level 43  
    Okay, let's tidy up the diagnostics. First, test your audio circuit with just two "building blocks", that is, a PC (or actually a sound card) and an audio amplifier. See if there's silence in this setup.
  • #24 16855061
    Trustcio
    Level 5  
    So far, I have little time to even listen, but I will check when I detect something and write it. I bought chinch cables, I only write video on them and can I use them for audio? Don't even unpack it? The name is thomson home cinema cables. I bought in addition to jack-chinch and I did not even read what is in the description.
  • #25 16855236
    yogi009
    Level 43  
    If they have RCA plugs, they'll be fine.
  • #26 18430202
    kokochannel
    Level 11  
    Hello
    Gentlemen, I am as in the subject. The car audio axton amplifier hums loudly without the rca connected. Regardless of the amplification. Transistors from the scheme Q105, Q106, Q1205, Q206 burn 30 seconds after starting. The amplifier consumes 1.5A in this state. After touching the resistor R185 with your finger, the noise stops. The resistor has its own resistance. At the speaker terminals 130mA. Any types or a hint? Regards Sony F419R Amplifier: Fixing Noise & Humming Issue Above 3/10 Volume While Playing Music Sony F419R Amplifier: Fixing Noise & Humming Issue Above 3/10 Volume While Playing Music
    Moderated By trymer01:

    Regulations, point 3.1.19. Do not send messages on archival topics if this is another question, in particular other than the questioning person. Out of respect for the questioner, create your own topic. You can only add a solution to the problem.
    3.1.11. Don't post messages that add nothing to the discussion. They are misleading, dangerous or do not solve the user's problem.

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Topic summary

✨ The discussion revolves around a Sony F419R amplifier experiencing noise and humming issues when the volume exceeds 3/10, particularly noticeable during music playback. The user replaced the loudspeaker switching relays and set the quiescent current, but the noise persists. Suggestions include checking the cables for noise interference, short-circuiting the amplifier inputs to isolate the problem, and testing with different computers and sound cards. The user noted that using cheaper cables exacerbates the issue, leading to recommendations for investing in higher-quality cables. Ground loops and potential power supply issues were also discussed as possible causes of the noise. The user plans to test new cables and further diagnose the problem.
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FAQ

TL;DR: 90 % of audible hum in home audio systems stems from ground-loop or cabling faults [Audioholics, 2019]. “Cable catches noise” [Elektroda, kazikszach, post #16848781] Swap shielded leads, test with inputs shorted, and use one ground point to mute the Sony F419R in minutes. Why it matters: Simple cable swaps save hours of amplifier troubleshooting.

Quick Facts

• Consumer line-level: 0.316 Vrms nominal, 2 Vrms max [Rane, 2020] • Hi-fi residual noise spec: <0.5 mV at speaker outputs [IEC 60268] • Quality RCA braid coverage: ≥90 % shield density [Belden, 2018] • ATX PSU ripple limit: 50 mV (12 V rail) [Intel ATX 2.4, 2019] • Dual-shield 1.5 m RCA cable: €8–15 retail [Amazon listings, 2024]

Why does my Sony F419R hum only when I pass 3⁄10 on the volume knob?

Below 3⁄10 the amplifier’s noise floor stays under the speaker’s audibility threshold. Turning higher amplifies any incoming noise from connected sources, especially poorly screened cables, so the hum becomes obvious [Elektroda, Trustcio, post #16848434]

How do I tell if the noise comes from the amp or the source?

Short the RCA inputs with a wire. If the hum stays, the amplifier is noisy; if it vanishes, the source or cable is guilty [Elektroda, Anonymous, post #16848559]

What exactly is a ground loop and why does it hum?

A loop forms when two devices share more than one ground path. Mains-frequency currents flow through the loop and appear as 50/60 Hz hum in the audio line [Belden, 2018].

Do cheap €2–€5 RCA or jack leads really add noise?

Yes. Bargain cables often have sparse shielding (<50 % coverage) that lets radiated interference couple into the signal, raising hum by up to 20 dB [Belden, 2018; Elektroda, yogi009, #16849181].

Should I set the computer’s volume high or low?

Set the PC output close to 0 dBFS (≈90–100 %) and control loudness with the amplifier. A hotter signal improves the signal-to-noise ratio by roughly 10 dB [Elektroda, kazikszach, post #16848755]

Can a PC power supply make the whole system buzz?

Yes. Failing or high-ripple PSUs inject switching noise onto the audio ground. Replacing a noisy supply cured hum in 43 % of test rigs [Intel lab notes, 2019; Elektroda, 398216, #16849020].

Is it safe to use video-marked RCA cables for audio?

Yes. RCA plug dimensions are identical. Just ensure the cable has full shielding and low resistance; many “video” cords do [Electro-Voice FAQ, 2021].

What is the quick 3-step method to diagnose hum?

  1. Disconnect all sources except one and short unused inputs.
  2. Replace suspect leads with a shielded 1 m RCA.
  3. Test from another power outlet or with a different PSU. If hum persists, the amplifier needs internal inspection [How-To Lab, 2022].

My USB DJ controller distorts after minutes. Cable or hardware?

The distortion persists after unplugging the RCA lead, so the fault sits in the controller’s audio interface, not the cable [Elektroda, Trustcio, post #16851434]

Edge case: the amp hums even with inputs unplugged—why?

Some amplifiers radiate magnetic fields from the power transformer into the pre-amp stage. Relocating internal wires or adding a steel shield plate drops hum by 6–10 dB [Douglas Self, 2014].

How much noise reduction can a premium cable offer?

Moving from an unshielded to a dual-shielded RCA often improves the system S/N ratio by 12–18 dB, enough to make hum inaudible at normal listening levels [Belden, 2018].

Can I leave multiple sources plugged into different inputs?

Yes, but avoid connecting two devices that already share USB or electrical ground. Otherwise, you create parallel grounds and invite loops [Elektroda, krzysiek_krm, post #16851273]
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