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

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]

Perhaps the cables are picking up noise

Short circuit the amplifier inputs, e.g. with a piece of copper wire. If you have chinch plugs, make a short circuit in them and connect them like that. Then increase the gain and listen. If the noise increases, you have a problem with the amplifier. If it does not rise or is faint, then you have a problem with the source (s) of the signal to the amplifier, plugs or cables. Also check the noise balance. Probably the amplifier has channel balance. Therefore, check the noise with no external signal source connected for twisted one channel and then the other. Try to compare if the feelings are similar. If it is possible to switch off unused inputs, switch them off.

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

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.

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

There are two options:
1 cable catches noise
2 hums the output on the computer.
Please check with another computer or cable.

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?

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).

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.

And branded cables or total "china"? Use those that just have a solid screen.

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

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.

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

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?

Did you buy this RCA-RCA cable? Do we theorize?

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?

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.

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.

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.

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.

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.

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

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.

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.

If they have RCA plugs, they'll be fine.

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

Moderated By trymer01:

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