Anthem mca50 faint noise at idle

[Ssmokeyy]

So I have a mca50 5 channel amp. I use 3 channels for the front channels only. I notice a faint noise when at idle. I added a ground cable from my Integra drx 8.4 to the anthem mca50 mo change. So I removed the xlr cables from the anthem. Faint noise is gone. So I change to rca cable to test for bad xlr input. As soon as I installed the rca cable noise is back. So now I don't know what to do. What's the next step to fixing this problem? Cables are all shielded and very high end. Audioquest power cords, svs hdmi cables, cat6a data cables, monster pro studio xlr cables

 

[staticV3]

Is what you're hearing a uniform hissing noise (white noise), or is it an electrical interference noise, like high-pitched whine or mains hum?

 

[Ssmokeyy]

I think more white noise uniform

 

[staticV3]

I think more white noise uniform

Sounds like your AVR just has poor quality Line out with a lot of noise (low SNR).

To reduce the noise, here are a few things that you could try:

-Play around with the Integra's settings (Music Optimizer, Upsampling, Cinema Dedicated Mode, Direct listening mode, etc.)
There might be a setting that adds noise to the output.

-Use a passive attenuator (e.g. Behringer Monitor1) between the AVR and Amp. Reduce the volume using the attenuator, then increase the volume on the Integra to compensate.

-Replace the MCA 50 with an Amp that has lower gain.

-Replace the Integra with an AVR/AVP with higher SNR Line outs.

 

[Ssmokeyy]

I have a hard time believing that a $3300 avr just has ****** line outs. Here is a file of the sound. Also I just noticed that when everything is starting the noise doesn't come until the main relay clicks on in the integra. Its mp4 and says I can't upload that type of file. Need to find out what type I can first.

 

[staticV3]

I have a hard time believing that a $3300 avr just has ****** line outs.

Based on your report, I'm afraid that's the only logical conclusion.

Expensive equipment performing poorly is hardly surprising anymore if you've read Amir's reviews for some time.

Price doesn't make quality. Good engineering makes quality.

 

[Ssmokeyy]

So I change it to a zip now the 8 second video is to large it says.

 

[tmtomh]

As @staticV3 says, audible hiss from the speakers is a very common effect with even some pretty expensive gear.

@Ssmokeyy , can you be more specific about what exactly you are hearing?

• Just to be 100% clear, this is hiss coming from your speakers, not directly from the amp's case, yes?
• If so, is this hiss that you can hear only when you walk up near the speakers, or can you also hear it from your normal listening position when no music/sound is playing?
• Do you notice any difference in the volume of the hiss when you have the MCA50 connected with XLR vs RCA?

If the sound is coming from the speakers but you can only hear it when you walk up close to them (like let's say within a foot or two), it's not necessarily idea but it could be normal.

If the sound is audible from your normal listening position, that could be a few things, including what staticV3 has mentioned.

It could be the MCA50 has a high noise floor.

It could be that the Integra has a high noise floor.

It could be that the Integra's gain (which is a different thing than its wattage/power) is too high for the MCA50 to operate without producing that audible hiss.

Finally, it is still possible that it could be a ground loop. I know from experience that hum is not the only sound that can be transmitted over a ground loop - hiss can too. If it is a ground loop, I would expect there to also be 50 or 60Hz hum (or maybe a 100Hz or 120Hz harmonic) audible from your speakers. However, it could be at such a low level that you can't easily hear it, or it could be that the drivers and crossover networks in your speakers are such that the ground hum is attenuated so much that it's inaudible, while the hiss goes into the tweeters and is at frequencies where human hearing is much more sensitive.

If it is a ground loop, I would also expect that the hiss would be louder with the RCA connection than the XLR, since XLR has built-in noise cancellation. However, this is not 100% determinative.

One thing to try is to TEMPORARILY install a "cheater" plug with no ground pin between one of the amp's power plugs and your AC wall jack. You should NOT run the equipment this way. But in my opinion it's okay to try this just to quickly turn the gear on to see if the hiss is still there - that should just take a few seconds, as you will hear the hiss or you won't. As soon as you find that out, turn everything back off and remove the cheater plug. If the hiss is gone (or much lower in volume) then it's a ground loop. If not, then it's not.

Only other thing I can think of is maybe to try getting some dummy caps for the MCA50's jacks for the two unused channels. Sometimes an amp can make more noise when nothing is connected to one or more of its channel inputs.

 

[Timcognito]

Unplug every other device on that circuit and check. Run an extension cord from another circuit in your home and check. Leave only the the amp and speakers connected and check. Add devices then check subtract each component and check. Slowly add each components together until the hiss comes back, and leave that last device connected and remove others one by one and check.

 

[Ssmokeyy]

So the avr is plugged into a 10awg 20 amp line from the main box no stops on the way. The amp is plugged direct into the wall on another 10awg 20 amp braker direct no stop to main panel. There is 5 20 amp lines ran to the front of the room 3 10awg 2 12awg. the noise is louder with the xlr than it is with the rca. Next step i will unplug everything else and power down the other gear and test again.

 

[Timcognito]

So the avr is plugged into a 10awg 20 amp line from the main box no stops on the way. The amp is plugged direct into the wall on another 10awg 20 amp braker direct no stop to main panel. There is 5 20 amp lines ran to the front of the room 3 10awg 2 12awg. the noise is louder with the xlr than it is with the rca. Next step i will unplug everything else and power down the other gear and test again.

Okay doesn't hurt to put every thing on one circuit and try that the ground loop could be at the panel. As you know xlr shares a ground so maybe inside the amp. Not an EE or electrician but built my own house and have chased these things. Once it was a dimmer through the air. Good luck.

 

[Ssmokeyy]

I'm the only one that hears it at my listening position but I also know what I'm hearing. It's only at idle and it's quiet. I have a video of it but I can't figure put how to upload it here. I tried changing the file to zip file but no it says the file is to big. It's only a 8 second clip. I don't have time today but soon this week I will try the cheater plug.

 

[Chrispy]

So when not playing anything from a source, the volume adjustment on your pre-amp changes the amount of noise? Some combos simply will make some noise, but if not audible from your seat....

Best way to share a large file might be something like sharing via google drive or similar.

 

[Ssmokeyy]

No changes to loudness. Tried it tonight dose not change volume.
Good news maybe. I have a crown xls 2002 for my rear subs. I unplugged it and the noise is gone. Plugged it back in and unplugged the xlr cable to it. Noise gone. Plugged xlr back in no noise. Move the cable noise back.

 

[Ssmokeyy]

Found the problem. Sub amp to integra drx 8.4 xlr cable was trash. I used a monolith xlr cable and replaced it with blue jeans cable xlr cable. Not only is the noise gone but the subs sound better than before. Now I'm thinking of removing the monolith speaker cables from the system.