Amp and speaker hiss - do I go back an AVR?

[alucard]

Jul 11, 2017 9:35:53 GMT -5 @texzick said:

Sorry I could not get back yesterday.
Our intent is to check the wall plug you are using for power.
Everything in the system is referenced to 0 volts- circuit ground in electronics- and need to know if there is voltage floating on that reference to chassis ground.
1) check neutral to ground with equipment plugged in, but "off"
2) Then unplug everything, take neutral to ground readings again
3) plug in everything, turn "on" and check a third time.
Pls use a low setting on your meter, using 200vac setting may not show what we are looking for.

As I said on page 1, if there is voltage between the neutral- ground, there is a wiring problem. In a perfect world that reading should be 0 volts, but in reality, sometime there will be a small voltage there. The question is how much voltage. If there is 2-2.5 volts or more, you need a new line run because you can not find any tap offs someone may have added after the circuit was installed, or the wire gauge is undersized for the load it carries. If we are using that circuit to run a light or power tool, it's not a problem, but with electronics it's a big deal.

If you think about it, digital is 0 volts off, 5 volts on, a floating voltage of 2.5 volts or more on the reference will drive the processor nuts, causing intermittent problems.
In audio, a floating voltage on reference can be audible noise.
After I got the XPA-5, I installed a new 20 amp breaker & 12 gauge 3-wire to the plug because I also run a rear projection tv monitor off it.
The last thing I want is a supply line voltage fluctuating due to high current draw.
That line is called an "isolated line" because nothing is tapped off and only goes to one service outlet. In the business world that circuit will have an orange plug.
A dedicate line is one that has a dedicated hot (breaker) but the neutral-ground is shared with another circuit.
Most houses have all shared lines, meaning there is up to 3 outlets using one breaker & wires.
Usually shared lines are not an issue until there is high current draw or something with inductive load is spiking the line as the coil field collapses & re-energizes.
Busy day today, but I'll check back

Jeff

@texzick , my results are below

Unplugged: 0.060v
Plugged in/off: 0.096v
Amp/Pre On: 0.244v

[leonski]

Seems like negligible readings. Though the real pros continue to use an analogue meter (Maybe a Simpson 260?)


www.simpsonelectric.com/products/test-equipment/vom-multimeters/260-8-260-8p

When I started working in a wafer fab, this was IT and all we had.

[alucard]

Unfortunately the CMX-2 did not help nor a power line isolation transform (tripp lite IS100). I'm going to send the amp back. My space is limited (18"D x 18"W x 8.5"H) - the XPA Gen3 will fit snugly but I prefer something smaller. Is 0.5" clearance between top of Gen3 and shelf enough breathing room? I'm also considering the BasX A-5175.

[Axis]

Really, your going to send the amp back ? I wish I would have recommended that.

[leonski]

Let's wait and see what the techs have to say about the piece in question.
I wish I had the actual numbers but I'll bet tha no-less than 1/2 the amps sent back for 'noisy system' are without fault.

I KNOW it's a PIA, but due dilligence sometimes requires 'going thru the list' in order to find Root Cause.
And it does sound like alucard DID put in a lot of work tracking this down.

Stay Tuned: I hope this gets updated after more information comes in.

[bluemeanies]

Sorry but I must have missed something..I did not realize you were gettting a buzz from the amplifier, but rather the speaker.
Of course I have not had time to read all of the post.
If the amplifier had a buzz I would have tried other outlets throughout the house to start and if it was still an issue send it back.
Maybe all of this work wa good for nothing and it was a mechanical problem with the amplifier.

[DYohn]

The sound was from the amplifier itself, physically? OK then.

[alucard]

Jul 15, 2017 8:06:42 GMT -5 bluemeanies said:

Sorry but I must have missed something..I did not realize you were gettting a buzz from the amplifier, but rather the speaker.
Of course I have not had time to read all of the post.
If the amplifier had a buzz I would have tried other outlets throughout the house to start and if it was still an issue send it back.
Maybe all of this work wa good for nothing and it was a mechanical problem with the amplifier.

Jul 15, 2017 8:33:22 GMT -5 DYohn said:

The sound was from the amplifier itself, physically? OK then.

Two issues:

1) Amp hiss: more like a high pitch noise. Not loud but annoying. It seems to bother me more at some times than others, sometimes I dont really notice it. This was coming from the amp with nothing plugged into it except power. I tried other outlets.

2) Speaker buzz: issue occurs when preamp (XMC-1) is grounded. Ground lift plug solved the issue, as does using jensen isomax transformer on the RCA cables, but I wanted to get away from using those. When I upgrade the HDMI board I may send it in for that replacement and ask that they inspect the grounding.

[DYohn]

Again demonstrating the impossibility of actual troubleshooting on the Internet.

1) if the amplifier is physically buzzing it likely has a mechanical issue like a poorly mounted transformer.
2) if there is humm in the speakers that is solved by lifting a ground then you either have a ground loop or "noise" such as a DC offset on your home wiring system. This is the issue I've been focusing on and it is unlikely to be a problem in your gear. If using the ground lift adapter solves the problem then use it, or not, your choice. Some gear is more immune to these sorts of issues than others, but again I will say it is unlikely to be any sort of defect, it is much more likely being caused by your house or something in it.

Getting a pro into your home to investigate might help solve your problems.

[alucard]

Jul 15, 2017 11:02:12 GMT -5 DYohn said:

Again demonstrating the impossibility of actual troubleshooting on the Internet.

1) if the amplifier is physically buzzing it likely has a mechanical issue like a poorly mounted transformer.
2) if there is humm in the speakers that is solved by lifting a ground then you either have a ground loop or "noise" such as a DC offset on your home wiring system. This is the issue I've been focusing on and it is unlikely to be a problem in your gear. If using the ground lift adapter solves the problem then use it, or not, your choice. Some gear is more immune to these sorts of issues than others, but again I will say it is unlikely to be any sort of defect, it is much more likely being caused by your house or something in it.

Getting a pro into your home to investigate might help solve your problems.

For #1 I am working with the vendor and will be returning for inspection or refund if they cannot replicate the issue.
For #2 I was thinking some with the house wiring too. I also believe it could be causing issue #1 since other amps hum, although not the same higher frequency as the class d amp we've been troubleshooting here.

[leonski]

Jul 15, 2017 11:02:12 GMT -5 DYohn said:

Again demonstrating the impossibility of actual troubleshooting on the Internet.

1) if the amplifier is physically buzzing it likely has a mechanical issue like a poorly mounted transformer.
2) if there is humm in the speakers that is solved by lifting a ground then you either have a ground loop or "noise" such as a DC offset on your home wiring system. This is the issue I've been focusing on and it is unlikely to be a problem in your gear. If using the ground lift adapter solves the problem then use it, or not, your choice. Some gear is more immune to these sorts of issues than others, but again I will say it is unlikely to be any sort of defect, it is much more likely being caused by your house or something in it.

Getting a pro into your home to investigate might help solve your problems.

Exactly why I suggested an Isolation Transformer.    Won't pass DC and can provide 'balanced' 60v / 60v to your connected device.

'D' amps operate at a very much higher than 60hz frequency, so it seems reasonable that instead of a hum or buzz, it be higher frequency.

When the pro comes?    Make sure he has a way to check House Ground Impedance, using something like a 'Megger'.

[Deleted]

Unplugged: 0.060v
Plugged in/off: 0.096v
Amp/Pre On: 0.244v

alucard- those reading are very acceptable. It tells me your ground, neutral & wiring are working/connected properly.
I would get the A-5175 without hesitating to fit your space, a good deal.

[slk55amg]

I am using an Emotiva XPA5 ( Gen1) and a sony ES5300. Dead silent. Both run cool, solid as a rock. 9 yeras later, both perform as the day they arrived in 2009.