Grounding BasX A2 to receiver?

[brianlh]

I have what seems to be a ground loop between my receiver (anthem mx-1140) and my BasX A2.  

I would like to try to ground the Anthem to the BasX via the chassis ground on the MX-1140.  However, the BasX A2 does not have a ground contact point.  If I understand correctly, I should scrape some paint off (Doh!) and use one of the screws on the back of the A2 as the grounding point?

-thanks,

Brian

[ttocs]

You could use a different screw with no paint or anodizing.

I've discovered a little about ground loops over the years, and there are a variety of ways to alleviate them, one of which is to do the opposite of how they are created. Plug the amp and receiver into the same outlet.

But also check to see if it's possibly the incoming coax from the cable company. That's where mine came from about 8 years ago. I ran the coax through a Panamax power conditioner and it solved that hum issue.

[leonski]

Cable / small dish are Notorious creators of ground issues.

Start by unplugging everything.....than plugging back IN one at a time until hum returns.

I try to avoid these issues by using TOSLINK (optical digital) whenever possible....

My Panamax ALSO has all sorts of 'other' connectors which I've never been forced to use!!!


Do you have a couple 'helps'?

First? An OUTLET CHECKER. This is an inexpensive device which will identify any outlet problms.....Hot / Neutral reverse among others.

Second? An inexpensive multimeter. You can get one for maybe 25$ at Harbor Freight which will allow you to read voltage between amp and receiver.....GROUNDS.......so you can get an idea if that's the start of the problem....
Such a meter has many uses.
My Cheap-o has thermocouple inputs and I use THAT out on the Grill.......just for entertainment purposes.....

[brianlh]

Thanks guys - I have an overly complex setup - 9 separate amps counting the subwoofers. This is the last grounding issue, and its driving me a bit nuts trying to track it down. I can just barely hear the hum when the room is dead quiet, so maybe I should just learn to live with it.

I don't have a multimeter, but I'm going to pick one up and see If I can learn anything.

I was hoping it was the cable TV wire, but removing it from the equation didn't change anything. I don't actually use it for TV, I was running ethernet signals over it via an injector. So I spent a couple of hours and ran a dedicated line, but no luck. It's better to have the real ethernet cable anyway, so at least it forced me to finally run one.

[ttocs]

Dec 17, 2022 12:58:56 GMT -5 brianlh said:

Thanks guys - I have an overly complex setup - 9 separate amps counting the subwoofers. This is the last grounding issue, and its driving me a bit nuts trying to track it down. I can just barely hear the hum when the room is dead quiet, so maybe I should just learn to live with it.

I'd keep trying to fix it.

How many electric circuits are involved?
How many speakers or subwoofers are sounding the hum?

Whichever subs or speakers have the hum, leave those powered up. Unplug all other devices including preamps and processors, tv, cable box, etc. If the hum is still going, then unplug one amp at a time to see if the hum stops. If the hum has gone away, then plug in one device at a time until the hum is heard, then, unplug that item and plug in another item. Repeat until you know which items cause the hum to show up and which ones don't. This should tell you what is common amongst the hum "causing" devices. I put causing in quotes because those items may not really be causing the hum, but the electric circuits they are plugged into, or even some other source "connected" to something related to those circuits. Hum can be "caused" by something 50 feet across the house, like my A/C Condenser that wasn't grounded good enough so it caused hum whenever it operated.

I'm just trying to point out that there are a myriad of combinations that can cause hum to show up.

[brianlh]

Dec 17, 2022 13:23:59 GMT -5 ttocs said:

Dec 17, 2022 12:58:56 GMT -5 brianlh said:

I'd keep trying to fix it.



How many electric circuits are involved?

How many speakers or subwoofers are sounding the hum?



Whichever subs or speakers have the hum, leave those powered up. Unplug all other devices including preamps and processors, tv, cable box, etc. If the hum is still going, then unplug one amp at a time to see if the hum stops. If the hum has gone away, then plug in one device at a time until the hum is heard, then, unplug that item and plug in another item. Repeat until you know which items cause the hum to show up and which ones don't. This should tell you what is common amongst the hum "causing" devices. I put causing in quotes because those items may not really be causing the hum, but the electric circuits they are plugged into, or even some other source "connected" to something related to those circuits. Hum can be "caused" by something 50 feet across the house, like my A/C Condenser that wasn't grounded good enough so it caused hum whenever it operated.



I'm just trying to point out that there are a myriad of combinations that can cause hum to show up.

Thanks.  I promised my wife I would stop messing with the system this weekend - I said nothing about not posting about it on the internet , so I will walk through these steps on Monday night or so.  I started upgrading the system on 11/6/22 and we have yet to watch a movie on it, as I keep messing with it.  I had not upgraded in 13 years and added quite a bit of stuff all at once.

Circuits: 4x 20 dedicated amp circuits.  As you can imagine, these problems didn't start until I had to add circuits to handle the new loads.  While I would never drive my system at 100%, the total output watts are around 9000, going by the max watts on the back of the equipment.  I had to split between 4 circuits since they don't add up nicely into a 15 amp plug.  I have a 5th 20 amp circuit in the room that currently isn't being used; that being said, its a good 12 feet from the nearest amp.

Only my HT equipment is plugged into these; however, now that you mention it, I realize that I have a network switch and other misc. items (NVidia shield tv, etc) plugged into these circuits.

Speakers:  I have gotten this down to just the 2 speakers hooked up to the BasX A2.  I did have other issues with my L/C/R, but I was able to fix them using an earthquake ground isolator.  Using a ground isolator on the basX just makes the problem worse; which makes me wonder; maybe this isn't a ground loop and I've been trying to solve the wrong problem?

I have a total of 15 speakers (9.X.6) and 4 subwoofers.  The subwoofers run through a miniDSP 2x4 HD and are treated as 1 subwoofer by the MX-1140.  I also have 2 butt kicker LFE's, each driven by a dedicated DA-1000 amp. 

So, 21 channels total driven.  Everything is dead quiet, except for the 2 speakers with the tweeter hum.

One thing to note -   All of my equipment is 3 prong - except for the Anthem MX-1140 and the BasX A2, which are both 2-prong.

I will attempt the above on Monday after the wife/kids go to sleep and update the thread with my results.

[leonski]

Multiple circuits If I undderstand correctly, SHOULD be dropped from ONE side of the box......

Get an outlet tester yet? A meter would be nice, too.....and while you're at it? A KILL-A-WATT meter.....

Total cost of above? Certainly less than 75$

[ttocs]

Dec 17, 2022 20:41:50 GMT -5 leonski said:

Multiple circuits If I undderstand correctly, SHOULD be dropped from ONE side of the box......

Correct. But just to clarify . . . 

In the graphic below representing 6 of the 7 circuits for my system, each circuit is 20A, each outlet location has a pair of receptacles and each receptacle is a dedicated circuit. Four wires are involved for each pair of receptacles of one outlet location. Two Hots on opposite phase, a shared Neutral and a shared Ground. These are Isolated Ground circuits which are wired differently from "normal" outlet circuits. In the case of the top left outlet location, the upper receptacle is Circuit #15, and the lower receptacle is Circuit #17.  15 and 17 are on the same side of the box, but are opposite phase from each other, which keeps the electrical load "balanced", which means that roughly similar loads are expected to be on each receptacle so they will draw on both phases roughly equally (in a perfect world). Circuit 15 is on Phase B, and #17 is on Phase A. If both were on Phase A, then the Neutral wire could be overloaded with high demand from both receptacles.

Load Balancing is an important aspect of household electrical wiring.

These are my outlets at the front wall and side wall. There's one more set of outlets on the rear wall.


This is a 20 breaker panel that shows how Phase A and B are able to be on both "sides" of the panel. Odd numbered circuits are on the left side of the electric panel, and even numbered circuits are on the right side. Circuits 1&2, 5&6, 9&10, 13&14, 17&18, are all on Phase A. Circuits 3&4, 7&8, 11&12, 15&16, 19&20, are all on Phase B.

[brianlh]

Dec 17, 2022 20:41:50 GMT -5 leonski said:

Multiple circuits If I undderstand correctly, SHOULD be dropped from ONE side of the box......

Get an outlet tester yet? A meter would be nice, too.....and while you're at it? A KILL-A-WATT meter.....

Total cost of above? Certainly less than 75$

I still need to run out to the store and grab those;  Its a bit of a drive and I haven't found the time quite yet.  Might have to do this during my lunch break on Monday.

So - my circuits are not on one side of the box.  Rats.  I did not consider this and didn't tell the electrician who installed them.  I am using 2x on each side.  The 5th circuit is on the right side of the panel, but has nothing plugged into it.  

Moving them is probably possible, but will take some careful planning, as my box is about full;  I have 36x slots, but the house was not wired very efficiently way back when and I think grouping them all together will require swapping other breakers.

[ttocs]

Dec 18, 2022 12:44:03 GMT -5 brianlh said:

Dec 17, 2022 20:41:50 GMT -5 leonski said:

Multiple circuits If I undderstand correctly, SHOULD be dropped from ONE side of the box......

Get an outlet tester yet? A meter would be nice, too.....and while you're at it? A KILL-A-WATT meter.....

Total cost of above? Certainly less than 75$

I still need to run out to the store and grab those;  Its a bit of a drive and I haven't found the time quite yet.  Might have to do this during my lunch break on Monday.

So - my circuits are not on one side of the box.  Rats.  I did not consider this and didn't tell the electrician who installed them.  I am using 2x on each side.  The 5th circuit is on the right side of the panel, but has nothing plugged into it.  

Moving them is probably possible, but will take some careful planning, as my box is about full;  I have 36x slots, but the house was not wired very efficiently way back when and I think grouping them all together will require swapping other breakers.

They don't need to "all" be on one side, but pairs of circuits for similar loads is better to be consecutive numbered circuits, like, #15 & #17, or, #10 & #12, etc.

I wouldn't go about swapping breakers around without some guidance from someone who knows about planning how a breaker panel is arranged. I did this about 6 years ago thinking I could "arrange and group my av circuits" and ran into some odd behavior related to imbalance. Some pairs of circuits were "doubled up" on the Neutral, and others weren't. So I swapped things back to how they were before. This is when I learned a tiny bit about load balancing. My electrician knew what he was doing. So one thing I learned was not to arrange circuits in a panel so it "looked better".

[leonski]

I don't know if what I saw is important or NOT.
I looked up a random video on 'balanced load' and just looked......

First? Guy talked about AMPS and the meter / bill part of things. His claim was that balancing amps actually reduces your bill.
What does my meter actually measure? Watts /VA? Or amps? Ive always been told that power is WATTS.......than learned later about PF.
So dividing it up differently shouldn't make a difference?

But one thing in the video that disturbed me was his fast and loose with what he measured. The voltages didn't 'add up'
If your house is like mine.....2 hots and a neutral AND a long copper ground rod.......very near the box and several fee long......
The 2 hots should be pretty close to the same voltage. Say 115 or so....with 230 across? Is that right? The guy in the video
couldn't seem to do that and was very concerned with amps.
I'd like to find out what happens IF L1 (line 1) and L2 are different voltages as they are LIKELY TO BE and you feed different parts of your stereo FROM THEM
Now, you have several volts difference ON THE SAME NEUTRAL feeding your gear. Won't that be a potential problem?

That was the reason for a single-side feed.....

I'd like to have an electrician chime in on this!

[KeithL]

As a broad generalization, with home gear like audio equipment, the "primary side" is isolated from the "secondary side".

In fact, in a typical home, you may have "230 VAC power" for things like your stove and dryer... and "115 VAC power" for other stuff...
And, in most cases, the source is a "230 VAC center-tapped transformer"... with "230 VAC taken across the outside" and "115 VAC taken from each side to the middle" and "the middle grounded".
This means that the "ground" on all of your 115 VAC outlets is basically the same...
But, for a given pair of different 115 VAC outlets, on "different circuits", the "hot" lead may be at the same voltage, or may be 230 VAC apart (each 115 VAC waveform being out of phase with the other).

Now, for most AC powered equipment, including audio gear, this doesn't really matter... because the mains supply is isolated from the internal circuitry.
So, REGARDLESS OF THE CIRCUITRY POWERING IT, the "circuit ground" on your amplifier is referenced to "Earth ground" or "true ground".
So, IF YOU HAVE A NON-DIFFERENTIAL AMPLIFIER, the "black speaker terminal" will be at "circuit ground" regardless of the ground associated with the power line.
(And, on a fully differential amplifier, while neither speaker terminal is at circuit ground, they are both still referenced to an internal circuit ground, which is tied to "real ground".)

Note that SOME equipment, including many hand tools, is NOT isolated from the true grounds and voltages on the power lines...
So, for example, if you plug a hand drill into one 115 VAC circuit, and an electric heater into a different 115 VAC outlet, they MAY have internal parts that are "230 VAC apart"....
HOWEVER, with such gear, it should be insulated in such a way that those parts will NEVER come into contact with the operator or each other. 
In the distant past you would hear of errors where, for example, "a screw head on a TV cabinet was 'hot' at a dangerous voltage", but manufacturers are quite careful these days.
(But this is why certain simple devices like hand tools and heaters can be quite dangerous if damaged - or if you take them apart.)

And, yes, it would be bad if different neutrals were to be at significantly different potentials...
However, because they SHOULD be tied together, the result would be that significant current would flow between them (they would be "trying to reach the same voltage").
In general, if this happens to a significant degree, it can only occur due to some sort of fault, and will blow a circuit breaker somewhere...

HOWEVER, under some circumstances, it is possible for a large amount of AC current flowing in one circuit to induce a small AC voltage in that circuit's "ground line"...
And, if a piece of audio gear plugged into that circuit is connected to gear plugged into a different circuit, that AC voltage may end up being referenced in the audio signal passing between them.
And THAT is why you sometimes get "ground hum" when you connect various pieces of audio gear together that are powered by different circuits.
(It's generally a very small AC voltage, which can be difficult to measure, and to track down, but audio gear is very sensitive to 60 Hz, which is both "a power frequency" and "an audio frequency".)

It's also worth mentioning that, in some older homes, the different circuit relationships may be somewhat different...
And, in some of those, rather than a "center tapped 230 VAC transformer" the source is "two or three of the legs of a three phase transformer"...
And, in those situations, while each circuit may have 115 VAC or 110 VAC, they may be at a 120 degree phase angle to each other rather than the typical 180 degrees (180 degrees is "fully out of phase"). 
And, in that case, even though each is "individually right" they "will not add up properly".
However, since all "115 VAC" equipment only uses a single one, and all are referenced to the same ground, this is not a problem.
(Although it will require special wiring, and impose special requirements, for 230 VAC appliances.)

As far as I know most current home "power meters" do calculate "true watts", rather than "volt-amps", as they should...
And the small difference between "true watts" and "VA" in something like a home audio amplifier isn't an issue.
Note that the term "power factor" is a numerical representation of how far "true watts" varies from "volt-amps"... with a PF of 1.0 meaning that they're equal.
(A non-inductive resistor, or an incandescent light bulb, will have a PF of 1.0 )
In general, with consumer power usage, there is little interest in the exact PF of the total of all the appliances in your home.
But, with major commercial accounts, which consume massive amounts of power, there is often a "penalty" for an overall PF that varies too widely from 1.0 .
(This is why most "heavy industrial equipment" is "power-factor adjusted" - but consumer gear is generally not.)

Dec 18, 2022 20:17:15 GMT -5 leonski said:

I don't know if what I saw is important or NOT.
I looked up a random video on 'balanced load' and just looked......

First? Guy talked about AMPS and the meter / bill part of things. His claim was that balancing amps actually reduces your bill.
What does my meter actually measure? Watts /VA? Or amps? Ive always been told that power is WATTS.......than learned later about PF.
So dividing it up differently shouldn't make a difference?

But one thing in the video that disturbed me was his fast and loose with what he measured. The voltages didn't 'add up'
If your house is like mine.....2 hots and a neutral AND a long copper ground rod.......very near the box and several fee long......
The 2 hots should be pretty close to the same voltage. Say 115 or so....with 230 across? Is that right? The guy in the video
couldn't seem to do that and was very concerned with amps.
I'd like to find out what happens IF L1 (line 1) and L2 are different voltages as they are LIKELY TO BE and you feed different parts of your stereo FROM THEM
Now, you have several volts difference ON THE SAME NEUTRAL feeding your gear. Won't that be a potential problem?

That was the reason for a single-side feed.....

I'd like to have an electrician chime in on this!

[KeithL]

I absolutely agree...

Arranging the circuits to "look better" is absolutely NOT the best idea...
In general an electrician is going to try to "balance the loads on the two sides"...
However, they will also often try to avoid potential issues...
For example, in most cases, there are several outlets on each circuit....
And, in a modern home, it might "make sense" to put the outlets in each room on the same circuit...
But, in the past, this was usually NOT the case...

Often a given circuit would be "run down one wall" or "run down one side of the house"...
And, for example, you would NOT want a single circuit going to the kitchen counter and the bathroom sink outlet.
(Because you're likely to pop that circuit breaker if someone tries to use a hair dryer in the bathroom while the microwave in the kitchen is on.)

In the case of audio gear it's "nice" to think that "everything in your theater room is on a separate circuit"....
But, in reality, that "separate circuit" has it's own circuit breaker, and its own wire run to your breaker panel, but shares "it's side of the big transformer" with half of your house...
So, would you prefer it to be on the same side as your air conditioner, which pops on and off at odd times, or the side with your dryer, which you only run occasionally, and can avoid running if it causes interference?
(That's a trick question... if you have an electric dryer it probably runs on 230 VAC and so may use both sides of the transformer... or an entirely separate winding.)

Dec 18, 2022 13:45:02 GMT -5 ttocs said:

Dec 18, 2022 12:44:03 GMT -5 brianlh said:

I still need to run out to the store and grab those;  Its a bit of a drive and I haven't found the time quite yet.  Might have to do this during my lunch break on Monday.

So - my circuits are not on one side of the box.  Rats.  I did not consider this and didn't tell the electrician who installed them.  I am using 2x on each side.  The 5th circuit is on the right side of the panel, but has nothing plugged into it.  

Moving them is probably possible, but will take some careful planning, as my box is about full;  I have 36x slots, but the house was not wired very efficiently way back when and I think grouping them all together will require swapping other breakers.

They don't need to "all" be on one side, but pairs of circuits for similar loads is better to be consecutive numbered circuits, like, #15 & #17, or, #10 & #12, etc.

I wouldn't go about swapping breakers around without some guidance from someone who knows about planning how a breaker panel is arranged. I did this about 6 years ago thinking I could "arrange and group my av circuits" and ran into some odd behavior related to imbalance. Some pairs of circuits were "doubled up" on the Neutral, and others weren't. So I swapped things back to how they were before. This is when I learned a tiny bit about load balancing. My electrician knew what he was doing. So one thing I learned was not to arrange circuits in a panel so it "looked better".

[KeithL]

I realized that I said a lot about line voltages and circuits... but I didn't answer your exact question.

First you need to remember that line voltage is AC voltage.
That means that "the lines having different voltages" is NOT the same as if they have different ground potentials.
If one circuit measures 120 VAC then it carries a sine wave that goes from about -170 V peak to about +170 V peak (I'm not going to look up the exact RMS to peak conversion).
And, if another circuit runs on 115 VAC then it carries a sine wave that goes from about -163 V peak to about +163 V peak.
They may, and probably do, have the same ground references... but nothing in the measurement, or the difference between them, actually tells us that.
Since the ground reference is probably the same, and the secondary side is isolated anyway, this isn't going to make ANY difference to the gear you're using.

And, if the equipment you're talking about is a preamp, or a source component, or a processor, then it has a regulated power supply... so that difference is meaningless.
And, if it's a power amp, with an unregulated power supply, the most it will mean is a difference of a few percent in the maximum power available.
(Some vintage gear is actually sensitive to small differences like that, and especially some tube gear, but most modern gear is not.) 

Average line voltage across the USA varies widely... from a low of about 110 VAC, to a high of about 127 VAC (where I used to live on Long Island).
It can also vary by more than +/-5% in a single location over the course of a typical day.
The single item that was historically the most sensitive to line voltage was old style incandescent light bulbs.
(Remember that, for a resistor, power consumed is proportional to the voltage squared.)
(And, yes, incandescent bulbs actually were rated for "110 VAC" or "120 VAC" - for those who actually bothered to read the rating.)
Plug a "110 V" incandescent light bulb into a 125 V circuit and it will run brighter and whiter but at a noticeably reduced service life...
Plug a "120 V" incandescent light bulb into a 110 V circuit and it will be a bit dim, and somewhat yellowish, but will have a significantly longer life (maybe as much as double).
(When you run an incandescent filament at a higher temperature it makes whiter light, and is more efficient, but burns out much more quickly.)
However, of course, modern LED light bulbs are almost totally INSENSITIVE to line voltage.

Dec 18, 2022 20:17:15 GMT -5 leonski said:

I don't know if what I saw is important or NOT.
I looked up a random video on 'balanced load' and just looked......

First? Guy talked about AMPS and the meter / bill part of things. His claim was that balancing amps actually reduces your bill.
What does my meter actually measure? Watts /VA? Or amps? Ive always been told that power is WATTS.......than learned later about PF.
So dividing it up differently shouldn't make a difference?

But one thing in the video that disturbed me was his fast and loose with what he measured. The voltages didn't 'add up'
If your house is like mine.....2 hots and a neutral AND a long copper ground rod.......very near the box and several fee long......
The 2 hots should be pretty close to the same voltage. Say 115 or so....with 230 across? Is that right? The guy in the video
couldn't seem to do that and was very concerned with amps.
I'd like to find out what happens IF L1 (line 1) and L2 are different voltages as they are LIKELY TO BE and you feed different parts of your stereo FROM THEM
Now, you have several volts difference ON THE SAME NEUTRAL feeding your gear. Won't that be a potential problem?

That was the reason for a single-side feed.....

I'd like to have an electrician chime in on this!

[leonski]

I TEND to not be in full agreement with Keith's talk about PF.

Today? Might not be a big issue in a home. Especially IF you are always over 0.9 or so.

But in FACTORIES where draw is potentially HUGE and the PF can drop below maybe 0.8 or 0.85, the power company may in some cases
have an add-on to the bill.
Not a trivial sum. My company had a 6 digit electric bill MONTHLY because of the incredible power usage nature of semiconductor processing.



And while VOLTAGE varies a bit across time and location, the FREQUENCY, which is the important part, is for all practical purposes SPOT ON......Maybe max of 0.01% or LESS off......

And while modern gear CAN run successfully (even those with Linear PS) from maybe under 115vac to over 130vac? I'm concerned with 2 legs in your house being that 15vac apart, feeding 2 pieces
of gear.
Let's take WORST CASE SCENARIO and say one is wired with a Hot / Neutral REVERSE.....at the PS. While the plug and all house wiring is fine......

My Panamax shuts OFF the its outlets OVER 135vac and UNDER 95vac and it works........

As for tube gear?    Much vintage designed for maybe 110 and running at near-120 CAN end up making problems.    I've see where SOME remakes of say......the Dynaco ST70 use
a slightly different winds ratio on the power transformer so the B+ stays within range given the higher voltage LIKELY to be encountered by modern users.....


I shut stuff OFF and unplug when my voltage drops beneath about 115. Around HERE? that is brown-out territory........

[brianlh]

Alright - problem fixed. And I really should have caught this before. I followed the advice way at the top and carefully unplugged RCA cables, etc. Turns out, it's my ethernet cable -> Anthem. I did a poor job of re-testing after replacing the cable injector with a dedicated line. I really thought I had tested it, but clearly not or not correctly.

I am leaking from a PoE injector that runs one of my wifi access points - I figured that out by turning them off one by one. I did not realize this could happen (And I feel like it should not be)? My ethernet cables are not the grounded type, so somehow I am getting noise that is being transmitted.

Anyway, for now, all I had to do was setup WiFi on the MRX-1140 and stop plugging in the ethernet cable. I can still use my dedicated drop for the TV/Shield/etc

After reading all of the above, I am going to leave the circuits alone and as-is.

-thanks,

Brian

[brianlh]

An slight update.  Thanks to all of the helpful suggestions in this post, I was able to solve a follow up problem.

I plugged in an HTPC that was only used to play games via steam, etc.  Well of course - this caused a new ground loop via the HDMI connection.  This was a loud buzz for for the L/C/R channels; the other 12 speakers where not affected.

The noise increased based on how much load the GPU was under - an Nvidia 2070. Unplugging the HDMI cable removed the ground loop entirely.

I was able to fix this by - 

1. Buying a grounding block via amazon 
2. Getting some 12 gauge wire and clips, and the compression tool.
3. Connecting the following to the grounding block

A. My anthem 1140 via the chaiss ground screw.
B. My Emotiva XPA-5 (had to scape some paint off)
C. My OSD Nero XA3200 (had to scape some paint off)

Bingo - ground loop gone.

thanks so much everyone for your suggestions above.

-Brian