Think I could use help running my Crown XLS 1502's correctly

GrimSurfer

GrimSurfer

Senior Audioholic
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221 9 11
#61
Nice looking rig, Dan. The first thing I'd suggest is to space the Crowns out more because the owner's manual for the XLS says to keep things away from the top and bottom because that's where there the magnetic fields are the strongest with these amps.

The second thing I'd do is try to figure out the frequency of the hum/noise. Download some pure tones and see which one is closest to what you've been hearing (think of it as an A-B test). If it's ~50-70 Hz, you're likely facing a ground loop issue.

If this is the case, do not, under any circumstances, change the grounding plug/pin on your gear. Doing so increases the risk of electrocution on gear that isn't double insulated.

You can play around with how your gear is plugged in using its original cords. Try to get everything on the same circuit... or same socket, if that's feasible/safe.

If this is not the case, tell us what frequency is the closest. This could tell us whether the hum/noise is EMI/RF and where it might be getting picked up by the audio chain (such as if speaker wires are even fractions of a specific wavelength up to 1 lambda, which would make them really good antennae).
 
GrimSurfer

GrimSurfer

Senior Audioholic
Ratings
221 9 11
#63
.So that begs the question:
"Is there a fundamental difference between the design of the Crowns and your AVR, or is the ground there purely due to the additional risks posed by the pro audio environment?"
Yup. Pro gear is usually grounded because it could be used in difficult environments, like under a marquee or on stage where there's a risk of moisture.

Pro gear almost always uses balanced connectors between components to bring EMI and RF interference down to ground.

Also, low levels of internal noise in the amplifier stage isn't a big issue in PA gear because they are used in high noise environments (relative to a famIly room etc.) and at very high volumes (which is where these amps operate best) the internal noise is masked.
 
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AcuDefTechGuy

AcuDefTechGuy

Seriously, I have no life.
Ratings
7,394 19 6
#64
For one thing, AVR-amps and AVR-derived Amps (especially Yamaha) have pretty conservative protection circuits. The Yamaha MX-A5000 11Ch amp will go into protection mode if All-7Ch is driven. So that's probably why they don't need that 3rd/Ground Prong.

But those 200W x 7 and 300W x 7 consumer amps are more powerful.
 
KEW

KEW

Audioholic Warlord
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#66
Yup. Pro gear is usually grounded because it could be used in difficult environments, like under a marquee or on stage where there's a risk of moisture.

Also, spurious noise at low levels isn't a big issue in PA gear because they are used in high noise environments (relative to a famIly room etc.).
Well, the question I was really getting at is how much additional risk is associated with using a pigtail plug to by-pass the ground. If it is essentially the same risk as using a typical non-grounded AVR in a home environment, then the pigtail is a cheap and easy permanent solution!


I think his noise issue is more than just high noise levels as part of the design of the pro amps. There have been so many people who have bought them for home use and been delighted with their cost/performance ratio, I consider them well established as a good option for home audio.
If he was talking about a hiss he could hear with the volume maxed out when he put his ear near the tweeter, then I might believe it is the less than perfect noise floor of a pro amp, but Danzilla seems to be describing something that no one would be happy about!
We have had several "show me" guys give the Crown amps a try and they are always impressed that it makes for a totally viable alternative to high dollar home gear!

These Crown amps have made significant inroads into the home market (at least among us "forum audio geeks") because of the RCA inputs, the variable input level switch, and a fan that rarely comes on, or when it does runs at a low speed so fan noise is not a problem. These factors resolve all of the most glaring issues of of using a pro amp for home systems (except ground plug).
 
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GrimSurfer

GrimSurfer

Senior Audioholic
Ratings
221 9 11
#67
Cuts down on a lot of headache from consumers complaining about hum noise.
A third prong is used to reduce the risk of electrocution in gear that is not double insulated. Pro gear uses this to advantage by also employing balanced connectors, which drain EMI/RFI to ground (thru the ground plug).

It's just as easy to get ground loops in two plug and three plug circuitry. Just plug them into sockets with different electrical potentials. Electricity will then flow from highest potential to lowest potential. If the path of least resistance is through a pre amp, amp circuit, you'll get hum from the ground loop.

Commercial buildings use bus bars to ensure common ground. Homes have only one connection to ground (the electrical code in most states doesn't permit multiple grounds). This is normally the panel to a water pipe. Bus bars are the most robust/reliable.

Any miswiring at the socket (such as a loose ground wire or reversing neutral and ground) can establish the ideal conditions for a ground loop, regardless of how the building's electrical circuit is configured.
 
GrimSurfer

GrimSurfer

Senior Audioholic
Ratings
221 9 11
#68
Well, the question I was really getting at is how much additional risk is associated with using a pigtail plug to by-pass the ground. If it is essentially the same risk as using a typical non-grounded AVR in a home environment, then the pigtail is a cheap and easy permanent solution!
A pigtail is a cheap, easy and DANGEROUS solution. If somebody gets electrocuted, you're liable... or dead. If there's a fire, the ensuing investigation will give your insurance company a reason to leave you high and dry. If there's a surge, your gear will fry if internal protection circuits cannot shunt to ground.

I just don't see any goodness that would come from a pigtail. None whatsoever.

A two pronged AVR is double insulated. It doesn't need a ground plug. Removing a ground plug on a piece of gear makes it more dangerous than a double insulated device.
 
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S

snakeeyes

Audioholic Samurai
Ratings
962 1 1
#69
Cuts down on a lot of headache from consumers complaining about hum noise.
Ya that’s brilliant! :) Definitely a nice way to go.

By the way I figured out that my main worries were on how MP3 sounded on certain songs. I now just run my music through the Apple TV 4K streamer and eliminate the AVR internal streamer limits. That successfully “uncorked” it. :)

Now I can save up for better speakers for when I want the next step up. That might take me several months of course. :)
 
KEW

KEW

Audioholic Warlord
Ratings
4,930 22 9
#70
A pigtail is a cheap, easy and DANGEROUS solution. If somebody gets electrocuted, you're liable... or dead. If there's a fire, the ensuing investigation will give your insurance company a reason to leave you high and dry. If there's a surge, your gear and fry if internal protection circuits cannot shunt to ground.

I just don't see any goodness that would come from a pigtail. None whatsoever.

A two pronged AVR is double insulated. It doesn't need a ground plug. Removing a ground plug on a piece of gear makes it more dangerous than a double insulated device.
I would agree with you if you know that the Crown is not double insulated!
If we know that then my question is answered.
 
GrimSurfer

GrimSurfer

Senior Audioholic
Ratings
221 9 11
#71
A third prong is used to reduce the risk of electrocution in gear that is not double insulated. Pro gear uses this to advantage by also employing balanced connectors, which drain EMI/RFI to ground (thru the ground plug).

It's just as easy to get ground loops in two plug and three plug circuitry. Just plug them into sockets with different electrical potentials. Electricity will then flow from highest potential to lowest potential. If the path of least resistance is through a pre amp, amp circuit, you'll get hum from the ground loop.

Commercial buildings use bus bars to ensure common ground. Homes have only one connection to ground (the electrical code in most states doesn't permit multiple grounds). This is normally the panel to a water pipe. Bus bars are the most robust/reliable.

Any miswiring at the socket (such as a loose ground wire or reversing neutral and ground) can establish the ideal conditions for a ground loop, regardless of how the building's electrical circuit is configured.
I would agree with you if you know that the Crown is not double insulated!
If we know that then my question is answered.
If it has a ground plug, then it is unlikely to be double insulated. Double insulated circuits cost money. So do grounded circuits. There's no financial or performance advantage to do both... it doesn't make sense either.
 
ski2xblack

ski2xblack

Audioholic General
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779 6 4
#72
But when I turn the gain down a few clicks on the Crowns and eliminate the hum and go back and forth between the Crowns and Emotiva there is a noticeable drop in dynamics and midrange presence a little on the highs when the denon is at the same volume level between both amps.
The Emo's have fixed gain at full tilt boogie, so you're amplifying the noise floor with them as much as you would with the Crown with it's gain controls maxed. Louder typically sounds better to the ear, but be careful the dynamics and mids aren't also coming along with higher noise as well. The crown with the gain controls reduced somewhat will probably improve the s/n by a factor of two on the input. It may be inherently noisier than the Emo (Harmon aims for "good enough", and even though the Crown is aimed at primarily pro use in PA systems, it's noise spec should be plenty good enough for home use). I'm surprised that the Emo doesn't result in even more hiss and noise than the Crown.
 
D

Danzilla31

Audioholic Field Marshall
Ratings
932 2
#74
Okay I've got a couple ideas give me like an hour and I'll let you guys know what I found out between the advice you've given me and the article I read from Audioholics I've got some ideas on how to proceed
 
S

snakeeyes

Audioholic Samurai
Ratings
962 1 1
#75
Don't
Don't listen to him there's nothing wrong with being a little high maintenance
I think there is quite a learning curve to understand all the possibilities. My main AVR was purchased in October 2017 and I’m learning new things almost weekly from the people on this forum. (My last AVR was from 2003 so I was moving forward 15 years in technology. LOL :) )
 
D

Danzilla31

Audioholic Field Marshall
Ratings
932 2
#76
I think there is quite a learning curve to understand all the possibilities. My main AVR was purchased in October 2017 and I’m learning new things almost weekly from the people on this forum. (My last AVR was from 2003 so I was moving forward 15 years in technology. LOL :) )
I know man we're like Michael J Fox in back to the future. When he goes to the Future Lol
 
KEW

KEW

Audioholic Warlord
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#77
If it has a ground plug, then it is unlikely to be double insulated. Double insulated circuits cost money. So do grounded circuits. There's no financial or performance advantage to do both... it doesn't make sense either.
You are probably right, and unless some electronics savvy guy who has had one of the Crowns on his bench says otherwise, I'll consider it a non-starter.
If you go back to my original post, I was never saying to use a pigtail unless it turned out that the ground was only used on the Crown only due to the dangerous conditions it would be used in ... such that the risk equated to an in-home AVR.
Can someone who knows electronics discuss the risk?!
I am loathe to ever remove a safety feature!
On the other hand, a pro amp is intended for use in some pretty dicey situations (dragging equipment over cords, rain at outdoor concert, etc) and as ADTG pointed out they are not usually used for home consumer audio gear.

So that begs the question:
"Is there a fundamental difference between the design of the Crowns and your AVR, or is the ground there purely due to the additional risks posed by the pro audio environment?"
In a previous life, I was a Safety Engineer, so I am very conscious of making decisions that can lead to death or injury; however, part of being the Safety Engineer (not Safety Police) is finding out why a safety feature is needed and if it applies to the situation.
A good example is we got written up by OSHA for not having latches on our rigging hooks:
Latch shown on this hook:

When I approved the hooks without the latches I did my homework. The riggers did not want the latches because they got in the way and they did not understand the purpose of the latches (which was when I realized they had destroyed/removed the latches off of the hooks they had bought before my time). After investigating why the hooks were sold both, with and without latches, I found that the latches were critical for keeping stiff wire rope from coming off the hook unintentionally. However, this was not heavy construction and we only used chains for all of our lifting and the latch is not required for use with chain. Consequently, I did not "make" the riggers use hooks with latches (which was the default until learning otherwise).
Regarding OSHA, I prepared a response pointing out where in the OSHA manual latches were not required with chain and they rescinded the citation/fine.
So I am inclined to understand why a safety feature is present rather than fall "in line" too quickly!
 
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lovinthehd

lovinthehd

Audioholic Overlord
Ratings
5,058 18 47
#78
Can someone who knows electronics discuss the risk?!
I am loathe to ever remove a safety feature!
On the other hand, a pro amp is intended for use in some pretty dicey situations (dragging equipment over cords, rain at outdoor concert, etc) and as ADTG pointed out they are not usually used for home consumer audio gear.

So that begs the question:
"Is there a fundamental difference between the design of the Crowns and your AVR, or is the ground there purely due to the additional risks posed by the pro audio environment?"
The risk I referred to is ongoing use of a cheater plug, it's not recommended. Although I did do it for a while with no problems....

ps posted this before I saw the rest of the discussion about lifting the ground on the amp....if it does turn out to be the issue the Ebtech unit is an idea.
 
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KEW

KEW

Audioholic Warlord
Ratings
4,930 22 9
#79
I think there is quite a learning curve to understand all the possibilities. My main AVR was purchased in October 2017 and I’m learning new things almost weekly from the people on this forum. (My last AVR was from 2003 so I was moving forward 15 years in technology. LOL :) )
The new AVR's have lots of nooks and crannies that Gremlins can hide in, and if you don't do right by your family members and one happens to die in the house, I'm convinced there is enough circuitry there to host a malcontent spirit! Christine the car was a little far-fetched, but Christine the AVR is totally viable!
 
KEW

KEW

Audioholic Warlord
Ratings
4,930 22 9
#80
The risk I referred to is ongoing use of a cheater plug, it's not recommended. Although I did do it for a while with no problems....

ps posted this before I saw the rest of the discussion about lifting the ground on the amp....if it does turn out to be the issue the Ebtech unit is an idea.
I understood that, just questioning whether the Crown might be as safe as an AVR without the ground - which might be the case if they only added the ground because of the more dangerous "on-the-road" treatment that pro gear sees.
GrimSurfer is pretty convinced that there are fundamental differences in the design of the pro amp that require the ground to maintain safety in the home environment. I am inclined to believe him.
 

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