Adion
bigron1 wrote :
In fact I don't like power cables full stop.
They're always a potential threat.
They're always a potential threat.
At up to 3000w rms that you listed you should consider your speaker cables an equal threat, that is not safer than a power cable!
I wouldn't think setup speed would be that much different, rolling out just a speaker cable (and setting up the amp) vs rolling out speaker and power cable (and not having to set up an amp)
Inviato Sun 24 Jan 16 @ 4:17 pm
Charlie Wilson
bigron1 wrote :
They're all powerful (@ 550w rms per channel into 4 ohm).
This is not powerful! if your going to buy an amp I suggest basing your power off 8 ohm so your covered for any eventuality.
The equivalent Peavey, Crown, and QSC amps are all about the same price, Behringer are a lot cheaper
PV, Crown and QSC. it is hard to compare PV with the other two they are in a different market place.
They're all powerful (@ 550w rms per channel into 4 ohm).
This is not powerful! if your going to buy an amp I suggest basing your power off 8 ohm so your covered for any eventuality.
The equivalent Peavey, Crown, and QSC amps are all about the same price, Behringer are a lot cheaper
PV, Crown and QSC. it is hard to compare PV with the other two they are in a different market place.
Inviato Sun 24 Jan 16 @ 4:57 pm
VDJ Ron
@groovin
"It's not a race!" but it is a race to get into and out of a venue. Venue staff are needed to open up on my arrival, and close after I finish. They always want me in and out quick.
"Who says the power and signal cables have to run alongside each other? Even if/when I do run them that way, the signal cables are shielded and balanced." Do you enjoy crawling around on the floor trying to hold the cables together so you can tape them down? However if you don't run them together there will be wires and tape all over the place. A mess in fact.
"As for the "need" for wide speaker spread, the farthest I'd set my speakers is maybe 15ft apart. Usually they're 8-10ft. Few (If any) gigs have required different." It appears you don't work on many big stages, I often want a speaker on the extremes of a stage, both left and right. Mind you, I do karaoke.
Adion the 3000WRMS is just a thought which I have not tried.
If we did a little experiment and removed the insulation on a speaker cable at low voltage DC, and UK mains cable at 240v AC I think I would prefer to encounter the speaker cable. What would you choose ?
240V AC can easily kill.
Charlie we do have 8 ohm speakers which did require a significantly more expensive amplifier than similar 4 ohm speakers. It also was heavier.
Between us we bought 2 x pv1500, and 1 pv2600 last year.
Would you like to explain the advantages of 8 ohm speakers?
I have mention two disadvantages.
Keep in mind that our amplifier world is drastically changing, and the class D amplifiers mostly seem to be able to drive 2 ohm loads.
"It's not a race!" but it is a race to get into and out of a venue. Venue staff are needed to open up on my arrival, and close after I finish. They always want me in and out quick.
"Who says the power and signal cables have to run alongside each other? Even if/when I do run them that way, the signal cables are shielded and balanced." Do you enjoy crawling around on the floor trying to hold the cables together so you can tape them down? However if you don't run them together there will be wires and tape all over the place. A mess in fact.
"As for the "need" for wide speaker spread, the farthest I'd set my speakers is maybe 15ft apart. Usually they're 8-10ft. Few (If any) gigs have required different." It appears you don't work on many big stages, I often want a speaker on the extremes of a stage, both left and right. Mind you, I do karaoke.
Adion the 3000WRMS is just a thought which I have not tried.
If we did a little experiment and removed the insulation on a speaker cable at low voltage DC, and UK mains cable at 240v AC I think I would prefer to encounter the speaker cable. What would you choose ?
240V AC can easily kill.
Charlie we do have 8 ohm speakers which did require a significantly more expensive amplifier than similar 4 ohm speakers. It also was heavier.
Between us we bought 2 x pv1500, and 1 pv2600 last year.
Would you like to explain the advantages of 8 ohm speakers?
I have mention two disadvantages.
Keep in mind that our amplifier world is drastically changing, and the class D amplifiers mostly seem to be able to drive 2 ohm loads.
Inviato Mon 25 Jan 16 @ 3:08 am
VDJ Ron
My karaoke singers, and I did not detect any difference in the sound quality of the Peavey pv1500, and the Inuke 3000.
My small, light, and powerful Inuke 3000 was part of a 1000 W RMS active laptop stand. It was the most solid stand I have as yet owned. It also looked ok.
I don't think there is much of a difference in amplifiers of the same class, and power nowadays. All are made in China.
My small, light, and powerful Inuke 3000 was part of a 1000 W RMS active laptop stand. It was the most solid stand I have as yet owned. It also looked ok.
I don't think there is much of a difference in amplifiers of the same class, and power nowadays. All are made in China.
Inviato Mon 25 Jan 16 @ 3:46 am
Adion
bigron1 wrote :
Adion the 3000WRMS is just a thought which I have not tried.
If we did a little experiment and removed the insulation on a speaker cable at low voltage DC, and UK mains cable at 240v AC I think I would prefer to encounter the speaker cable. What would you choose ?
240V AC can easily kill.
If we did a little experiment and removed the insulation on a speaker cable at low voltage DC, and UK mains cable at 240v AC I think I would prefer to encounter the speaker cable. What would you choose ?
240V AC can easily kill.
Who said anything about low voltage?
3000W @ 8ohm adds up to a voltage of 150V and a current of nearly 20A
That can easily kill as well.
Inviato Mon 25 Jan 16 @ 7:29 am
VDJ Ron
Adion were off on a big question again. It is interesting.
http://peavey.com/support/technotes/poweramps/bridgemode.cfm
http://www.candlepowerforums.com/vb/showthread.php?261353-When-does-DC-voltage-become-dangerous
You have took an extremely simplistic view, neglecting factors such as crossovers, and bi-amp setups which distribute the load.
Put simple I would keep well away from a naked live 240v AC UK power cable.
It normally would be PAT tested to ensure safety in public venues, but there are no such regulations for speaker cables.
An interesting example of a quite powerful system is a car battery/starter motor. The battery terminals are heavy duty, yet you can touch them without fear of death.
The rectified, and reduce voltage on the rails of an amplifier are much less dangerous than the supply voltage in the UK.
http://peavey.com/support/technotes/poweramps/bridgemode.cfm
http://www.candlepowerforums.com/vb/showthread.php?261353-When-does-DC-voltage-become-dangerous
You have took an extremely simplistic view, neglecting factors such as crossovers, and bi-amp setups which distribute the load.
Put simple I would keep well away from a naked live 240v AC UK power cable.
It normally would be PAT tested to ensure safety in public venues, but there are no such regulations for speaker cables.
An interesting example of a quite powerful system is a car battery/starter motor. The battery terminals are heavy duty, yet you can touch them without fear of death.
The rectified, and reduce voltage on the rails of an amplifier are much less dangerous than the supply voltage in the UK.
Inviato Mon 25 Jan 16 @ 1:40 pm
Adion
It was only an example to show the range that you could be in for PA class audio. I did also use 8 ohm in the calculation, but that is typically only the minimum impedance of the speaker. At some frequencies the impedance will be higher.
If you want an example that is closer to your personal use case, take a look at the specs of the Peavy 1012: http://assets.peavey.com/literature/manuals/80304759.pdf
Even bi-amped, the low frequency part of a single speaker is still capable of handling 1000W continuous, and peaks up to 2000W
At around 100Hz, the impedance climbs to 30 Ohm, which means an average of 5A @ 170V is flowing through the wires. (And that is an alternating current, so the peak voltage will be even higher)
I'd still be careful with broken speaker cables as well!
If you want an example that is closer to your personal use case, take a look at the specs of the Peavy 1012: http://assets.peavey.com/literature/manuals/80304759.pdf
Even bi-amped, the low frequency part of a single speaker is still capable of handling 1000W continuous, and peaks up to 2000W
At around 100Hz, the impedance climbs to 30 Ohm, which means an average of 5A @ 170V is flowing through the wires. (And that is an alternating current, so the peak voltage will be even higher)
I'd still be careful with broken speaker cables as well!
Inviato Mon 25 Jan 16 @ 2:01 pm
PhantomDeejay
I shouldn't really bother since you seem to know everything, but please remember:
AC power outlets have short circuit breakers (board security ? I don't know how you call them in UK) specially designed to prevent humans from getting electrocuted.
Powered amps have fuses / circuit breakers designed to protect the equipment itself, not human beings from getting electrocuted
Let's do some simplified maths around laws of electricity:
V=IxR and P=VxI
That makes us this nice formula P=IxIxR
If we put 6000 Watts on one side and 8Ohms on the other we have a current flow of 27.4 Amperes.
Now let's say that we take this cable and we "connect" it directly on a humans body. What we change on the above equation is the resistance (R).
Let's take the best case scenario which is that the human body can have a resistance up to 100000 Ohms. (In reality it depends on many factors and it can be anywhere from 100 Ohms to 100000 Ohms)
If we do that we have that the current flow will be 0.24 Amperes. It doesn't seem much, right ?
Yet, you may die by electrocution with any current greater than 0.1 Amperes depending on the route of the electricity on your body (entry/exit points) while death is almost certain with currents greater than 0.2 Amperes because your body can no longer breath as well.
If all these mean nothing to you let's take another combination of the above 2 laws: P=VxV/R
This means that for a power output of 6000Watts (at 8 Ohms) the amplifier needs to provide 219 Volts!!!
Yes! It needs to provide the same amount of volts as your AC plug!
The same power at 4 Ohms require 155Volts, and at 2 Ohms 110 Volts
Conclusion: High Wattage amps are as dangerous as AC plugs. Don't underestimate them. It's very foolish to think that they cannot harm you because they provide DC current or because you assume they don't produce enough current to kill a human.
PS: It's the current (amperes) that kills, but it's the Volts that make the current move. One cannot exist without the other. On your car example you have a 12 Volts battery which even on worst case scenario of human resistance been as low as 100 Ohms it can only provide 0.02Amperes of current which are enough for a nice shock, but not enough to kill you.
AC power outlets have short circuit breakers (board security ? I don't know how you call them in UK) specially designed to prevent humans from getting electrocuted.
Powered amps have fuses / circuit breakers designed to protect the equipment itself, not human beings from getting electrocuted
Let's do some simplified maths around laws of electricity:
V=IxR and P=VxI
That makes us this nice formula P=IxIxR
If we put 6000 Watts on one side and 8Ohms on the other we have a current flow of 27.4 Amperes.
Now let's say that we take this cable and we "connect" it directly on a humans body. What we change on the above equation is the resistance (R).
Let's take the best case scenario which is that the human body can have a resistance up to 100000 Ohms. (In reality it depends on many factors and it can be anywhere from 100 Ohms to 100000 Ohms)
If we do that we have that the current flow will be 0.24 Amperes. It doesn't seem much, right ?
Yet, you may die by electrocution with any current greater than 0.1 Amperes depending on the route of the electricity on your body (entry/exit points) while death is almost certain with currents greater than 0.2 Amperes because your body can no longer breath as well.
If all these mean nothing to you let's take another combination of the above 2 laws: P=VxV/R
This means that for a power output of 6000Watts (at 8 Ohms) the amplifier needs to provide 219 Volts!!!
Yes! It needs to provide the same amount of volts as your AC plug!
The same power at 4 Ohms require 155Volts, and at 2 Ohms 110 Volts
Conclusion: High Wattage amps are as dangerous as AC plugs. Don't underestimate them. It's very foolish to think that they cannot harm you because they provide DC current or because you assume they don't produce enough current to kill a human.
PS: It's the current (amperes) that kills, but it's the Volts that make the current move. One cannot exist without the other. On your car example you have a 12 Volts battery which even on worst case scenario of human resistance been as low as 100 Ohms it can only provide 0.02Amperes of current which are enough for a nice shock, but not enough to kill you.
Inviato Mon 25 Jan 16 @ 3:00 pm
VDJ Ron
I know I don't know everything Phantomdj, and I'm glad of your wisdom. If I disagree, I'll argue my case against anyone. You are a resident expert. I'm a qualified mechanical engineer who studied electronic, and electrical engineering around 45 years ago. It does not trouble me if I'm wrong, as long as I learn. This thread is becoming something special. Your expertise has ensured that.
Respect.
Respect.
Inviato Mon 25 Jan 16 @ 3:45 pm
VDJ Ron
I forgot to thank Adion for his comments.
I found the last one particularly interesting.
I found the last one particularly interesting.
Inviato Mon 25 Jan 16 @ 6:42 pm
blckjck
PhantomDeejay wrote :
AC power outlets have short circuit breakers (board security ? I don't know how you call them in UK) specially designed to prevent humans from getting electrocuted.
Just to clarify if someone else reads this. Standard circuit breakers are only there to keep the wiring from being overloaded. They will allow you to be electrocuted. If you are a shorter path to neutral, the electricity will flow thru you and most likely will not trip a regular breaker. Ground fault circuit interrupting breakers (GFCI) are designed to help you avoid electrocution.
Heck, you can hook up a copper wire into your standard breaker, run it outside your house, stick it into the ground, and turn on the breaker. It will not trip the breaker. But, it still has to potential to electrocute you. DON'T TRY IT!
Inviato Mon 25 Jan 16 @ 10:58 pm
PhantomDeejay
blckjck wrote :
Ground fault circuit interrupting breakers (GFCI) are designed to help you avoid electrocution.
That! :)
Honestly if I would try to translate the Greek term it would be meaningless to you and therefore I used the closest translation I could find.
Greek to English term would end up to something like: Automatic Escape Relay.
Which effectively means a device that automatically breaks the circuit if it detects that electricity has "escaped" from the standard circuit to Ground cables or even worse via other objects to the Ground. It measures the potential difference between the phase and neutral conduits and if it detects a "loss" of 30mA it breaks the circuit.
I hope we are talking about the same device... :)
Inviato Mon 25 Jan 16 @ 11:25 pm
blckjck
PhantomDeejay wrote :
That! :)
Honestly if I would try to translate the Greek term it would be meaningless to you and therefore I used the closest translation I could find.
Greek to English term would end up to something like: Automatic Escape Relay.
Which effectively means a device that automatically breaks the circuit if it detects that electricity has "escaped" from the standard circuit to Ground cables or even worse via other objects to the Ground. It measures the potential difference between the phase and neutral conduits and if it detects a "loss" of 30mA it breaks the circuit.
I hope we are talking about the same device... :)
blckjck wrote :
Ground fault circuit interrupting breakers (GFCI) are designed to help you avoid electrocution.
That! :)
Honestly if I would try to translate the Greek term it would be meaningless to you and therefore I used the closest translation I could find.
Greek to English term would end up to something like: Automatic Escape Relay.
Which effectively means a device that automatically breaks the circuit if it detects that electricity has "escaped" from the standard circuit to Ground cables or even worse via other objects to the Ground. It measures the potential difference between the phase and neutral conduits and if it detects a "loss" of 30mA it breaks the circuit.
I hope we are talking about the same device... :)
We are talking about the same thing. I like your name better. It more accurately describes how the device functions.
Inviato Mon 25 Jan 16 @ 11:40 pm
Mobile Zombie
A big difference between 219VAC output from an amplifier compared to mains outlet is that in the amp case the output are isolated from ground.
This means that no current can flow through your body to the floor as in the case of mains.
Of course if you expose yourself to 219VAC amplifier output voltage between your both arms, the case is equally harmful.
That's why one hand should stay in your pocket. LOL
This means that no current can flow through your body to the floor as in the case of mains.
Of course if you expose yourself to 219VAC amplifier output voltage between your both arms, the case is equally harmful.
That's why one hand should stay in your pocket. LOL
Inviato Tue 26 Jan 16 @ 10:53 am
PhantomDeejay
MrJackson2014 wrote :
A big difference between 219VAC output from an amplifier compared to mains outlet is that in the amp case the output are isolated from ground.
This means that no current can flow through your body to the floor as in the case of mains.
This means that no current can flow through your body to the floor as in the case of mains.
That's plain wrong thinking over there...
If you touch a single conduit of AC current and electricity can't find a way to close the circuit (in other words to travel through your body somewhere) you still don't get electrocuted.
On the amp example, if you touch one conduit and then you touch the "earth" you will get electrocuted. The reason is that the earth is considered to have "zero" dynamic differential and the current will close circuit through you to travel to the earth. One of the basic laws of electricity is that the current travels through the fastest way (in other words through the way with the less resistance) from higher to lower voltage.
Since earth's voltage is considered to be "zero" all currents will travel to earth if they can close circuit instead of "keep going their previous path" to another differential point.
PS: You can't "isolate" even a car battery from earth. If you put a wire on one pole and the other on earth, current WILL flow from battery to earth...
Inviato Tue 26 Jan 16 @ 11:56 am
Mobile Zombie
I appreciate your efforts, but I have been designing PSU's and amps for half of my life...
Why do you think all consumer electrical devices must be isolated from mains?
Why do you think all consumer electrical devices must be isolated from mains?
Inviato Tue 26 Jan 16 @ 12:28 pm
PhantomDeejay
Their ground safety is used for current that may escape from the circuit and flow on the chassis of the device.
In such case if you touch a chassis and you close circuit with earth you will get electrocuted.
Ground safety is there so that if current escapes it will travel through the safety conduit down to earth (instead of you). Since the conduit has much less resistance than your body, in the hypothetical scenario that the device leaks current when you touch it most of the current will travel to earth from the ground conduit instead of your body (You and the ground conduit are connected in parallel). Also the GFCI (as it's called from the Americans) will detect either the leak of current, or the current flow through earth conduit (depending on it's design) and will brake the circuit.
That's why we use Ground safety. Also, not all consumer electrical devices use ground safety. On most countries devices are forced to use ground safety only on devices with a metal chassis or exposed metal parts that may produce risk to the consumer if the circuit of the device leaks current.
Also since you say that you design PSU's and Amps you should also know that there's a difference between Ground safety and a circuits "ground" which is used as a conduit...
Anyway, as I said above my English don't help me to explain it the best way I can. However, 100 or 200 V can be lethal no matter how they are produced (by your electric company, by a diesel AC generator, by a transformer, e.t.c.)
If you want to say people otherwise, fine. However I don't wish to be held responsible for someone's foolishness if they get an electroshock because they thought that a power audio amp can't harm them. And remember we were talking about amps capable to produce 3KW RMS (or 6KW Max, or 12KW Peak). Not amps that produce 50 or 250 Watts.
In such case if you touch a chassis and you close circuit with earth you will get electrocuted.
Ground safety is there so that if current escapes it will travel through the safety conduit down to earth (instead of you). Since the conduit has much less resistance than your body, in the hypothetical scenario that the device leaks current when you touch it most of the current will travel to earth from the ground conduit instead of your body (You and the ground conduit are connected in parallel). Also the GFCI (as it's called from the Americans) will detect either the leak of current, or the current flow through earth conduit (depending on it's design) and will brake the circuit.
That's why we use Ground safety. Also, not all consumer electrical devices use ground safety. On most countries devices are forced to use ground safety only on devices with a metal chassis or exposed metal parts that may produce risk to the consumer if the circuit of the device leaks current.
Also since you say that you design PSU's and Amps you should also know that there's a difference between Ground safety and a circuits "ground" which is used as a conduit...
Anyway, as I said above my English don't help me to explain it the best way I can. However, 100 or 200 V can be lethal no matter how they are produced (by your electric company, by a diesel AC generator, by a transformer, e.t.c.)
If you want to say people otherwise, fine. However I don't wish to be held responsible for someone's foolishness if they get an electroshock because they thought that a power audio amp can't harm them. And remember we were talking about amps capable to produce 3KW RMS (or 6KW Max, or 12KW Peak). Not amps that produce 50 or 250 Watts.
Inviato Tue 26 Jan 16 @ 1:14 pm
Adion
I think what MrJackson means is that the + and - outputs of an amplifier are floating compared to the ground. There is a potential between the 2 wires of 170V, but if you would touch just one of the wires, you would 'pull' that wire towards the ground, and it effectively becomes 0V compared to ground.
The other wire is now oscilating around that potential, and touching the other wire as well would allow current to flow.
I'm not entirely sure that it's the case in all PSU or amplifier designs that neither wire is grounded though, so I would still be careful :p
The other wire is now oscilating around that potential, and touching the other wire as well would allow current to flow.
I'm not entirely sure that it's the case in all PSU or amplifier designs that neither wire is grounded though, so I would still be careful :p
Inviato Tue 26 Jan 16 @ 1:42 pm
PhantomDeejay
BTW: After doing some translation:
Isolated circuits (eg by using a 1:1 transformer) reduce the danger of electrocution, that's true. Also it's true that you are not in a potential risk as soon as
1) You touch one conduit only and
2) The other conduit is not closing circuit with Ground conduit by mistake or malfunction.
Therefore: Yes, isolated circuits provide more security. But that doesn't mean that electrocution is still not possible.
Isolated circuits (eg by using a 1:1 transformer) reduce the danger of electrocution, that's true. Also it's true that you are not in a potential risk as soon as
1) You touch one conduit only and
2) The other conduit is not closing circuit with Ground conduit by mistake or malfunction.
Therefore: Yes, isolated circuits provide more security. But that doesn't mean that electrocution is still not possible.
Inviato Tue 26 Jan 16 @ 1:46 pm
blckjck
PhantomDeejay wrote :
If you touch a single conduit of AC current and electricity can't find a way to close the circuit (in other words to travel through your body somewhere) you still don't get electrocuted.
On the amp example, if you touch one conduit and then you touch the "earth" you will get electrocuted. The reason is that the earth is considered to have "zero" dynamic differential and the current will close circuit through you to travel to the earth. One of the basic laws of electricity is that the current travels through the fastest way (in other words through the way with the less resistance) from higher to lower voltage.
Since earth's voltage is considered to be "zero" all currents will travel to earth if they can close circuit instead of "keep going their previous path" to another differential point.
PS: You can't "isolate" even a car battery from earth. If you put a wire on one pole and the other on earth, current WILL flow from battery to earth...
On the amp example, if you touch one conduit and then you touch the "earth" you will get electrocuted. The reason is that the earth is considered to have "zero" dynamic differential and the current will close circuit through you to travel to the earth. One of the basic laws of electricity is that the current travels through the fastest way (in other words through the way with the less resistance) from higher to lower voltage.
Since earth's voltage is considered to be "zero" all currents will travel to earth if they can close circuit instead of "keep going their previous path" to another differential point.
PS: You can't "isolate" even a car battery from earth. If you put a wire on one pole and the other on earth, current WILL flow from battery to earth...
This is correct in that the Earth will conduct electricity. And that it closes the electrical path. However, it is not the destination for the electricity. Power plans sink conductors from their neural lines into the earth at various points along their distrobution. When you touch the "hot" leg, your body and the earth become more conductors to the neutral leg completing the path back to the power plant.
With your car battery example. If only one terminal is in the ground, and nothing touches the other, then nothing happens. If there is a conductor from both to the earth, then the earth merely becomes a conductor itself. It is still not a destination.
Inviato Tue 26 Jan 16 @ 2:56 pm
