And also @jean-paul : Here's a cheat sheet for North American power layout at least in an end user setting.
"The standard U.S. household wiring design has two 120 volt "hot" wires and a neutral which is at ground potential. The two 120 volt wires are obtained by grounding the centertap of the transformer supplying the house so that when one hot wire is swinging positive with respect to ground, the other is swinging negative. This versatile design allows the use of either hot wire to supply the standard 120 volt household circuits. For higher power applications like clothes dryers, electric ranges, air conditioners, etc. , both hot wires can be used to produce a 240 volt circuit."
https://wiki.robotz.com/index.php?title=A/C_Electrical_Wiring_Information_for_North_America
"The standard U.S. household wiring design has two 120 volt "hot" wires and a neutral which is at ground potential. The two 120 volt wires are obtained by grounding the centertap of the transformer supplying the house so that when one hot wire is swinging positive with respect to ground, the other is swinging negative. This versatile design allows the use of either hot wire to supply the standard 120 volt household circuits. For higher power applications like clothes dryers, electric ranges, air conditioners, etc. , both hot wires can be used to produce a 240 volt circuit."
https://wiki.robotz.com/index.php?title=A/C_Electrical_Wiring_Information_for_North_America
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? I'm not sure what you mean? If you connect "PE" (ground) to the metal box the amp is built into, that's considered "safe" in North America. The idea being if there's a fault, the current will dump to ground and blow the fuse/trip the breaker. It's designed more to protect the wiring (and the building from fire) than the user TBH, but it's the standard.
There is a FCC and CE mark on the back of the amp, it may not have the details of the person certifying it.
Some CE marks are self certified, and some need an attorney of the company, who can be arrested, to be appointed for a period of 3 years, must be EU resident, that was for medical devices though.
If the amp takes so much power, better to earth it, not such a big job, change the socket, solder a small piece of wire to the earth pin of the socket, and bolt the other side after crimping a lug to the chassis.
Some CE marks are self certified, and some need an attorney of the company, who can be arrested, to be appointed for a period of 3 years, must be EU resident, that was for medical devices though.
If the amp takes so much power, better to earth it, not such a big job, change the socket, solder a small piece of wire to the earth pin of the socket, and bolt the other side after crimping a lug to the chassis.
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You mean the 3 pin version as never found on consumer audio devices? 🙂 Sharp eyes, I only now notice the CE marking.
The point is that the device does not have PE and apparently is certified. Now I connect all metal casings to PE for various reasons but it is good to first check how things are done internally. I am pretty sure grounding/ground and PE are THE most difficult to understand items in audio/electricity considering the often awkward DIY endeavours one regularly sees.
The point is that the device does not have PE and apparently is certified. Now I connect all metal casings to PE for various reasons but it is good to first check how things are done internally. I am pretty sure grounding/ground and PE are THE most difficult to understand items in audio/electricity considering the often awkward DIY endeavours one regularly sees.
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Yes, I forgot to mention that a three pin socket can be used in more or less the same chassis cut out in place of the two pin socket...
India has two sets of marks, IS: Number, (ie the standard required) and the CM/L Number (Certified Manufacturer/Licensee) Number, so this tells you the standard being followed, and the makers' details as well, which can be found on the Bureau Of Indian Standards (BIS) website.
They are normally together on the equipment, or nearby, easy to check if needed.
This simply says CE, I have no idea if that is legal or not.
I would expect UL, and corresponding German / EU details as well, this thing is on the expensive side.
India has two sets of marks, IS: Number, (ie the standard required) and the CM/L Number (Certified Manufacturer/Licensee) Number, so this tells you the standard being followed, and the makers' details as well, which can be found on the Bureau Of Indian Standards (BIS) website.
They are normally together on the equipment, or nearby, easy to check if needed.
This simply says CE, I have no idea if that is legal or not.
I would expect UL, and corresponding German / EU details as well, this thing is on the expensive side.
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It more seems a cheaply produced device sold for a relatively high price (as often with recent audio devices).
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That happens a lot in Audio, and consumer electronics in general..
Today's Motorola phone will a Lenovo model, slightly different shape, after six months.
Today's Audi will be a VW model after 2 years, and Skoda after further 2 years....
Oppo has taken over One+ phones, same cycle...
Today's Motorola phone will a Lenovo model, slightly different shape, after six months.
Today's Audi will be a VW model after 2 years, and Skoda after further 2 years....
Oppo has taken over One+ phones, same cycle...
An IEC Class II device or appliance may have metal enclosure. Naturally, the enclosure must be double insulated from the mains live internally.
One frequently experiences a tickle when touching the metal case of a Class II device, this is becase the EMI filter capacitors (Y capacitor) form a voltage divider between mains and neutral, the case being the center. This is harmless, but clearly can be source of audio hum.
A Class I device might have different issues, regarding ground loop. There are techniques to prevent it. But as always, everything is about cost. Sometimes a Class II double insulation could cost less, than a simple metal case and protective earth, plus a ground loop breaker.
One frequently experiences a tickle when touching the metal case of a Class II device, this is becase the EMI filter capacitors (Y capacitor) form a voltage divider between mains and neutral, the case being the center. This is harmless, but clearly can be source of audio hum.
A Class I device might have different issues, regarding ground loop. There are techniques to prevent it. But as always, everything is about cost. Sometimes a Class II double insulation could cost less, than a simple metal case and protective earth, plus a ground loop breaker.
And notice that the audio ground on the RCAs are NOT connected to the chassis and that the XLR shells are isolated as well (Black plastic connectors). I wouldn’t be a bit surprised if those RCA’s didn‘t feed directly into differential pairs, same as pins 2 and 1 of the XLRs. That “audio ground” may even be isolated from the chassis by the usual 10 ohm resistor. This can be tested with an ohmmeter to see if true. All this is the usual practice for equipment which DOES have a safety ground - or if one is expected somewhere in the system. So obviously they were thinking about the possibility of ground loops when they designed the thing. It wouldn’t have hurt to put the safety ground on it.Interestingly the case seems devoid of the Class II marking:
Then I noticed something else that might be in play here. 120 and 240 volt status lights, and dual voltage labels - and NO switch for that. That tells me it’s a universal voltage PFC switching supply in there (Since it is the only way to do this). What surprises me is that THAT doesn’t have a safety ground. The innards would need to be veeeerrrry well insulated and very well designed to qualify as “double insulated”.
Things that were made in China don’t always have REAL safety certs - they find ways around that too.
The radios of both current valves were a guarantee for electrocution. If the plug was connected in such a way that the chassis was connected to the live, your life was in danger.
And many inexperienced users/repairers did not tighten the metal screws of the bakelite knobs enough, leaving them exposed to hand contact when handling them....
so if you received a shock, you just had to turn the plug, easy! And here they complain that today there are no safety standards? Is there no longer brave? 😳
And many inexperienced users/repairers did not tighten the metal screws of the bakelite knobs enough, leaving them exposed to hand contact when handling them....
so if you received a shock, you just had to turn the plug, easy! And here they complain that today there are no safety standards? Is there no longer brave? 😳
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Yes the tube world has not changed much since then. A popular scheme is to connect the metal chassis of extreme high gain devices to Audio GND .... and leave the PE pin of the 3 pin IEC inlet floating and then start a thread here about hum.
Like in printers/scanners one can regularly see the well known external fully closed plastic power bricks built IN devices. It saves a lot of certifying. These have 2 pin power cords and are double insulated.
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Every few weeks/months somebody suggests building a directly line connected amp over on the tube forum - and it gets shut down rather quickly.
Ive found that the hassle of dealing with ground loops just isn‘t worth the “savings” of an unbalanced input. The few extra components it takes to make the input either full differential or transformer coupled allows one to spend their time and energy on more important things that getting rid of a damn hum.
Ive found that the hassle of dealing with ground loops just isn‘t worth the “savings” of an unbalanced input. The few extra components it takes to make the input either full differential or transformer coupled allows one to spend their time and energy on more important things that getting rid of a damn hum.
Or just build stuff correctly and safe at the same time and also have no hum 🙂 Shortest path from A to B and quite simple as well.
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Member
Joined 2003
I did say:
"I would expect UL, and corresponding German / EU details as well, this thing is on the expensive side."
I wonder how it was allowed to be sold there, maybe as a single unit for personal use shipped from abroad...that might get around rules.
Self certified CE is possible, legal, and has no bearing on safety.
Simply that those standards were borne in mind.
UL and the equivalent (VDE?) EU marks are better guarantees of safety, I think.
There was a stylized S mark, Swedish I think, that is also well known and respected, and equal to the German VDE mark.
Bear in mind that the low volumes and location abroad of the factory will make it difficult to punish the sellers, if at all the judge allows it.
"I would expect UL, and corresponding German / EU details as well, this thing is on the expensive side."
I wonder how it was allowed to be sold there, maybe as a single unit for personal use shipped from abroad...that might get around rules.
Self certified CE is possible, legal, and has no bearing on safety.
Simply that those standards were borne in mind.
UL and the equivalent (VDE?) EU marks are better guarantees of safety, I think.
There was a stylized S mark, Swedish I think, that is also well known and respected, and equal to the German VDE mark.
Bear in mind that the low volumes and location abroad of the factory will make it difficult to punish the sellers, if at all the judge allows it.
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Actually, it is triggered by the difference between the live and neutral current (not voltage), typically <30mA. If there is an unbalance, one can assume the difference flows through someone's body towards earth. It has no and should not have any connection to earth. The only requirement is to separate the neutral and ground before the differential current breaker.
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The IEC class refers to the protection against exposure to mains voltage. The rectifier on the secondary of the mains transformer has nothing to do with it. Yes you can connect this signal ground to the metal case. But at some conditions, a ground loop might arise.