Speaker amps for headphones
Nov 11, 2013 at 12:31 PM Post #1,396 of 3,871
I'm not.

And it gets even more confusing. In the NEC, "bond" refers to an actual earth connection, "ground" as the fault return path (the "third pin" being the most common example), and then you have the component's internal reference ground which has nothing inherently to do with either of the previous two.

se

Oh no!
 
OMG!
 
CSA might actually be clearer! Don't tell the Americans!  
eek.gif

 
CSA:
 
"Ground - a connection to earth obtained by a grounding electrode"
 
"Bonding - a low impedance path obtained by permanently joining all non-current-carrying metal parts to ensure electrical continuity and having the capacity to conduct safely any current likely to be imposed on it"
 
"Bonding Conductor - a conductor that that connects the non-current-carrying parts of electrical equipment, raceways or enclosures to the Service Equipment or System Grounding Conductor"
 
etc.
 
obviously battery operated equipment does not necessarily need to be bonded to a grounding electrode to operate or work safely.
cars don't
airplanes don't
ships don't
etc.
 
Nov 12, 2013 at 6:54 AM Post #1,397 of 3,871
And it gets even more confusing. In the NEC, "bond" refers to an actual earth connection, "ground" as the fault return path (the "third pin" being the most common example), and then you have the component's internal reference ground which has nothing inherently to do with either of the previous two.

se


The third pin in a 120 Vac cable is the bonding pin.
The bonding wire is connected to that pin.
In the receptacle, same thing, the third wire is the bonding wire.
It's primary purpose is Safety Ground.

The "internal reference ground" should probably be referred to as "signal ground" or, better still, "common" or "signal common".
 
Nov 12, 2013 at 10:07 AM Post #1,398 of 3,871
The third pin in a 120 Vac cable is the bonding pin.
The bonding wire is connected to that pin.
In the receptacle, same thing, the third wire is the bonding wire.
It's primary purpose is Safety Ground.

The "internal reference ground" should probably be referred to as "signal ground" or, better still, "common" or "signal common".

 
Oh crap. I did write those out backwards, didn't I? Was recently reading a Mike Holt piece about how the NEC often states "grounded" when it should be "bonded." Sorry about that.
 
In any case, the salient point is that neither a rod stuck in the dirt or the third pin on the plug has anything to do with a component's internal ground.
 
se
 
Nov 12, 2013 at 12:20 PM Post #1,399 of 3,871
The whole safety ground, signal ground, earth ground, signal common thing is a topic only Steven Hawking understands, and sometimes I think he just makes it up as he goes along.
 
Next topic:
 
Headphone Amps for Speakers
 
Nov 12, 2013 at 12:50 PM Post #1,400 of 3,871
Nov 12, 2013 at 1:10 PM Post #1,401 of 3,871
I'm making a speaker taps adapter and have some questions. This is one of my first attempts at DIY and I have much to learn so bear with me. I have an amp with common ground and I'm putting a TRS female on one end of the adapter. I've seen Canare Star Quad recommended over and over again, so I bought some without really thinking.

The problem is this: there are 4 wires in the Canare. I'm only going to connect one wire to the sleeve, and the other end will go to a single negative terminal on the amp. Should I leave the unused 4th wire in the cable, or should I take the whole thing apart and just use three wires without the shield or outer rubber layer? Or, should I connect both L- and R- to the sleeve? My TRS female has screw terminals because I'm still trying to learn how to solder, and I'm not sure if putting two wires on the same terminal would make a good connection. 

I also have regular speaker wire that I could use instead. It will fit into the TRS female, but it's really old. Obviously, another option is to order some wire that's more suitable to my purposes. I'm eager to put something together right now though, as I'm currently using a horrible looking adapter I made by opening up a cheap 3.5 mm extension cable from Radioshack. 

I don't really mind replacing the wire in the future. I can easily use what I have now and then replace it with more suitable wire once I make another order. Nothing is soldered, just screws, so it would be simple to change the wire. 

Thanks!
 
Nov 12, 2013 at 1:25 PM Post #1,402 of 3,871
I'd just use all four wires in the Canare. Sure, only three are necessary, but it'd make for a nice symmetrical cable and it's not much extra effort to terminate that last wire.

se
 
Nov 12, 2013 at 1:32 PM Post #1,404 of 3,871
I'd just use all four wires in the Canare. Sure, only three are necessary, but it'd make for a nice symmetrical cable and it's not much extra effort to terminate that last wire.

se

Ok, that will work. For a good connection, would it be best to twist the ends and then screw them on the sleeve, or to stack the two ends without twisting them? Does it matter?
 
Nov 12, 2013 at 2:10 PM Post #1,407 of 3,871
http://www.switchcraft.com/Drawings/1230_CD.pdf


As I said, I'm using a jack with screw terminals because I can't solder. I don't solder the wires to the speaker tap or the headphones to the jack, so I think it should work fine. 


Oh, ok. In that case. Perhaps it would be best to just use the three wires. At least on the jack end. Think you'll have a bit of a rough time getting both those wires of the Canare screwed down.

se
 
Nov 12, 2013 at 4:44 PM Post #1,408 of 3,871
Yup. You notice you rarely hear anyone having problems with low- and mid-fi gear that only uses RCAs and are in double insulated chassis so they only have a two prong plug?

se

 
Fer shure.
 
The low and mid-fi systems are also fairly simple single ended set-ups without 75 foot cable runs.
 
Nov 12, 2013 at 4:58 PM Post #1,409 of 3,871
Fer shure.

The low and mid-fi systems are also fairly simple single ended set-ups without 75 foot cable runs.


And the sad thing is, the so-called "high end" can't seem to figure out how to make double insulated chassis. And even if a chassis could qualify as double insulated, they still burden people with the three pin power cable. In fact, if a piece of double insulated gear had only a two pin cable, people would take it less seriously, as if giving people the most common cause of ground loop and other noise is some kind of "high end" virtue.

se
 
Nov 12, 2013 at 5:10 PM Post #1,410 of 3,871
And the sad thing is, the so-called "high end" can't seem to figure out how to make double insulated chassis. And even if a chassis could qualify as double insulated, they still burden people with the three pin power cable. In fact, if a piece of double insulated gear had only a two pin cable, people would take it less seriously, as if giving people the most common cause of ground loop and other noise is some kind of "high end" virtue.

se


I think we more or less have to thank the various "safety" organizations for that. There are some places where you cannot sell a two pin solution. We pay now for bad design's sold decades ago.
 

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