OK, so I dusted off the ol' soldering iron...

Michael Jones

New member
...and although its been longer than I care to admit since the last time I had the iron hot, my practice run went really well.

I can still "tin the leads" like nobody's bid-nez, and I managed to get nice joints without big globs of solder on them. Nice, smooth even, shiney joints!

I'm going to sacrifice a few more XLR connectors, just for a little more practice before going for the real thing.

In looking over the connectors there are of course the three pins, but I notice another lead for a ground! (I assume its for a ground, it has a big "G" next to it) Its bigger that pins 1-3 and has a hole in it. If this IS a ground, what does it get grounded to??

Also, my wires are 20 ga. and I'm using a 25 watt iron. Is this sufficient, or should I look into a better iron?
Oh, yeah, one more thing, anything special to look for in flux? in solder?
Any favorite brands?
 
Dude just import a kid from Taiwan and he'll have you fixed up for a song.

I don't see how you guys have the patience to do those soldering jobs. I don't mind doing some repairs but when I was looking into making a bunch of Dsubs the number of total solder points was staggering.

If you don't have one those propane soldering irons are pretty handy. They get hot instantly and you can use the exhaust as a heat gun for shrinkwrap.
 
We just got one of the really nice Weller soldering stations at my guitar shop, the ones with a separate pencil style iron and a power station, which has variable temperatures. It rocks. It gets hot as fast as an induction style soldering gun, yet is easier to control than a standard soldering pencil as the weight of the power supply is not in the pencil. Expensive, but the way to go.


Light

"Cowards can never be moral."
M.K. Gandhi
 
The wiring guys that came in to do my snake/studio patch panels wired the chassis of each connector together and those were wired to the large drain wire - then it was run to earth ground outside. All the patch panels are dead quiet...
 
Yes - they bussed the connector chassis' together on the patch panels, and ran that to the drain wire... same with the 2nd patch panel in the booth... this all went to a common XLR bay in the control room, and he did the same on the bay...

From the control room XLR bay, the ground was run to the earth ground outside...
 
Hello Bruce, can you clarify something for me please? I'm a little confused.
When you say " they bussed the connector chassis' together on the patch panels,"

IS..... CONNECTOR CHASSI TOGETHER.... the "CABLE" XLR(connector) chassi, or the patch PANEL connector CHASSIS ? or....the patch panel XLR chassis? Thats a little confusing for me. I don't understand how you could tie all the CABLE XLR chassi together, unless it was by way of the PANEL XLR connector CHASSI pins. All soldered to a ground buss wire.


furthermore
"......and ran that to the drain wire.. same with the 2nd patch panel in the booth... this all went to a common XLR bay in the control room, and he did the same on the bay... From the control room XLR bay, the ground was run to the earth ground outside...

Are you saying the "drain(ground buss?) wires from ALL the panels XLR chassi PINS, all led to a common grounding point at the Control Room PANEL XLR chassi PINS, which were also tied together by a buss wire that ultimately led to the supply ground outside?

Hmmm, if this is so, I'm really confused now, as I have always been led to believe that would create gound loops. Unless I'm missing something. Which is entirely possible as these grounding issues are mindboggling. Maybe if I saw a diagram, it would help. But.....I know how that is.:rolleyes:

My gut feeling tells me somewhere along the line, I was told the ONLY wire that goes to the supply ground, is the MAIN GROUNDING BUSS that ties all the OUTLET grounds together in the studio. NOT the audio grounds, as they get their ground from the equipment. Man, can SOMEONE clarify this damn grounding shit once and for all.

DO YOU CONNECT PANELS, PANEL XLR chassi PINS, and or any MIC CABLE, LINE LEVEL BALANCED, AND LINE LEVEL UNBALANCED PLUG CHASSI PIN GROUNDS DIRECTLY TO A SUPPLY GROUND BUSS? Because IF they are, then you have audio ground directly tied to the neutral side of your SUPPLY, which in turn is also tied to ground, is that not correct? ARGGGGGGGGGGGGRRRR!!! drive me crazy!

here we go again:confused:
fitZ
 
I'm going to sacrifice a few more XLR connectors, just for a little more practice before going for the real thing.

If you aren't typing tongue-in-cheek you can use a solder sucker to remove the solder easily, then use the connector in your studio without sacrificing it for experimental soldering practice.

In looking over the connectors there are of course the three pins, but I notice another lead for a ground! (I assume its for a ground, it has a big "G" next to it) Its bigger that pins 1-3 and has a hole in it. If this IS a ground, what does it get grounded to??

Short answer:

Tie pin 1 (signal ground) and the "G" tab (chassis ground) together.


"Ground" can mean a lot of things. The ground pin on the XLR connector (pin 1) is signal ground, and connects directly to the shield of the xlr cable.

The tab, labeled "G", is the chassis ground, and is a mechanical ground connection of the connector body, and the chassis, panel or plate the XLR jack is bolted or screwed to.

There are non-audio applications where XLR connectors are used, typically in the high-end instrument marketplace where multiple probes do not share a common ground. In this case, the shielding of the cable is not tied to the same ground as the panel. It instead is tied to the signal ground that is isolated from chassis ground.

Also, my wires are 20 ga. and I'm using a 25 watt iron. Is this sufficient, or should I look into a better iron?

25W iron is fine for 20ga if you are soldering the wires to tab-style connections, and might struggle a little bit if you're soldering to connectors that have barrels, like the XLR connectors you are describing. 25W just means it takes longer to heat up the joint, 30-35W probably is closer to what is "ideal", but you can do it just fine with 25W and make good connections. Just takes longer for the solder to flow since the barrel on the XLR connector will absorb a certain amount of heat, heat that takes longer to produce with a 25W iron as compared to a 30W, 35W or 40W iron. This is why weller soldering stations are nice to work with... you can adjust the heat to whatever works best for you.

Oh, yeah, one more thing, anything special to look for in flux? in solder?

Electrical solder typically is a rosin core, 60/40 mix of tin and lead, and flows reasonably well. Thinner diameter solder is easier to work with, though you'll obviously feed the joint more "inches" of solder, because a good solder joint is based on volume. Thicker solder takes longer to heat up, and you have to feed it about 1/4" or 1/2" worth of solder, the thinner stuff you might feed a whole inch.

The stuff at radio shack is tolerable, it doesn't flow very nice, and sad to say its not consistant in manufacturing. If you want to be anal, serious, and really do this correctly, I will recommend Kester's Electronic Silver Solder as my choice. It has a unique blend of 62% tin, 36% lead, and 2% silver alloy with a rosin flux core, and flows better than anything you have ever soldered with.

AND, you can use a 15-20W iron to solder the XLR connectors that you have, with great ease. Its a lower temperature solder, has stronger mechanical stress resistance and higher conductivity than hobby-grade electronic solder (the radio shack stuff or equiv).

I recall it being double to quadruple what radio shack solder costs (if you buy RS solder in larger spools), but to me its worth every penny.

The last batch I purchased was from Mouser Electronics about a year ago, I'm sure they still carry it.

Its damn good stuff. You think you tin well now... try the kester solder... :D
 
Fitz,

Yeah... I'm not a wiring expert, but had gotten pretty much the same type of info you had regarding grounding, so I was surprised at what they were doing....

BUT -- these guys are top-notch and know their stuff... they handle pretty much all the business for local TV/radio/studios around here....

Let me try and describe it more clearly....

I have a 24-connector panel in the main studio (shared by both studio 1 & 2). I also have an 8-conn panel in the booth.

Each panel has a combination of Neutrik XLR and XLR-combo connnectors. The studio panel is fed with 26-ch GEPCO multicore and the booth panel an 8-ch GEPCO multicore.

The cable of both panels come into the control room to a 32-conn. XLR patch bay.

OK so that's the layout...

Now what they did with the wiring.... of course, they wired each channel's 3-conductors to the appropriate Neutrik points. They then "jumped" the shield of each Neutrik conn. together on each studio's panel (so - in addition to the normal multicore wiring on each connector, they also joined the shield of each connector together...)

They connected this "shield buss" to the drain wire in the multicore.... and the drain-wire in the multicore is just a copy of the common ground running inside the multicore....

Back at the control room patchbay, they did the exact same thing... so basically we have a common ground for ALL panel connectors tied to a common point at the control room patchbay. The control room patchbay's chassis was then run straight to earth ground outside.

I don't know enough about wiring to indicate whether this was a good way or bad way to do it, and there may very well be different wiring solutions for different installations/rigs...

All I know is that once they saw my setup, this was the solution they proposed and the proof is in the pudding.... the multicore channels are dead quiet and I have no hint of ground loops anywhere in the system!
 
Hello Bruce, thanks for the concise answer. Now I don't feel SO stupid.:rolleyes: At least I know now I wasn't having a brain fart. But thats cool. It tells me there is more than one way to skin a patch bay:D The whole grounding issue, even with pro electricians and theorists is still, at least from what I've read on the net, something of a quagmire.
Well, if THEY can't even agree, then I'm sure not going to accept every explaination as fact anymore. IN fact, the whole AC thing, is somewhat of a mystery. I've noticed on the net, there are people claiming that corporate bitterness over the DC/AC
battle in the 1800's still rages today, to the point the Smithsonian won't hardly acknowledge that Tesla was indeed the inventor of AC, as their exhibits on the subject are backed financially by of all things, General Electric, which was founded by Edison/who lost the DC/AC wars.
Ha! that tells me something. Furthermore, try and find a school history book with Tesla's name in it. Even the history of electricity, not to mention radio, is being systematically distorted and changed. So I got to wondering why, and to my astonishment, the answer lies in FBI's confiscation of Teslas documents when he died.
To this day they have not been released. That also tells me something. On futher digging on the net, it turns out Marconis claim to radio invention fame is a falsehood, also touted in school history books, which is proved by the fact of the Supreme Courts ruling some time ago that not only did Tesla invent it, corporate powers that be, to this day try to keep Marconis name attatched to radio, just as Edisons is attached to electricity.
In the history of radio, many corporate battles raged, and if you look hard, you will see evidence of corporate theivery, lies, deciet, and the whole gamut of stealth behavior by corporate beaurecrats. No difference with electrical corporations. To this day, at the first A/C generating plant, which now is held by General Electric(from what I've read), although Tesla built it(backed by Westinghouse), a sculpture of Tesla, is kept in the dark, even though it is in a historical electrical plant. Ha. The nerve of corporate bastards never ceases to fucking amaze me.
Even a 3rd grade Teacher through whose class he trys to keep Teslas name alive, sent a bust of Tesla made by this class, to the Smithsonian, only to be rejected with no explaination. This is only the tip of the iceberg. Given these facts, I tend to question many things of this nature. Because of growing up accepting the lies of the powers that be as fact, only to find out the truth, tells me that according to their doctrine, 2+2=5, as well as there is grounding theory based on something that may go deeper than suspected. Let me put it this way. When Tesla tested a machine he designed as a Death Ray device in the 30's, according to a document by Yale university, the very day that he tested it, the largest explosion on the face of the earth, took place in Soviet Russia. Ever hear that one in the history books? Check it out.
This is only one of many facts on Tesla, who many think now, was the greatest inventor in the history of the world. But yet, his name draws a curious blank even in engineering circles. Michael, no offence, this is just what I read. Maybe you would care to comment. And I know this stuff is beyond the scope of this bbs., but maybe it will illustrate why I question things.

http://www.parascope.com/en/0996/tesla4.htm


On following further links, I was led here. Which REALLY tells me something, right or wrong. Sometimes I am impervious to reason. Sometimes not.

http://www.theyrule.net/

Cheers
fitZ:eek:
 
Michael Jones said:
OK. So you had a ground between ALL the connectors, the chassis, and earth?

Yes, that is the "proper" way.

Older synths with linear powersupplies whose unbalanced audio out jacks are isolated from the metal chassis, on occasion hum like this, and if thats the case, you just snip the wire from pin 1 (signal ground) to patch bay ground ("G" tab) and usually the hum goes away.

Though this is very rare. My fender Chroma polaris is like this... it hums like a MoFo when it shares grounds. I solved it permanently by soldering between the output jacks of that synth and the analog out on the system board, a jenson transformer, high Z to low Z, and changed the output jacks to TRS 1/4" jacks (like a stereo headphone jack). Now it has balanced output, and the mixer, the chroma polaris, and me, are happy :)
 
quote:
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Originally posted by Michael Jones
OK. So you had a ground between ALL the connectors, the chassis, and earth?
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quote:
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Orginally posted by frederic
Yes, that is the "proper" way.
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OK, that's all fine and well, but what if you have a wooden chassis?
 
Yes, that is the "proper" way.
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OK, that's all fine and well, but what if you have a wooden chassis? [/B]

Solder pin 1 to the "G" tab, then tie them all together, then tie that to one big ground.

The shield by itself will reduce the amount of RFI that goes through it, because it is metal and has a thickness. However, its highly more effective (exponentially so) if you ground the shields, as the RFI will mostly be routed to your studio ground. What little tiny itty bitty bit of RFI that does get through, will be phase-cancelled by the balanced, twisted pair on the audio cable, feeding your equipment differential inputs.

Find a ground :)
 
Solder pin 1 to the "G" tab, then tie them all together, then tie that to one big ground.

I don't get it. The shields already get ground from the mixer, via pin 1, is that not correct frederic? IF so, when you again ground all the XLR chassi (G) pin, to the shields, and then to a another ground, isn't that a ground loop?:confused:

I'm only asking so I learn frederic, not to argue.:confused:

fitZ
 
"IF so, when you again ground all the XLR chassi (G) pin, to the shields, and then to a another ground, isn't that a ground loop?" -

Yes, Fitz, it's called a ground loop, it's (non)affectionately called an "antenna", and it's called CRAP.

ANY time you create a complete circuit for a SHIELD ground, instead of making it a single path from THE common ground to NOWHERE, you've got a possible ANTENNA that will pick up anything that's floating around and introduce it into your ground system. Once it's in that ground system, it's EVERYWHere.

Power supplies need a complete circuit to work, and so do audio signal circuits - balanced lines were created to cancel noise that (theoretically) gets on both of the signal leads. However, the SHIELD around those leads should only connect on ONE end, which is usually the source of the signal. most studios set this up to be the console, and the console ground is then attached to the STAR ground for the power supply. If you connect all these "G" terminals on your XLR connectors together, it won't matter because they are already connected internally to the chassis of the connector, which is USUALLY mounted in a METAL panel along with a couple dozen other connectors.

Where the problem comes in is if you then connect the pin 1's of these connectors to the "G" connectors also - now, you've just caused a loop between the cable shields and the chassis grounds. If there is ANY noise anywhere near the cabling, it can be inductively coupled into the shield, which, BECAUSE it's now a complete circuit, can act the same as a TRANSFORMER and there will be ground current. That isn't good.

I'm not sure if I missed something somewhere in this thread, but the ONLY place it should be OK to connect Pin 1 and "G" tabs together on an XLR panel would be at the console, and only then if the console is being used as the star ground for the studio.

Just 40 years of experience talkin', don't take it serious... Steve
 
But....

A steel chassis sandwiched into a wood framed wall isn't a ground. So the only advantage of a steel chassis is that each ground lead on the XLR can be soldered to the chassis, and then ONE lead can go from the chassis to a dedicated ground. Right?

As an alternative, all of the ground leads on the XLR's could have a lead comming off of them, and all of those could be bundled into a wire, and that wire could go to a dedicated ground. Yes? No? Maybe?
 
knightfly said:
I'm not sure if I missed something somewhere in this thread, but the ONLY place it should be OK to connect Pin 1 and "G" tabs together on an XLR panel would be at the console, and only then if the console is being used as the star ground for the studio.

Just 40 years of experience talkin', don't take it serious... Steve
I don't know enough about wiring to argue, and like I said - maybe their solution in my rig only makes sense in my rig......... but I also can't deny the results of the way the crew did my wiring - it's completely noise free...........
 
A real answer

Michael,

After seeing Steve's post I'm sitting here thinking about this, and wondering why it makes so much sense, yet seems so wrong. So after a little staring at the screen I called the guy who designed and soldered (I helped solder) the audio cabling in both my pro studios a very long time ago. After a lot of catching up, pleasantries and such, my retired audio wiring friend set things straight in his usual, extremely blunt manner.

So, I owe you an apology. I genuinely thought I was giving you good advice, based on how I recall my pro studio being wired way back when. Also, I'll be doing this real soon myself so its important for me to have it correct as well.

Anyway, I asked about grounds and he immediately stated that the mixer is the focal point of your studio from a wiring perspective, therefore the "studio ground" IS the mixer's ground. Having any other ground accidentially or intentially is hum suicide.

I asked about patch panels, and this is what he told me.

Patch panels do not assume a ground between the jack and the rack plate. All commerically made patch panels, even the shit ones (he defined shit as dbx, hosa, behringer, nady, anything not hand soldered basically) isolates the ground (sleeve) of the patch bay from the metal enclosure if you're lucky enough to have a metal enclosure.

Then we talked about ADC patch bays like I have... and he said the spacing material between the jacks is a baked composite product that fully insulates all jacks from one another. Now its hard plastic of some kind. No shared grounds. The enclosure is grounded to the rack rails which better be grounded to the third prong of your electrical, but the jacks themselves are not, except by the cable soldered on that goes back to the mixer.

Then I asked about XLR panels - he said that the XLR has three connections, pin 1 being ground, and THAT is the ground that goes back to the mixer through the shielding of the soldered on cable. He sasid XLR connectors technically have four paths to conduct - pin 1, pin 2, pin 3 and the shell casing, but the shell casing is not used in audio applications. In scientific test instrument applications pins 1, 2, 3 are connected to multi-conductor shielded cable and the shield terminates in the shell housing of the plug, which connects to "G". Audio doesn't use the "G" tab or the shell for any audio purpose. I said I remembered we had wires off the XLR "G" tab soldered to pin 1, he said no, those "G" connections were attached to the steel panel the jacks were mounted in, and the reason for this is to prevent the transmission of hum and noise should large antennas (people) plug an XLR plug into a jack, while the input channel is on. The hum your body picks up is shunted through the shell of the connector plug, into electrical ground, and the mixer doesn't have to bend meter needles listening to it. This is a safety catch for stupid people who plugs things in with input channels not at infinity.

So again Michael, sorry I had it wrong. I really believed I had it right.

So much for good intentions..
 
Just went back and re-read Bear's comments after grabbing 4 hours sleep, and Bruce, your guys did nothing wrong I can spot. Tying the chassis connections together just ensures that a loose screw between the mounting panel and the connector won't CHANGE the ground potential of the shell. Nothing was said in your case about tying pin 1 anywhere but star point.

And the fact that your rig is mausoleum@midnite quiet proves (to me, anyway) that they didn't make a mistake.

Frederic, your guy knows what he's doing, don't lose him.

Michael, the ground LUGs on your XLR's can be commoned to a single wire leading back to star point - the ground PINs (as in pin 1) should only go THROUGH the connectors and continue their journey to the end of the last cable connected to the last "thing" - which would probably be a mic. At that point, the pin 1 circuit should stop. The point of the shield is to shield. period. NO connection for current to flow in the shield, or it becomes an antenna... Steve
 
[QUOTEFrederic, your guy knows what he's doing, don't lose him.
[/QUOTE]

He's retired now, but no I don't intend to lose him. He definately knows his stuff.

His entire career was audio... studios, amp design, commercial 70-volt audio, that sorta stuff.
 
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