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

Howdy Guys, well I didn't mean to stir up a hornets nest, but at least things were set straight both ways. Thanks Steve for the clarification. I feel better now:D

This is what threw me. Bruce wrote:

" The control room patchbay's chassis was then run straight to earth ground outside." NOT THE XLR CHASSI's!. GOT CHA!

I know it is VERY hard to describe this stuff. Anyway this is all clear now. But I'm going to RESTATE it so I know it is correct, OK?

Starting at a MIC...The XLR.Cable Shields are NOT connected to pin 1. They are terminated to NOTHING, is that correct? At the other end of the Mic cable XLR, the shield IS soldered to Pin 1. Correct?

At the Studio XLR PATCH PANEL, on the BACK side, ALL Pin 1's are tied together by a common buss wire, as well as EACH shield of a balanced pair whether it be individual or multicore, is soldered to its own respective XLR pin 1. Correct?
Also, the master foil shield of a multicore cable is solered or tied to this common buss across all Pin 1's. Correct?

This multicore or single sets of balanced cables, then goes to the backside of a CONTROL ROOM XLR patch panel where they are soldered in the exact same manner as the Studio Patch panel. Correct? Which means, UNLESS, a balanced cable is connected from the Control Room XLR Panel to the mixer. there is NO GROUND connection to any shield at any point. Correct? But if ONE cable is connected between the mixer and the control room Patch panel, now you have GROUND at ALL panel XLR connectors PIN 1? Correct?

AT the mixer.... All XLR CABLE connectors (pin 1) are soldered to the shield of each balanced pair of a Multicore or individual cables which extend to a Control room XLR patchbay. At this end, the cable XLR connectors are wire identical as at the Mixer XLR connector. However, in a multicore, with fans at each end, WHAT happens to the foil sheild at each end? Nothing? it is just terminated?

Ok, now for the panel AND XLR CHASSI connections. At the studio Patch panel, A buss wire is soldered across ALL XLR CHASSI PIN (G)'s, correct. In the event of more than ONE panel, a buss wire is also soldered between each SET of Pin (G) buss's, correct?
Now, since the XLR chassi's are phyisicaly mounted to a steel panel, Pin(G)'s are already connected to the panel. Now it is only a matter of soldering a wire, from the studio panel Pin (G) buss, to a Pin (G) buss at the control room panels. From there, a wire must now go to a power supply ground. Correct?

To ABSOLUTELY make this clear, at NO POINT other than Mixer PIN 1 connections, do any XLR connector shields obtain audio ground. Correct?

I sure the heck hope so.

BUT now, this also brings up another quagmire, which is EXACTLY what my question was about in the "grounding" thread from hell.
To refresh your memory, the question was in regards to a SECOND grounding point(ROD) when a sub-panel is added to a residential supply panel. I need no explaination OTHER than this.

IF, the NEUTRAL side of the supply is grounded, whether by rod or water pipe, and by code, your added sub panel MUST have its own grounding rod IF it is beyound say 60',
and both the supply ground, and sub panel ground must be connected TOGETHER, does this in effect make a complete circuit for ground? That was the question. Whether both grounding points had to be tied together at the sub panel grounding buss. No one ever answered me. And IF it does, I was told this makes for ground differentials that show up in audio. Thats all I wanted to verify. Ok, I'm done.
fitZ:)
 
ANY time you create a complete circuit for a SHIELD ground, instead of making it a single path from THE common ground to
Click to expand...

Hey, wait a minute. IF, an XLR cable is plug into a MIXER, and the other end is plugged into the Control room patch panel, then all the Pin 1's on the panel connectors are grounded, but now if you plug ANOTHER cable between MIXER and PANEL, does that not make a complete circuit? Mixer Pin 1 to panel connector Pin 1, bussed to another Pin 1 and back to the Mixer on another channel, right? And the mixer PINS 1 are COMMON GROUND, right? What am I missing here Steve?:confused:
fitZ
 
not make a complete circuit? Mixer Pin 1 to panel connector Pin 1, bussed to another Pin 1 and back to the Mixer on another channel, right? And the mixer PINS 1 are COMMON GROUND, right? What am I missing here Steve?:confused:
fitZ [/B]
Click to expand...

Think outside the box, forget what you know, just for a minute.

pin 1 on the mixer channel 5 is signal ground for that channel. it extends all the way through your cabling, patch bays to the microphone.

For grounds, you really want a "star" configuration, where grounds extend from the mixing console to "whatever".

*IF* you ground a "far away ground", such as a patch panel to earth ground, you've created a "ground loop".

The loop is... mixer pin 1 through all the cabling (shields) to the end device, to EARTH GROUND, and back through the earth, to the EARTH GROUND of the mixer.

There's your loop :)

The earth, and a pure copper shield, will conduct electricity differently, thus you'll have a small voltage difference. One will be zero, the other will be about a volt. This single, itty bitty volt, will be picked up by your mixer because its actually a volt, 60hz ac :)

hummmmmmmmmmmmmmm

Thats why you want a star type ground system, everything tied back to the mixer.
 
frederic,
pin 1 on the mixer channel 5 is signal ground for that channel. it extends all the way through your cabling, patch bays to the microphone.
Click to expand...

Take out the mic. Then what? With 2 cables between the mixer and the bay, isn't that a loop like Steve described?
 
RICK FITZPATRICK said:
frederic,

Take out the mic. Then what? Isn't that a loop like Steve described?
Click to expand...

If pin 1 on one of the patch panels along the way hit earth ground, then your loop is from that point.

Remember, we were talking patch bays here :)
 
Rick, if I EVER said to ground pin 1 ANYWHERE, it was a typo. I thought I said you could ground the SHELL of the xlr's, which is NOT the pin 1 connection but the FOURTH, "G" tab that is electrically part of the metal chassis of the connector.

Pin 1 should not connect to ANYTHING but itself, clear from the MIXER (not a patch bay, or a dog turd, just the MIXER) - pin 1 should present one continuous shield around the two signal leads for as far as they go, through whatever connector bays they travel, til they reach the mic they are connecting to the mixer.

Pin 1's function is to be a STATIC shield, keeping any stray noise from impinging on the signal conductors. What little gets through it should be killed by the fact that ONE of those signal conductors gets polarity reversed and ADDED to the other, once the signal is back at the mixer. This has the effect of canceling the noise, which will be the SAME on both signal leads (until one is reversed), while ADDING the signals, which are already out of phase and get put IN phase at the mixer. (When you add in-phase signals, they get bigger. )

The star quad arrangement takes that concept one step further and uses two counter-wound conductors PER leg of the balanced signal, and if correctly wired it will contribute to even less noise - it does this by the twisted pair syndrome - if you've ever used flat twin lead on a TV antenna, and didn't twist the lead on the way into the house, you've gotten ignition noise from cars. Twisting the lead causes the radiated noise to strike BOTH wires still, but out of phase in half the cases, so the noise is canceled. Same idea with Star Quad.

Final point - I mentioned a STATIC shield - this means that NO CURRENT can flow in that shield. This is why it is imperative that the shield goes NOWHERE. One end gets connected to a common ground. Period. This puts the entire shield at the same potential, since you must have current flow in order to have a voltage drop, or an open circuit to have a voltage difference. (A drop is caused by current in a conductor, while a difference is caused by either a voltage DROP or an open circuit.

Most of these practices can also be utilized with UN-balanced wiring, but NOT with Rat Shack cables, not with Hosa, not with Monster, etc - only by soldering your own cables the RIGHT way.

Final final (finally) here's probably the best link around for clearing up just how to wire what to what, and when/why -

http://www.rane.com/note110.html

just remember - a patch bay is only supposed to allow you to break into a circuit, NOT provide any grounds or other changes in and of itself. It helps to think of a patch bay as just an extension of the rear panels of your gear, so you don't have to crawl behind stuff to swap cables around when you want to use something a different way... Steve
 
Steve, you are most generous. Frederic, you are too. Bear, you did your best to describe your system. Thankyou all for your extended explanations and for not verbally slapping me up side the head.:D Wouldn't have done anything anyway cause it's so thick. Well, that about wraps this one. I GET IT, finally. Final. End. Done. Roger Over and out

Adios amigos

fitZ;)
 
Cool - now, about that AC/DC/Neutral shit... :=)

Seriously, we ARE gonna go head to head on this one, I'm too fkn stubborn to "let one get away" - but I promise it'll be relatively painless (won't hurt ME, anyway :=) just you, me, whiteboard, lotta colored pens, truncheon, jumper cables, salt water foot bath, c-clamps, vice-grips, duct tape... Sounds like fun, I'm gettin' all excited just thinkin' 'bout it (sounds of fiendish laughter, NOT fading away....)
 
knightfly said:
Cool - now, about that AC/DC/Neutral shit... :=)

Seriously, we ARE gonna go head to head on this one, I'm too fkn stubborn to "let one get away" - but I promise it'll be relatively painless (won't hurt ME, anyway :=) just you, me, whiteboard, lotta colored pens, truncheon, jumper cables, salt water foot bath, c-clamps, vice-grips, duct tape... Sounds like fun, I'm gettin' all excited just thinkin' 'bout it (sounds of fiendish laughter, NOT fading away....)
Click to expand...

Oh, thats all irrelevent crap. Help my change my valve cover gaskets in this 30 degree weather and I'm happy :)

Guess you know what I'm doing today!
 
Hahahahahahahahaha...........hahahahahahahahahaha.........

(choke)...hahaha....ha.....ha......er......wait a minute (gulp...uh..that sounds like ..:eek:

TORTURE!!!!! fuck. No. Please no. PULEEEEEEEEEEEEEESE Steve, don't!! I have a low pain threshold. You know how those whiny Calironiaa city dudes are. I even whince at the thought of shaving.....coils you say.....duct tape and wires? Salt water.........YOUR FUCKING EVIL! I know, your gettin back at me for years of me torturing you with my stupid, irrelevant, bad spelt, misinformed, opinionated, misquoteing, unscientific, amatuer, and otherwise garbage threads and questions from hell.

hehehehe, it was all a mistake Steve. All of it. I promise I'll leave this bbs for good, ok? Just don't hook me up....you will NEVER hear from me again.....Steve?.....steve?
...knightfly.......(sparks crackle with LONG RT-60) OMG.

er...frederic, I'm pretty good with a wrench and got some gloves. Need help? Got anywhere for me to hide..er from the weather, you know? Does it have a lock on the door? Good, I'll be right out..hehehe.:D
 
[QUOTEer...frederic, I'm pretty good with a wrench and got some gloves. Need help? Got anywhere for me to hide..er from the weather, you know? Does it have a lock on the door? Good, I'll be right out..hehehe.:D [/B][/QUOTE]

Not too bad with a wrench here either... just that my hand's don't work when its 31 degrees. Of course my crewcab doesn't fit into the garage -at all- so working on it inside out of the wind is not an option.

If I swing the mirrors in, I can get the cab in, but there's not enough ceiling height to open the hood enough to get at the firewall area.

Just one of those things that never seem to work out. But, I did make a trip to home cesspool and pickup the vocal booth doorframe, leaving oil all over the roads LOL
 
But, I did make a trip to home cesspool .....
Click to expand...


Hahahahaha, thats a good one frederic. At least you can follow your oilslick back to the house. Yea, I know what you mean about that kind of weather. Can't do anything in it but die. I almost got frostbite up in Maine when I was a kid. Had no idea it could do that or get that cold. Got caught in a blizzard while hunting with my dad. Holy moly.
Those Atlantic storms are something out of a movie. Glad I'm where its only raining cats and dogs, not blocks of ice!:p
 
I don't particularly like rain either...

I've been waiting six weeks now for the roofing monkey to come install a few slate tiles which slid off in an earlier windstorm.

Its a small job, so they keep delaying me.

This is after we contracted a different roofer, who gave us a quotation, then a "we'll arrive" date, and didn't show. When I called them to find out why, I got "this number has been disconnected, no further information is available".

@(#$@#

I'd do it except I've never done slate, and experimenting on my roof is a bad idea. Asphalt shingles I can do in my sleep.

At least I got the vocal booth door installed. Though, I had to lop off an awful lot on the bottom so it would clear the top of the stairwell.

I realized AFTER I installed the frame and the door, that the studio floor is a hair below the top step. So, the door only opened about 16".

Of course, I was IN the vocal booth, so I had to take the door off the hinges to get out, trim, then put back.

Duh.

Only me.
 
Of course, I was IN the vocal booth, so I had to take the door off the hinges to get out, trim, then put back.
Click to expand...

:eek: OH NO! That is funny! I thought that crap only happens to me.
Reminds me of the time my dad and I rebuilt my Chevy 350. Installed the whole kit and kabootal, only to run like shit. My dad is a great mechanic, and he tried everything he knew. Finally decided the cam wasn't aligned with the crank correctly. We tore it down, put a some kind of degree plate that he had, on the cam and it was ok. Now he was baffled. Ran like total crap. He thought about it for 2 days. Finally, it dawned on him. The previous engine burned oil like a kerosine heater. He got out his hacksaw and cut the catalytic converter out and welded a straight pipe in place. Ran like a top. Ha! Damn oil had clogged that converter to the point exhaust wouldn't hardly go through it. #^*^&%%t@%&*. Oh well, at least I wasn't paying for it.

Hey, did you ever see that episode of candid camera where the cabinet maker was cutting shelves for a bookcase. He would measure the opening, go and cut the piece, only to discover that it wouldn't fit. He'd measure it again and scratch his head, and then go and cut another piece, only to discover it didn't fit again. Now he was getting pissed. Third times a charm is the rule of thumb. Ha! Still didn't fit. He threw down his tape and threw the board across the room, and cussed like hell. Then he cut another, and when it didn't fit, he blew his top. I think he thought he lost his mind. Little did he know every time he went to cut the shelf, someone would move the end of the bookcase an inch or so. I never laughed so hard in my life.
 
:eek: OH NO! That is funny! I thought that crap only happens to me.
Reminds me of the time my dad and I rebuilt my Chevy 350. Installed the whole kit and kabootal, only to run like shit. My dad is a great mechanic, and he tried everything he knew. Finally decided the cam wasn't aligned with the crank correctly. We tore it down, put a some kind of degree plate that he had, on the cam and it was ok. Now he was baffled. Ran like total crap. He thought about it for 2 days. Finally, it dawned on him. The
Click to expand...

Oil clog :) heh-heh.

Since we're admitting to dummas adventures...

Years ago, I was building a 451 dodge stroker engine (400 "B" block with a turned-down 440 crank), and I spent all winter measuring, weighing, hand filing, balancing, etc. Early spring I assembled the entire engine, all was well. Put it in the truck, fired it up, no oil pressure, shut it down immediately.

Okay, no oil, that was dumb. Poured in 5 quarts of synthetic oil, then walked around to the driver's door, and noticed an awful lot of oil on the ground.

Yeah, forgot to put on the oil pan. Of course the three friends helping, all excited to see a twin-turbo stroker motor fire up for the first time, didn't notice it either.

Years ago I replaced the rear axle in an old 81 ford crewcab. All was fine except I remembered to attach the leaf springs to the front purches, but forgot to attach the back shackles. I got about 12 feet in reverse.

I made an engine stand years ago, essentially a 3d trapazoid, so I could build an engine, put it into the stand, then let it run for 2 hours. Worked well, until I put in a big-block chevy, which for whatever reason decided not to idle at 1500 RPM, but instead quickly go from 1500 RPM to 7000 RPM. Over it went!

Oh, stuff like that :)


previous engine burned oil like a kerosine heater. He got out his hacksaw and cut the catalytic converter out and welded a straight pipe in place. Ran like a top. Ha! Damn oil had clogged that converter to the point exhaust wouldn't hardly go through it. #^*^&%%t@%&*. Oh well, at least I wasn't paying for it.

Hey, did you ever see that episode of candid camera where the cabinet maker was cutting shelves for a bookcase. He would measure the opening, go and cut the piece, only to discover that it wouldn't fit. He'd measure it again and scratch his head, and then go and cut another piece, only to discover it didn't fit again. Now he was getting pissed. Third times a charm is the rule of thumb. Ha! Still didn't fit. He threw down his tape and threw the board across the room, and cussed like hell. Then he cut another, and when it didn't fit, he blew his top. I think he thought he lost his mind. Little did he know every time he went to cut the shelf, someone would move the end of the bookcase an inch or so. I never laughed so hard in my life. [/B][/QUOTE]
 
Hey frederic, the oil one is funny too although I bet it wasn't to you. Don't feel bad though. I poured a quart of oil into my radiator one time. Ha! That was a joy to clean up. What a moron.

I made an engine stand years ago, essentially a 3d trapazoid, so I could build an engine, put it into the stand, then let it run for 2 hours. Worked well, until I put in a big-block chevy, which for whatever reason decided not to idle at 1500 RPM, but instead quickly go from 1500 RPM to 7000 RPM. Over it went!
Click to expand...


Man oh man, I bet that one scared the crap out of you, huh?
Since were talkin goofs, heres a good on for you frederic. And this was my dad. He had a 76 Dodge van given to him, that he spent 2 years refurbishing. I mean EVERYTHING. He did it all himself all the way to the paint job. Finally the day came to take it for a test drive. Brand new rebuilt 340, transmission, front end, you name it he rebuilt it. 12 miles down the road the engine came to an abrupt halt. Wouldn't even crank through. Towed it home, tore down the upper end and found what seemed like varnish on everything that gas touched. DUH!! He forgot to put in fresh gas. The car was sitting for 5 years before dad got it. Man oh man was he pissed. Had to tear that whole engine down and clean every last part. Then he got a new gas tank for it. The old gas was just like varnish.
Those kind of mistakes are hard to swallow.

But my worst woodworking mistake came when I went to install a library full of bookcases. I did all the field measurements, but forgot about the entry doors. When it came time to install them, they wouldn't fit through the door. Crap, $80,000 worth of fully assembled and finished cases had to be semi disassembled, and reassembled in place, then a new finish touch up applied in the field. We were 1500 miles from the shop, and a deadline to meet. I never lived that one down.
 
Sorry for the delay, Rick - Torture? Naah, the word torture implies a lack of consent - trust me, by the time I'm done you WILL consent... (SOFL, R) - (Sounds Of Fiendish Laughter, Reverberating)

Besides, I like to think of my favorite "tools" more as "training aids" - (SOMFL, REM) - (Sounds Of MORE Fiendish Laughter, Reverberating Even More)

Frederic, you need to learn to like yourself more - working on vehicles in less than 50+ degree weather outside of a heated shop is a sure sign of self-hate... :=)

Say, anybody else having trouble accessing John's site or have I been fired? Just curious... Steve
 
Frederic, you need to learn to like yourself more - working on vehicles in less than 50+ degree weather outside of a heated shop is a sure sign of self-hate... :=)
Click to expand...

*I* like me. My F350 crewcab hates me :) Or my house hates me, I haven't figured that out. The truck doesn't fit in the garage though, its too high LOL.

I even spent 3 hours shuffling things around inside (like my welding table, my two rover/buick hybrids, my turbo collection, etc) to make room!

Say, anybody else having trouble accessing John's site or have I been fired? Just curious... Steve [/B]
Click to expand...

I can't access it either... but not only through its DNS name, but also directly via IP. According to my traceroute, the entire segment the server is on simply is missing.

Power outage?
 
You must log in or register to reply here.
Back
Top