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[coky]

Hello !

i need help with the connections of a ssl 6000?..i think that depends on the situation it is not necessary to connect the earth ...  I need to do the connections of the SSL with a protools , as with different outboard and effects.

Lot of thanks!!

Coky.

[Dave Hecht]

  First, we have a full name policy on PSW. Your full name needs to  be in your signature, body of message, or user profile. Please get that taken care of.

 As for your question - I'm not sure which ground you're referring to. There is a ground lug on the connector panel under the console. This needs to be connected to the ground lug on the front of the computer. Normally, computer and audio psu's are grounded through gnd lug on their ac connectors. This arrangement usually works quite well if the studio's ac is wired properly.

Dave Hecht

[ssltech]

I agree with Dave, the post is a little confusingly-worded, which may simply be because English is not a comfortable language for the original poster, or it might be because the original poster is just not sufficiently familiar with the manner in which these things connect.

The Console ground (either a post at the connector panel in the case of external patchbays, or a copper Ground bar bolt under the patchbay on internal-patch models) MUST absolutely and categorically be connected to the computer ground terminal, and SSL supplied a cable specifically for this purpose when the console was new. Without that direct ground connection, the fader levels are prone to fluctuation and noise effects. Also, Multiple VCA solos can 'offset' the fader reference causing some VERY odd things to happen.

There are a number of different 'grounds' to consider, and I'm afraid that the original post doesn't offer much to go on... Can you be more specific about what you mean? I have a couple of guesses, but the answers are fairly installation-specific.

We need more to go on, and Dave would like to start with your name... I think your location would be helpful also, because of the difference in electrical safety and grounding regulations in different geographic regions.

Keith Andrews

[coky]

Sorry, but yes english is not my language. My name is Gabriel Ordo

[ssltech]

Ah... I thought so.

You're thinking is a little bit 'prefabricated'... Stop thinking about the SSL being different from any other central audio router, and you'll be much better off. I think the problem is that you don't have a clear grasp of the REASONS for grounding and ground lifting: Let me try to give a quick explanation.

Basically the SSL should be the central item to which everything else is connected. As a result, with "star" grounding philosophies (if you don't understand star grounding, you will be best advised to get someone who does... You'll never get a clean installation if you don't understand how it works!) the SSl becomes the center of the star.

Take a THICK wire from the ground post on the 6K to your central ground rod. This is your audio ground.

On any balanced audio items which have both power (electrical) and audio ground connections, connect ALL THREE terminals at the patchbay/console ("near") end, and only the HOT and COLD (plus and minus) connections at the device ("far") end. For unbalanced devices, connect the signal and gtound of the device to the hot and cold (plus and minus) of the cables, but in all cases, DO NOT CONENCT THE SHIELD AT THE DEVICE END.

THe shield needs to be connected to ground in order to work as a shield, but since all shields are connected at the patchbay "near" end, there ned be no connection at the far end... in fact connecting both ends allows loops to be set up with power ground connections.

Other people will argue for grounding the source and lifting the destination, or vice versa... whichever you shoose, pick one and stick RELIGEOUSLY to it.... any one can work well, but excess grounds are your enemy.

Be ready to re-connect shields on any devices which buzz, but you probably won't find many that do.

Remember that in the EU, you must NOT interfere with POWER grond connections... disconnecting the power ground makes you legally liable for any electric shocks experienced by any users, and it's just the WRONG way to chase hum anyhow.

Remember, it's not an SSL thing: It's just how you install a studio... -ANY studio!

Keith

[sodderboy]

ssltech wrote on Tue, 04 September 2007 07:08

disconnecting the power ground makes you legally liable for any electric shocks experienced by any users, and it's just the WRONG way to chase hum anyhow.

I agree with this as one of the RULES, but what about a tube mic PSU in a live room connected with a mic line run over 45 feet?  Most mic runs are over 50 feet with the shield connected at both ends.  I saw modded power cables (ground lifted) in use in the UK, Europe, and the USSR.  In the states it is a ground lift.  The long length double chassis connection has to be broken, and lifting a mic line shield, even for a self powered mic lifts the second connection but does not eliminate hum induced across the long run.  Another way would be to put 150:150 iron in the path i guess.
I agree that seeing lifts on everything in a control room is amateur, but I see them more than often in live rooms where equipment is connected through long wire runs.

Might this be a situation for, gulp, uh. . . balanced power?  I have an Ebtec single outlet mini-balancer on order for a test with live room re-amps, keyboards, and mic psu's.
Mike  

[ssltech]

I've done that using a short male-to-female XLR mic ground-lifter adaptor in the XLR output. Basically the 3-pin XLR output gets ground lifted, and the mic is safety-grounded at the PSU... Always worked for me although there can be exceptions to ANY rule.

None the less, when starting a studio installation you HAVE to have a plan and understand why you're adopting that plan in order to effectively chase down the inevitable exceptions!

Keith

[Dave Hecht]

Gabriel,

 I agree with Keith on the electrical ground / lifted audio shield issue. One thing to add: after the console is installed, get an amp and monitors installed next. If you have no hum at this point, add each piece of gear one at a time and listen for hums & buzzes. Fix each individual problem before adding the next piece. This way, it's much easier to track down any problems, rather than trying to guess where any hums are coming from.

 Also, can you add you full name to your user profile? Thanks.

Dave Hecht

[sodderboy]

The ground-lift mic cable works for me less than half the time.  I almost always find that long low-signal runs that are amplified 40 or 50 dB like to have the shield connected on both ends.  I just finished a 500 foot line-level Belden multipair(yuk!) run that worked only when shields were connected at both ends.  Otherwise there was crosstalk and humaplenty.

The SSL patchbay DL connection panel is very conducive to the additive, stepped install.  Each group is connected with a DL or 2.  There are other posts regarding the order of groups added in a stepped install.  Funny.  I took a small 2 bay job and just quickly hooked everything together- and had to disconnect it all in order to discover that a bad 240V step-up transformer that was causing hum in the strangest of un-related places.  Otherwise it would have taken forever to find.

I assume the 6000's VCA faders are jumped already.  We are going to see many SSL's surviving into the next 30 years by discarding the computer.
Mike

[ssltech]

+1 vote on the "Monitors-and-nothing-else" starting point.

I did that with my first ever Amek 9098 install; just the Amek and a pair of genelec 1031's. It was so quiet I could only hear the amp hiss, and no difference when I plugged in the XLR to the speakers. I was convinced that I must not be montorintg the stereo buss (nothing was assigned, but the fader was at the top, and the monitor pot was WIDE-OPEN) so I patched a tone to a channel fader, assigned it and crept the fader off the endstop. -I almost crapped when I heard 1kHz clear as day! -Loud enough to be painful at the listening position with the fader at -40dB, and yet I couldn't hear a darned THING when I muted/unmuted the monitors with my ear right up to the tweeter... The AP read a -103dB noise floor, and +28dB before onset of clip distortion... 131dB of USABLE dynamic range... -Made a bleiever outta me! -One week later I installed a second 9098i and measured 1dB LOWER noise floor!!!

Anyhow, Dave's prescribed method of adding connections in blocks has worked well for me for years, and I will never bring a room up ANY other way.

As for Sodderboy's point; yes, there will sometimes be exceptions and circumstances which require a different strategy, but for the most part, I hope that we agree insofar as a CONSISTENT grounding plan -no matter which one you choose- needs to be deployed at the outset, and that way you should find yourself having to address much fewer of these 'exceptions'. Nothing frustrates more than a persistant power hum which perversely gets worse, the more things you try to cure it!

Keith

[MI]

ssltech wrote on Tue, 04 September 2007 08:08

*snip* Let me try to give a quick explanation. Basically the SSL should be the central item to which everything else is connected... *snip* Remember, it's not an SSL thing: It's just how you install a studio... -ANY studio! Keith

I've been enlightened!!!! Thank you so much.

You guys are like gods...not the God, but a god!

Now I'll be correcting a whole bunch of XLR's removing the shield that's connected.


One question, so I run like a 14 AWG (plastic coated) copper wire from the
console's ground screw (MCI JH-636) to a 2 foot long spike in
the ground? (or am I way off here?)


I'm still in shock! Thanks again!!!

Mario

[MI]

One more thing...

Does the same non shield connection apply to XLR inputs on powered monitors and to the Amplifiers?

Thanks.

Mario

[Dave Hecht]

[quote title=Mario I. wrote on Tue, 04 September 2007 20:16][quote title=
One question, so I run like a 14 AWG (plastic coated) copper wire from the
console's ground screw (MCI JH-636) to a 2 foot long spike in
the ground? (or am I way off here?)

Mario [/quote]


 You're on the right track. However, I'd use heavier cable for the main ground to the stake. You'll also probably need the ground stake to be considerably longer than 2 feet. Typically, I see them anywhere for 8 feet to 15 feet, depending on soil conditions.

Dave Hecht

[steve p]

ssltech wrote on Tue, 04 September 2007 05:08

THe shield needs to be connected to ground in order to work as a shield, but since all shields are connected at the patchbay "near" end, there ned be no connection at the far end... in fact connecting both ends allows loops to be set up with power ground connections.

This is exactly how i did it,

And the rack gear chassis can be grounded to the "star" if needed

no hum at all  


peace,


steve

[ssltech]

Dave Hecht wrote

You're on the right track. However, I'd use heavier cable for the main ground to the stake. You'll also probably need the ground stake to be considerably longer than 2 feet. Typically, I see them anywhere for 8 feet to 15 feet, depending on soil conditions.

I'd go for 4 gauge, or even bigger... specially if it's a long run. -Zero-gauge welding cable is a BIG fave, and local shops tend to stock it.

'Soil conditions'... Here in Florida, if you dig down six feet, you hit wet sand. Hence, in Florida we don't tend to dig too deep. In Liverpool the ground was damp clay and HARD to dig/drill into. Mercifully I could USUALLY find a metal water riser, about 12" in diameter... but beware of other people using them as power ground and the possibility that a plastic pipe replacement "downstream" can make life VERY dangerous. I always made the connection right where the pipe disappeared into the ground for good.

Keith