SSlmixed.com Forum
Tech discussion => 4K,6K,8K Series => Topic started by: tlmaen on November 06, 2022, 06:34:57 PM
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Hi guys,
I am getting my first 4k console this week.
I am planning the patchbay right now, as I have to do it completely from scratch (except for the standard SSL Patch-rows).
My former Neumann Console used a different grounding scheme than SSL.
Its not a star ground its a meshed Ground. So every Module, Cable, Multicore, etc is grounded everywhere and as often as possible.
Also all of the multicores are grounded at both sides.
This worked very well for that console, but I have read that a proper star grounding is crucial with an SSL.
I can't remember where, but I read somewhere that you have to lift the ground pin on one end of the multicores...
I have to rewire all of my multicores from all of the outboard and Converters, Mic-lines, etc.
The Neumann Console has a Lemo Patchbay. I have to resolder everything to the new TT patchbay.
So I would like to do it right (and only one time)!
How is it done right?
Thank you!
T
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The grounding scheme stuff is why I strongly suggest clients move onto modern dsub bays with switching normals and grounds these days. They make installation so much more simple. Mosses and Mitchell makes some really nice ones if you want to keep with the original manufacture. The materials cost of a new bay might be intimidating but if you might end up saving money then if you try to reuse a solder jack bay and have to clean the old wires off the jacks and such. Absolute nightmare. For console connections the solder jacks are fine, nothing ever moves really, but if you decide to change anything up for the outboard, being able to configure the order on the dsub bays is huge. The only drawback with this is sometimes you need to make a descrambler cable/panel if your layout doesnt all fall into groups of 8pair.
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I forgot to say that the patchbay is a remote patchbay.
I do not have to change anything between the console and the existing SSL patchbay (hopefully)
I bought a few used M&M patchstrips for my outboard gear with solder lugs (My assistant will desolder it and make it nice and shiny :) ).
I don't have to deal with DL Connectors, only multicores to the extra patchbay strips...
I am not a big fan of D-Sub connectors, prefer the soldered connection.
All of my Outboard/Converter Multicores are in Banks of 8/16/24.
I am moving things around with patchcad for some days, getting slowly to a good layout.
But I need some light in this grounding thing!
T
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its been a long time since I installed a SSL, perhaps Jix will chime in too.
My recollection is that most all if not all I/O on an SSL is balanced, If that is the case, then a mesh ground system is desirable as no ground is ever used for audio transmission, only for noise immunity. Integrating unbalanced equipment into the system is where you can get into trouble. Best to convert external to balanced to make ground paths irrelevant.
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That would be great because its dead quiet right now. Would like to keep it that way.
I have almost no unbalanced equipment, except for a few reverbs, but I have some balancing equipment for this case.
Can anybody confirm that the SSL is completely balanced?
Does anyone else is using a meshed grounding scheme?
T
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The Mic lines have to have grounds on both ends, or you won't get phantom power, if you need it.
Some SSL DL connectors are wired 1 - 24 or 1 - 32. We had both and I had to wire them so they are all 1 - 24. This is to the "outside world". The DL connectors between the SSL the Patchbay can be wired either way.
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Channel inserts aren't balanced. Sorry. And 651 inserts aren't properly balanced.
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Just seen this post and hope this helps.
1 With ANYTHING coming in or out of the SSL patchbay, the SSL Tech ground should be the main studio tech ground which is a 0BA (or M6) Brass screw hanging out of the connector panel which may link to your 661 SSL supply or your main tech ground directly to your fusebox or tech ground stake in the ground. Keep it clean and direct.
2 SSL DL 96 way connectors from the studio always have ALL the screens connected and ALL the screen wires soldered to the patchbay.
3 NONE of the internal SSL console wiring has the technical ground connected at the patchbay to avoid ground loops.
4 The patchbay screens are shorted to the frame which is the main tech ground as mentioned.
5 The SSL has two copper bars running through the console. One is more logic stuff and the other is more analog stuff (upper buscard with the 6 way Bicc connectors on) but they join together at the end at that point under the patchbay.
6 As I understand it, all the mic, line and multitrack track inputs are fully balanced BUT, maybe the inserts are not fully balanced as Andy Miller has mentioned.
7 There are more complicated issues with the SSL tech ground system so, please contact me directly if you wish to discuss this.
6 All this is complicated, depending on your studio or house wiring layout (ie: different circuits, fridges or dimmer lights on the same circuit etc).
Hope this helps in a way and regards from Jim L
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Channel inserts aren't balanced. Sorry. And 651 inserts aren't properly balanced.
That sounds funny :-) 'not properly' means just impedance balanced?
I hoped you would chime in, Jim!
1 With ANYTHING coming in or out of the SSL patchbay, the SSL Tech ground should be the main studio tech ground which is a 0BA (or M6) Brass screw hanging out of the connector panel which may link to your 661 SSL supply or your main tech ground directly to your fusebox or tech ground stake in the ground. Keep it clean and direct.
2 SSL DL 96 way connectors from the studio always have ALL the screens connected and ALL the screen wires soldered to the patchbay.
Does this also refers to an external patchbay?
So this means that all of my Outboard Gear Multicores needs to be connected with the screen to the Patchbay...
I don't have a dedicated star Gnd connection in my Studio, it was just not needed with my Neumann Console.
The Fusebox is directly beside my control Room, wich is kind of a star gnd point, as all of my power cables go directly to the Fusebox.
Its in the same room as the Console PSU
4 The patchbay screens are shorted to the frame which is the main tech ground as mentioned.
Ok, but that would create a gnd loop if the screen is also connected to the gnd at the outboard gear?
(I think that's what I read. can't remember where. It says 'do not connect the screen at both ends...')
7 There are more complicated issues with the SSL tech ground system so, please contact me directly if you wish to discuss this.
What kind of issues? I am sure its also helpful for other people...
Thank You!
Best,
Tilmann
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Hi Tilmann
Remote patchbays are a different matter and depends on if you have a wooden rack or a metal one as the SSL metal patch tech screens could be become the SAME as any unbalanced gear case AC earths. This could be important as well as mic source grounds and a singer who touches the mic could get a shock and even die if the studio tech and normal ground wiring is not done correctly and something goes wrong.
Hardly anyone deals with this but it could be important of course.
Screening both ends could also be a problem but, if the console and effects etc are on the same circuit, it may not be. When I wire Pro Tools to/from an SSL I do NOT screen at the PT end as the SSL does that anyway.
Connect me directly so I can answer as I am not quick with all this writing stuff.
Hope this helps from Jim Lassen
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Just figured out that all of the Remote patchbay Connectors are Siemens/Tuchel Brand. They are 30Pin connectors.
I guess it was first installed in a broadcast Station/Truck.
I have to look at all the paperwork wich comes with the Console tomorrow.
The Rack for the patch will be a wooden Rack, but I had great success covering the inside with Alufoil and ground it if necessary.
Floating everything wich is connected to the ADDA is probably a good idea...
Everything in my control Room is connected to the same Powerline.
Anything special to consider with the switch mode PSU? (I may ask Malcom Toft if he have some advice)
Thanks,
T
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The old console at Le Studio also had Tuchels. I guess that’s what they used back then.
You will need a big ground wire from the console lug Jim talks about to an external grounding point.
That is usually at the least a copper stake in the ground outside the building. At Le Studio our ground was a copper grid that was in the lake. Tom Hidley used to route the air conditioning condensation drips onto the ground stake soil to keep it as conductive as possible when it was hot and dry. Smart.
The idea of having a tech ground separate from the power ground is to eliminate the crap that travels
down the power ground from getting into your console audio. If tying into the power ground worked for you before it my still work but don’t think the 3rd pin on the power supply cord is going to be enough. Look at the size of those ground bars under the console. You’ll still need a heavy gauge wire connecting to a ground point. Consider a metal cold water pipe if there is one you can get too.
There are rules for audio grounding and there are various ways to achieve the same results.
Basically, the shields should only be connected at only one end of the wire (except mic lines). I discovered at some of the studios that were wired before I was employed that they had connected the audio shields at both ends of the wires to everything. It still worked great. Grounding is a bit Voodoo. I’m pretty sure since the console patchbay section is coming pre-wired it should be fine.
My suggestion is once the console is installed connect only the console related patchrows.
Connect up some monitors so you can listen for ground issues as you proceed with connecting the rest of the stuff. By connecting your gear in steps, you can find issues as they happen and deal with them before proceeding to the next piece of gear. The worst thing you can do is connect everything up, find out you have hum, and them try to trouble shoot it. For the outboard gear if you think about it once you plug in the patch cord to a line in or insert, you’re now connecting the console ground via the patch cord to that wire. I never bus the grounds at patch rows, but others may.
I’d probably connect the shields for the outboard gear to the patch point and the gear and see what happens. You’ll certainly have to do this with external mic pres or you won’t get phantom power getting to the mic. Again, try each piece individually to listen for hum. With unbalanced gear like a Yamaha SPX90 I’ve always had to isolate the metal chassis of the unit from the metal rack rails.
I use Gaff tape on the back of the rack ears and heat shrink on the rack screws (with plastic washers) where they could touch the chassis. If you have metal rack rails the chassis of all the rack gear is connecting through the rack rails. The chassis is usually tied to ground. Oh no another potential ground loop. Good luck. I hope your install goes flawlessly.
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Thanks for your explanation!
I got the 'Console' yesterday. its in a lot of boxes and the two halfs of the Frame.
Happy that its in my place right now, was a nightmare with that Brexit sht.
I just read quickly through the documentation. It was first installed in a danish broadcast station.
That's probably why it is all Tuchel.
Not one shield is connected to the Patchbay, only hot & cold. Even the mic lines (they must be grounded at the other end...)
Each Patchbay has only one separate tiny Gnd wire going to the console.
But I couldn't fire out the other end, its big spaghetti right now...
I can start putting it all together in January have to finish a few mixing projects.
I think I will first install the Console in the same manner as my Neumann Console, and then take it from there if there are any issues.
The Neumann Console has six PSUs, all connected with only one normal IEC Power Cable.
But I will prepare a big copper Gnd Wire to my Fusebox, the internal Copper bar left some impression on me...
thanks,
T
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Found a very interesting and detailed white paper about grounding and shielding. worth reading.
He is also explaining why it not makes sense to have a separate Gnd Rod (wich is dangerous and not allowed).
https://www.jensen-transformers.com/wp-content/uploads/2014/08/generic-seminar.pdf
My patchbay are made of solid metal, so every connection shares the same ground.
Its not possible to add or lift gnd from/to certain connections.
So my options are very limited. But I guess it worked for the last 40 years...
T
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that is a very good paper, you can also see the paper at the Rane website
https://www.ranecommercial.com/kb_article.php?article=2107
https://www.ranecommercial.com/kb_article.php?article=2127
Cheers
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Channel inserts aren't balanced. Sorry. And 651 inserts aren't properly balanced.
The G series Service Manual says the inserts are balanced...
611G upper Buscards Pin 4/5, 7/8
True for E Series as well?
T
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that is a very good paper, you can also see the paper at the Rane website
https://www.ranecommercial.com/kb_article.php?article=2107
https://www.ranecommercial.com/kb_article.php?article=2127
Cheers
Yes, also a good resource!
But Bill Whitlock somewhat disagrees with 'the absolute best way to do it' on the Rane Page.
He recommends connecting the Shield at the Driver side (See 3.6).
In that section he talks about grounding, mesh ground and hybrid ground.
Really interesting.
T
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Basically, the shields should only be connected at only one end of the wire (except mic lines).
Yes because it will prevent ground loops, no because it allows radio frequency pickup! It's the real pain with grounding arrangements in studios. If possible you should always connect the screen right the way through, which is fine when running to equipment with a ground lift switch but causes problems when it doesn't. Or when it does have a ground lift switch but it has a horrible switch mode supply inside which puts noise between the mains ground and the signal ground anyway.
So yes we often do end up breaking the screen, but we really shouldn't. Particularly as studios get ever noisier at the RF end with every piece of kit having switch mode supplies and a few processors chuntering away in it.
There is a kludgy solution to break the screen but put a small capacitor (say around 1nF) across the break, so it conducts RF but doesn't conduct 50Hz/60Hz.
The real problem is that if equipment (desks and outboard) were designed / built for this to all work properly then no-one would be available to afford it. (Since leaving the audio industry a lot of my time has been spent with people who solve grounding and shielding problems all day for other industries, in fact I've long been involved with writing international standards on this stuff which is a thankless and horrible task.) What we want is the performance of medical equipment, which is really, really good at managing this stuff (it has to be!), but is eye-wateringly expensive. So we're left with trying to connect to the dodgy "classic" reverb, or a single coil unshielded Strat...which would make a professional grounding and shielding engineer say "you don't want to be doing that"...sorry, yes we do! So back to the rules of thumb and keep trying things until it works...
By the way, re ground spikes, and mesh in a lake etc, it's rarely the ground to earth that's a problem unless you're right next to a radio transmitter or you're running a studio across several different buildings. The whole studio can float up and down, and that's absolutely fine. The challenge is to either stop the noise generated in the studio from circulating in the studio at all, or to make sure it doesn't circulate through anything critical by keeping loops and aerials short, or by cancelling out any noise that does circulate by balancing.
Just seen the post about "which end to disconnect": any two audio EMC engineers will give you two different answers on this (this has been argued about at least back to the 1980s, and probably longer). An instrumentation EMC engineer will say as above "don't cut it at all". I'd say the actual answer is "it all depends" - on where the RF source is that you're protecting against, and which piece of equipment has the best RF ground. Which you won't know until you try. As above, grounding and shielding is a very specialist subject, people who do it that's all they do. So take advice from people who've got good experience, but don't treat it as a "rule" unless they actually are EMC professionals.
Cheers,
Andy
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Channel inserts aren't balanced. Sorry. And 651 inserts aren't properly balanced.
The G series Service Manual says the inserts are balanced...
611G upper Buscards Pin 4/5, 7/8
True for E Series as well?
T
No they aren't balanced on E or G series, the "cold" wire is connected to ground on both send and receive. If you look through the circuit diagrams for the 611 cards you will see there are no balancing amplifiers for the insert sends or returns.
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[/quote]
No they aren't balanced on E or G series, the "cold" wire is connected to ground on both send and receive. If you look through the circuit diagrams for the 611 cards you will see there are no balancing amplifiers for the insert sends or returns.
[/quote]
Ah, was wondering, because I only found it in the pin List of the Buscards, not in the Schematics...
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Basically, the shields should only be connected at only one end of the wire (except mic lines).
Yes because it will prevent ground loops, no because it allows radio frequency pickup! It's the real pain with grounding arrangements in studios. If possible you should always connect the screen right the way through, which is fine when running to equipment with a ground lift switch but causes problems when it doesn't. Or when it does have a ground lift switch but it has a horrible switch mode supply inside which puts noise between the mains ground and the signal ground anyway.
So yes we often do end up breaking the screen, but we really shouldn't. Particularly as studios get ever noisier at the RF end with every piece of kit having switch mode supplies and a few processors chuntering away in it.
There is a kludgy solution to break the screen but put a small capacitor (say around 1nF) across the break, so it conducts RF but doesn't conduct 50Hz/60Hz.
The real problem is that if equipment (desks and outboard) were designed / built for this to all work properly then no-one would be available to afford it. (Since leaving the audio industry a lot of my time has been spent with people who solve grounding and shielding problems all day for other industries, in fact I've long been involved with writing international standards on this stuff which is a thankless and horrible task.) What we want is the performance of medical equipment, which is really, really good at managing this stuff (it has to be!), but is eye-wateringly expensive. So we're left with trying to connect to the dodgy "classic" reverb, or a single coil unshielded Strat...which would make a professional grounding and shielding engineer say "you don't want to be doing that"...sorry, yes we do! So back to the rules of thumb and keep trying things until it works...
By the way, re ground spikes, and mesh in a lake etc, it's rarely the ground to earth that's a problem unless you're right next to a radio transmitter or you're running a studio across several different buildings. The whole studio can float up and down, and that's absolutely fine. The challenge is to either stop the noise generated in the studio from circulating in the studio at all, or to make sure it doesn't circulate through anything critical by keeping loops and aerials short, or by cancelling out any noise that does circulate by balancing.
Just seen the post about "which end to disconnect": any two audio EMC engineers will give you two different answers on this (this has been argued about at least back to the 1980s, and probably longer). An instrumentation EMC engineer will say as above "don't cut it at all". I'd say the actual answer is "it all depends" - on where the RF source is that you're protecting against, and which piece of equipment has the best RF ground. Which you won't know until you try. As above, grounding and shielding is a very specialist subject, people who do it that's all they do. So take advice from people who've got good experience, but don't treat it as a "rule" unless they actually are EMC professionals.
Cheers,
Andy
Thanks Andy!
Another Issue I see is if you only connect one end, you will end up with unconnected shield wires, if you connect multiple devices in a a row.
Only the first Device will have a connected screen (If the pachtbay has isolated Gnds).
I will leave all of my Cables with both ends connected and see how it Performs in my Studio...
T
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Ah, was wondering, because I only found it in the pin List of the Buscards, not in the Schematics...
Yes it's a shame there was never a schematic of the 611 motherboard, it makes things like this harder to work out. The insert feed will come from the output of the input card, or from the output of the EQ card, or from the output of the dynamics card, depending on how the "Dyn to", "EQ to", and "Pre Post" switches are pressed. I don't think when the 4000 was originally designed it was fully realised how people might use the insert points - those outputs were never really designed to plug into something on the other side of the studio! Unfortunately we couldn't change it for the G series as would have involved changing the 611 motherboard, and we didn't have the time or resources to do that.
I did sort it on the 9000 though :)
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I don't think when the 4000 was originally designed it was fully realised how people might use the insert points - those outputs were never really designed to plug into something on the other side of the studio!
Well, to insert some outboard gear... 8)
I have some 50 Lundahl Transformers laying around, for the worst case...
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Hi all
Sorry but I don't have the time time to deal with all of this as it could be complicated so, bear with me here.
Basically the SSL console tech screens deal with everything going in or out of it via the Analog DL connectors as they are all screened to and from the patchbay. The bantam screens short to the metal patch front panels which are shorted to the frame and end up at the main tech ground 0BA (M6) bolt under the patchbay by the DL connector panel
Contact me for a phone call (whatsapp or whatever) so I can explain quickly on the phone as it all depends on your wiring circumstances.
I have wired many studios over 30 years or so and each one is different so, contact me about this so we can chat on a phone (not writing as I cannot type quickly!)
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Channel inserts aren't balanced. Sorry. And 651 inserts aren't properly balanced.
Hi Amiliar, sorry for bothering you again with this topic...
I checked some things on my channel amplifier card and came across the 'patch return' section.
It seems like the Patch Return is fully balanced (T5).
Also the edge connector Pins 29 & 32 are connected to the upper Bus card Pins 7/8, wich is the 'Ins Return'.
Couldn't find the 'Insert Send' though
Am I wrong here...?
Best,
Tilmann
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Hi Timean
Just answered another of your questions and just seen this!! It is too late for me now so I will be brief.
I have wired both soldered patchbays and 25 way D versions and both have + and - (advantages or disadvantages). Can talk about this if you like so, contact me.
The SSL tech ground system is great and everything that goes into or out of it via the DL's is grounded by the SSL console. I have never gounded 25 way's at the other end as the SSL does it anyway and the grounds at the ProTools end have all their grounds connected anyway. I leave one screen available in case it is required at the other end but, have never had a problem.
One needs to investigate the outboard gear and look at the grounding and other wiring before making your mind up. It's a complicated subject but simple really! 110volt (or different AC power sources), DC power supplies, data and computer cables can complicate matters but it is NOT a big deal really.
Must eat and crash out now as I am so tired and it is 04:46am UK. I have some vast experience of SSL consoles (more than most) since 1980 but answering questions does NOT pay my rent and I don't have much work right now as the whole Pro-Audio industry has changed a lot over 20 years or so!
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Hi Jim,
I leave everything as it is. So everything is grounded at the console side.
At the Patchbay there is almost no shield connected (few exemptions...)
The rest is grounded at the Outboard gear side.
Will see how it works... (worked for 40 years)
Thanks,
Tilmann
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Hi Timaen
Thanks for your comments along with those from other people. Actually I did not work on SSL console frames (4, 5, 6 , 8, G or 9K's) when I was at SSL for 7 years. I just found about them afterward I left when I installed some and worked with George Gilbert (ex SSL test engineer) enlarging consoles and then reducing them later!
I just worked on most of the external wiring and the assemblies that go into them plus some fab custom stuff (a 4 buss 688 for example as a one off ... wonder where it is now, probably in the USA with a heavily modified motherboard) and also all the new computer system (11u 691 rack plus 694 Floppy stuff, Real Time, Events, Synchroniser systems and the 696 Master Transport Selector with the SSL designer Jim Smith as they were being developed. Also worked with other SSL design engineers like Trevor Stride (688 , stereo module and 5K) and Graham Hinton (683 prog Eq) so it was an interesting time for me then.
The reason why some wires on the patch are not screened is because they go back into the SSL for channel or centre section stuff and get grounded there INSTEAD on 6 way Bicc's etc.
It's complicated but simple and avoids screening a cable at both ends. The Bicc's from the patchbay are tech grounded to the upper buscard which is grounded to the copper bar (white wire) which is linked up at the end under the DL connector panel, along with the bantam jack frames via a green wire to go to an external ground point (computer or 661 PSU etc). The 651 has it's own ground wire going to the copper bar. Hope you understand this!
On that note, the reason why there may be only one copper bar throughout the console is because the logic (Total Recall etc) stuff was not in place then so, the one copper bar was for the analogue stuff (that's my opinion anyway).
I have documented all the SSL 4 and 6K grounding system and it is on this forum somewhere but I agreed with Matt Sartori that it could be paid for to obtain access with any contributions going towards helping to pay for the upkeep of this site which is not free to publish of course.
Hope this helps from Jim Lassen in the UK and most of this is based on my memory going back for a few decades so, bear with me!