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[Brian Wynn]

[I never trust video world, maybe because most of my work used to be doing sound for video and some film.]

Hi Kevin,

Not to Hi-Jack the thread, Would it be possible to post a simple diagram of the DI box inserted into your chain? (Showing the entire chain)

Also as you mentioned video, what did you find most successful for recording cameras to a recorder?

I know the questions are basic, As we do small Theater Productions and just started adding some Live Instruments.

Always looking for ways to improve audio.

Now we use 16 mics, 10 wireless and 6 wired. We use the 16 D.O. of the mixer to go to an Alesis HD 24 XL, and was wondering the best way to get one channel of each of the 4 cameras into the HD-24.?

The Cameras have XLR out, and I just record to tape and at least I have back-up.

Any thoughts would be welcome, I will be more than happy to start a new thread if that would be better.

Regards,  John

Interested thread.  I would love to hear the solution to the problem for the SC48.

John if you feel bad about Hi-Jacking the thread then don't do it.  Sorry dude if your going to ask question's then start a new thread or PM your question's.  Thanks

[Kevin Maxwell]

Hello!

I am starting to get a little uncomfortable with the direction the thread here and on DUC are taking.

Calls from the network bout how this information got public etc.
I only seek guidance to avoid such issues.

Let me get a few things clear.

>The board has NOT been out for a gig ever since. A replacement output card was available the next day, and installed.
>We only checked all inputs on the board and found them to be  working yesterday.
>I did not realize the replacement board came in from an official channel. We requested a fellow vendor in town to send his in if possible. None the less, I am highly obliged, and have shared my thanks.
>Support from Avid has been prompt.
>I am a sound engineer and not a vendor. My preferred vendor bought the board on my request.

Now, there have been similar cases. I can almost guarantee that with the instant answers I got for my problem.

My console was not powering up successfully. There was no deliberation over what could be the problem, I was told in AN INSTANT : "The output card is fried. A similar case was faced recently. Nothing can be done.". Period.

I again appreciate the truth. But does this only happen with the SC48's or is this a mere coincidence ? Never ever heard of another console ever going down.

Therein lies my problem.

Regards,
Sidhu

I am not sure who you are talking to (regarding the direction that this thread has taken) but I will guess it is me. And I don’t know what you are talking about when you said –

"Calls from the network bout how this information got public etc.
I only seek guidance to avoid such issues.”

The information became public because you posted about it on a public forum. We all want to avoid such issues as a console dying on us and leaving us in a bind.

I have been thinking of recommending the SC48 for a few different places and I was hoping to use one for an upcoming theatrical show. Reliability is a top priority for me so that is why I jumped on this discussion. I am always hesitant to discuss equipment failures in public because some people seem to think things will never or should never fail. And they hear of one failure and they freak out. And as much as I would like equipment to never fail - stuff breaks. I have seen so many different pieces of gear fail over the years that it doesn’t surprise me any more. And a lot of that gear was some of the most expensive piece that you could buy. I try to always have a backup plan or a workaround in mind. Now if a piece of gear breaks and the support is fantastic then that means a lot to me. But if a piece of gear constantly is breaking then I am likely to steer clear of it no matter how good the support is.

I have heard of many different consoles going down. Or were you only referring to the Digidesign/Avid series of consoles.  I was doing prep for a big live show that was also one of the first HD video shoots. The sound company (not a little one by any means) that we had arranged to supply identical large digital consoles (not a Yamaha and not a Digidesign/Avid) for the house and monitor positions calls us and tells us that they where having reports of them crashing and they suggested that we use a couple of their PM1D systems instead. BTW I had them hire Doug Fowler to take my place and do the house mix because I had another booking at the same time. And the reports I got back were he did a fantastic job.

It is good to know that they were very quick to help you. But in one place in your message it says -

“We disconnect the ribbon, and Voila! the console boots. I recover what I can. Wait for the replacement board to come in. 5 minutes to curtain. I am repatched and a little nervous.”

And then in another it says –

“>The board has NOT been out for a gig ever since. A replacement output card was available the next day, and installed.”

So was it fixed that night for the show to go on with that SC48 or was it fixed the next day?

[Kevin Maxwell]

While transformers may offer some overvoltage protection, there are plenty of events which will march right on through the transformer and still potentially damage circuitry.  For example, if one leg of the isolated differential pair gets shorted to 115V mains, that 115V 60 HZ AC signal will go right through the transformer as if it were an audio signal.  If the protection components (varistors, transorbs, etc.) try to clamp that voltage but aren't sized to handle that much power (especially for a continuous short), they'll blow and possible take out other circuits with them.

Good audio transformers will even pass common-mode transients -- even though common-mode is exactly what a transformer is supposed to reject.  The very characteristics which make a transformer good for audio also creates capacitance between the primary and secondary windings.  A lightning strike nearby may create a high-voltage transient on both legs of the isolated differential pair;  some of that transient will travel through the winding capacitance and hit your outputs.  Is it enough to blow the protection devices?  Maybe.

I guess I have been very lucky then. Are you saying that I shouldn’t be using the isolation transformers? Or are you just letting people know that it won’t necessarily protect you from the type of failure you described and that that may be what happened to the SC48 in question here. So even a line level isolation transformer may not have helped. If it is a press feed we usually used a press box that include transformer isolations and a distribution amp. So it is likely that if a problem came from video world it wouldn’t take out the house mixer. It might take out the press box.

I made a service call for a blown channel strip on an analog console and as best we could figure out the culprit was a active DI that failed and blow out the front end on the channel. But I have to ask what kind of failure would take out the output card on an SC48 like they said. 

Sheldon said“What's known at this time is that the output was subjected to a very high voltage/current from the connected equipment - far beyond what standard protection mechanisms can handle and of sufficient strength to burn the traces on the PCB and damage many of the components in line. This is exceptional.”

Did someone make one of those widow maker type of adapters for something that uses electrical connectors adapted to audio connectors and then it got plugged into the wrong place somewhere. It is surprising to see what some people do sometimes. Or else some piece of equipment failed in a rally bad way to cause this kind of damage.   

[Nitin Sidhu]

Hey Kevin!!

No no,

Nothing at all guided towards you or anyone here. This info is meant to be public. Sheldon has been fantastic in getting this to the notice of his support staff. I seemed to have been reading something and posting something cause that is not what I meant, and I have edited accordingly. Apologies.

The faulted board was booted to recover the latest possible settings. On the day of the show.

A replacement board was made available on the day of the show itself.

A replacement card was sent to the vendor the next day to replace on the faulty board.

The faulty board has not seen a gig since.

I have today asked for delivery of two LA Audio DBT's transformer balancing interface.
http://www.laaudio.co.uk/product_dbt_1339.aspx

Will something like this help shield one against such issues. ?

Regards,
Sidhu

[Nitin Sidhu]

Sheldon said“What's known at this time is that the output was subjected to a very high voltage/current from the connected equipment - far beyond what standard protection mechanisms can handle and of sufficient strength to burn the traces on the PCB and damage many of the components in line. This is exceptional.”

Did someone make one of those widow maker type of adapters for something that uses electrical connectors adapted to audio connectors and then it got plugged into the wrong place somewhere. It is surprising to see what some people do sometimes. Or else some piece of equipment failed in a rally bad way to cause this kind of damage.

What I know is Ch 11&12 were feeding the Video console.

What the sound crew tell me is that they had both lives feeding a small 16ch. Yamaha console. With outs from the Yamaha feeding the DV recorder and a couple of cameras. Moreso, the cameras were using an Active DI box inline.

What was also verified, was that 48v was not enabled on the video sub mixer.
I have asked if any repatching was done on the Video side when the mixer went dows, and so far it is being denied.

Another very interesting development, which has been brought to notice :
One extension board, Belkin, also connected to the same UPS as the SC48 was, also smoked at the same time. Everything connected to this board, adaptors etc continue to work. Nothing plugged into this power distribution box was connected to the output of the console. One channel of a soundcard (power feed from mention extension box) was feeding channel number 47.

So it seems like a definitive on a power spike. How and why it affected the output card and the extension board, I have no idea.

Also, the video guys were drawing power from the sound distro.

Will post the same on the DUC.

Sidhu

[Riley Casey]

Every portable sound system vendor should have half a dozen line level audio isolation transformers with pin one lift switches in their work box on show site.  They are simply good for what ails ya' on so many levels its hard to imagine being in the business of interfacing with other production elements without them.

I have today asked for delivery of two LA Audio DBT's transformer balancing interface.
http://www.laaudio.co.uk/product_dbt_1339.aspx

Will something like this help shield one against such issues. ?

Regards,
Sidhu

[Tim McCulloch]

Every portable sound system vendor should have half a dozen line level audio isolation transformers with pin one lift switches in their work box on show site.  They are simply good for what ails ya' on so many levels its hard to imagine being in the business of interfacing with other production elements without them.

We provided an arena side hang/racks to cover VIP boxes that the tour wasn't prepared to handle.  One show in an arena, rest in theaters...  The system engineer from Clair had a pair of iso transformers that went between us and them.  "Standard procedure" he said.

I've never gone wrong by following Clair's practices.

[Brian Ehlers]

I guess I have been very lucky then. Are you saying that I shouldn’t be using the isolation transformers? Or are you just letting people know that it won’t necessarily protect you from the type of failure you described and that that may be what happened to the SC48 in question here.

Nope, I'm not trying to discourage the use of isolating transformers.  As others have said, they are useful problem solvers, and I consider them mandatory whenever connecting two pieces of equipment which are powered from different mains and/or simply located a long distance apart.

I only wanted to point out that transformers will not stop all electrical faults.  Another point I'm trying to make is that, no matter how hard you try to design something to be fault-toleratnt, Mr. Murphy can always come up with a more serious fault which will take you out.  It is incredibly expensive to both design and build fault-tolerant hardware.  That's why avionics cost so much more than pro audio gear.

Another way to protect outputs on an important piece of gear (such as your console) is to run them through a line amp of lesser value -- something you don't mind replacing.  For $100 - 600 you just saved your console -- and the show.

[TJ (Tom) Cornish]

Another way to protect outputs on an important piece of gear (such as your console) is to run them through a line amp of lesser value -- something you don't mind replacing.  For $100 - 600 you just saved your console -- and the show.

And probably negated some of the "tone" of high-end gear at the same time.

[Stu McDoniel]

I guess I have been very lucky then. Are you saying that I shouldn’t be using the isolation transformers? Or are you just letting people know that it won’t necessarily protect you from the type of failure you described and that that may be what happened to the SC48 in question here. So even a line level isolation transformer may not have helped. If it is a press feed we usually used a press box that include transformer isolations and a distribution amp. So it is likely that if a problem came from video world it wouldn’t take out the house mixer. It might take out the press box.

I made a service call for a blown channel strip on an analog console and as best we could figure out the culprit was a active DI that failed and blow out the front end on the channel. But I have to ask what kind of failure would take out the output card on an SC48 like they said. 

Sheldon said“What's known at this time is that the output was subjected to a very high voltage/current from the connected equipment - far beyond what standard protection mechanisms can handle and of sufficient strength to burn the traces on the PCB and damage many of the components in line. This is exceptional.”

Did someone make one of those widow maker type of adapters for something that uses electrical connectors adapted to audio connectors and then it got plugged into the wrong place somewhere. It is surprising to see what some people do sometimes. Or else some piece of equipment failed in a rally bad way to cause this kind of damage.

The facts are this.. an isolation transformer will give you a clean sine wave but is will NOT stop sags and surges and spikes etc.. I am talking about just the transformer itself.  An isolation transformer setup with surge proctection
is really GREAT for you electronic gear.   I run all my low voltage stuff on an isolation transformer with surge protection
and run the amplifiers straight off the line voltage.   Years ago I remember talking to the FOH guy with Marshall Tucker Band and he turned me on to the Isolation transfomer thing.   If you have digital gear you want to really look into this.
I took a tour years ago in college with Best Power who made UPS units for nuclear power plants.  They had a system setup to look at the grid over the U.S. and you would NOT believe the phase reversals and sags and surges on your
AC lines..The power conditon is worse then you can imagine in the U.S.   This company had a class they gave to us on using Isolation transformers and surge protection.   If anyone tells you that you dont need Isolation and AC conditoning
they are full of crap..

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