Jump to content

"no laptops used may be plugged into ac power" how to get round this


Recommended Posts

  • Members

a gig i'm working with in mid january is being run by someone who, from past experience, is very stubborn, and also very smart. he tends to do things that make little sense, except to him. heres the latest one, and i'd love some input for this.

we have dances each night of the event which require djs. most of the djs are using laptops with external controllers, external hard drives, etc. the guy in charge of the soundsystem has insisted that no laptops can be plugged into ac power because they create to much crosstalk and noise in the soundsystem.

i have experienced this, but it was solved effectively with a di with ground lift switch and some 1/4 to 1/8 cables. it has never been a problem after this is done.

if i can not convince him that di boxes and 1 to 1 transformer isolation can solve this problem, i will lose half or more of the djs. i want to present reasoned arguments and handle this diplomaticly, because thats the only way i'm going to get things done with this guy, and besides its more professional.

please help!

Link to comment
Share on other sites

  • Replies 63
  • Created
  • Last Reply
  • Members

I guess the first thing would be to ask him if he'll even listen to the proper way to do it. If he's so stubborn that he won't then getting a bunch of info is a futile effort. I've used an 1/8 to 1/4 mono into a do and out to foh for years and never had one problem. You know the same. Are you hoping that he'll believe you or are you trying to find another way to convince him?

Link to comment
Share on other sites

  • Members

The first plan of attack would to use ground lifted, transformer isolated DI's (not active). Under some conditions a special transformer with dual electrostatic shields can be necessary due to RF capacitively coupled across the transformer.

Now this works 95% of the time, but there are some switching power supplies that are very noisy, and on some laptops they can cause HF ripple currents to flow where they should not flow and cause noise that can not be resolved with a DI (because the because the cause is unrelated). This is where eliminating the power supply can really help. Just had this happen with an apple notebook, fully transformer isolated but HF noise was being coupled across the transformer. He plugged the power supply in at intermission and I saw signal on the meter but could not hear it. It was oscillation >20kHz, something that you want to avoid because of the potential for damage. Unplug the supply, the interference was gone.

Link to comment
Share on other sites

  • Members
Quote Originally Posted by RoadRanger View Post
No LPF's on the channel strips? Guess I'm spoiled with running digital smile.gif .
Sometimes the problem is ground current related... ie. injecting RFI into the grounds via the LPF's if the signal is strong enough.

If it's getting in over the audio inputs, generally, the LPF's are set (by design) with the -3dB point around 30kHz, so if the noise is even 40-50kHz and strong enough, it can certtainly be a problem.

It depends on how the noise is getting in, and what it is. I didn't have the equipment on hand to analyze this, and certainly not DURING the show wink.gif
Link to comment
Share on other sites

  • Members

the guy in charge is grandfathered in for years and years..one of those "he'll do it for free" type things and i'm regretting my involvement with this whole thing at this point, but it'd be rude to back out now. anyone else ever worked a fan based convension like for anime or treckies? i shouldnt have.

Link to comment
Share on other sites

  • Members
Quote Originally Posted by spottyaudio View Post

we have dances each night of the event which require djs. most of the djs are using laptops with external controllers, external hard drives, etc. the guy in charge of the soundsystem has insisted that no laptops can be plugged into ac power because they create to much crosstalk and noise in the soundsystem.


if i can not convince him that di boxes and 1 to 1 transformer isolation can solve this problem, i will lose half or more of the djs. i want to present reasoned arguments and handle this diplomaticly, because thats the only way i'm going to get things done with this guy, and besides its more professional.

please help!
I'm not sure what you're function is at this gig, but why not ask him to allow the DJ's to use an isolating device (supplied by him) UNLESS he is still experiencing noise. Then he gets to literally pull the plug. The DJ's would have to be warned in advance, but most would probably still be willing to do the gig, because humans usually reckon that things will work the way they want them to.
Link to comment
Share on other sites

  • Members

 

Quote Originally Posted by spottyaudio

View Post

the guy in charge is grandfathered in for years and years..one of those "he'll do it for free" type things and i'm regretting my involvement with this whole thing at this point, but it'd be rude to back out now. anyone else ever worked a fan based convension like for anime or treckies? i shouldnt have.

 

Yup, you screwed yourself there for sure. Always remember "No good deed goes unpunished" frown.gif . Personally I'd just pull out saying you can't work with the sound provided - no reason to ruin your rep dealing with those idiots mad.gif.
Link to comment
Share on other sites

  • Members

The only way I can see to do strictly under his conditions is to use extended life or multiple laptop batteries...and yes, this is ridiculous rule. Would he take an output from an "old school" cd based system?

I'm not recommending this, but an "outside the box" idea would be to connect your laptop wirelessly to his mixer through an IEM system or something similar. Take the headphone out of the IEM receiver into a stereo pair on his mixer and output your line level audio into the sender unit. Now, admittedly, this introduces more issues than the laptop power supply...but if the guy is just being hard headed...it might be an ugly work around.

In that line of thought...I'm guessing there is not optical out (Toslink) on your system and an input on his...a fiber connection wouldn't cause any AC problems.

Link to comment
Share on other sites

  • Members

 

 

 

 

 

So I'm assuming that you can't get enough power with the built-in battery? Does your laptop have an extended range battery available? How about swapping to a new battery mid show?

 

 

 

 

I DJ regularly on the side for fun and extra $ and the short answer to your question is *no,* running on battery power is not acceptable. I bring my own DIs for just this sort of thing if I use someone else's sound system; better yet, I bring my own PA.
Link to comment
Share on other sites

  • Members

Here's the problem.

E25D6B52-ABFF-49A6-9924-FB9C1E9B6E43-295


Quote Originally Posted by spottyaudio View Post
the guy in charge is grandfathered in for years and years..one of those "he'll do it for free" type things and i'm regretting my involvement with this whole thing at this point, but it'd be rude to back out now. anyone else ever worked a fan based convension like for anime or treckies? i shouldnt have.
I'd definitely walk. And if he likes working for free, have him mow your lawn after.



For free.
Link to comment
Share on other sites

  • Members

 

Quote Originally Posted by flanc

View Post

I'm not recommending this, but an "outside the box" idea would be to connect your laptop wirelessly to his mixer through an IEM system or something similar.

 

IEM's tend to be noisy and not particularly HiFi - they don't have to be for what they are used for...
Link to comment
Share on other sites

  • Members

 

Quote Originally Posted by spottyaudio

View Post

the guy in charge is grandfathered in for years and years..one of those "he'll do it for free" type things and i'm regretting my involvement with this whole thing at this point, but it'd be rude to back out now. anyone else ever worked a fan based convension like for anime or treckies? i shouldnt have.

 

I don't think it's rude at all. You didn't make up the rules and if you can't accommodate you can't accommodate. It's pretty much that simple. Just tell the powers that be that due these specific requirements you'll have to decline and let the folks putting this shin-dig on deal with the hassle. If you're the only one to back out so be it. If they do indeed lose 1/2 the talent then they will likely make changes. Someone has to back out first for that to happen.
Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.


×
×
  • Create New...