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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: AllenDeneau on November 08, 2012, 01:59:22 AM
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Hey all, just checking in to see what devices and how you prefer to send a signal from your mixer into an in-house system such as a mic input.
Seems I run into a number of places it's advantageous to utilize the in-house system for better meeting coverage or remote sound etc... Typically, I take a sub mix or aux out (line level) into a DI box with a -40dB pad and into the available jack, which is almost always a mic input. So far it's worked with good results but I'm wondering if there's a better way or better tools to accomplish this when all I have is a line level signal out and a mic level input...
Most typically I'm sending from a Peavey FX16 or a Soundcraft LX7 via the aux or sub group out...
Anything better?
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It appears a good solution to me.
There are other ways to do it. For example, there are mixers that deliver a mic level at the output (such as the old Mackie VLZ). Or you could build yourself a -20dB or -30dB attenuator, which you can even make balanced: it only requires 3 resistors which will fit in the XLR plug. But I do not think this will be really better than a DI.
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The isolation from a DI might be important if the mic input has phantom power on it and your desk outputs are not robust enough.
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The isolation from a DI might be important if the mic input has phantom power on it and your desk outputs are not robust enough.
Yup, a big +1 to that. My primary work is in hotels of all types, and this is always a concern. So is adequate/properly-wired AC distro...
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The isolation from a DI might be important if the mic input has phantom power on it and your desk outputs are not robust enough.
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Rob, I'm not sure I am following.. Are you saying using a DI is important for the isolation?
My Peavey, can't remember the soundcraft numbers right now, is a +22dB out on all sub and aux mixes, so I'd think I'm ok right?
To be honest, I never really even considered phantom power being applied on the in-house system, you learn things every day.. So if there is phantom power applied, is the only issue that I'd have to pad even more? I suppose I could have an issue at the desk too with the phantom power making it's way back to my output....
Sure wish more hotel/convention halls would also port a line in jack next to all mic inputs, would make life super easy...
Thanks all. Wasn't sure if there were any nifty little devides I'd not heard of before.. Doesn't sound as if there are huh?
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Rob, I'm not sure I am following.. Are you saying using a DI is important for the isolation?
Very often a house mic input will have phantom power enabled for something like a lectern mic. When using a house mic input to interface with an existing system you want to consider (at least) two things:
1. Inputting correct level (mic level)
2. Blocking house phantom from being applied to your console out-feed
A good DI should do both for you, level and isolation.
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Very often a house mic input will have phantom power enabled for something like a lectern mic. When using a house mic input to interface with an existing system you want to consider (at least) two things:
1. Inputting correct level (mic level)
2. Blocking house phantom from being applied to your console out-feed
A good DI should do both for you, level and isolation.
Thanks Dick, that is what I was thinking, I guess I did follow, LOL!
Now, is there a benefit of using an active or passive DI in the case of phantom power isolation?
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Very often a house mic input will have phantom power enabled for something like a lectern mic. When using a house mic input to interface with an existing system you want to consider (at least) two things:
1. Inputting correct level (mic level)
2. Blocking house phantom from being applied to your console out-feed
A good DI should do both for you, level and isolation.
Real number 1: Electrical isolation from house system. Transformers are your friend.
Generally the inputs will be mic level, so a DI output is good, you may even need a pad as well.
I always use a transformer inline with a feed to a house system, level is dealt with as needed.
Mac
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Real number 1: Electrical isolation from house system. Transformers are your friend.
Generally the inputs will be mic level, so a DI output is good, you may even need a pad as well.
I always use a transformer inline with a feed to a house system, level is dealt with as needed.
Mac
Mac, what transformer do you use? Do you use a passive or active DI? Any benefit?
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Mac, what transformer do you use? Do you use a passive or active DI? Any benefit?
If you use an active DI, make sure it has a transformer.
I use whatever transformer the shop sent. Could be an IL-19, could be a Jensen.
Mac
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If you use an active DI, make sure it has a transformer.
I use whatever transformer the shop sent. Could be an IL-19, could be a Jensen.
Mac
Cool thanks. So you see any issue with using a passive DI? I've always, I think, used a passive DI with no issues but you never know...
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Use a passive DI. I use a Radial JDI.
It hasn't been said explicitly yet so here is...
Phantom power from another system into an output of a mixer MAY cause damage to your mixer!!
I found out the hard way (actually was easy for me) that the outs on my LS9 survived phantom. It did, however, make noise and not work well till I corrected the problem!
Sent from my iPhone using Tapatalk
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Use a passive DI. I use a Radial JDI.
It hasn't been said explicitly yet so here is...
Phantom power from another system into an output of a mixer MAY cause damage to your mixer!!
I found out the hard way (actually was easy for me) that the outs on my LS9 survived phantom. It did, however, make noise and not work well till I corrected the problem!
Sent from my iPhone using Tapatalk
Thanks Rob. Were you not using a DI prior to that? What did yo do to rectify the problem?
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I use a Shure M67 / M267 mixer for this application.
These are the nearly indestructible mixers of the audio world. Transformer out. Line level in (selectable)
Also the whirlwind director. This has selectable attenuation but lacks the handy meter (and limiter) of the M267.
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Thanks Rob. Were you not using a DI prior to that? What did yo do to rectify the problem?
Doing an internet search for "IL19" might give you some hints. A similar product is Rapco's ISO-BLOX. The limiting factor for these types of transformers is signal level and amount of <100hz signal is present. These small transformers have very little iron, so at high levels and with lots of LF, the core saturates.
Radial's Pro AV1 in "XLR" mode provides a true line-level transformer with ground lift if needed. It will take a decent amount of LF, too.
I presume you'll drive the house rig from a matrix or AUX, and have independent control over the output level.