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Author Topic: Low Keyboard Signal Strenth at Live Events  (Read 1060 times)

Alec Spence

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Re: Low Keyboard Signal Strenth at Live Events
« Reply #30 on: August 21, 2019, 12:50:17 pm »

I'm going to have to dig into the design of DI boxes to learn more.
Not really.  Your problem was that you were running at too low a level for standard kit (though you combo/mixer tolerated it better).  Once you fixed the output level of your keyboard, all is fine.  None of this has anything to do with DI boxes.
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Don Martz

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Re: Low Keyboard Signal Strenth at Live Events
« Reply #31 on: August 21, 2019, 12:52:30 pm »

Passive DIís are more problem than they are worth.  On acoustic instrument I find they can be a pain.  As general DIís for events when Iím taking all comers I use just active boxes and do away with the faff.  Keys are usually fine with a decent passive box, but a pair of the BSS 116ís are always fine, even things like the lowly Behringer DI 100 boxes will always work.
OK, I just read an excellent Sound On Sound article on DI's and in regards to passive DI's it stated: "By selecting the winding ratios and impedances carefully, the transformer can be arranged to provide a reasonably high input impedance (up to about 150kΩ) to the unbalanced instrument source, while also stepping down the signal voltage by about 20dB and providing a low-impedance, fully-balanced output suitable for connection with a mic preamp."  So there you go, 20db exactly as Art said.  I guess I'm convinced that I should either use an active DI or turn my keyboard up to full volume whenever the soundman complains of too little signal.

-Don 
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Bob Faulkner

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Re: Low Keyboard Signal Strenth at Live Events
« Reply #32 on: August 21, 2019, 12:56:38 pm »

We use all active DIs in our system.  There's been too many issues with passive DIs (very similar to your situation Don).  You may want to keep a couple of active DIs with you when you play-out.  The sound person will love you for it!
 
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Tim McCulloch

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Re: Low Keyboard Signal Strenth at Live Events
« Reply #33 on: August 21, 2019, 02:36:06 pm »

OK, I just read an excellent Sound On Sound article on DI's and in regards to passive DI's it stated: "By selecting the winding ratios and impedances carefully, the transformer can be arranged to provide a reasonably high input impedance (up to about 150kΩ) to the unbalanced instrument source, while also stepping down the signal voltage by about 20dB and providing a low-impedance, fully-balanced output suitable for connection with a mic preamp."  So there you go, 20db exactly as Art said.  I guess I'm convinced that I should either use an active DI or turn my keyboard up to full volume whenever the soundman complains of too little signal.

-Don

What level of soundperson are you dealing with?  I ask because this is starting to sound like amateur bullshit to me.

First, on your console, there is at least a 20dB difference in expected signal level between line in and mic in (more like 50dB, but that's what the gain knob is for).  The PURPOSE of a DI box is to take an unbalanced signal of *any* level and turn it into a balanced, mic-level signal to be connected to the MIC input of the console.  How much gain is required at that point is a matter of the impedance matching (transformer turns ratio) ratio and input level.

I suspect your "soundpersons" were freaking out because they thought they should see approximately line-level coming out of the DI, which wont (or should not) happen.  There are a couple of DIs - that you're unlikely to see in LAB Lounge-level use - that *do* have line level outputs but those in the $500 category.

If *any* input requires more input channel gain than is customary, especially if it's a LOT MORE, one should IMMEDIATELY suspect a bad mic cable (one-legged), a bad patch cable, bad sub-snake channel (one legged) or a defective DI (it does happen).  Typically this scenario is accompanied by hum/buzz and a thin sound with much less low end but depending on the exact failure mode, can be full range but low level (DI transformer with shorted windings).

Don, if you were within 100 miles of me I'd drive to you and prove my thesis.  I think your soundpersons are full of shit and/or have broken stuff.\\

edit: I'm a lousy speller
« Last Edit: August 21, 2019, 03:24:53 pm by Tim McCulloch »
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Debbie Dunkley

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Re: Low Keyboard Signal Strenth at Live Events
« Reply #34 on: August 21, 2019, 02:47:39 pm »

What level of soundperson are you dealing with?  I ask because this is starting to sound like amateur bullshit to me.

First, on your console, there is at least a 20dB different in expected signal level between line in and mic in (more like 50dB, but that's what the gain knob is for).  The PURPOSE of a DI box is to take an unbalanced signal of *any* level and turn it into a balanced, mic-level signal to be connected to the MIC input of the console.  How much gain is required at that point is a matter of the impedance matching (transformer turns ratio) ratio and input level.

I suspect your "soundpersons" were freaking out because they thought they should see approximately line-level coming out of the DI, which wont (or should not) happen.  There are a couple of DIs - that you're unlikely to see in LAB Lounge-level use - that *do* have line level outputs but those in the $500 category.

If *any* input requires more input channel gain than is customary, especially if it's a LOT MORE, one should IMMEDIATELY suspect a bad mic cable (one-legged), a bad patch cable, bad sub-snake channel (one legged) or a defective DI (it does happen).  Typically this scenario is accompanied by hum/buzz and a thin sound with much less low end but depending on the exact failure mode, can be full range but low level (DI transformer with shorted windings).

Don, if you were within 100 miles of me I'd drive to you and prove my thesis.  I think your soundpersons are full of shit and/or have broken stuff.

This whole thread I have been thinking, "But this is what the gain knob is for - isn't it?
Regardless of what level the OP is providing the sound person, it shouldn't make ANY difference - should it?
My gains take care of everything handed to me for the most part. Any strangely hot / low levels cause me pause for thought but that is rare and I'm talking way off - not 20db....
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Robert Lofgren

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Re: Low Keyboard Signal Strenth at Live Events
« Reply #35 on: August 21, 2019, 03:08:06 pm »

You may need to engage the pad on an active DI as there is a risk of distortion since compared to a passive DI the active one has limited input headroom.

I forgot(?) to engage the pad on a j48 connected to a keyboard once and this was not good. This did not show up until late into the show when the keyboard player played at full tilt.
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Mike Caldwell

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Re: Low Keyboard Signal Strenth at Live Events
« Reply #36 on: August 21, 2019, 09:05:53 pm »


I have said in the past and continue to say when a band is really good I have a relaxing time of it. When they arenít I am working so hard to make it work (not just solos and I usually  get a lot of compliments either way) but, I am exhausted at the end of the show with the band that I have had to work hard to get that way.

I agree 100%!!!!!

Chasing levels all night and sometimes to the point of re-trimming the channel or channels is more damage control than artistic mixing!!

ProSoundWeb Community

Re: Low Keyboard Signal Strenth at Live Events
¬ę Reply #36 on: August 21, 2019, 09:05:53 pm ¬Ľ


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