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What happened with our electric drums?
Old 17th July 2019
  #1
Here for the gear
 

What happened with our electric drums?

Hello, guys. I am new here, and relatively new to sound engineering (two semester of recording classes at local community college, plus some experience in running our church's audio).

I have a question that's more or less a thought experiment now, as the "problem" has been solved. But the experience left me somewhat surprised, and I wanted to kind of pick your brains on the matter.

The story.
In our church, we have a set of electric drums. Almost never used, no one to play them, small church. They are usually unplugged from electrical socket and are just sitting in the corner, awaiting further instructions. Sometimes they were used by guests or something, so I never disconnected them, left them on channels 9 and 10 on our board.

Anyway, I noticed something that to me was strange at the time. The drums picked up the rest of the stage, even when they were not on. And since I have them on a board, I found when channels were unmuted, I could use them as sort of another microphone? I experimented, and it was funny hearing the talents louder than normal, since I guess it was compounding of the two sources.

My first thought was, live sound version of bleed, leakage, spill. Someone told me, they have something like a microphone on each area: high hats, toms, cymbals, etc., and basically, those microphones picked up the sound of the stage.

The "problem" is easy fix. I just unplugged them from the snake.

But I am curious now, what exactly happened, and if, in theory, it is ever a good idea to use this one weird trick to make the vocalist sound louder. I can see this leading to a feedback loop and that annoying screech that makes the whole congregation cringe?

Basically, what happened, exactly, and what is the potential for this, if any? I also can't be the only one this happened to? Maybe someone had similar "problem" ?
Old 17th July 2019
  #2
Old 17th July 2019
  #3
Gear Guru
 

Quote:
Originally Posted by Alex Panasenko View Post
Anyway, I noticed something that to me was strange at the time. The drums picked up the rest of the stage, even when they were not on. And since I have them on a board, I found when channels were unmuted, I could use them as sort of another microphone? I experimented, and it was funny hearing the talents louder than normal, since I guess it was compounding of the two sources
electric drums or electronic drums?
What is the make and model of the drum set?

Quote:
My first thought was, live sound version of bleed, leakage, spill. Someone told me, they have something like a microphone on each area:
If you have "electric" drums - they might be real drums with actual microphones inside. Or even actual microphones clipped on the rims? Are they real drums- like with a shell and heads? Can you tune them with a drum key?

Most electronic drums consist of rubber or plastic "pads" under which is a pickup or sensor. This is a "microphone" in the technical sense - a piezo contact mic. The cables coming from each pad are supposed to go into a drum "brain", a device that reacts to each sensor and spits out a predetermined sound appropriate to that pad. So if you hit the snare pad, you would (normally) hear a prerecorded snare sound.

However in this usage, the mic in the pad is acting ONLY as a "trigger". It's not supposed to be a "mic" - it just tells the "brain" when to 'release' its sound. That is to say, that if you strike the pad with a stick, a mallet, or your fist, the exact same sound will come out of the "brain". The actual sound of mic inside the pad is not used - it is just a voltage used as a "switch" to trigger the samples.


Quote:
The "problem" is easy fix. I just unplugged them from the snake. But I am curious now, what exactly happened,
If the drums are acoustic drums with mics inside, those mics will pick up stuff. Not very well, or cleanly, but they will pick them up.

If your drums are electronic - the rubber pad type - then the cables from the drums should go into the drum "brain" - a small box usually mounted somewhere on the drum rack. Not directly into the snake! These mics may also pick up stuff, but even worse than 'real' mics.

Quote:
and if, in theory, it is ever a good idea to use this one weird trick to make the vocalist sound louder.
Is this the same one weird trick that flattens your belly? Or the one that lowers your insurance bill? I would advise against this as:
1. if the drums are regular drums with internal mics, those mics are distant and maybe even blocked from the other sound sources. This cannot be a "good sound". If you want to mic up the singer, wouldn't you want the put the mic in the open and near his mouth and not inside a wooden tub 10 feet away?

2. if the piezo mic triggers on drum pads are what is picking up the sound, not only is it indirect, but As Microphones, piezos are the worst. These are fine for triggers but they make really crappy "mics".

If you want to get the vocalist louder, turn the vocalist up. If you are getting feedback, reposition your monitor speakers and maybe even your fronts. Tell the rest of the band to turn down. You know, all the usual stuff.

Post the model of the drums and a photo if you can.

Last edited by joeq; 17th July 2019 at 10:17 PM..
Old 18th July 2019
  #4
Here for the gear
 

Electronic ones. They have those rubber pads, and have the wires running into the "brain." I had them connected from the "brain" into the snake instead of, like, portable amps.

Most likely they are piezo, I didn't see anything on them that resembles a "typical" mic, and they must have picked up something from the stage, otherwise I'd not see any signal on the meters (I solo-ed channels with the drums and the meter showed incoming signal). It was picking up enough to make for an audible difference when the channels were added to the mix, I am sure of that.

I have to look when I am there next, I don't have any pictures ready and don't know all the gear name by heart.
Old 18th July 2019
  #5
Gear Guru
 

Quote:
Originally Posted by Alex Panasenko View Post
Electronic ones. They have those rubber pads, and have the wires running into the "brain." I had them connected from the "brain" into the snake instead of, like, portable amps.
if the pads are going into the 'brain' and then the brain into the PA, then theoretically the only way sound could be coming out of the brain is if one of the piezos in the pads is stimulated loud enough to trigger a drum. If the piezos were going directly into the PA, there might be low level rumble or something. But connected properly, the drum brain should be producing drum hit sounds. That's all.

I had a trigger setup in my acoustic drums and if I was not careful setting my sensitivity, a nearby bass amp might trigger my floor tom. But this "false triggering" would sound like a bunch of spastic boom boom ba-boom tom hits. Producing whatever tom sound was currently programmed into the brain. Not like a "reinforcement" of the bass amp.


Quote:
Most likely they are piezo, I didn't see anything on them that resembles a "typical" mic, and they must have picked up something from the stage... It was picking up enough to make for an audible difference when the channels were added to the mix, I am sure of that.
this is just a guess, but if none of your piezos are going into the PA directly, maybe there is some other mic type thing associated with drum kit, a mic for the drummer's vocal or a talkback mic or something like that. Look at the 'brain' and see if there is anything else going into it besides the actual pads.

Or maybe there is a "real" drum or two connected to the kit that is miked up?

If your random stage volume is triggering the electronic drums, you would hear bam bam bam - the drum samples - because the piezos inside the pads are merely acting as switches. For them to be acting as mics, they would need to be connected a different way. See if any are going straight into the snake. Look for anything else that might be associated with those channels, because to me, that is not how such a pad kit should work.
Old 20th July 2019
  #6
Here for the gear
 

Sound X DMI-1458 electronic drum set.

I didn't see any microphones on or near any of the drum parts. (Unless there's one in the "brain"?).

I just tried to have the drums plugged in the snake (drum to "brain," and "brain" to snake, snake to board, etc.). (There is no drum to snake option, it's only through "brain" and then to snake.) Something is coming through on the channels 9 and 10 (channels which Sound X is on). Unless I am imagining it, it definitely sounded like the vocalist in the total mix was louder with channels assigned to Sound X added to the mix, and nothing when assigned channels were off.

But whatever happened, I'll just have to have them not plugged in until they are actually needed. Problem solved. And it wasn't really a problem; it didn't interfere.

I just found it weird that even though the world drum set was unplugged and no turned on, there was still something coming through on the channels it is assigned on.
Old 20th July 2019
  #7
Gear Guru
 

Quote:
Originally Posted by Alex Panasenko View Post
Sound X DMI-1458 electronic drum set.

I didn't see any microphones on or near any of the drum parts. (Unless there's one in the "brain"?).
even if there was, you say it happens even when the drums were not turned on.

Quote:
Something is coming through on the channels 9 and 10 (channels which Sound X is on). Unless I am imagining it, it definitely sounded like the vocalist in the total mix was louder with channels assigned to Sound X added to the mix, and nothing when assigned channels were off.
A lot of boards have a switch for mic and line. So line input "9" on your console would be your drums and mic input "9" would be a mic coming in on that same channel. Both might be "9" just depending on where that switch is. But you said you physically unplugged the drums from the snake brought up 9 and 10 and the effect did not happen? Or did it?

Quote:
I just found it weird
it definitely is weird, but I would still bet on a logical explanation. Even though it is in a church, it's probably not a Miracle.

Quote:
that even though the world drum set was unplugged and no turned on, there was still something coming through on the channels it is assigned on.
When you say "unplugged" do you mean the drums were "unplugged" from AC power, or do you mean that they are "unplugged" from the snake?

If they are unplugged from the snake and you are still getting this effect, then somewhere between the snake and your board, some other signal has to be sneaking in. Check the back of the board - trace the wires and see what is really plugged into 9 and 10.

Just out of curiosity, have you actually tried to play the drums through the system or just have noticed this side-effect when the channels are up?
Old 21st July 2019
  #8
Here for the gear
 

The drum set was not plugged into wall outlet, the "brain" was off, all the drums were going into the brain, and from it, into the snake, from snake into board through the XLR port (not Line In). I had my drums channels' faders on the board up to about 3/4 way to Unity Gain, unmuted them, trim was set at UG, Main at UG. The meters on the channels showed activity, though below yellow, and definitely not into clipping.)

This way, there was definitely different characteristic to sound coming out of the speakers. It seemed louder.

If my drum channels were muted (or in some other way taken out of the main mix), there was no difference. (I think--I don't remember for sure--the meters still showed some activity, even with channels muted.)

When the set was unplugged from the snake, also no difference, and nothing on the meters for those channels.

I am beginning to think, all this is because my "experiments" were simply amplifying noise floor, and all I was adding into the mix was amplified channel hum? But I don't understand why vocals seemed louder in this case.
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