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Low signal from keyboard??


Jeff_D_in_MD

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I'm having trouble getting good volume at rehearsals (no gigs yet, but we're looking for one and I want to solve the problem beforehand). My keyboard (Yamaha P-120 or Casio PX-310) is connected directly to the mixer (Yamaha MG32/14FX), either via 1/4" cable or 1/4" -> direct box -> XLR. Meanwhile, the guitarists' amps are mic'ed and the mic signal is fed to the board.

 

I find that I usually must set all available amplitude controls (keyboard volume knob, mixer preamp, and mixer AUX outputs) near maximum in order to hear myself well in the mix, whereas the guitars are always set much lower. It's not the case that the guitars are too loud, because their volume is actually quite reasonable and could go much higer, but rather that I have much less headroom than they do.

 

So, is the output from a keyboard typically less hot than that from a mic? I have tried running the keyboard signal through an amp (Roland KC-150) first and getting output from that, but the signal then was much too hot for the mixer input.

 

How are you folks connecting to the board? I'm probably doing something wrong, but we do not have a dedicated sound person to help troubleshoot.

 

Yamaha P2 acoustic, Yamaha P120 digital, Nord Electro 3HP, QSC K10.

FOR SALE: Nord Electro 2-61.

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I often go through a DI into a mic in. However, level is down. You are having a more severe problem. It sounds like your boards are sending -10db rather than +4db. This is a choice some makers make on some boards as it makes it easy to connect to a home stereo system.

 

There are a number of solutions:

 

Use an active DI. These typically are capable of sending line level rather than just mic level. Usually there will be "pads" to reduce the level by 20db and 40db so you can get levels of cut to prevent the input being too hot.

 

Use a pre-amp. A tube pre-amp can be quite small and improve your sound significantly. I picked up some low end ART ones for $20 in a Musicians Friend blowout recently and they work quite well. You will want to go in a line in, so you may need a female XLR to male TRS cable to go with if the preamp does not have an TRS out.

 

Put your DI on the output of your existing amp. This will probably give you enough level. Its at least worth a try.

 

It really should be possible to just connect your KC-150 out to a TRS in on the MG32 (one of the stereo channels) and have everything just work.

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It really should be possible to just connect your KC-150 out to a TRS in on the MG32 (one of the stereo channels) and have everything just work.

 

It does "just work," but the signal is low. (To be precise, the Casio signal is definitely low; I haven't brought the Yamaha to rehearsal since we got the Casio in the room.)

 

It sounds like your boards are sending -10db rather than +4db.

 

The Casio PX-310 specs say the line out provides 1.0V RMS at 2.3 kOhm impedance. Not sure how that converts to dB. The Yamaha P-120 manual does not provide specs on the output level.

 

Put your DI on the output of your existing amp.

 

Good idea. The line out on the amp is explicitly labeled +4dB.

 

Yamaha P2 acoustic, Yamaha P120 digital, Nord Electro 3HP, QSC K10.

FOR SALE: Nord Electro 2-61.

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The Casio PX-310 specs say the line out provides 1.0V RMS at 2.3 kOhm impedance. /quote]

 

Google^H^H^H^H^H^HWikipedia is your friend. Line level

 

As you can see, 1V is neither fish nor fowl. But not by so much that you should not be able to tweek it with the pad control (the white knob at the top of the channel strip)

 

Of course when you put it through a DI, it drops you to mic level.

 

Also, when you connect your unbalanced output on the synth to the balanced line in on the mixer (not using the DI) because only one leg is being driven your signal is effectively half (-6db) down. So the signal from your Casio, plugged directly into the board, is 2*log2(1/1.228)-6 db down (the times two is because this is volts and Watts is proportional to volts squared. That's about 10db down. That should be in the range manageable by the pad control on the channel.

 

 

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Thanks for the link. I was going to start searching for info on my own.

 

Of course when you put it through a DI, it drops you to mic level.

 

So, what you're saying is that the DI may make matters worse.

 

Also, when you connect your unbalanced output on the synth to the balanced line in on the mixer (not using the DI) because only one leg is being driven your signal is effectively half (-6db) down.

 

I found some info online about converting unbalanced to balanced output, but nothing as definitive as "buy this gizmo and plug it in."

 

That should be in the range manageable by the pad control on the channel.

 

Did you mean the Gain control? The Pad button is off; turning it on further attenuates the signal by 26dB. Meanwhile, at the

last rehearsal (with DI) the Gain knob was nearly at max.

 

Yamaha P2 acoustic, Yamaha P120 digital, Nord Electro 3HP, QSC K10.

FOR SALE: Nord Electro 2-61.

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I always assume that all the way up is the normal position. ie, to get 1V you would need to be at max.

 

I'd like to be able to set the volume control on the keyboard to 1/2 or 2/3 initially, so that I have the option to turn myself up a bit when appropriate. That is why this low-volume issue is problematic.

 

I think I will lug my Yamaha to rehearsal for comparison with the Casio, and if necessary buy an instrument preamp like you suggested in an earlier post. This one seems like it might do the trick:

http://www.musiciansfriend.com/product/ART-Tube-MP-Project-Series-Tube-MicrophoneInstrument-Preamp?sku=180643

 

Yamaha P2 acoustic, Yamaha P120 digital, Nord Electro 3HP, QSC K10.

FOR SALE: Nord Electro 2-61.

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