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Amp Output - "Line Out" vs DI

drpepper

drpepper

Supporting Member
Jul 20, 2009
4,805
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Columbia, Maryland
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#1
My band has recently stepped up from vocals only on the PA. We added a sub and are doing kick, bass, and guitar. Our board is a Yamaha EMX5000.

My head has DI, so we're using that for bass, and we've been micing the guitar. I decided to check out the guitarists head (Carvin SX300), and it has a "CABINET VOICED LINE OUT OUTPUT." It's a single 1/4" jack. The total information in the manual is this "The voiced 1/4" LINE OUT gives the same response as if you were micing the speaker. Special equalization reduces the harsh highs that are normally associated with a line out signal." And among the specs, there is the item that says "Line Out: 1.5 VAC @ full power" (My first inclination is that this refers to the Voiced Line Out Output - but ?)

The EMX manual deals with connection instructions in terms of example scenarios. That's nice, but it doesn't have an example scenario for "Line Out" from a guitar head.

So, I'm trying to figure out what's the proper connection for that voiced line out. Or do these types of amp outputs not go directly to the board?

The board has two channel types. The main channels have an Input A (XLR), Input B (1/4"). There are two additional channels labeled "Line" that each have a pair of RCA and pair of 1/4" inputs.

For DI, the example scenarios show use of 1/4" Input B on main channels. The other examples for this input is from a guitar "Effect Unit" and a "Synthesizer"

emx1.jpg


The example uses of the 1/4" line input are from a "Drum Machine" and from a "Keyboard" (which happens to be the same picture as the synthesizer in the previous example - where the keyboard is stereo and the synthesizer is mono).

emx2.jpg


Specs listed in the EMX manual include levels and use. Input B specs are 50 kOhm load impedance, for use with 600 Ohm Lines, and input level ranges from .078 mV at -80db to 1.23 V at +4db. The line input specs are 10 kOhm load impedance, for use with 600 Ohm Lines, and input level ranges from 1.55 mV at -54db to 24.5 V at +4db.

If the amp's line out listed as "1.5 VAC @ full power" is referring to the output level of the voiced output, and if 1.5 VAC is the same thing as 1.5 V on the input level specs for the EMX, then it falls well within the range for the line input channels.

Are those the correct reading of the specs?
 
#3
the very best high-end guitar processors and modelers have line-outs that sound really good, maybe even almost as good as a speaker with a $100 mic on it ;)

just use a mic.
 
#4
to answer your actual question (sorry :rolleyes:), that simulated out would indeed just go to a channel on the board; XLR or 1/4" doesn't really matter, except that if it's too hot for the XLR, the 1/4" input will (depending on the board) not have that problem.
 
#5
Thanks. I did some more searching elsewhere (ended up on a couple of guitar forums), and I do see where the common conception is that line out on a amp heads sounds bad. I saw two post that referred to specific amps that ran against that grain. I'd like to hear what this one sounds like before passing on it.

We're only supplementing with the PA for imaging/blending. The stage sound will be out front in the mix. If it turns out that this particular head's output sounds passable, we'll try it, as it would be marginally more convenient and more controllable. If not, no big deal.

And the further reading also seemed to suggest that the "1.5 VAC" is referring to value that I need to be concerned with for the input level on the board. Since the max before clipping on the main channels (XLR or 1/4") is 1.23 volts and the line input is 24.5 volts, it would be safer to go with the 1/4" line input (the name kind of hints in that direction anyway - do'h).
 
#6
Sounds like your board (as with most) handles line level (+4 dB) inputs on each channel via 1/4" jack and turn the channel trim all the way down. This is the preferred connection to a line out. Set the levels (as applicable) on the two devices for good gain staging.
The dedicated line inputs on the board are typically used for stereo connections to playback gear (CD players, tape decks, etc), but can also be used as a return from an effect processor, if desired.
 
#9
Mixers that have a mic and 1/4 input either have an internal pad/attenuator or a pad switch to lower the level to accept line level inputs. Don't use adapters to convert it to XLR that would not be good going into a mic level input. 1/4" cable is fine if you are within 20' of the mixer.

+4 db is about 1.23 volts. I'm pretty sure that there is enough headroom that your mixer will be fine. The 1.5 volt spec on the amp is the max voltage when the amp master volume is all the way up!

How it will sound...........that's for you to decide.
 

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