My instrument preamp has a line-out jack. What's that?

Delmont

Member
My BBE Acoustimax instrument preamp has an XLR jack that I use for connecting to the PA.

But there's also a jack that says Line Out.

What's that for?

Thanks!
 
Hi,
The unit has instrument level, line level, and microphone level outputs.
These meet the voltage and impedance expectations of various pieces of equipment.

Instrument level output would be for anything that usually expects an instrument - Pedals, amplifiers. (Usually TS 1/4")
Microphone level output is for mic preamplifiers in audio interfaces, PA systems, etc. (Usually balanced XLR)
Line level output would be for hardware effects/processors, audio interfaces, PA systems, recording units with line level inputs. (Usually TRS 1/4")

Simple as that. :)
 
Okay, you're writing to someone who really would ask what mix means.

The reason I ask is that I want to use a boost pedal with the preamp. Here's what I've been told so far:

1. Put the pedal before the preamp.

2. Don't put the pedal before the preamp. It could overload it.

3. Get a TRS Y-cable, put the long end into the FX Loop jack, and put the two Y-ends into the boost pedal.

4. Forget the Y-cable and Loop jack. Just put the boost pedal AFTER the preamp. (There was no mention of TS versus TRS cables on that one.)

What are TS and TRS cables? What's an ordinary guitar cable? Would that work?

 
The safe and simple option would probably be to put the boost pedal after the BBE, unless the point of it is to drive the BBE harder?
If the boost expects an instrument to be plugged in, then you should give it the BBE's instrument level output.


TS cables have a silver Tip and Sleeve whereas TRS has Tip, Ring, and Sleeve.
A standard instrument lead is TS.
 
Great! Correct me if I'm wrong:

- The Line Out jack is instrument level.

- Regular guitar cables are fine on both sides of the boost pedal.

Am I there?

Thanks!
 
No, the line out jacks is just that. It's not the same as instrument level.

If you're outputting the BBE to a device that normally expects an instrument (like an amp or effects pedal), use the instrument output which, I think, is on the left side?
 
Here, maybe this is helpful.

View attachment 100977

The vast majority of guitar effects pedals are going to expect an instrument level input,
whereas the vast majority of studio effects units are going to expect line level in.

If the end of your chain is an amp, everything is/should be inst level in and out.
 
Just be careful not to get too many pedals in the loop...or you end up like this.
 

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Hi,
The unit has instrument level, line level, and microphone level outputs.
These meet the voltage and impedance expectations of various pieces of equipment.

Instrument level output would be for anything that usually expects an instrument - Pedals, amplifiers. (Usually TS 1/4")
Microphone level output is for mic preamplifiers in audio interfaces, PA systems, etc. (Usually balanced XLR)
Line level output would be for hardware effects/processors, audio interfaces, PA systems, recording units with line level inputs. (Usually TRS 1/4")

Simple as that. :)

well put..
 
The safe and simple option would probably be to put the boost pedal after the BBE, unless the point of it is to drive the BBE harder?
If the boost expects an instrument to be plugged in, then you should give it the BBE's instrument level output.


TS cables have a silver Tip and Sleeve whereas TRS has Tip, Ring, and Sleeve.
A standard instrument lead is TS.

Yeah, that's the question in the subject line: What's a line out jack? I know that on my recording deck I can choose between mic and line, but I've never gotten what line means.

Meanwhile, I do see the output jack. I'll use it. Thanks!
 
I don't really know much about the technical specs I'm afraid.

That said,

Every piece of gear with an input is designed to expect a certain type of signal.
There are different levels (voltages) and impedances of inputs and outputs, and line is one of the many types.

Line-level is, I guess, a man-made standard that we work at. It's a known quantity and more or less any piece of analog studio gear will happily 'talk' at line level.
I'm assuming there's a relationship to the physical limitations of tape or some other medium, but @ecc83 would be the man to ask about that.

Raw signal out of an instrument or microphone is going to be much quieter than line level, so we amplify accordingly to get it there.
There's also impedance to consider and other things but I do not know enough to be telling you about that. ;)

I think* line level is more robust in terms of picking up interference and noise?
Hopefully someone will confirm but I think if you had to do a 20m cable run and had the choice between mic/line/instr level output, you'd go balanced line.

I know that on my recording deck I can choose between mic and line, but I've never gotten what line means.

That switch is saying 'are you presenting me with a very low level signal that I'll have to amplify, or a line level signal which I can record straight to 'tape'.
Generally if you plug in a mic over XLR the switch does nothing, but some devices will let you plug microphone or line source over 1/4", which is where the switch matters.

If, for example, you got an mp3 player with line-output and hooked it up to a mic-preamp, you'd probably overload the mic preamp and distort a lot because it is expecting a much quieter signal.
Make sense at all?
 
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How do Delmont. The precise nature of a 'Line' input or output is very Humpty Dumpty. It means whatever the maker of the kit WANTS it to mean! Probably the near best answer to "what is a line INPUT?" is, "One that does not expect a singal from a microphone or guitar! Definition of a line OUTPUT therefore becomes.."One that expects to be connected to a LINE input!"

To take your box of trick specifically (and WHAT nice people! No hassles or buggerings about. Found the model, found a well written spec', found a manual and without joining ANOTHER bloody spambot or divulging the colour of my maternal grandmothers eyes!) The difference between the 'line' out and the XLR out seems to just be the source impedance*. Line is 2k Ohms, XLR 600R. (XLR is also probably 'impedance' balanced)

'line' levels in pro studios are well defined. The 'Operating Level' where you would find say speech at most of the time is +4dBu (see *) that is about 1 volt rms (*again). The MAXIMUM level or 'headroom' would be at least 10X that at +22dBu or 10 volts rms. However, a lot of 'prosumer' gear cannot deliver the max levels and so we have a lower level of -10dBV ('V' for volts. Yes! There are TWO (at least!) dB levels systems. Well, you wouldn't want it EEEESy would you?) Neg 10 is 0.316 V (316milli volts) and so the headroom is 10X that (if yer lucky) at 3.16V which brings us (rather neatly I feel!) to the max out of the FX box at +10dBu = 3.16V.

Confused? You should be but don't feel bad. EVERYONE, forumites, gear manufacturers, we all have made level figure boo-boos at some time.

A word about a word? "Overload" In the context of low power audio electronics, pedals and preamps and AI and such, the word is needlessly scary. You will not damage a pedal or AI or anything else by driving at MANY times its rated input. Gear has a high input 'impedance' and cannot draw any significant power from even pro gear at 10volts +. There will be no smoke no matter how you hook up audio or how hard you drive it...Indeed! GUITAR oriented kit is DESIGNED to be 'overloaded'! If a guitar amplifier cannot run all night at 150% clipped over its rated power it does not deserve the name 'guitar amp'!

*dBu, =decibels unloaded and is referenced to 0.775 volts (don't ask!) rms. *rms: the 'normal' way alternating voltages are specified (others are peak, peak to peak) don't sweat it 'rms' is rarely given but always assumed. dBV is referenced to 1volt rms and is more or less the standard in the guitar electronics industry. You don't NEED to know these things but it is a good idea to make some attempt to understand them.

Dave.
 
Cluck! Missed 'source impedance.

This is the internal resistance (to current flow) of a piece of gear. Better to have it low because that has benefits..
1) The signal can feed multiple inputs with little loss of level.
2) The effect of cable capacitance* will have little effect on the high frequencies even for long, +5mtr, cables.
3) The lower the source impedance (aka Z) the less prone is the system to pick up noise, hum and Radio Frequencies.

The last point is very important. You will read of "balanced" operation? This is pretty mandatory for microphones but LINE levels signals can be unbalanced and a low output Z helps here.

Again, like 'overload' don't worry about Z, in OR out. In the guitar industry there has been the emergence of the technical fuckup called "True Bypass". This has been elevated to a desirable thing by marketing spoof. It ain't. Read up on 'Buffers'.

*Capacitance: Bit hard to simplify but it is a quality of electronic circuits that cause signal loss (in the case of cables) which gets worse as frequency rises. That means HF loss, often has the sobriquet 'Tone Suck'.
Dave.
 
If you insist on doing this, get yourself a real TRS > XLR (male to male) cable to come out of the booster. There's nothing really wrong with running a guitar cable, except that you never know how far away you'll have to run it, and a lot of times you end up having to either go through the crowd or take all kinds of strange paths to keep it out of the way. XLR cables can be chained (one into the other) to make them as long as necessary, and if there's a snake on the stage, it's more likely to have XLR than 1/4".

Some people would get a passive DI for that purpose. The really silly ones would just assume the club will have one. ;) But you've got all these fancy pedals to get you up to a healthy level, and a passive DI is going to turn that right back down. Then it runs to the PA - picking up noise the whole way - and gets turned back up. There are occassions where the ground lift on the DI might help, but I will always try straight wire first. You were going with straight wire from the pedal itself already!
 
I bow to your knowledge of gigging and rigging Ashcat but would just like to comment about the DI issue?

I have been told in the past that most 'sound men' expect and prefer a balanced mic level signal to be presented at the desk? Therefore a cheapish passive DI delivering an uber-low Z feed at about -30dB (a hot LDC) would be pretty interference proof.

Corse! THESE days they will probably have an $400 phone solution with WiFi!

Dave.
 
actually a sound guy told me over beers the headline act travelling through Dallas was in fact doing just that! it was all bluetooth mixed and mastered for the stage...and the sound guy was having a beer....I said "hey shouldnt you be working?" and he said all this...

the band sounded great believe it or not, its way over my head this technology keeps going. the band ran all their own sound and somehow did it all. weird?

add: maybe it was all lip syncd? lol
 
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actually a sound guy told me over beers the headline act travelling through Dallas was in fact doing just that! it was all bluetooth mixed and mastered for the stage...and the sound guy was having a beer....I said "hey shouldnt you be working?" and he said all this...

the band sounded great believe it or not, its way over my head this technology keeps going. the band ran all their own sound and somehow did it all. weird?

add: maybe it was all lip syncd? lol

"And the Geek shall inherit the Earth" !

Dave.
 
I cocked up! +10dB yooo is NOT 3.16V it is 2.449V (2.5V for jazz) 3.16V is +10dBV!

Bloody nightmare. "We" have been trying to kill off dBu since the 70s but because it makes their adpuff figures 2.2dB better kit makers won't budge.

Dave.
 
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