line out vs. line level out ?

[floyd]

Can someone explain the difference between the two ? And how would they be implemented in a Champ , for instance ?

[Ed_Chambley]

A line out, without a level is simply connecting to a tap on the Output Transformer or speaker lead with a ground.  This is not shielded cable, but speaker cable.  This will allow for a unbalanced (high impedance) to be send to a console that has the capability to receive an unbalanced signal.  Meaning the console has a transformer to convert the signal.  A line out with a level simply adds a pot to adjust the signal level.

A balanced out traditionally uses a XLR out and requires a transformer like a T109 Hammond and a circuit.  The simple way of converting unbalanced signal to a variable balanced signal is to just buy a direct box unless you really want a internal balanced line out.  The direct box has a transformer to convert the signal to a balanced signal which will work with the balanced input on the console.  Most modern day sound boards have the ability to connect a unbalanced signal.  Whirlwind higher end direct boxes are really nice and can handle Hz ranges lower and higher than needed for guitar.  Ebay, cheap.  They have the ability to change from ground to lift.  You can simply hook a speaker wire to the speaker and on the other end have a 1/4 jack into a direct box, or directly to the console if it receives unbalanced signal.

Normally on my older amps I do not want to modify, I modify a direct box with a pot to give me a send level.  I actually put this inside the amp and mount it and leave it.  If I need a line out it is always there and ready to use.  It is actually cheaper to buy the Whirlwind Direct Box used than buy the Jensen transformer that is inside it.

I have gone through the trouble to install the parts from the direct box into the amp, but I only did it once because it was a waste of time IMO.

[terminalgs]

also, like this:



R1 & R2 make up your voltage divider,  R2 determines the output impedance.  For R2, pick something low, like 100ohm - 470ohm.  If you make sure R1+R2 is 1K or higher, (1) it doesn't affect the speaker load, and (2) you can use 1/2W resistors.

you could put a pot wired as a variable resistor in between to act as a level knob.

Gerald Weber uses 2.2K/100ohm resistors on smaller amps; Fender used 2.2K/270 in 70's 75W+ amps, and 100K/10K pot on 70's 30W amps; gibson/epiphone used 47k/470 on 60's amps as "monitor" outs; Music Man RD50 was a 680/68 and they hung a .47cap across the 68R;

You can put it in a small box with alligator clips for your speaker leads if you don't want to make it permanent.

on the half dozen I've done, I've used 150ohm R2's.  it seems, for input into another amp, it can be higher (tho doesn't need to be),, 1K, or 10K??, just make R1 proportionally higher:  instead of 2.2K:100  make it 22K:1K. anyone else done this with higher R2's for amp inputs? 

[jjasilli]

I have a somewhat different take.  It has to do with voltage & impedance.  This topic is difficult enough but made worse by common use of vocabulary.  See:  http://en.wikipedia.org/wiki/Line_level

Line Level. Most traditionally this refers to old telephone equipment.  1VAC signal @ 600 Ohms impedance.  For guitar audio it may refer to what a DI box puts into a SS mixing board.  Nominally 1VAC @ Hi Z (low impedance, though 600 Ohms is no longer the norm).

Line Out.  This is really vague.  It might mean line level out, or not.  For a guitar amp, it typically means an output to feed an effects loop.  But the voltage & impedance is not yet defined.   So there may be a voltage & impedance mismatch depending on what type of effect is on the receiving end.  A stompbox in the effects loop will probably expect to see a low voltage (under 1 volt), high impedance source.  A rack effect in the effects loop may expect to see hi voltage from a low impedance source.  The manufacturer does not know what type of effects box the end user will put in the effects loop. One simple, good enough solution is to place a "level" control on the line out send.  That way the voltage can be adjusted to make the effects box happy enough, even though there may still be an impedance mismatch.  

EDIT:  Here's a pretty good article:  http://whirlwindusa.com/support/tech-articles/high-and-low-impedance-signals/