-10 or +4

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dobro

dobro

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I have to get some cables made for some monitors, and I have a choice of RCA for -10 or XLR for +4. My soundcard can handle either. So can my mixer.

1 Any recommendations about operating at either level?

2 It makes no difference which level you run at in terms of outboard gear, mics etc, right?
 
Well, I'm guessing maybe the RCA cables would be cheaper, and also more versatile, but if it were me I'd get the XLRs and plan to run at +4. Both the balanced cables, and the higher voltage = more pure audio signals.

-Shaz
 
i'd second that. By runnning at +4 you'll get a better signal to noise ratio.

bear in mind that any noise you send to an amplifier will be subject to the same gain as the signal, so a balanced system at +4 is ideal.

good luck

d
 
Okay, I understand some but not all of your answers.

So I'll open up this can of worms. Well, it's been a can of worms for me.

I understand the difference between balanced and unbalanced cable in terms of their construction, and also the benefit of balanced cable - the understanding I've been operating at up to now is that the main benefit of balanced lines is to cut down on hum, but that it doesn't make much difference on short cable runs.

What confuses me is the relation between balanced or unbalanced cable and operating at either -10 or +4. Can you use unbalanced cable at +4? Can you use balanced cable at -10? And most importantly, for short cable runs, how important is that improved signal to noise ratio using balanced cable at +4?
 
You can use either cable at either -10 or +4.

Lets see if I can simplify this... yes I think I can... Both properties (balanced cables and +4 voltage) are used for the same purpose -- to ensure the highest fidelity of your audio signal from point A to point B, but they operate on different principles, so let's take them one at a time:

First, the issue of -10 or +4. What the higher voltage combats is "atenuation". This is the natural attribute of the audio signal to diminish in voltage the further it has to travel. As the signal attenuates the ratio of noise to signal increases, however, if you start out with more voltage (+4 dB) the loss of signal is less of the overall ratio. For a real-world comparrison, consider that you and I each have different cars; your car has a 10 gallon tank and mine has a 20 gallon tank. If we each drive 5 miles, you have used half a tank, but I still have three quarters of a tank. The audio signal attenuation is like using petrol, so if you start with a "bigger tank" (+4 dB) you have more signal than noise when you get to the destination, as opposed to having a larger ratio of noise or "air" in your tank. Does that help it make sense?

Next, balanced cables. As you know, a balanced cable is nothing all that fancy -- it's just a 3 conductor cable, when you get down to it. To understand why the outer layer of conductor is important, you need to get your head around the concept of "induction". Do you have an electric toothbrush or razor that re-charges without any metal contact points? Have you ever made an electro-magnet or electric motor? All of these concepts rely upon induction, which is basically a method of transfering (by intent or chance) magnetic or electrical energy between conductors without them ever touching. Without getting too scientific, the basic principle of a balanced cable is that the third conductor attracts induced interference and routes it away from your audio equipment.

Phew!

I hope that helps!

-Shaz
 
That's the most clear and concise explanation of +4/-10 and balanced/unbalanced I've ever seen.

thank you!
 
Always try to use balanced cables, outside of the -10/+4 issues, the resistance of a unbalanced cable is higher on top of induction...high impedance cables vs low impedance cables..phantom power...DI boxes etc....
You need to see what operating level your main mixing tool uses, -10 or +4? Its usually easy to tell by the size of the power supply...80 watts(-10) or 600 watts (+4)... I have a -10 system but I still use balanced whenever I can even if it means having to move tracks around. Prosumer stuff typically is -10.... The cable itself doesn't care if its -10 or +4, its interchangeable as far as fit and function...high end desks usually have XLR (balanced), RCA (unbalanced) and 1/4 (unbalanced) all over depending on usage. So what about your patch bays..balanced, unbalanced or split 50?

Effective lengths of XLR are higher than RCA. too.

Yes, you can use unbalanced with +4 systems and
Yes, you can use balanced with -10 systems.

Sorry to add to the confusion!
Peace,
Dennis
 
shazukura - yeah, I've got it now. One deals with attentuation, and the other with interference. I don't know if the balanced cable and the higher voltage would make much of a difference over a length of only 2 meters, but at least I have a better idea of what's going on.

Thanks very much. That was a very clear explanation. :)

atomic - I don't use the mixer for tracking, I use it for playback. I just wanna route the output from the soundcard through the mixer to the monitors. I can set the card for +4 and I can set the powered monitors for +4, and the mixer manual says it can handle +4 inputs, so that seems okay. But what I'm wondering about now is the input to the card. First of all, I've got no idea what level my preamps run at - they're probably - 10, right? Second, I've got no idea if I can run signal from the pres to the soundcard at -10 and then have the soundcard outputs at +4. I can set the card that way if I like, I've checked, but I don't know whether I can get away with it without distortion. Any idea?
 
there's some mis-information that needs attention.

first: +4 refers to +4dBu which is a voltage magnitude of 1.23Vrms. this almost always refers to Pro-Audio levels. therefore Pro-VU meters are Calibrated to this. +4dBu signals are not inherently less suseptable to Noise than than other designs because of the higher Voltage magnitudes. they get their Better Signal-to-Noise from being balanced. virtually all +4dBu level lines are balanced.

second: -10 refers to -10dBV which corrosponds to .316Vrms which is mostly consumer equipment. again this level is not inherently more suseptable to noise because of the lower Voltage levels but due to its single ended design (non-balanced). a balanced line running at -10dBv can be made just as noise free as a +4dBU balanced line and a non-balanced -10dBV line is just as suseptable to noise as a +4dBU balanced line.

third: while a long line does have more resistance (actually impedance is the correct term), this is generally not the problem. the Capacitance is what gets you. your cable ends up rolling off the hi's due the the formed R/C network. no doubt that lower resistance cables may help, but what you want is a lower Z (impedance) per Unit length. this is what you pay for in quality cables. also, cheaper cables may have significant Inductance per Unit length, now the Low end is Rolled off. again, quality cables lower this value also. now with low quality cables you have an RCL network that gets you coming and going.

now to the question at hand, +4 or -10 cables. normally +4dBu cables are balanced and use XLR or TRS-1/4" Phono Plugs. -10dBV cables normamlly use RCA plugs. there may be exceptions to both of these. given the problem at hand, i'd recommend balanced whenever possible. but for short runs where the possibility of Ground Loops is minimal, single ended RCA cabling will work Okay.
 
If the card is switchable between -10 and +4 Id set everything for +4. Ive spent considerable time adjusting the line-in levels because the internal preamplifier on the soundcard itself always seems to be different than what the OS settings default to. I would probably just try it thru experimentation to see what performance you can squeeze out of it. Ive tried to learn how to document my experiments so that I can reconstruct post windows familiar blue screen of death. Sorry Im not more helpful.

Peace,
Dennis
 
Okay, I experimented with different voltages on the soundcard, and here's what I found:

1) - 10 in, - 10 out: far more sensitive on the input side, lower gain levels required, but relatively noisy.

2) - 10 in, +4 out: I thought keeping the sensitivity on the input side would be good, but it was just as noisy as the first one.

3) + 4 in, + 4 out: I had to really crank the gain on the pre to get the level up, and the resultant waveform still wasn't as big as the previous two, but the track was much quieter.

In all cases, there was balanced line from mic > pre, unbalanced line thereafter (both in and out of the soundcard).

Looks like a no-brainer. I don't like having to crank the gain levels of the gear way up like that, but quiet is quiet is quiet, so +4 in and out wins. Damn.
 
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