Cable Question

  • Thread starter Thread starter Popcorn
  • Start date Start date
P

Popcorn

New member
Hi,

In the process of wanting to make my own cables i've discovered that there's a great deal more to be learned about cables than just the right looking terminator connections. When i got on the telephone to order cable the saleswoman on the other end asked me each step of the way whether i wanted the cable balanced or not. When i asked her what she meant by balanced she said, "stereo". At this point in the conversation i had to tell her that i needed to think about it and we said our goodbyes. Fortunately, i have been given an excellent resource for cable questions on the net, but i believe that thist is still for a more advanced subscriber. One bit of info that i've been able to digest properly is that balanced cables are going to be far more efective in reducing hum/noise. Are balanced cables and stereo cables the same animal? How does one have anything to do with the other if anything at all? Let me describe my setup in detail...its rather simple.

1/4plug guitar to 1/4plug preamp to RCA soundcard(audiophile)

I am assuming based on simple logic that your cable (stereo, mono, unbalanced or balanced) is determind by your equipment. Now i know for certain that the Audiophile is an unbalanced unit and that my guitar sends a mono signal...(i think)...can you see the rediculous complication i've stumbled upon. There are two other pieces of equipment i use...MIC and Alesis NanoSynth. With regards to the MIC-is it better to have XLR or 1/4? And when your dealing with RCA cable? I know this can't be that complicated, but i'm obviously missing some basic key info. Any recommendations would be highly appreciated. Perhaps this thread will help someone else out that's been wondering.
 
Weather or not you need balanced cables will depend on the input/outputs of what your trying to connect. It seems like you will only need unbalanced. XLRs are usually connectors used on balanced lines. A balanced cable will have 2 wires inside wrapped in a wire shield, whereas an unbalanced will have 1 wire and a shield. Your typical guitar patch cord is unbalanced. There's a hot wire going to the tip of the connector, and a ground going to the sleave. Same with RCA connectors.

I think the cable rep was probably saying 'stereo' to convey the fact that there are more wires in the balanced; not a very good analogy.

Some low-end mics will use XLR connectors at the mic end, but 1/4" on the other end of the cable. This is still an unbalanced cable.

Are you saying you use a pre-amp with a 1/4" input? Does it also have balanced XLR inputs?
 
Cables

Hi Ziller,

Yes, the preamp i'm using is the Midiman Audio Buddy. It has two inputs that are 1/4 and two inputs that are XLR. This unit is providing an option for either type. According to your reply would this mean then that since it has both types of inputs that it can be both a balanced and unbalanced unit? I suppose i can go up to the Midiman Website to find out. The Nanosynth is probably unbalanced as well since it has RCA inputs and outputs. This is unfortunate. it looks like my system is unbalanced. Or perhaps it isn't necessarily a bad thing. It would be great to have definitive answers, but i'm suspecting that these answers come about by trial and error type learning. YIKES!
 
Cables

I forgot to mention that the only outs for the preamp are 1/4outs.
 
Unbalanced isn't bad for short line level signals. Certainly not for your average home recording setup. All the gear I have, except the mics, is unbalanced. I do have balanced outs on my mixer, but I don't use them (yet) :)
 
Thanks

Thanks Ziller-this is helping.

One more question....do you think that getting balanced cables despite having an unbalanced system could pose a problem or benefit? thanks in advance.
 
Popcorn, I am no cable guru so don't take what I say as gospel.

One thing to keep in mind is that unbalanced cables are much more prone to rf (radio frequency) interferance and humm. unbalanced cables are ok for running to PA speakers, don't ask me why this is, but for any kind of instrument or mic you should use balanced cables, otherwise you will get a LOT of noise.
BTW, a cable with an XLR connector on one end and a 1/4 on the other is a high impedance cable (not necisarily unbalanced, not sure about this), a cable with two XLR's is a low impedance cable.

It's best to use XLR's with a mic.
 
Recording Engineer Needed

Thanks Stratamatic,

Balanced cables is probably what i'll be getting, but before i make a final committment i'll be heading to my local recording studio to get the definitive answer. When i do get an answer i'll post the results here .

Thanks for the help,.
 
Do a search on this site on the phrase "balanced differential".

Then, go to this site, and read this article:

http://www.rane.com/pdf/note110.pdf

Then, after you've finished that one and understand it, look through the links here:

http://members.nbci.com/studio_tech/

under the heading "wiring and grounding".

Balanced TRS (tip-ring-sleeve) cables used in a single-ended TS-only (tip-sleeve only) system are pretty much a waste of money. However, there's much to be said for using balanced cabling *as much as possible when the equipment can make use of it*, and for converting from balanced to single-ended as seldom as possible, and doing the conversion as well as possible. Balanced bales can be 1/4" TRS or XLR, and there are many places in my studio where an XLR feeds a balanced 1/4" TRS connection...

That Rane app note will answer a lot of the questions that come up as to "why stereo TRS and balanced TRS are different". The Studio Tech webs site has a variety od additional information. As a new recordist, you can find some definitive answers there, and save a drive to the neighborhood studio.

Anyway, read up, and you'll find this stuff to be much less bizarre. Hope that helps...
 
Last edited:
Thanks for those links! I looked through those myself. Do you ever feel like the more you learn, the more there is to learn?

Anyway, this is how I see it, at this point.

A balanced cable is one with 2 conductors and a sleeve, where the sleeve is attached to the audio equipment elec ground, and one of the conductors is attached to the signal ground. This way, any noise picked up by the cable is routed out to elec ground, not into the audio circuit. For this to work, both peices of gear on each side of the connection must be sending and receiving a balanced signal. You cannot use a balanced cable on an unbalanced system, because you would end up having to tie the sleeve to one of the conductors, or not use one of the conductors, or solder the 2 conductors together, defeating the whole purpose (it would no longer be a balanced cable)

An unbalanced cable is one with 1 conductor and a sleeve. The sleeve is grounded to both audio ground and elec ground. Any noise picked up by the cable gets sent into the audio circuit.

I'm really not sure how the whole high/low impedence thing works. I've always kind of equated high impedence with unbalanced, and low impedence with balanced.

And I suppose we're really talking about signal to noise ratio. With a low level signal such as a mic, running over a 20' cord, there is a lot of room for noise to enter the picture. But with a line level signal (much higher), over a 2' cord, your not gonna pickup much noticable hum. A guitar output signal is somewhere between a mic level and line level, and I guess the early guitar engineers decided that the signal was strong enough not to warrent using balanced outs (the signal to noise ratio would be high enough). I don't know of any guitars that output a balanced signal. When recording an elec guitar or bass, I always try to use the shortest, best cord possible though, sometimes sitting right next to the console with a 6' cord. Though from reading that Rane article, it looks like you could go from guitar quickly into a direct box, which would convert the signal to balanced, and run a balanced cable from there.

Ziller
 
Looks like you've cracked it ziller! And no, you're never to old to learn ... I've been recording professionally for over 30 years and I'm still learning.

Wherever possible, go balanced. I'm amazed for instance to see how many home studio's use unbalanced cable to go into monitors which have both balanced and unbalanced inputs ('coz its got a jack in it and I've just got one of those here) This results in a cut of between 3 and 6 dB.

Balanced = better resistance against all sorts of interference.

Keep your cables short, that helps as well, and yes, running short unbalanced cable into a direct box or pre-amp is also sound advise.

By the way, I always make my own cable. That way I am sure that 1) I use the best quality cable. 2) I use the best quality connector. 3) the price stays reasonable.
I normally use Mogami cable and Neutrix conectors.
Just make sure your welds are nice, smooth and round!
 
Thaanks

Thanks Skippy, Ziller, Sjkoko2, Stratamatic,

Im still reading all the former links and threads. There are some really outstanding explanations there. So far i know that i'll be using a balanced mic cable XLR to my audio buddy preamp-the outs on the preamp have the capacity to either be unbalanced or balanced so i will use a balanced cable out to my soundcard in with RCA. I hope that since my Soundcard is an unbalanced unit that it doesn't nullify the balanced properties of the mic cable going into the preamp and the mic cable coming out of the preamp and into the soundcard. I want to use the same configuration for my guitar. Balanced cable out of my guitar and into preamp-balanced cable out of preamp and into soundcard. The one element in the chain that i'm not sure about is the soundcard. I know that it is unbalanced and RCA, but in what manner would it effect the rest of the balanced chain. Still reading..............................
 
I figure that if there is no harm in using a balanced cable-you might as well use a balanced cable. Wahat i have gathered that there are other benefits to balanced than just reducing noise. A wider range of sound being one of those benefits. (i think)
 
You wont be able to go balanced from the preamp to the soundcard, since the soundcard RCA ins are not balanced. Whatever is connected to each end of the cable must be either both balanced, or both unbalanced.

However, using an unbalanced cable between preamp and soundcard shouldn't have any effect on the balanced mic cable going into the preamp.
 
Hi,

I've just noticed that when you have a situation like the one i've described above where you have one end that is balanced like my preamp out and my soundcard in(unbalanced) that the unbalanced side seems to dictate your next move. Seems like the real solution isn in a post by the RECORDING ENGINEER. He has a post that explains connecting unbalanced equipmet to balanced equipment. Here's the explanation he gives:

To connect unbalance equipment and balanced equipment, simply solder the ground form the 1/4" or RCA (phono) to pin 1 (XLR) or sleeve (TRS) and connect the "hot" from the 1/4" or RCA (phono) to "hot" which is pin2 (XLR) or Tip (TRS) and solder the "hot" pin2 (XLR) or Tip (TRS) and the "cold" pin3 (XLR) or Ring (TRS) together. He also gives directions for connecting unbalanced output to a balanced input. For those of you interested in checking the original post go to the RACK forum and look for a post titled "Patch Bay-Sics.....Sanity Check.

I personally don't know how to actually go about doing this. When i look at the RCA input on my soundcard all i see is a hole...hehehehe...I suppose this procedure would require getting your soundcard out of your computer.

A great part of my concern is in possible damage to my gear if i am mix-matching unbalanced cables and balanced cables to balanced and unbalanced gear. Can I damage something here if i am using the different cables? Thanks for your patience.
 
Just a quick correction for Ziller. A balanced connection is not just a connection with one signal wire, one ground wire, and one shield. Balanced connections, more properly termed "balanced differential", actually send two separate copies of the signal, and balanced equipment uses this to reduce its sensitivity to electical noise from the environment.

The whole idea of "balanced differential" signal transmission over a shielded pair of wires is that both conductors experience the *exact* same electrical and noise environment (which is also why they are so precisely twisted, in good cable). Balanced differential transmission drives one center conductor with one polarity (the XLR's pin2, or the TRS connector's tip, swings positive) and the other with the exact *inverse* of that signal (XLR pin 3, or TRS ring, swings negative). This allows the receiving equipment to look at the *difference* between the signals on the pair (differential mode), and reject any signal that is identical on both conductors (common mode). The reason for all that extra work is noise cancellation.

Here's gross oversimplification. Just for grins, imagine a balanced line that has a signal that just happens to be exactly +500mv on pin 2 and -500mv on pin 3 at some point in time. Imagine that that line runs right under a computer monitor, whose mondo deflection magnets induce +3v (!) of noise in both the pin 2 and pin 3 lines. The receiving equipment subtracts the voltage on pin 3 from the voltage on pin 2: ((500mv signal + 3v noise) - (-500mv signal + 3v noise)). This leaves 1v of signal (500mv - (-500mv)), and 0v of noise (3v - 3v): the noise cancels itself out because it is *common* to both signals, and the equipment only cares about differential.

If you were to shield the conductors separately, or run them as separate single-shielded cables (like a pair of guitar cables run more or less side by side), the electrical environments of the two conductors would not be identical, and differentially-coupled noise allowed by the imbalance will become impossible to distinguish from the signal you're trying to send. In our example above, that might be 2.8v of noise on pin 2, and 3.1v of noise on pin 3. Whammo: you now have 0.3v of differential noise that gets added to your 1v differential signal, and there's no way to know which is which. No joy. Gotta make the environment as identical as possible for best noise rejection, which is why that pair is twisted and shares the single shield (pin 1 on your XLR, or sleeve on your TRS).

The rejection is never perfect for a whole boatload of reasons, which is why we still have to chase ground loops, noise and *cruft* out of our rigs. However, balanced differential signal transmission is a *vast* improvment over single-ended (like from your guitar to the amp)... And we didn't even need to talk about impedance (or any of that other jit that plastic-pocket-protector folks like me love so much) to get a basic handle on why.

High-quality recording microphones always use balanced signal transmission, because their output levels are very low, and the mic preamp needs all the help it can get to run at very high gains (60dB or so) and still reject the environmental noise. Without balanced differential inputs, recording as we know it would be a damned sight harder- as anybody who has ever listened to a Telecaster plugged into a Fender Twin Reverb set up for 60dB of gain can attest....

However, there's a blessing here too: once you get through the mic pre and get the signals up to line level, environmental noise is less of an issue: the environmental noises are by definition 60dB or so lower with respect to the signal you want to keep. So using single-ended from your preamp to the recorder is quite acceptable.

To achieve the maximum possible quality, use balanced as much as possible, even at line level: but if your equipment doesn't have balanced line ins, don't lose sleep over it. It's not worth getting neurotic about if you're a home recordist...

Hope that helps.
 
Last edited:
Amazing

Wow....Skippy, your degree of knowledge is really impressive and with this last posting you've made i feel i've got a good enough understanding to make at least a reasonable decision based on some knowledge which up until yesterday i had ZERO. I can't say thanks enough for your help. I'm sure that this thread can answer most questions audiophiles have if they follow it from its inception.
 
Thanks for the kind words: that makes the typing effort worthwhile. I 'm just a nerd without portfolio: been a EE for too long. Can't help myself...

The way I look at it is that none of us was born knowing any of this stuff, and passing along that information is just a way I can honor the memory of the people who patiently taught it to me- decades ago, now.

The stereo/balanced/single-ended/how-to issue comes up here once a month or so, and it has probably caused more consternation than any other wiring issue among new recordists. Anyway, it seems to me that getting good information into the hands of the folks who need it is always a useful pastime. Thanks again!
 
You must log in or register to reply here.
Back
Top