balanced input?

hey all, i was wondering whether anyone makes an effort to use balanced inputs (i mean the three-wire cables like a mic cable)

if so, what is the best way to get that signal into a soundcard? atm i only have a soundcard with 1/8" inputs…

cheers

Hi, try this link from the n-track forum.

http://www.ntrack.com/cgi-bin…+wiring


To run completely balanced you would need to get a new sound card with balanced inputs of which there are many. Or you could connect your mic to a preamp or mixer using a balanced connection they go unbalanced from mixer o/p to your soundcard.

thanks for that nick… that helped some…

i’m just not sure if i’m doing anything wrong when i connect my mic with balanced lead, going to a 1/4 jack, stepped down with an adapter to 1/8 is ok or not. the signal seems ok except when i give the top end some boost i get some hiss.

my reason for posting in the first place (which i admit i didn’t specify) was to see if there was a way of getting rid of that hiss and gaining the top end clarity.

i thought some sort of balancing would do it… write back if u know what the smell im on about!!!

Just to clarify things a bit: No chain is stronger than the weakest link - Every step from the instrument all the way down to the hard drive counts when it comes to sound quality.

The instrument you play has to be in shape, in tune and well played.

The room you record in has to be fairly dead (unless you want to take advantage of its acoustic properties), and at least free from unwanted noise sources (the PC fan may be a real pain here).

The microphone you record with has to be able to reproduce the sounds from the instrument you are trying to capture. Preferably, it should be a condenser mic (these have a better transient response and clearer high-frequency characteristic than dynamic mics), it should be phantom-power-fed (most condenser mics are; this calls for phantom power to be present at the mic input), and the cables should be balanced (this blocks out electric noise and hum very effectively).

The cables should also be the best affordable quality, but this is a minor issue…

The mic signal has to be amplified by a good mic preamplifier. Some sound cards, like the EMU 1820 (the one I use), have decent built-in mic preamplifiers, complete with phantom power for the mic. An alternative solution may be going via a mixing desk, still connected to the sound card via balanced cables, or maybe using a channel strip (beware, these things may be more expensive than a 16-channel mixing desk, and they usually carry only one signal channel).

The A/D converters should be the best possible quality. Record, mix and master in 24 bit, 48 kHz if at all possible and then bounce down into 16 bit 44 kHz as the last step - it does make a difference. (n-Track works in 32 bit internally)

The hard drive should be as fast as possible - preferably a SATA type with a large cache. This makes a difference when the track count goes up…

In order to benefit from a balanced configuration, every link in the chain all the way through the sound card has to be balanced. It is possible to connect unbalanced sources (like a keyboard or an electric guitar) to balanced equipment, but there will be some noise pickup. Balanced sources may also be connected to unbalanced inputs, but the noise levels will be way higher in this case, and this is not a recommended procedure.

Beware that some mic inputs in some sound cards (especially SoundBlaster types with an 1/8" line input [usually blue] and an 1/8" mic input [usually red]) are configured in a balanced manner, i.e. the tip is the signal wire, the ring is 5 V phantom power provided by the sound card, and the sleeve is ground. This is applicable for a PC microphone (stick mic delivered with the sound card).

In audio equipment the connections usually are: tip:left, ring:right, sleeve:ground. If a normal microphone is connected to this input, the result will be a lot of hum and excess noise. A stick mic is not designed for music recordings, but for IP telephony, voice recognition, online gaming etc.

I know I have been raving about this before, but to all us musicians out here it seemed like a very bad idea indeed to design an audio interface with a standard 1/8" jack interface having a nonstandard connection.

regards, Nils

Quote (angrypetal @ Feb. 04 2007,12:02)
thanks for that nick... that helped some...

i'm just not sure if i'm doing anything wrong when i connect my mic with balanced lead, going to a 1/4 jack, stepped down with an adapter to 1/8 is ok or not. the signal seems ok except when i give the top end some boost i get some hiss.

my reason for posting in the first place (which i admit i didn't specify) was to see if there was a way of getting rid of that hiss and gaining the top end clarity.

i thought some sort of balancing would do it... write back if u know what the smell im on about!!!

That sounds more like an impedance matching problem or a gain-staging problem rather than the use of unbalanced cables.

If your mic is a low impedance mic, then connecting it with adaptors to your soundcard input (high impedance) will cause issues. You really need a pre-amp or mixer to handle this.

it would be nice to know what make of microphone is being used and the make of the soundcard that it is being plugged into -

Dr J

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i’m just not sure if i’m doing anything wrong when i connect my mic with balanced lead, going to a 1/4 jack, stepped down with an adapter to 1/8 is ok or not. the signal seems ok except when i give the top end some boost i get some hiss.


Sure, you can do that, but then you’re unbalancing the input cable, and that defeats the whole point of the thing and will result in increased noise (hiss) as you noticed.

But, it won’t hurt anything, it’s just undesirable to do that especially with a low level signal.

And as Xon said, you won’t be getting the optimum impedance match doing it your way and that will also degrade your signal.

Best way of going balanced to unbalanced is through a balun, (a small audio transformer), and that can do any necessary impedance matching too.

Or the way it’s normally done these days is electronically using a capacitively coupled op-amp or discrete components as a differential amplifier.

Hang on, hang on. We need to distinguish between two concepts here… balanced/unbalanced and high impedance/low impedance. The confusion is increased by the fact that much of the time a low impedance source (eg mic) will use an XLR/balanced cable.

Converting a balanced to unbalanced connection should not introduce any noise specifically. Balanced connections only serve to reject noise induced into the cable so for short cable runs in and electrically noiseless environment should really make no difference.

Now then, I suspect (and we need to know as Dr J has said) that we have a low impedance mic being used here and it’s being connected to a high impedance input on a soundcard. The impedance miss-match will cause poor signal level (and ultimately more noise - usually in the high frequencies).

I am not confused about impedance nor am I confused about balanced/unbalanced Xon.

Please read the final version of my original post. (I tend to write - post - read - think - edit - repost - etc. - etc. :D )



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Converting a balanced to unbalanced connection should not introduce any noise specifically. Balanced connections only serve to reject noise induced into the cable so for short cable runs in and electrically noiseless environment should really make no difference.


Agreed, (with minor, insignificant reservations), but where is it stated that it’s only a short cable run?

And where is this hypothetical electrically noiseless environment? I’ve certainly never worked in one. :)

I wasn’t criticising your post Gizmo, just trying to point out that folks generally get confused between the concepts.

Your comments are correct and of course there is no electrically “silent” place nowadays. Saying that I run quite a few unbalanced cables in my studio and I’m more likely to get hum than hiss whereas impedance mis-match will cause hiss.

Anyway, I think we’re all basically agreed and just need to clarify a few things from the original post before we can go any further.

Ahhh, I see Gizmo - you have modified your post. You’re just trying to keep me on my toes eh… :slight_smile:

:;):

EDIT:

Too much irrelevant info, so I deleted it. :)

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if so, what is the best way to get that signal into a soundcard? atm i only have a soundcard with 1/8" inputs…


I think this could be all solved by having the mic run into a small mixer or preamp with a balanced input, and a short unbalanced cable from the output/insert of that desk/preamp going to the soundcard line input.

yes u guys are right, and once again ive caused problems, not thinking to include all the info.

my mic is a cheapish shure mic (pg58) with a 5m cable, the cable has a 1/4 jack end (looks like a mono jack, i suspect u would call it a tip and a sleeve only?) stepped down with an adapter to 1/8 (same style as the 1/4) going into (you’ll really laugh now) a Creative Sound Blaster pci card.

by the looks of what i’m reading, it looks like perhaps the best way is to us a small desk, or get a decent S/card which will take balanced inputs?

and btw, thanks everyone for helping a wannabe noob :D

Quote (angrypetal @ Feb. 05 2007,12:55)
yes u guys are right, and once again ive caused problems, not thinking to include all the info.

my mic is a cheapish shure mic (pg58) with a 5m cable, the cable has a 1/4 jack end (looks like a mono jack, i suspect u would call it a tip and a sleeve only?) stepped down with an adapter to 1/8 (same style as the 1/4) going into (you’ll really laugh now) a Creative Sound Blaster pci card.

by the looks of what i’m reading, it looks like perhaps the best way is to us a small desk, or get a decent S/card which will take balanced inputs?

and btw, thanks everyone for helping a wannabe noob :D

Nothing wrong with the SB PCI cards. They are ok as a starting point and it’s quite possible to make decent recordings with them.

So as for the mic, that’s pretty much low impedance then. You don’t say whether you are using mic-in or line-in on the soundcard. If you are using line-in your will get an impedance mis-match as suspected. If you are using mic-in, you may have a better impedance match but it’s common knowledge that mic inputs on low end cards are noisy - so that may be the source of your noise.

The best way forward, IMO, is to use a small mixer or pre-amp between the mic and the soundcard (and use the line-in). You will probably need to replace your mic cable with an XLR to XLR (balanced!!) cable as most preamps and mixer inputs (for low Z) will be XLR.

Then take the outputs of the mixer/preamp (phono/jacks/whatever) and use whatever connectors you need to get plugged into the line-in on the soundcard.

X
.
.

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and btw, thanks everyone for helping a wannabe noob


Hey angrypetal, after almost 45 years in this game I’m still a noob.

Every year the technology changes faster and every year my brain is more reluctant to change at all! :D
Quote (Gizmo @ Feb. 05 2007,22:34)
and btw, thanks everyone for helping a wannabe noob


Hey angrypetal, after almost 45 years in this game I'm still a noob.

Every year the technology changes faster and every year my brain is more reluctant to change at all! :D
Oh yes. Agree with that. And I'm Technical Manager for a software/systems company and all the guys who work for me are much more clever than me. Keeps my brain active (but tired).

OK, something is wrong.

If the PG58 is low-Z it is almost certainly balanced as well, and it should NOT be used with a cable that ends in a 1/4" 2-conductor plug. It should be used with an XLR/XLR cable, and plugged into a mic preamp with XLR input. (Yes, there are exceptions, but they’re for folks who really know what the heck is going on, and they’re relatively rare.)

Second: Unbalanced lines don’t cause more hiss – actually they cause LESS hiss by attenuating highs due to greater transmission line effects. They cause more buzz or hum, but only for longer runs.

In other words, balanced lines are for keeping EMI interference from getting into the signal, and this EMI is almost always not white noise (hiss) but synchronous noise from AC power, motors, and other electronic devices.

I’m not a gear snob. I feel that great recordings can be made using budget gear and built-in soundcards or Soundblasters. However, I don’t recommend using the mic preamps in built-ins and low-cost cards like SB’s. Get a little Behringer UB802 mixer for about $45 at zzounds.com and you’ll be much better off. I recommend against the UB502 for $45 because it doesn’t have phantom power, which you’ll need if you end up getting more mikes.

The new series is the xenyx line. I can’t tell whether these have phantom power or not; it’s not mentioned in the specs. So, I would avoid them until someone can say for sure.