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| IZZI |
 Posted: Tue Jul 19, 2005 6:48 pm Post subject: STUPID QUESTIONS ! |
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Joined: 11 Dec 2004
Posts: 3447
Location: Melbourne, Australia
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Please help me to have clear understanding about these:
1. What are the differents between balanced and unbalanced port in audio interface?
2. How does it affect to the sound?
3. If i want to plug my guitar directly to audio interface, should the input port be analog or digital?
4. What is impedance? which one is good, low impedance or high impedance?
5. Who are you?
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| Arr_U_C |
| Posted: Tue Jul 19, 2005 6:59 pm Post subject: |
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Joined: 22 May 2005
Posts: 314
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1. aku pun tak tahu
2. tak tahu gak
3. it should be either analog or digital
4. lagi le tak tahu
5. aku insan yg lemah yg diciptakan oleh tuhan yang maha esa
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| Erylasia |
| Posted: Wed Jul 20, 2005 2:47 am Post subject: |
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| afiqme |
| Posted: Wed Jul 20, 2005 8:07 am Post subject: Re: STUPID QUESTIONS ! |
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Joined: 05 Dec 2003
Posts: 2289
Location: Kuala Lumpur
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| izuanhafez wrote: | Please help me to have clear understanding about these:
1. What are the differents between balanced and unbalanced port in audio interface?
2. How does it affect to the sound?
3. If i want to plug my guitar directly to audio interface, should the input port be analog or digital?
4. What is impedance? which one is good, low impedance or high impedance?
5. Who are you? |
1. aku pun tak berape clear.. tapi yg aku tau balanced port untuk terima signal dari balanced cable (TRS, XLR) ... unbalanced port plak untuk terima signal dari unbalanced cable (TS, RCA) ..
2. sound pun different ... balanced line lebih clean dari unbalanced line .. pasal balanced line die low impedance .. so signal to noise die cantik pasal level die dah tinggi ... kalau unbalanced sound plak ... die akan bising skit & hot .. pasal die nak kena boost ko punye level tu...
3. always analog even the digital can give more clean signal ... digital sound die tak warm ... tips nih aku dpt dari sorang user yg pakai v-amp pro...
4. same jek .. utk recording low impedance la ... untuk dpt signal yg lebih clean dan kuat dlm mix .. kalau untuk amplifier guitar ko of course high impedance la.. kalau ko pakai low impedance gak @ line level mau meletup amp kau.. hehe!! mcm v-amp 2 output die line level .. pasal tuh die boleh terus pi mixing console tapi kalau ko feed terus masuk input amp bahaye skit la.. pasal signal die terlampau tinggi ... care lain ko cucuk kat return amp terus ... 
5. ntah la .. aku pun slalu tertanye2 sape aku..
nih jek la yg aku bleh jawab ikut pemahaman aku.. kalau salah tolong betulkan.. terima kasih!
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| synthdude |
| Posted: Wed Jul 20, 2005 11:41 am Post subject: Enlightenment on the subject |
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Joined: 06 Dec 2004
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The simple explanation:
<b>Balanced vs. unbalanced cables</b>
Balanced refers to a “three-legged” type of electrical signal that has two legs independent of ground. One is generally considered positive and the other negative in voltage and current flow with respect to ground. Both legs carry the signal. The benefit is that any noise that gets induced into the line will be common to both the positive and negative sides and is thus canceled when it arrives at its destination, assuming the destination is balanced. This phenomenon is called "Common Mode Rejection” and happens because the receiving device sees the common noise in the signal as being out of phase with itself, and cancels it. Balanced lines are generally best for long cable runs due to their ability to reject induced noises. XLR and TRS type cables are designed to transmit balanced audio from one balanced device to another.
Unbalanced cables are less complicated and less expensive but they have limitations. Any audio signal requires two wires or conductors to function. In an unbalanced situation, one of those conductors is used to carry both the audio signal and ground (shield). Unbalanced cables are much more susceptible to induced noise problems than their balanced counterparts because any induced noise in one conductor is not canceled by similar noise in the other conductor and may be carried with the signal into connected equipment. In general, unbalanced lines should be kept as short as possible (certainly under 25-30' maximum) to minimize potential noise problems.
<b>Indepth assessment of balanced connections</b>
Balanced connections in an audio system are designed to reject both external noise, from power wiring etc, and also internal crosstalk from adacent signal cables. The basic principle of balanced interconnection is to get the signal you want by subtraction, using a three-wire connection. In many cases, one signal wire (the hot or in-phase) senses the actual output of the sending unit, while the other (the cold or phase-inverted) senses the unit's output-socket ground, and the difference between them gives the wanted signal. Any noise voltages that appear identically on both lines (ie common-mode signals) are in theory completely cancelled by the subtraction. In real life the subtraction falls short of perfection, as the gains via the hot and cold inputs will not be precisely the same, and the degree of discrimination actually achieved is called the Common-Mode Rejection Ratio, or CMRR.
"Hot" and "Cold" for in-phase and out-of-phase are used throughout this article for brevity.
While two wires carry the signal, the third is the ground wire which has the dual duty of both joining the grounds of the interconnected equipment, and electrostatically screening the two signal wires by being in some way wrapped around them. The "wrapping around" can mean:
1) A lapped screen, with wires laid parallel to the central signal conductor. The screening coverage is not perfect, and can be badly degraded as it tends to open up on the outside of cable bends.
2) A braided screen around the central signal wires. This is more expensive, but opens up less on bends. Screening is not 100%, but certainly better than lapped screen.
3) An overlapping foil screen, with the ground wire (called the drain wire in this context for some reason) running down the inside of the foil and in electrical contact with it. This is usually the most effective as the foil cannot open up on the outside of bends, and should give perfect electrostatic screening. However, the higher resistance of aluminium foil compared with copper braid means that RF screening may be worse.
ADVANTAGES OF BALANCING
* It discriminates against noise and crosstalk.
* A balanced interconnect (with a true balanced output) allows 6 dB more signal level on the line.
* Renders innocuous ground-loops, so that people are not tempted to start "lifting grounds" This tactic is only acceptable if the equipment has a dedicated ground-lift switch, that leaves the metalwork firmly connected to mains safety earth. In the absence of this facility, the optimistic will remove the mains earth (not quite so easy now that moulded plugs are standard) and this practice must be roundly condemned as DANGEROUS.
DISADVANTAGES OF BALANCING
* Balanced connections are unlikely to provide much protection against RF ingress- both sides of the balanced input would have to demodulate the RF with exactly the same effectiveness for common-mode cancellation to occur. This is not very likely.
* There are more possibilities for error when wiring up. For example, it is easy to introduce an unwanted phase inversion by confusing hot and cold in a connector, and this can go undiscovered for some time. The same mistake on an unbalanced system interrupts the audio completely.
* More hardware means more cost.
More here: http://www.sweetwater.com/shop/cables/cables_buying-guide.php & here: http://www.dself.dsl.pipex.com/ampins/balanced/balanced.htm |
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| deadzid |
| Posted: Wed Jul 20, 2005 1:17 pm Post subject: |
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cool explaination! i was waiting for synthdude to answer this question! all this while, i thought the objective of converting unbalanced signal to a balanced one is to get a stereo output... guess it's more than just that...
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| synthdude |
| Posted: Wed Jul 20, 2005 1:54 pm Post subject: I just nicked it! |
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Joined: 06 Dec 2004
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Well, I thought I'd just quote from the experts since I didn't want to mess up the technical bits.
Anyway, from my experience through the years working with balanced and unbalanced connections, I can safely say the former is more noise-free and offers a more detailed sound than the latter.
But really, the difference is only important if you're going to record music where noise -- buzz, hum etc -- has to be kept to an absolute minimum. This applies mainly to acoustic music, especially solo instrument recordings, where there're quiet passages.
For rock, it doesn't matter much because it's a genre that thrives on the excitement of controlled "noise". In fact, rock music that's too clinically recorded can be rather unexciting or not so "hot", as Paris Hilton would put it.
Which is also why rock/heavy metal is still mainly recorded in 16-bit. 24-bit may extend the dynamic range considerably, but it tends to diminish the much-desired "dirty" aspect of the sound.  |
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| IZZI |
| Posted: Wed Jul 20, 2005 3:18 pm Post subject: |
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Joined: 11 Dec 2004
Posts: 3447
Location: Melbourne, Australia
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Thank you afiq!
synthdude.. Dont u know that question no 5 is the most important?.. anyway thanks uncle! muehehehe...
gurau2 jer okeyyyy...
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| IZZI |
| Posted: Tue Jul 26, 2005 10:18 pm Post subject: |
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Joined: 11 Dec 2004
Posts: 3447
Location: Melbourne, Australia
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i got these answers from http://www.tweakheadz.com/soundcards_page_2.htm
its kinda similar to synthdude's explaination but with more understandable format i guess..!
Q) What is the difference between balanced and unbalanced audio connections?
A) Balanced means it takes a 3 conductor plug like a headphone plug on each mono channel (as opposed to the little stereo jacks that carry both channels on a soundcard). Note that a balanced connection is NOT stereo even though they use the same "headphone style" TRS connector. (TRS stand for tip+ring+sleeve). Also note that to obtain the benefit of the balanced connection the output of the gear you connect must also be balanced. --> our soundcard should have balanced port!!
The unbalanced connector is often called a TS connector. (TS has just a tip and sleeve, just like a guitar patch cable) These may come on 1/4" phone jacks or on RCA (home stereo) plugs. (so how to balance our guitar signal??? mixer?)
Can you tell the difference? If the cable runs are short, it's hard to. If you turn the volume up all the way on your amp, you typically will find that unbalanced connections are noisier. The longer the cable run, the more noise in the signal. Unbalanced lines may pick up electrical interference or even act as an antenna for radio stations. But most of the time, in short runs, there are no problems.
Most soundcards that take balanced connectors will also take unbalanced, but the reverse is not true. If you are connecting unbalanced gear like a mixer with unbalanced outs, the balanced connections will not help. (mixer should have balanced port too!)
Q) I heard that balanced connections are always +4 impedance wise and unbalanced are always -10. Does this make a difference?
(A) First, impedance is separate from the cable format. Its a newbie myth that impedance is tied to cable format. On better gear, balanced i/o can be set to -10 and unbalanced i/o can be set to +4. But usually, balanced outs tend to be +4. Impedance does make a difference. +4 gear will overload a -10 input and -10 gear will come into a +4 soundcard at a low level. If your recording levels are too low, see if you can drop the card's impedance to -10 to match the device you are recording. If you are always getting distortion, set the card to +4. Cards that have balanced i/o are more likely to be switchable between -10/+4. Those with unbalanced RCA connectors are usually fixed at -10. Getting a soundcard or audio interface with balanced connections and switchable impedance is, in my opinion, the best way to go.
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| IZZI |
| Posted: Wed Aug 03, 2005 8:34 pm Post subject: |
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Joined: 11 Dec 2004
Posts: 3447
Location: Melbourne, Australia
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Why do I need to use a "DI" Box and what do they do?
DI Boxes find applications interfacing usually Unbalanced (also known as Single Ended) signal sources like: Drum machines, Guitar and Bass instruments and amplifiers, Keyboards, Computers, Samplers, etc to the Balanced world of mixing console inputs for live sound, recording and broadcast.
In Electronics terms DI Boxes act as High Impedance active buffers enabling low or high impedance unbalanced equipment or instruments to be connected to low impedance balanced signal lines by providing two output signals of equal amplitude or level but opposite in phase. When these two signals are recombined in a mixing console's Balanced Microphone input stage, any Hum or R.F interference which may have been introduced into the preceding cabling is effectively cancelled out or removed from the signal.
Importantly, when used to connect instruments such as Bass Guitars and Keyboards to mixing consoles, Active DI's usually have an input impedance of at least 2 Meg Ohms to ensure no detrimental loading to the input which can cause loss of high frequencies due to the loading effect or impedance mismatch usually encountered.
Most units have a ground lift switch to isolate the input and output grounds to prevent earth loops, and can be either (or both) phantom and battery powered. In some cases DI Boxes are also Mains / A.C Powered.
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