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Old 05-07-2005, 02:35 PM
DRAFT DRAFT is offline
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Default Help..Mbox..Unbalanced cables or balanced cables..

If the manual for the Mbox says that the line inputs accept TRS connectors and the the manual for my Yamaha MG16/4 Mixing Console says that the main L and R stereo outputs accept balanced TRS connectors, why did the guy at Sam Ash sell me an unbalanced dual 1/4" TS to RCA cable (when I went to buy a dual TRS cable) to go from the RCA record out from the mixer to the line inputs on the Mbox so I can run 10 mic pres into it. The Sam Ash guy says I need unbalanced because TRS is a stereo signal and I needed two mono signals, but then why do the manuals say otherwise? Somebody that knows what they are talking about please help me for I am confused and don't know what to believe. The mixer also has XLR outs on the main output, would that work as a connection? What would give me the best signal and sound quality? Thanks.
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Old 05-07-2005, 02:43 PM
orage orage is offline
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Default Re: Help..Mbox..Unbalanced cables or balanced cables..

That guy from Sam Ash doesn't know what he's talking about. TRS-TRS cables are not stereo...they're what we call balanced. While what he sold you will work, you are basically working with an unbalanced set of lines between your Mixer and MBox, which opens up a whole world of nastiness when it comes to unwanted noise and hum creeping it's way into your gear.

Go back and get a pair of TRS cables. XLR to TRS would work as well....

Whenever possible, you should attempt to use balanced options before you use any unbalanced outs from your mixer (ala the RCA record out)....
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Old 05-07-2005, 07:25 PM
Kawi Kawi is offline
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Default Re: Help..Mbox..Unbalanced cables or balanced cabl

is xlr the same as trs? Im looking for the same info. I have an mbox and a mackie mixer 1202. NOW,
1-should I come out of the mbox with" the only cable thats possible" a 1/4 inch mono tip or trs tip to an xlr into channels 1(L) and 2(R)?
2- Come out of the mixer from the xlr outputs to my mackie self powered speakers xlr?
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Old 05-07-2005, 07:52 PM
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albee1952 albee1952 is offline
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Default Re: Help..Mbox..Unbalanced cables or balanced cabl

A little wiring 101 for the newbies. TRS is considered a balanced connector as are XLR connectors. (except when referring to headphones and cheap mixer inserts). T(tip=hot or +, R(ring=cold or -), S(sleeve+shield). On XLR connectors, PIN 1 is shield, PIN 2 is hot(90% of the time) and PIN 3 is cold. a TRS to XLR is still balanced as long as each end is wired correctly. The advantage is in noise due to "common mode rejection". Any noise induced in the cable is equal on both signal conductors(hot and cold) and when it goes into the next stage(of circuitry) the hot and cold, being 180 degrees out of phase, makes the noise cancel itself out. The shield does nothing but "shield" the signal. An unbalanced cable uses the shield to carry half the audio signal. Using balanced cables also allows the correct solution to a ground loop(60 Hz hum). If your monitors hum, you can clip the shield wire at the monitor end of the cable so the shield still shunts noise "upsteam" but you only have one audio path to ground(to the upstream device such as your Mbox or 002).

Headphones use a TRS connector but it is wired with LEFT+ to tip, RIGHT+ to ring and -(both) to sleeve(I might be switched on L/R). The TRS insert jack on cheap mixers is a cost and space saving idea with insert send on the tip, insert return on the ring and shield to sleeve(common to send and return). Keep those unbalanced cables as short as possible(under 10' is preferred, 20' is as far as I would ever use under normal conditions). There is a lot more to this but now you have the basics.
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Old 05-07-2005, 08:08 PM
tomhartman tomhartman is offline
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Default Re: Help..Mbox..Unbalanced cables or balanced cabl

Dumb question....what about when you are going to a power amp that only accepts RCA phono plugs? The 002 wants TRS coming out, so if I get a cable that is TRS out of the 002, ending in RCA for the power amp, is that connection still considered balanced?

Thanks
Tom
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Old 05-08-2005, 08:58 AM
orage orage is offline
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Default Re: Help..Mbox..Unbalanced cables or balanced cabl

Quote:
Dumb question....what about when you are going to a power amp that only accepts RCA phono plugs? The 002 wants TRS coming out, so if I get a cable that is TRS out of the 002, ending in RCA for the power amp, is that connection still considered balanced?
No. RCA phono plugs are two conductor connectors. What typically happens in cables built XLR->RCA is that the shield (Pin#1) and common (Pin#3) get tied together, effectively making this cable unbalanced.
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Old 05-08-2005, 07:07 PM
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albee1952 albee1952 is offline
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Default Re: Help..Mbox..Unbalanced cables or balanced cabl

orage is correct but you can cheat on this and go QUASI-balanced like this. Get balanced cables with TRS plugs on one end and cut the other end off. Get 2 good RCA plugs(the Nuetrik are my favs) and wire as followsassuming when you strip back the cable you find a black wire, white wire and shield). Figure out which wire goes to the TIP in the TRS and solder it to the RCA tip. The wire from the RING of the TRS goes to the sleeve of the RCA. Tape the shield so it has no connection at the RCA end. This will operate as a balanced cable and shunt RF and EMI interference "upstream" to the balance outputs of your Mbox or whatever. The important thing to remember is that many RCA inputs are designed to operate at -10 so a +4 balanced line can overdrive it pretty easily.
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