1/8 jack input and XLR input difference

[pmk396]

Hi all,
This might be a noob question but can any one tell me the difference between 1/8 jacks and xlr inputs. Correct me if I'm wrong but I think that I heard before that using the xlr gives better quality/more professional sound but that the 1/8 jack is up to the task as long as the lead (wire from mic to recording device) runs for no longer than 4 metres (after 4 metres and the sound begins to lose quality). Am I correct in think that or are there way more differences?

 

[Alex H.]

The major difference is between balanced and unbalanced signals. Balanced means that there are three conductors: positive, negative, and ground. Unbalanced has only two conductors: positive and negative/ground. Balanced signals are more robust and can run over much longer distances with little/no risk of added noise.

The other thing to understand about 1/8" vs. XLR: connectors are just connectors. It's not as much which connector is used (though each has found a common/standard use), but how that connector is wired. XLR connectors can carry stereo, unbalanced signals if they're wired to do so. 1/8" TRS (tip-ring-sleeve) connectors can carry balanced mic or line signals if wired to do so. But when it comes to cameras and their audio inputs, 1/8" typically means unbalanced input at mic-level. While the camera may have a three-conductor jack (for 1/8" TRS), it's actually set up for unbalanced 2-channel operation (left +, right +, common -/ground). Some very-low-end consumer camcorders actually have mono (1/8" TS, or tip-sleeve) inputs.

Mics like the RODE VideoMic, that are monaural microphones yet have a 1/8" TRS connector, are wired to send the mono signal to both left and right channels of the camera's input. Since this is still an unbalanced signal, extending the cable for things like mounting the mic on a stand or pole can have adverse effects on the signal.

There's another determining factor in there when it comes to whether the 1/8" input is "up to the task": pre-amps. Many (most) lower-end cameras with 1/8" inputs have pretty shoddy pre-amps. While the connector is, by definition, up to the task of accepting any signal it's wired to carry, the pre-amp can be your killer. Even some cameras with XLR inputs have crappy pre-amps. Even worse, a lot of consumer camcorders have nast AGC (automatic gain control) that cannot be defeated, adding tons of noise and other nasty artifacts to the audio recording. The moral of the story is that the quality of your audio depends on every single piece in the signal chain.

 

[recordingwhiz]

way more...

first of all not all 1/8" (3.5mm) jacks are the same. most camera and portable recorder 1/8 jack inputs are stereo unbalanced mic inputs. that being said, some of the portable recorders with 1/8" jacks also offer it in LINE level as well.

lets start with the most common: mic in 1/8" will have a left and right with a common ground , this is unbalanced and NOT noise rejecting by design, this is the type of connection you want to maintain at a minimum distance. for mic adapter cables this is commonly done by unbalancing the mic and sending its hot to both left and right channels simultaneously, but ultimately this does unbalance the whole signal chain from mic to recorder. least desirable but necessary in alot of scenarios and also common for most on-cam mics such as the RODE vid mics and SVM, as well as the Senn and a few others that are actually manufactured with 1/8" connectors built in, they are really NOT designed to be extended, they can be , but be warned... they may and will likely pick up RF interference.

An XLR connector is a balanced signal and requires 3 conductors to remain balanced, by design it rejects noise and can be run up to hundreds of feet (just think of concerts where the mixer is 150' from the stage yet all the mic signals reach the mixer with good quality and for the most part no added noise). unbalanced and balanced signals in the "line level" do differ , in the mic world is not as relevant as they both plug into a gain stage (whether a mixer, pre or camera) Balanced in al aspects is a technicaly better signal, however it does NOT necessarily mean its better sound, it is all in how an un-balanced signal is used.

that is the basics without going on for months about certain measurements and all that kinda crap

Basically if its unbalanced as in a camera mic input or recorder mic input, keep it short as possible...that's why you use the beachtek and juiced link boxes for cameras (allows you to keep a balanced signal from Mic to the shortest point near the camera).
If your equipment has XLR then use those considering they are mic level or switchable.

Now all this pertains to "MIC" level, Line level is another beast that uses the same connectors.

Hope this makes sense

GG

edit: plus what C2v said