Skip to main content

PLease Help Me Better Understand Impedence!

Hi Folks,

I'm brand new to these boards and fairly new to recording, and could'nt be more excited that I found this site. I've got a couple questions I'm hoping someone can help with but first let me explain my setup. I've got an MBox and Pro Tools LE 7, a Mackie 1202VLZ mixer, various keyboards samplers and dum machines and I just bought a Universal Audio Solo 610 to record bas and guitar direct and for vocals. It's pretty basic but it's taken me a long time to piece together and I'm pretty proud of it.

My question is regarding the UA 610. I was asking a friend if I could use an XLR to 1/4 TRS cable to connect my 610 to my MBox. He said he thought there might be a problem with impedence but he was'nt sure. My thinking was by plugging into the MBox's line input I would be bypassing the MBOx pres. The 610 has a Mic/Line switch on the output. So, myquestions are:

1. Is it ok to use an XLR to 1/4 TRS cable to connect my 610 to my MBox
2. Will I actually be bypassing the MBox pres by connecting this way?
3. If I'm using an XLR to 1/4 TRS cable is the signal mic or line? Or is that determined by the position of the 610's Mic/Line toggle?
4. Does a signal's impedence get converted somehow when using cables with different connectors?
5. Am I making this harder than it actually is?
6. Is there a good signal flow "for dummies" resource out there you could recomend?

Thanks in advance for any feedback. I promise to keep the noobness to a minimum in the future. :lol:


dementedchord Sun, 10/15/2006 - 23:01
in no particular order yes /no/ yes... sorry..

1. yes
2. yes but the assumption is that it's the M-box line in your talking about
3a. the output of the 610 should be line level
3b. that toggle should be for the input of the 610 not the output
5.well a little atleast
6. your there

you said specifically the mic/line switch was for the output... double check that PLEASE... im doubtful... stranger shit has happened but not recently... as youve obviously surmised you dont want to "pre-amp" twice so the line in is the appropriate one for the M-box... also i dont have 610 so need to ask is the output on xlr or trs... it's entirely possible that all you need is a straight trs-trs cable... as to the impedence business dont want to get too heavy and give us both a headache but the idea basically is that the first needs to "drive " the second which drives the third... and drive here means provide current the problem is that when the output of the first is "higher" than the seconds input it often cant do that.... i know that's an over simplification but should help get you started.... BTW good first post... welcome to the club... see ya round the playground...

Kev Mon, 10/16/2006 - 01:35
Ths is a very important and much mis-understood subject.

Interfacing equipment and being aware of levels can be the source of many troubles in the studio.

A passive VU meter and some open ended cables or a box that allows you to experiment to get the right interfacing
and THEN
make or obtain the cables you need.
... sometimes this may involve a resistive pad.

I think you will find that the 610 has an output greater than the M-box can handle
so it is my suggestion to use a pad to kill a little level.
This will allow you to run the output of the 610 up and hot but still not crash the M-box line input.