XLR mic to 1/4 mixer - impedence matching or not?
Dumb newbie sound question here - I just picked up a really nice used Mackie CR 1604 16 channel board for a song. Only channels 1-6 have XLR inputs. The other channels are 1/4" only. If I ever want to run an XLR input into the 1/4 input only channels - do I need an impedance matching transformer or will one of the inexpensive XLR to 1/4 adapters work? I'm not schooled on the balance/unbalanced/impedance/etc thing. Thanks for any help - and if someone could provide me a quick explanation of this stuff, that would be great!!
Mackie sells an expander. If you need maximum amount of Mic inputs it's and economical way to go.
Search around for
If you just need 1 or 2 more mics there are many mic pre-amps you can use.
Just as a point of clarification: The XLR inputs indicate the presence of a mic preamp (along with a trim/gain control at the top of the channel strip). The mic preamp takes the relatively small output of the microphone and boosts it to line level. If you plug a mic into one of the other channels using an adapter the mic will not have sufficient output to be heard. The XLR10 that Seamonkey referred to isn't just a cable converter, it's actually 10 mic preamps.
I use that board also, with the expander, but all 16 inputs do have preamp gains on them so an xlr to 1/4 may work. The expander has it's own gain knobs too.
Here's the manual:
Per description, channels 1-6 are balanced and designed for mics. 7-16 are intended for line level applications and are unbalanced. There's more detail...read on!
When in doubt consult the manual:
The first set of items on our tour are the
sensitivity controls for the 16 input channels.
These knobs adjust the input sensitivity of the
mic and line inputs so signals from the out-
side world are brought into the mixer at
optimum internal operating levels. INPUT
SENSITIVITY controls for channels 1–6 have
up to 40dB of gain for line inputs and 50dB for
XLR inputs; controls for channels 7–16 have
25dB of gain. Note that all SENSITIVITY con-
trols are marked with a –10 setting. This is
the amount of gain needed to raise –10dBv
operating level equipment up to professional
Thanks all - so what is the typical line level sensitivity, -10db? This is the stuff I don't understand well. I have the manual - I have 25db of gain for the 1/4 unbalanced inputs - so if a +4db is needed, and a line input is -10db, I should have enough gain to boost those 1/4 inputs right at the board, right? If not, I'll probably pick up a mic preamp - I don't foresee needing more than a couple more. So this also begs the question - what good are those other 10 channels sitting there with line level inputs?
bump - any more help for a noob? Thanks!
" Mackie cr1604 line mixer". Popular home studio mixer too back in the 90's.
If you plug mics into line inputs, you might get away with the mic in front of a guitar cab belting it out, but the line input is expecting mill volts, while the mic sockets are expecting microvolts - there's a big difference. Guitars are a little low but are ok in the jack sockets, as are computers, keyboards, cd players that kind of stuff - but mics are just not hot enough!
Ok thanks for the help everyone. Hoping to get a chance to play around with it more soon. Since my drummer mixes his drum mics at his kit on a PV6, I don't foresee needing more than 6 mic inputs anyways. It seems like a really nice board - we already used it to record our last gig and it did a great job, super quiet and easy to use.
In this case the impedance is irrelevant. What's important is the signal level required by the input to get the required output. On loud sources such as kick, snare, and toms, some consoles have enough gain available. Most however do not. It won't hurt anything to whip up a couple of XLR-F-to-TRS-M cables and find out.
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