Assorted questions related to my gigging setup.

Napalmhardcore

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Mar 11, 2010
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Hi,

I have a collection of questions. Some of which I've tried searching for with no success and others I may be able to find answers to. I thought since I'm asking for help anyway it wouldn't hurt lumping them all in together.

I play gigs at pubs, local festivals etc but have been largely clueless about the details of my equipment (it makes sound when I plug this in here, so that'll do kind of approach). I have recently gone about educating myself in what does what exactly and how to optimise my setup. Some answers have eluded me so that's why I've made this post.

Firstly, I own a Carlsbro Cobra 1100 PA mixing head which I've lost the manual for. I have contacted Carlsbro twice but received no reply. They do not provide downloadable manuals on their site and Googling didn't help (I found a Cobra 1100 manual but it wasn't for my particular model). On the unit is a "post out" jack. Does anyone know what this is for? I assume it's another name for "line out" but am uncertain and don't want to damage anything by connecting to it. Also when I bought (2) speakers for it, the owner of a local music shop ordered them for me after inspecting the Cobra 1100. It has two speaker outs on the back (although I believe the system is mono). Can I safely connect one speaker to it or will that effect the impedance?

Secondly the unit has four "high z" input jacks on it and 4 "low z" XLR inputs. I understand that a "high z" input is high impedance, which is suitable for guitars with passive pick ups. The low impedance XLR inputs are balanced and suitable for microphones or other line level equipment. What confuses me is I have an electro acoustic with a battery powered pre-amp. Should this ideally be connected via XLR? What happens when something suited to a high impedance jack is plugged into a low impedance jack and vice versa? Can this cause damage in any way?

And lastly, if a dynamic mic (Shure SM-58) is plugged into an XLR which is outputting phantom power will this cause damage? I understand that certain microphones like condensers require phantom power to work but it never seems to get mentioned the effect of plugging a regular mic into a phantom powered input.

Any help would be much appreciated.
 
Solution
Yes you can connect one speaker, no problem.
Find out what impedance your speakers are.
Example: you have 2X 8 ohm speakers. When you plug both in, this is a 4 ohm load. The amp produces full power.
When you plug one speaker in, this is a 8 ohm load. This produces half power.

The pre-amped guitar plugs into the high Z jack. This requires 1/4" to XLR adapter cable, available at music store.
The SM58 mic plugs into the Low Z jack. No, the phantom will not affect it.
That's why they call it: "phantom." It does not do anything unless you use a phantom powered mic.

Yes a regular mic can be used on a phantom input.
Yes you can connect one speaker, no problem.
Find out what impedance your speakers are.
Example: you have 2X 8 ohm speakers. When you plug both in, this is a 4 ohm load. The amp produces full power.
When you plug one speaker in, this is a 8 ohm load. This produces half power.

The pre-amped guitar plugs into the high Z jack. This requires 1/4" to XLR adapter cable, available at music store.
The SM58 mic plugs into the Low Z jack. No, the phantom will not affect it.
That's why they call it: "phantom." It does not do anything unless you use a phantom powered mic.

Yes a regular mic can be used on a phantom input.
 
Solution

Napalmhardcore

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Mar 11, 2010
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18,590


Thanks very much :)