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Discussion Starter #1
I bought a gemini gx250 (basically a powered speaker) that i can plug into for those "little louder than acoustic" type gigs. If i dont use it, the guitar players cover me up completely! So my question is, if sometimes I would want to plug a vocal mic and my sax mic (and maybe even a trumpet mic) into this thing, I could go into a mixer and then out from the mixer into the gx250. At the same time, i could add some nifty effects (reverb and what not), so which mixer do you guys use/recommend ??

Thanks,

David
 

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daviddoria said:
so which mixer do you guys use/recommend ?
Well, I'm partial to digital, so Midas XL8. Only about $350,000.00. Ohh, wait, you wanted something more affordable?

If you need six XLR inputs, then how about a Mackie DFX 12, or a Yamaha MG124cx. I would probably got the Yamaha over the Mackie.
 

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XLR is the standard for good quality mixers. Cheap, low quality mixers will have 1/4" outputs. As long as they are balanced TRS outputs you are fine, just get, or make a TRS to XLR shorty cable adapter. Pin 2 on the XLR is hot, which goes to the tip of the TRS, pin 1 is always the ground, and goes to the sleeve of the TRS. Pin 3 is cold, and goes to the ring of the TRS connector.
 

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Discussion Starter #5
Sorry, I am very new to the electronics side of this business, but I do have a degree in EE, so that should help :)

What is "balanced TRS"? Does that just mean the L and R channels are getting the same signal? Because it is indeed not a stereo output... well, there is a L Out and R Out, so can i just convert 1 of them to XLR (with a converter that i just buy... 1/4" to XLR)?

I looked in the manual:
http://www.behringerdownload.de/1202FX/1002FX_1202FX_ENG_Rev_A.pdf

but I didn't know what I was doing/looking for hahahaha

I just want to go from the output of this mixer into a powered speaker (gemini 250)
 

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daviddoria said:
Sorry, I am very new to the electronics side of this business, but I do have a degree in EE, so that should help :)

What is "balanced TRS"? Does that just mean the L and R channels are getting the same signal? Because it is indeed not a stereo output... well, there is a L Out and R Out, so can i just convert 1 of them to XLR (with a converter that i just buy... 1/4" to XLR)?

I looked in the manual:
http://www.behringerdownload.de/1202FX/1002FX_1202FX_ENG_Rev_A.pdf

but I didn't know what I was doing/looking for hahahaha

I just want to go from the output of this mixer into a powered speaker (gemini 250)

On a quarter inch male there is a tip, a ring and a sleeve.

When wiring a TRS male to an XLR conncector to make an adaptor, the tip goes to pin 2, the ring to pin 3 and the sleeve to pin 1 (ground). Or you can buy an adapter TRS to XLR.

I you're goin to a powered speaker, just go from the output of the mixer (left or right), to the input of your powered speaker with whatever flavor of connector the input of your speaker has.

This should work as a primer for balanced audio, especially if you are an EE:

http://en.wikipedia.org/wiki/Balanced_audio
 

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Discussion Starter #7
cool - that looks good, i'll have a look

so is this not a "powered output"? because i've heard that if you plug a powered output (from an amp) into a powered speaker that is bad news.
 

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I have a yamaha mixer with effects that i sometimes use live .i think its a 312. pretty good little mixer and light to carry.I also have a mackie efx thats not powered and i use headphones with it. it sounds the best to me of the cheaper small mixers .both worthy choices IMO.
 

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Discussion Starter #9
Ok i get it, this is not "powered output" because it has not been amplified yet, because it hasn't gone through a big device with a big heat sink , only a measley little mixer :)

Thanks for the help/suggestions :)
 

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daviddoria said:
Sorry, I am very new to the electronics side of this business, but I do have a degree in EE, so that should help :)
Are you serious? :? You actually have a degree in electrical engineering? Or were you being facetious?

I suggest that you get and read the Yamaha Sound Reinforcement Handbook. Or, if you want to start out with a lighter load, get the Mix Magazine Live Sound Reinforcement book.
 

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Discussion Starter #11
I am serious lol. Doubtful because of my ridiculously easy questions? hahaha. It's surprising what you have to know to get a degree in EE. I am an image processing guy, which falls under that title, believe it or not. Only had to take a couple of courses in analog electronics.

Those books look great, thanks for the recommendations!
 

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daviddoria said:
cool - that looks good, i'll have a look

so is this not a "powered output"? because i've heard that if you plug a powered output (from an amp) into a powered speaker that is bad news.
JC has good advice. I'd go with the Yamaha handbook.

As an EE (gawd I can't believe that you can get an engineering degree without studying analog electronics), you know that there are different types of amplifiers. Getting from from mic/instrument level to line level is an amplification of voltage. It takes power (P=IE) to do work (moving a speaking), and so one needs to amplify voltage X amp (higher current) to do work. That's why to get from line to speaker level, you need a POWER amplifier.

If you plug a power amp into a power amp, you've plugged a device that's expecting to do work (speaker movement) into a device that's expecting a line level input. NOT a good thing.

Luckily, unless you have a mixer that has an internal power amp, the output will be some flavor of line level.

The only problem here, is there are two levels considered line level. Pro gear puts out +4 dBm, while consumer gear puts out much less (I forget and am too lazy this morning to look it up). Usually, balanced gear will put out the pro line level, and will be either 1/4 inch TRS or XLR, while consumer line level will be unbalanced RCA connectors.

Man, this stuff is hard too explain...
 

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Discussion Starter #14
Well one more thing...
http://www.geminidj.com/product_manuals/GX-200&250.pdf

There is a "line in" and a "mic in". someone told me it maybe that "mic in" has phantom power. But this gx250 does not have phantom power, but there are still both a "mic in" and "line in".

I had concluded that there were just 2 "levels", one before the big power amp (line level) and one after (speaker level), so what is "mic level"??
 

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Mic level is just what you think it is. That's an extra (voltage) amp, or preamp, that bumps a mic input up to line level, so you can go to speaker level through a power amp.[knee bone connected to the...]:)

Condenser Mics have their own preamp, usually in the body of the mic that bumps the VERY small voltage created by the changes in capacitance between two charged pieces that are the diaphragm of the mic. The part that moves is usually a piece of mylar with gold coating (sputtered). The preamp needs to be powered with a DC voltage. This can be accomplished with either a battery or with Phantom Power. A battery is obvious. Phantom power is a clever design whereby a DC voltage is sent down a mic cable to the mic to power the condenser mic's preamp, thus obviating the need for a battery.
 

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I was looking at the other thread where you are trying to use the Q-nano wah effect. With the behringer, here's a way to try and hook it up.

Bring your atm35 in through a mic input, say channel 1. Turn the 'pan' knob all the way to the left. Connect the left main output to the input of the q pedal device. Connect the output of the q pedal device to the line input (say channel 2). Pan channel 2 all the way to the right. Go from the right main out to your powered speaker. If you play with the 'gain chain' (how much you amplify the signal at each point in the system), you should get the effect you want. Caution: if you want to use the internal effects with this routing, use the effects on the channel two, and TURN OFF the internal effects going from channel 1.

Hope this helps.
 

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Discussion Starter #17
ok good, now i get "mic level"

however, i dont understand what all that routing is about... how is that different from going from the mic into the q pedal, then from the q pedal to channel 1 and just changing the gain there?
 

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daviddoria said:
ok good, now i get "mic level"

however, i dont understand what all that routing is about... how is that different from going from the mic into the q pedal, then from the q pedal to channel 1 and just changing the gain there?
Going from the mic to the q pedal, you're going from a device that puts out mic level, into the input of a device that wants to see line level (or close to it) at it's input. The routing that I have has the gain structure at nominal line level everywhere except the mic input.

Usually on mixers there are several auxilliary outputs and inputs to route signals to and from various line level devices. Unfortunately, Behringer chose to make only two outputs, the left and right main outs, so that's what have to be used in my scenario.
 

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Discussion Starter #19
ahh i see. so are the 1/4" inputs (right under the XLR inputs) also mic level? or are they line level? what is the output of a guitar?
 

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Yes, on your mixer the 1/4" inputs are line level inputs.

Of course, there is another level called 'instrument level'. This is the level that guitar pickups output. I believe different pickup designs output slightly different levels. This is why your mixer has a 'trim'. The inside numbers indicated 'trim' for the mic input, the outside numbers are for the 'line' input.

Best practice indicates that when using your mixer normally, you would adjust the level on the 'level' rotary fader to zero (unity gain), and the main output fader to zero (unity gain), and then use the 'trim' to find a nominal input/output level for the mic/mixer, before it goes to the poweramp/speaker.
 
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