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How do I connect my Zoom H4n to a Yamaha MG82CX that someone else is setting up?

Just because the connectors match doesn't mean it works, and playing connector-converter doesn't help. I've always been confused as to the difference between LINE IN and MIC, not to mention different kinds of mic technology.

My immediate concern is to confidently make it work Friday, without being able to experiment in advance.

More generally, I'd like to know what the three different "impedance" specifications mean, and how to convert db of different bases. I'll ask specific questions on the tech later, but I have a specific problem to cope with for Friday's Chinese New Year community show.

Here's the specific situation:

The mixer has a REC OUT jack with these specifications

Output Impedance = 600 Ω 
Appropriate Impedance = 10 kΩ 
Nominal Level = Lines –10 dBV (0.316 V) 
Max before clipping = +10 dBV (3.16 V)
    (where 0dBV = 1 Vrms)

The Recorder has a EXT MIC jack: (mini stereo phone jack)

Input impedance = 2 kΩ
Input level =  −7 dBm _ −47 dBm
(0 dBm = 0.755 Vrms)

A common enough cable can connect those two together. Think it would work? Why does the output have two different impedances? Why do none of the inputs have anything that matches any of the outputs?

Another choice is the INPUT jacks: (TRS full-size phone jacks)

Input impedance = 480 kΩ unbalanced
Input level = +2 dBm _ −32 dBm

The Zoom recorder does have an input level adjustment. The Yamaha mixer has various other jacks with different characteristics, but using the right output means it won't be in use by something else and it will not be affected by the output volume settings if he changes them during the performance.

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Leave the Zoom's input gain adjust at default (100, if it's the same as my old H2) -- the H2's numeric adjustment just scaled the already-digitised signal, which was no good and resulted in a loss of bit depth.

I wouldn't use the Mic In unless it doubles as a Line In -- or just use the XLR Ins and set them to Line Level if possible.

The Mic In has a lower input impedance - the more you boost a circuit (like a mic preamp circuit) the noisier the signal gets, and the higher the impedance the more noise there is to begin wtih. You should preferably be using the TRS ins if you have TRS out of a mixer.



So, impedance... Impedance describes the relationship of voltage and current. Remember Ohm's and Kirchoff's Laws?

Good quick read: https://electronics.stackexchange.com/a/21788/72394

Pinched from Whirlwind's web site:

Impedance (Z) is the measure of the total opposition to current flow in an alternating current circuit. It is made up of the sum of two components, resistance (R) and reactance (X).

In audio we talk about output and input impedances. Output impedance is effectively the internal impedance (resistance) of the circuit as measured across its output. Input impedance is the impedance as 'seen' by anything connected across a device's input.

Having balanced ('matched') output and input impedances used to always be done to establish optimum power transfer, but nowadays it's not desirable in audio environments. (there's a few places where impedance matching is still done, but it's usually with very old or niche equipment like ribbon mics and their preamps).

Where high (or mismatched) impedances can cause issues is in long cable runs: you can experience 'reflections' (quite literally part of the signal bounces back, mingles with the outgoing signal and causes spikes, interference etc) and it reduces the overall signal level.

It's a pain with digital signals like AES3, it falls off a cliff pretty quick once the circuitry can't distinguish the edges of 0s and 1s.

It's why having low impedance cables can be A Good Thing.

Impedance is all about voltage - but we must consider current and a circuit's resistance. NB: impedance is not uniform across the frequency spectrum; you can have varying impedances at different frequencies but audio equipment's designed to be uniform across its operating range.


Unless you have an existing electronics education or background, this next bit's a little counter-intuitive at first.

(I don't claim to have anything past a functional understanding of essentials, what I've learned in my job and read when studying.)

If you have a mixer and a recorder, having a high input impedance on the recorder will result in a higher voltage (so higher signal level, and larger signal to noise ratio) across its input, which is good - a high input resistance prevents current from passing through too easily and the output supplying the signal can more easily supply a good voltage level to the input circuit.

If the input impedance to the matched the output impedance from the mixer, you would see input signal level reduction if you hooked up more than one device in parallel to the output. Parallel resistance is a bit weirder than series resistance.

Impedance bridging, or 'voltage matching' (where the mixer's output impedance is lower than the input impedance of the device connected to the output by at least a factor of 10) is the norm in pro audio. It allows for the full output voltage to 'develop' across the input impedance and requires a higher output voltage - so less current draw - resulting in less distortion and better frequency response.

That Whirlwind page has a great hosepipe analogy (an electronics teacher explained it similarly to me, using pipe diameters in a central heating system):

Think of this as having a nozzle at the end of a garden hose. The garden hose is a low impedance source (there is little resistance to the flow of water) and the nozzle is the higher impedance of the input being fed by the hose.

When the nozzle valve is closed (open circuit):

  • Input impedance is VERY high
  • Pressure (voltage) is at maximum
  • Flow (current) is zero

Now open the nozzle just a little:

  • Input impedance reduces but remains high
  • Pressure reduces but remains high
  • Flow is small

As you continue to open up the nozzle:

  • Input impedance reduces further
  • Pressure reduces
  • Flow increases

With the nozzle open all the way:

  • Input impedance is very low
  • Pressure falls dramatically
  • Flow is greatest

In the case of a high impedance guitar output (7,000 to 15,000 Ohms or more) driving a relatively low impedance input of a mixer (2,000 to 10,000 Ohms), it's like connecting a garden hose to a fire nozzle. The hose just can't produce enough flow (current) for the size of the opening (impedance) to maintain the pressure (voltage).

Some further reading... It's worth at least getting your head around the concept of impedances because we all come across it so often in audioland.

Hi-Z outputs on guitars are just high output impedance :) Which is why DI boxes are used, to reduce the signal to a low impedance for feeding into a line level mixer input (and converts it to a balanced signal, which inhibits interference).

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Im not really sure what question you're asking here. Something like this will work:

http://www.amazon.com/gp/aw/d/B00AFEMMVQ/ref=pd_aw_sbs_e_2?refRID=07RD4BJ5YAT4464CRVGC

Going into the XLR inputs

The output of the mixer is at -10 and the range listed by +2 to -32 means that if you set the gain to 0, it will accept a level as high as +2db without distorting

As you turn the gain up to max, it will bring a level as low as -32 and bring it up to an acceptable level

Because the -10 output of the mixer is between +2 and -32 you'll be able to just adjust the gain up to an acceptable level using that cable to input to the combo trs xlr jack

  • I don't know what's not clear about the Title and the first sentence, or I'd edit the question to improve that. Your discussion of db values doesn't consider that they are in different units (dbV, dbm) so I don't think they can be compared directly as the same quantity. The +2 to −32 input level is a TRS, not XLR. The XLR input is −10 through −42 and has different impedance as well. You imply that the impedance values are not relevant and are just ignored... doesn't the resistence have a direct bearing on the voltages transferred? – JDługosz Feb 12 '15 at 5:23
  • You're right, I didn't see the different db units, but for an application like this, it doesn't make a very big difference. The impedance only because relevant when you're transferring a large amount of power, like you would to speakers, where you match the impedance exactly between the amplifier and the speaker. As far as the input/output levels, you have such a large amount of gain with a -42 to +2 range that regardless of the reference voltage for the specific unit, your -10 level will easily be accommodated. I've done plenty of recording from various mixers into an h4n with no issue – user12945 Feb 13 '15 at 6:23

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