I'm about to buy a Audix ADX 10 FLP mic to record my flute. It's a condenser mic. So It comes with a phantom power box.

It has a mini XLR plug.

My question is:

If I want to plug the mic (and its phantom box) to a "guitar" effect (1/4" plug). What should I put in-between ?


  • Are you going to record the unprocessed flute mic sound on an audio track, and then run it separately into the guitar effects, or do you want to record it with effects baked in? Or is this for actual recording at all, or for playing live? Mar 31 at 11:04

Ooh, this sounds like fun.

The guitar pedal is expecting a hi-Z (high impedance) input, like what comes out of a guitar. So what you need is one of these:


Which is the same thing you'd use to plug a microphone directly into a guitar amp (something every band has done at least once).

So the signal chain will be:

Flute -> Mic -> Phantom power adapter -> XLR cable -> Impedance transformer -> pedal

Have fun! By the way, you can get a cheaper version of the transformer that doesn't have a cable between the jack and the plug, but I wouldn't. Step on it, and you have a good chance of breaking both the transformer and your pedal.

  • 2
    I don't know that you really need a transformer; I've connected a low impedance mic to a high impedance input with good results before. It's usually the other way (high z out into low z in) that causes major problems.
    – Edward
    Mar 28 at 21:53
  • How does using impedance transformer compare to using a microphone preamp? Mar 29 at 5:34
  • 2
    I agree with Edward – low-Z into a hi-Z input isn't really a problem at all (not in audio frequencies at least). Where there is a problem is with dynamic mics, because their low output level would require cranking the gain and thus boosting the noise level, but this shouldn't be an issue with a condenser one. (More precisely: the condenser capsule actually has an even higher impedance than a guitar PU, but every half-decent condenser mic has an impedance decoupler built in so it can be used in both a hi-Z and low-Z setting.) Mar 29 at 9:08
  • 1
    I'd still get the transformer—it's not very expensive and will be useful with a dynamic mic in the future. @user1079505, a microphone preamp will not work in this case. It's designed for bringing a microphone up to line level, which will be way too hot to go into a guitar pedal.
    – mamster
    Mar 30 at 13:56

This would probably work with just a simple XLR → ¼"TS cable. An impedance transformer would give you higher signal level, but isn't really needed.

Nevertheless, if you can afford it I would recommend you actually use a proper microphone preamp. Standalone preamps are sold mostly for studio applications; typically the main feature is that they use a tube instead of just transistors. Now, you may not need a tube, but it actually does improve the sound of many instruments and if you're going for a bit of a “dirty electric flute” then it is probably right for you as well. A tube-driven signal is a bit compressed and saturated, which will make it come out better in a band mix; unlike guitar-specific overdrives however, a tube preamp can also be made to sound as clean as you want and will not dramatically increase the feedback susceptibility. Most preamps actually have a phase invert switch: this often helps a lot to reduce feedback in live applications but is absent in guitar effects.

The preamp will also offer a better SNR, and it provides phantom power from the power supply so you won't need a battery. (Which means you can use a small in-line adapter like the Audix APS910, instead of the clunky box APS911.)

Two models you could look into are the ART TubeMP and Presonus TubePre.

With both a simple adapter or transformer as well as with a preamp you may run into mains hum issues, because the guitar FX has an unbalanced input. This may be fixable by experimenting with various grounding configurations – unfortunately there's no silver-bullet solution. ...Well, there is actually: using balanced connection, but this is one of the things the guitar world has unfortunately never learned. Depending on what kind of effect you need, you may however be able to get a version intended for vocalists instead, and that would then have balanced XLR connectors already.

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