dynamic to guitar pedal
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Newmarket
Well-known member
Try just going straight in at first. What type of pedal ?
Newmarket
Well-known member
And what is the source ? Much will depend on the level you get out of the mic.
Impedance isn't really an issue. Guitar pedal is likely 1Meg input Impedance - high in any case.
May cause frequency peaking with the mic signal but that's not really an issue for Drive/OD I'm guessing or if you are looking for 'character' from the delay/reverb.
Impedance isn't really an issue. Guitar pedal is likely 1Meg input Impedance - high in any case.
May cause frequency peaking with the mic signal but that's not really an issue for Drive/OD I'm guessing or if you are looking for 'character' from the delay/reverb.
TwentyTrees
Well-known member
Your mic is unlikely to need a 10:1 transformer at the output to successfully bridge impedances to the pedal, which as Newmarket notes is likely to be in the 1M territory. Indeed, you may be able to flip it as a 1:10 for 20dB extra gain if needed - a standard 200 Ohm mic output would then look like 20k to the pedal, not an issue at all. You'll only know if that extra gain is needed once you've tried going straight in to see what happens.
Of course, one thing the transformer would help with is debalancing your mic output for the pedal's unbalanced input. Whether that's a material consideration depends on the output arrangement in your mic.
Either way, sounds like a fun experiment!
Of course, one thing the transformer would help with is debalancing your mic output for the pedal's unbalanced input. Whether that's a material consideration depends on the output arrangement in your mic.
Either way, sounds like a fun experiment!
skipwave
Well-known member
I do this a lot. Both on the way in for fun artist monitoring and processing tracks through a Sansamp at mix time.
As others have pointed out, there’s no big concern about not impedance matching (really bridging), except if the pedal you are using only sounds good with passive guitar pickups.
If you need to tame some frequency response peaking caused by a wily mic output transformer, experiment with installing a load resistor directly across the output terminals inside the microphone connector. Some people really like what a 600 ohm resistor does to the response of an SM57.
First try simply using a cable that shorts pin 3 to ground at the 1/4” unbalanced end going into the pedal. This is important because a lot of pedals use that sleeve of the TS connector to make the ground connection for the power to the pedal circuit (saves battery). A short cable is best as this arrangement makes the whole cable unbalanced.
If that sounds weird, try loading the microphone with a resistor. If that sounds good but tainted with interference (typically radio broadcast or digital hash) try a 1:1 microphone isolation transformer at the pedal end of the cable to maintain balanced transmission as long as possible. You could use your backwards 10:1 turns ratio transformer there but you lose -20dB signal level, which will probably require you to turn up the gain of the pedal a lot more, boosting noise floor. Use it as intended, 1:10 and you’ll likely want to knock down the level by attaching a 100k pot to the secondary
As others have pointed out, there’s no big concern about not impedance matching (really bridging), except if the pedal you are using only sounds good with passive guitar pickups.
If you need to tame some frequency response peaking caused by a wily mic output transformer, experiment with installing a load resistor directly across the output terminals inside the microphone connector. Some people really like what a 600 ohm resistor does to the response of an SM57.
First try simply using a cable that shorts pin 3 to ground at the 1/4” unbalanced end going into the pedal. This is important because a lot of pedals use that sleeve of the TS connector to make the ground connection for the power to the pedal circuit (saves battery). A short cable is best as this arrangement makes the whole cable unbalanced.
If that sounds weird, try loading the microphone with a resistor. If that sounds good but tainted with interference (typically radio broadcast or digital hash) try a 1:1 microphone isolation transformer at the pedal end of the cable to maintain balanced transmission as long as possible. You could use your backwards 10:1 turns ratio transformer there but you lose -20dB signal level, which will probably require you to turn up the gain of the pedal a lot more, boosting noise floor. Use it as intended, 1:10 and you’ll likely want to knock down the level by attaching a 100k pot to the secondary
You don't need to connect it "backwards". The 1:10 ratio will bring the level up by 20dB, which will make it close enough to the level a typical pedal expects, and the impedance will be converted from 150/200 to 15/20k, which is also close enough to the typical source impedance of an electric gtr/bass.
It will also take care of whatever problem there may be regarding the balanced-to-unbalanced connection.
Remember these Shure xfmrs were extensively used in the 60's for connecting microphones to the second input of a Fender amp.
Use a Normally-open switch (NO) across the mic. When teh contact closes, it mute the mic and does not enter the circuit in high-impedance state, which is bad for noise performance.
