Running Dual Mics in Parallel?

[Wabatuckian]

I'm wondering what will happen if I double mic my amp with only a splitter.

Since the new impedance will be the half of the sum of each mic's impedance, I'm sure that'll change the sound -- maybe it'll lo-fi it?

Also, I'm sure the time alignment will be different for each mic if I don't use exact, high-quality duplicates. What effect would this have? A bit of a doubling effect, maybe?

Thanks!

 

[PitchTempoAndriy]

The electrical loading and the acoustic timing are two separate things here.

For two equal passive source impedances in parallel, the equivalent is Z/2, not half their sum. With unequal values it is Z1×Z2/(Z1+Z2), in the simplified circuit model. That alone does not predict a pleasant “lo-fi” sound: the mics also load each other, and you lose independent level control. A bare Y is not a mic mixer; active/phantom-powered models need particular care. Rane explains the output-combining issue here.

The timing difference is mainly about the sound paths to the capsules, not whether the mics are expensive duplicates. Summing two slightly different arrivals from the same speaker can give comb filtering — peaks and notches, rather than a separate double-tracked performance.

If you have two mic inputs, record separately and compare the blend in mono while moving one mic; that keeps balance and polarity adjustments available. Which two mics and input device are you considering?

 

[Wabatuckian]

The electrical loading and the acoustic timing are two separate things here.

For two equal passive source impedances in parallel, the equivalent is Z/2, not half their sum. With unequal values it is Z1×Z2/(Z1+Z2), in the simplified circuit model. That alone does not predict a pleasant “lo-fi” sound: the mics also load each other, and you lose independent level control. A bare Y is not a mic mixer; active/phantom-powered models need particular care. Rane explains the output-combining issue here.

The timing difference is mainly about the sound paths to the capsules, not whether the mics are expensive duplicates. Summing two slightly different arrivals from the same speaker can give comb filtering — peaks and notches, rather than a separate double-tracked performance.

If you have two mic inputs, record separately and compare the blend in mono while moving one mic; that keeps balance and polarity adjustments available. Which two mics and input device are you considering?

Know what? I'm an idiot. I knew Z/2 and have no idea what I was thinking there I've always added the reciprocals of the impedances, and worked out the reciprocal of the result of the answer.

For 4Ω + 4Ω + 8Ω , 2/8 + 2/8 + 1/8 = 5/8, then 8/5 = 1.6Ω

That's extremely embarrassing.

I have some cheap mics that use TS plugs, and was just going to put two in series to see what it sounded like. Just seeing what I can play with without letting the magic smoke out.

 

[TalismanRich]

I'm wondering what will happen if I double mic my amp with only a splitter.

Since the new impedance will be the half of the sum of each mic's impedance, I'm sure that'll change the sound -- maybe it'll lo-fi it?

Also, I'm sure the time alignment will be different for each mic if I don't use exact, high-quality duplicates. What effect would this have? A bit of a doubling effect, maybe?

Thanks!

AH, the other hot word in the recording world beside "glue"... . LoFi. A term that everyone throws around as if it's some well defined sound, yet nobody can say what it really means. You've got that Astatic mic. Just plug that it, and you'll get LoFi.

You have two mic inputs. If you want to play with a dual mic setup, just record to two channels and you can play with them any way you want.

 

[DrewPeterson7]

I'm wondering what will happen if I double mic my amp with only a splitter.

Since the new impedance will be the half of the sum of each mic's impedance, I'm sure that'll change the sound -- maybe it'll lo-fi it?

Also, I'm sure the time alignment will be different for each mic if I don't use exact, high-quality duplicates. What effect would this have? A bit of a doubling effect, maybe?

Thanks!

Do you only have a single channel of mic inputs to work with?

I'll be honest - I definitely prefer two mics on a cab to one. But it takes a while to get the positioning and phase relationship between the two right, and in practice, for rhythm guitars in particular, more often than not I lean pretty heavily on my "primary" mic, a Shure SM57. And, if you can really get the positioning of that one right (and my process is to first start by getting as good a tone as I can out of that mic, before reaching for a second t flesh it out), you're already gping to be 95-98% of the way there simply by doing two takes and double-tracking your rhythm part.

If you only have a single input to work with, I wouldn't bother with a second mic.