matched ribbon mics used on different sources = bad idea?

[jtdeans]

if i have a matched pair of ribbon mics (121s) and i decide to record guitar with one, could this possible change the character of the mic to make the "matched pair" unmatched?

would this really matter? if so, should i always use the mics together on one source, even when i dont want to record both?

[Max]

Don't worry.
If the mic's character would be changed, it would mean that the ribbon was streched and that you should have it re-ribboned.
A guitar won't harm your Royers.

[stevebozz]

my understanding of matched pairs is that they are engineered to work together in a balanced way, when using them with stereo micing techniques. Using them by themselves or on different things, the 'matchedness' of the mics won't benefit or harm the tone.

[Professor]

This is an interesting question, because I'm going to have to say that fundamentally the answer is yes, but not for the reason you're thinking.

Microphones will age just like any other piece of gear. Capacitors dry out, rubber gaskets and washers dry, ribbons stretch and slacken, dynamic or condenser diaphragms stretch or slacken, wires corrode, etc. etc. That's why there is really no 'exact sound' of any vintage mic... not all U-47s aged the same way.
Having microphones that start as a matched pair is a cool thing, and they will stay very close to a matched pair for a very long time. But eventually they will start to age and they will likely age in slightly different directions... which will ultimately un-match them.
Of course, that will take many, many years, and will happen if they are used on different sources, the same source, or if they never leave the comfort of their jeweller's boxes.
Now if one is always left on the shelf and the other is always out and in use, they will spread out a little faster because they will be exposed to different environmental conditions. Like if one mic is always getting warm, moist air from the singers while the other is always on the shelf... or if one is taken on location while the other stays home... that sort of thing.

In the end, I wouldn't worry about... and indeed, I don't worry about it.
My matched pairs show up on individual sources all the time. My C-414s only occasionally go up as a pair, my TLM-193s go up a little more often but are still used more for mono instruments (like one on kick and the other on vocals), and my AEA R-84s are up as single mics much more often than they are up as a stereo pair. The only exception might be my Earthworks QTC-1 & SR-77 pairs and my Gefell M-930s which do tend to see more action as matched pairs. But even then, they still go up solo from time to time. I think that's all I haved for matched pairs, but after four years of use on them, I don't know of any which are drifting away from being matched, at least not to where I notice I have a 'dark one' and a 'bright one' or anything like that. And one of my 414s even took a hit while micing a snare drum, although I made sure to open it up to work that out.

So yeah, don't worry about it. They will un-match eventually no matter what you do, but it will likely take 10, 20, maybe 30 years or more.

-Jeremy

[jtdeans]

Interesting jeremy, it was as much as i assumed logically about microphones... i suppose in the end it doesn't matter THAT much, as if someone will hit play on a CD engineered with an unmatched pair of mics on overheads and say "man, i love that song, but one of his drum overheads sounds brighter than the other, this album sucks!" not getting lost in the barren land of the gear obsessed is hard... so much beautiful equipment out there, sometimes in doing research i forget what this whole thing is about...

- jonathan

[thethingwiththestuff]

i dont even take my ribbons out of their boxes when i use them. comes out sounding amazing with a 50dB shelf at 1k.

[Professor]

Well see the thing to be careful with here, is that I am actually a big advocate for buying microphones in pairs or more, and buying matched pairs whenever possible. Assuming the goal is to eventually have a functional studio that can accomodate any kind of outside client... except maybe a commercial voice-over studio.
I prefer to record instruments in stereo whenever I can, so at a minimum, I like to have two of any particular microphone available. Having matched pairs doesn't necessarily mean that the sound of the mics will be superior, but simply that I can have repeatable results. I need to know that if the client comes back in 3 months time, I can look at my notes and photos, see that I had the 414 pair in M/S over the piano (or whatever) and recreate that setup to get me as close as possible to the same sound so the new tracks match the old ones.
Matched pairs are all about predictability for any particular setup. If the mics are close, but their overall frequency response is within a +/- 1.5dB range, what happens if I have one mic up by 1.5dB at 1kHz and the other down -1.5dB at 1kHz? Well, I get a 3dB spread at that frequency, and if the mics are placed as say, an XY pair over a drumset, then accidentally reversing that 3dB spread will mean I have twice as much energy at 1k on the other side of the drumset next time I setup. And it might not be 3 months between sessions, maybe I have to setup for a group Mon, Tues, & Wed, tear down and setup a different session on Thurs, Fri, & Sat, and then come back to the first band the following week.
Is it going to be a tragedy if they're not matched? No, not really... indeed, I might never even notice.
But if I can buy matched pairs I will.
I just don't expect them to stay matched forever. Twenty years from now, they will probably have drifted apart... not many marriages can last that long, right? But at least over those twenty years I'll a nice, predictable set of mics, and even if one does it's own thing for a session or two, they will still stay close for quite a while.

-Jeremy

[jtdeans]

if i have one U195 that i've used on about 10 sessions, and i've been thinking about getting a second to perhaps use as drum overheads would it be a waste? and following your statement of if one mic is 1.5db down the other is up at any given freq then could you not label one L and the other R to differentiate between the two, so as to allow you to replicate your setup on every session knowing that you used one on... blah blah blah, you get the picture... seems like a fix to me, although of course there still would be some difference (not some, there would be)

not to not get off topic or anything...

- jonathan

[Professor]

A couple of Soundelux U-195s are probably going to be a tight enough match, even after a little aging, that there won't be anything to worry about. Even if there is an age gap of a year or two, although as time goes on it's more of a craps shoot. Labelling the mics as L and R, or 1 & 2, or whatever is the simplest and most obvious way around it. At big studios where they own eight or ten U-47s, they will have them numbered, lettered, named, or in some way designated for exactly that reason. When they're working with big artists, it's entirely likely that there might be weeks or months between sessions of vocal overdubs or whatever, and they are going to make sure that same mic goes up for each session, unless they choose a different flavor for a particular track. In that case it's expected that none of the mics would be likely to 'match' each other, but repeatability is still the goal.

-Jeremy

[Andy Peters]

my understanding of matched pairs is that they are engineered to work together in a balanced way, when using them with stereo micing techniques.

No, the manufacturer just builds them in the standard way, then measures the response of each mic. Those with similar characteristics are considered "matched."

-a