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Matched pairs, required or not?

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Matched pairs, required or not?

Postby Ron Snijders » Wed Jun 26, 2013 11:23 pm

So, I'm in the world of 'buying microphones'. I've been building a rather alright collection of them (for a beginner, at least :) ) and now I'm wondering: do I really need to buy a matched pair of mics if I want to be able to use them in stereo recordings? I'm currently looking at C414 XL II's, and there are some excellent deals to be had in the second hand world. But nothing great seems to come along for matched pairs.
Will two of the same model of modern mic really sound so different that I'll need to buy a pair, or is it safe to snap two of'em off the 'Bay and be done with it?

Some searching lead me to this article, but that mostly seems to consider different mics altogether.
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Re: Matched pairs, required or not?

Postby The Elf » Thu Jun 27, 2013 5:50 am

A pair of mic's with closely matching response are preferable for accurate stereo imaging. In previous discussions on this subject the feeling seems to be that the more you pay the less likely factory matching is an absolute necessity.

I can imagine that the manufacturing tolerance of the 414 would be very tight, but I would try to go for the factory matched pair if at all possible.
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Re: Matched pairs, required or not?

Postby Hugh Robjohns » Thu Jun 27, 2013 8:58 am

Ron Snijders wrote:I'm wondering: do I really need to buy a matched pair of mics if I want to be able to use them in stereo recordings?

Coincident or XY stereo mic techniques place the greatest demands on microphone matching because small level differences between the outputs of the two mics are used to create the stereo positioning information. Therefore small differences between the frequency responses and polar patterns of the two mics will have a significant impact on the precision and stability of the stereo image, and since these characteristics are what the XY technique is all about, it's kinda important!

MS and spaced mic stereo techniques are much less demanding of mic matching.

The high-end mic manufacturers tend to work with pretty tight production tolerances and very good manufacturing consistency, so pair matching often is strictly required. For example, I've got nine or ten Sennheiser MKH mics bought at different times, many second hand, with wildly different serial numbers and none as matched pairs, and yet they are amazingly closely matched in both frequency and polar responses, and I have no issues at all with using them in random pairs for XY applications.

On the other hand, some budget mic manufacturers have very loose production tolerances and their mics are all over the place. Sometimes even their matched pairs aren't very matched -- they're just the closest they could find in that batch on that day!

Most manufacturers will offer matched pairs, and theoretically they should then check for close matching of both frequency and polar responses. However, many only check for on-axis frequency response, not off-axis... which isn't actually sufficient. In most cases, matched pair kits are really about up-selling expensive accessories!

The only practical way of checking the actual matching of two mics is as I described in that article you found.

I'm currently looking at C414 XL II's, and there are some excellent deals to be had in the second hand world.... Will two of the same model of modern mic really sound so different that I'll need to buy a pair, or is it safe to snap two of'em off the 'Bay and be done with it?

With the AKG C414 I'd expect the production tolerances to be sufficiently tight that you shouldn't have a problem with two random models -- although do make sure that they are of the same generation (there have been many variations on C414 over the years!). Again, it is very easy to check whether the two samples you have are adequately matched, and if they aren't you an always buy a third and then sell the least well matched! ;)

H
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Re: Matched pairs, required or not?

Postby Strangy » Thu Jun 27, 2013 9:03 am

as Elf / Hugh above.

One other consideration if buying off ebay/2nd hand, be aware that a stereo matched pair from 15 years might not be as matched as when they rolled off the production line!

One could have been a vocal mic in a smoky room for the last 10 years and the other locked away, enjoying the easy life in a locker! Just something to think about…
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Re: Matched pairs, required or not?

Postby Tim Gillett » Thu Jun 27, 2013 10:50 am

Reading through Hugh's article on matching mics for a stereo pair it occurred to me that those two same mics, however closely matched or not, could just as easily have been two candidates in a test of their compatibility with a particular vocalist (in a mono, not stereo situation).

Hugh's suggested mono nulling test I also find interesting. If done correctly it would seem a pretty stringent test of the differences between two otherwise similar mics. The test could go beyond just a listening test and include displaying the difference signal on a spectrum analyzer.
Such a test could also be used as a way of checking out other factors which might affect a mic's response, such as various input impedances, or even the effect on frequency response of an external windsock.

In the light of our previous discussion I also wonder which application is the more demanding of a mic's fidelity to another mic's response - in a stereo X/Y pair as here, or in matching each of those mics to a particular vocalist?
So if two mics are matched closely enough for an X/Y pair, would they still give significantly different results as separate mics, on separate takes with the same vocalist?

Perhaps this could be the subject of another discussion in another thread.

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Re: Matched pairs, required or not?

Postby Ron Snijders » Thu Jun 27, 2013 6:14 pm

Thanks for the thoughts and advice! :) I'll just take the gamble and buy the separately then. As Hugh said, I can always buy a third one and flip one at a minor loss.

... Now to buy a house and build me an actual studio to use them :headbang:
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Re: Matched pairs, required or not?

Postby Ron Snijders » Thu Jul 11, 2013 9:17 pm

So, today I got my second Sontronics Sigma in. Still waiting for the second C414XLII to arrive.
Well, the Sigmas are very NOT alike. So not alike that I actually suspect that one of them is broken. They also have slightly different grilles and brand/serial number tags. I dropped Sontronics a line on Facebook to see if they can repair it (though I'm guessing warranty will be a no-go since I bought the mics second hand).

Some comparison sound files:
https://dl.dropboxusercontent.com/u/38292593/Sigma%20-%20060...
https://dl.dropboxusercontent.com/u/38292593/Sigma%20-%20070...

https://dl.dropboxusercontent.com/u/38292593/Sigma%20-%20060...
https://dl.dropboxusercontent.com/u/38292593/Sigma%20-%20070...
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Re: Matched pairs, required or not?

Postby Urthlupe » Fri Jul 12, 2013 4:16 pm

Tim Gillett wrote:Reading through Hugh's article on matching mics for a stereo pair it occurred to me that those two same mics, however closely matched or not, could just as easily have been two candidates in a test of their compatibility with a particular vocalist (in a mono, not stereo situation).

Hugh's suggested mono nulling test I also find interesting. If done correctly it would seem a pretty stringent test of the differences between two otherwise similar mics. The test could go beyond just a listening test and include displaying the difference signal on a spectrum analyzer.
Such a test could also be used as a way of checking out other factors which might affect a mic's response, such as various input impedances, or even the effect on frequency response of an external windsock.

In the light of our previous discussion I also wonder which application is the more demanding of a mic's fidelity to another mic's response - in a stereo X/Y pair as here, or in matching each of those mics to a particular vocalist?
So if two mics are matched closely enough for an X/Y pair, would they still give significantly different results as separate mics, on separate takes with the same vocalist?

Perhaps this could be the subject of another discussion in another thread.

Tim

Please god, no.

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Re: Matched pairs, required or not?

Postby Hugh Robjohns » Fri Jul 12, 2013 5:22 pm

;)
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Re: Matched pairs, required or not?

Postby Ron Snijders » Fri Jul 12, 2013 11:13 pm

So, just to keep you all updated :) Sontronics responded today and they offered to either fix the mic or send me a new ribbon motor so I can do it myself. It appears to be very easy to DIY, so I'm going with that. Since I have two mics from very different production batches (the electronics don't even look the same), I'm still waiting for an answer to my question if popping new ribbons in both of them will leave me with two reasonably well-matched mics or not. Else I'm considering flipping the old one (with a new ribbon, of course) and getting a second one of the newer model.

Man, I hope those C414s turn out to be nice and even... But I guess I could've guessed that ribbons would be more trouble than LDCs.
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Re: Matched pairs, required or not?

Postby Tim Gillett » Sat Jul 13, 2013 2:53 am

Urthlupe wrote:
Tim Gillett wrote:Reading through Hugh's article on matching mics for a stereo pair it occurred to me that those two same mics, however closely matched or not, could just as easily have been two candidates in a test of their compatibility with a particular vocalist (in a mono, not stereo situation).

Hugh's suggested mono nulling test I also find interesting. If done correctly it would seem a pretty stringent test of the differences between two otherwise similar mics. The test could go beyond just a listening test and include displaying the difference signal on a spectrum analyzer.
Such a test could also be used as a way of checking out other factors which might affect a mic's response, such as various input impedances, or even the effect on frequency response of an external windsock.

In the light of our previous discussion I also wonder which application is the more demanding of a mic's fidelity to another mic's response - in a stereo X/Y pair as here, or in matching each of those mics to a particular vocalist?
So if two mics are matched closely enough for an X/Y pair, would they still give significantly different results as separate mics, on separate takes with the same vocalist?

Perhaps this could be the subject of another discussion in another thread.

Tim

Please god, no.

Loopy

The discussion never took place. If it had, no one would have forced you to read it, let alone participate.

Mate, what's your problem?

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Re: Matched pairs, required or not?

Postby Urthlupe » Sat Jul 13, 2013 7:58 am

Tim Gillett wrote:The discussion never took place. If it had, no one would have forced you to read it, let alone participate.

Mate, what's your problem?

Tim

Tim, I have PM'ed you to explain the nature of my problem - as this is not the place.

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Re: Matched pairs, required or not?

Postby Hugh Robjohns » Sat Jul 13, 2013 9:45 am

Ron Snijders wrote:Since I have two mics from very different production batches (the electronics don't even look the same), I'm still waiting for an answer to my question if popping new ribbons in both of them will leave me with two reasonably well-matched mics or not.

It depends on how good Sontronic's manufacturers are at maintaining consistent ribbon sizes and tensions...

I'm not surprised you've found two units from different places/ages sound different. It doesn't take much abuse to stretch a long ribbon and leave it sounding decidedly lack-lustre.

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Re: Matched pairs, required or not?

Postby Ron Snijders » Sat Jul 13, 2013 10:08 am

Hugh Robjohns wrote:
Ron Snijders wrote:Since I have two mics from very different production batches (the electronics don't even look the same), I'm still waiting for an answer to my question if popping new ribbons in both of them will leave me with two reasonably well-matched mics or not.

It depends on how good Sontronic's manufacturers are at maintaining consistent ribbon sizes and tensions...

I'm not surprised you've found two units from different places/ages sound different. It doesn't take much abuse to stretch a long ribbon and leave it sounding decidedly lack-lustre.

H
Am I reading too wishfully if I think you're implying that the difference in electronics shouldn't matter much, as long as the ribbons are well matched?

And yeah, I think that's a lesson I needed to learn. If I ever go down this route again with ribbons, I guess I'll budget for ribbon replacements before I decide to buy.
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Re: Matched pairs, required or not?

Postby Hugh Robjohns » Sat Jul 13, 2013 10:51 am

Ron Snijders wrote: Am I reading too wishfully if I think you're implying that the difference in electronics shouldn't matter much, as long as the ribbons are well matched?

The 'electronics' in the Sigma is only a simple impedance converter, and while different component tolerances etc could potentially impose measurable differences, it would have to be a pretty rubbish design to become audible under normal circumstances. Ribbon 'damage' is a far more likely cause of obvious sonic differences.

I think the Sigma has a fairly long ribbon. The longer the ribbon the greater the chance that it will sag and stretch under its own weight, and the greater the potential stretch damage if exposed to strong air blasts.

always store your ribbon mics with the ribbon vertical (to prevent stretch damage), and protect them from strong air blasts. Always cover them when not in use (a plastic or cloth bag is sufficient), and angle them at 30-45 degrees to the source if you suspect air currents are likely -- eg in front of guitar cabs.

If I ever go down this route again with ribbons, I guess I'll budget for ribbon replacements before I decide to buy.

Some of the low-end ribbon manufacturers offer a number of free ribbon replacements.

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Re: Matched pairs, required or not?

Postby Ron Snijders » Sat Jul 13, 2013 11:37 am

Thanks for taking the time to help my ill-informed self :) I'll just replace the ribbons in both of them and hope that they're manufactured within suitably tight tolerances then.
And thanks for the tips on 'ribbon care'. I knew about the upright storing and protection of air blasts, but I hadn't considered that a guitar amp puffs out quite some air as well. I should've known though, my Peavey 5150 used to make my trouser legs move when I still was a hairy metal guitarist :D
As for the free ribbon replacements: I'm afraid the Sigmas are about as low-end as I'm prepared to go in buying mics. I like the shiny ones :bouncy:
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Re: Matched pairs, required or not?

Postby ManFromGlass » Sun Jul 14, 2013 12:16 pm

Ron Snijders wrote:T I like the shiny ones :bouncy:

Now that's refreshing. The hell with specs, my eyes are too old to read them, as long as the mic is shiny or impressive looking in some form then I say it must be good enough! If only it was that easy for mic choice!
Cheers
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Re: Matched pairs, required or not?

Postby Ron Snijders » Sun Jul 14, 2013 2:08 pm

It's why I bought two C414s, they have a golden grille, c'mon! :D
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Re: Matched pairs, required or not?

Postby Ron Snijders » Sat Jul 20, 2013 2:38 pm

And to just wrap up the Sontronics story: all's well that ends well, right? I got my two new ribbon motors in and replaced them. The mics now sound very much the same. I haven't done the 'Hugh-test' yet, as I don't really have the space to set it up decently. But setting them up next to eachother and yapping a bit in the middle between them lead to a recording in which I can switch between mics without hearing any difference myself.

Massive to Trevor and Lisa at Sontronics (who probably won't read this here, but I'll mail them as well :) ).
And I guess this whole thread has made me look like quite a stupid fart. I ask about C414s, get a 'shouldn't be too big a problem' and promptly buy two ribbon mics that turn out to be from quite different generations... You live, you learn, I guess :D
So massive thanks to the people posting here as well!

Now I wonder if my MD-421-N and MD-421 II are stereo compatible... They're only 30 years apart!
(Please don't shoot me.)
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