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[Mark Lemaire]

Quote:

You may be able to match the mics, but so what? You will never be able to match the acoustics. Those spacing differences will create far larger response variations than any mic to mic differences.

If you record orchestras and choirs (what I do for a living), a slightly un-matched pair is not very useful except to use as spots on different things- that is, I use them seperately, NOT as a pair. The distance from the orch makes the stereo pair's exact matching quite relevant.

If, on the other hand, your typical use might be close miking an acoustic guitar, miking two singers doing duets, etc, etc, then I agree that the differences between the different mikes are dwarfed by the different sounds that come off an instrument at close range.

[Stephen Andrew Bright]

It is my understanding that you will never get a closely matched pair using mics made 10 years apart. Aside from the age difference in the capsules,  the parts in the mics are likely to be different as well. My suggestion is to sell the one you don't like as much and look for another one made in the same year as yours. At least then you will be working with the same components.

I have actually built matched pairs of vintage Schoeps mics on eBay several times by finding consecutively serial'd mics from different sellers on different continents.

Stephen

[Mark Lemaire]

With all due respect to Stephen and other folks, this has not been my experience.

I have three beautifully matched stereo pairs of Neumanns: a pair of M269s, U67s, and KM86s. All are used daily in critical orchestral applications where exact matching is a necessity.

With the exception of the M269 pair, none of them were made in the same year. All have pretty different histories. The U67s are separated by some thousands of serial numbers. They were all stereo matched and modded by the guy who runs this forum.

I've no idea if Klaus changed out components that did not 'match', and have no in-depth knowledge of his methods. I do know that the mics function admirably.

It's all in the skills of the microphone tech. Your mics are so closely matched already that many posters here suggest you simply call it 'close enough'.

It may seem intuitive to suggest that you sell one of your U87s to get one that is closer to the other in manufacture date, but in my experience, that is not necessary if the mic tech has the skills. Not all do.

[Phil Mayor]

My 1968 U87 looks like a completely different microphone to my 1998 U87 internally. I'm assuming it would be difficult to match those, not that I would want to. I record rock, pop etc and I've never felt the need for an exactly matched pair of microphones.

[Klaus Heyne]

Your 1968 model is a U87. Your 1998 version is the successor model, U87A, introduced in 1986.

While fairly closely related in timbre, the processing of polarization voltage, gain, output, s/n, and other parameters are different from the earlier model and a bit harder to match between them than if both were the same U87 models.

[Jim Williams]

Stephen Andrew Bright wrote on Mon, 07 June 2010 09:14

. I have actually built matched pairs of vintage Schoeps mics on eBay several times by finding consecutively serial'd mics from different sellers on different continents. Stephen

Anyone with the time, fortitude and chops can select components and pre-match them. You need a quality DVM with enough digits to match resistors up to 10k ohms within 1 ohm. That insures a .01% match. Capacitors can be matched with a quality capacitor bridge. Transistors can be matched using a curve tracer. JFETS must be individually tested and selected as they have greater variation in specs than bipolar transistors.

That effort also allows one to choose the brand of components without the bean counters selecting them for you.

[David Satz]

> I have actually built matched pairs of vintage Schoeps mics on eBay several times by finding consecutively serial'd mics from different sellers on different continents.

I would certainly not put it that way. For one thing the terms "matched pair" and "vintage" are rather like oil and water to begin with, since capsules age and change their characteristics over decades even if they're safely locked away in a drawer somewhere. Instead, however, they are subjected to great variations in their conditions of use--and eBay sellers in my experience are notably bad at knowing or telling the full truth about that.

In addition, manufacturing tolerances were considerably less tight in the years when any microphone was made that deserves to be called "vintage" today. Unless you can control the detailed characteristics of your capsules, you can't make a matched pair of any microphones, new or old. Microphone amplifiers are purely electronic, rather than spanning the realms of acoustics and electronics as capsules do.

So (barring accident or incompetence) the amplifiers within any one microphone series are always more uniform in their characteristics than the capsules are. The more significant manufacturing variations among condenser microphones--both in dB and in their audible consequences--are always in the capsules. Yet it is the amplifiers that carry the serial number for the microphone as a whole, which tends to make "consecutive serial numbers" mainly a vanity concern.

--best regards

[Stephen Andrew Bright]

Hi David:

I should have added that I also send them back to Schoeps for service, and while that still may not make for a perfectly "matched pair" according to Schoeps' definition, they come back sounding indistinguishable to me (and with lower self-noise).

Actually, it was Schoeps that suggested I get amps that were made at the same time in order to get a good "closely matched pair." So while it doesn't speak for the capsules' condition, at least it gets you in the ballpark with the same amp components.

I mentioned this as an alternative to getting capsule adjustments (from the 2 or 3 guys with a 2-year waiting list) to compensate for a 10-year age spread in a pair of mics, and because these days it really is possible to find a 30-year-mic made at the same time as yours.

Best,
Stephen

[Klaus Heyne]

This thread is getting a bit frazzled. Back to what I know, and what I think matters to the initial inquiry:

1. Neumann's FET mic amps of the same series/version are typically within about 1/2 dB or less across the frequency range. If more, then there is usually a defect.

2. Neumann's Mylar capsules of the same type can spread from piece to piece as far as 4dB across the range when new (thus the

[DavidSpearritt]

Mark Lemaire wrote on Tue, 08 June 2010 06:53

I have three beautifully matched stereo pairs of Neumanns: a pair of M269s, U67s, and KM86s. All are used daily in critical orchestral applications where exact matching is a necessity.

Mark, how have you determined that these pairs are exactly matched?

[Mark Lemaire]

An interesting question. Here, for what it's worth, has been what I have done whenever I am comparing two mics that I am going to use as a pair.

When I got the pairs back from Klaus (each pair was done in different years), I put them up as close to each other as I could, facing the same direction, in my studio. Then I ran them through preamps set to the same level (I mostly use Millennia Media). I turned them up as hot as I could stand and listened for matching levels of self-noise.

After that, I spoke, sang, or played guitar into each mic (close and far) and then played back the results with the mics panned to center and switched back and forth between them, listening for differences in tone or character between the two.

If I need to replace a tube or some other thing happens that suggests to me that I need to double-check whether the mics still match well, I do the above again.

Of course in actual sessions I am not setting the mics in the same place, so there are differences between what each one picks up. But I like to know that the differences are more derived from the mic's locations than the differences in the sounds of the different mics themselves.

I am not a scientist. And I know that my voice or guitar will not, for instance, produce low bass tones for me to compare. Still, I use the term "beautifully matched" because these stereo pairs have created lovely recordings for me and my clients over the years, with no one questioning whether the mics 'match'.

Let me know, David, if I have not answered your question fully enough.

[Klaus Heyne]

Mark Lemaire wrote on Thu, 10 June 2010 23:55

I am not a scientist.

Science as applicable to sensory investigation (in this case, hearing)  is largely an empirical undertaking (lest we forget how Bell came up with the loudness dB!)

So, you did just fine, from a scientific standpoint. You used the scientific method as fully as available to inquiry into a sensory phenomenon- hearing- that is still largely unexplored and unquantifiable.

Frequency response similarities between two mics don't go very far (see also the recent thread on ribbon mIc pairings) and leave out an important aspect of a microphone's character: timbre. You could theoretically find a Chinese-made cheapo with similar frequency response curve as a Neumann U87, yet the two mics will hardly sound alike.

[Dino Ziogas]

Take into account that any differences between the mics will be more prominent in coincident stereo arrays. Due to their nature, spaced stereo techniques are less prone to microphone mismatch.

One way to determine suitability of two mics for use as a [coincident] stereo pair is the following:

Have the two mics placed one on top of the other with the capsules as close as possible and facing towards the same direction. Have someone talk to them from around 60-70cm away and towards the middle distance of their diaphragms to ensure even pickup [you can use a speaker instead of an assistant].

Have the mics routed in two channels and pan them full left and right. Turn monitoring in mono. Use a regular amount of preamp gain for one mic and while turning the other mic channel out of polarity ["out of phase"] adjust gain so you get the deepest null possible. Now, you've calibrated the signal chains as much as possible. Flip the second mic phase back to normal. Turn monitoring back to stereo.

Have the assistant walk in a perfect circle around the mics [tie him with a string, he he - if the image does not stay reasonably centered you've got mismatch.

As a final check, turn one mic left and one right [45 degrees each] and by use of the assistant still walking make sure you get a good tracking of the source.

[Mark Lemaire]

Dino- Thanks for the idea! Now, I must find a piece of string...

[DavidSpearritt]

Thanks Klaus and Mark. I am not convinced about the necessity for  "matched pairs" from the marketing of SDC's. I think Mark's approach, checking noise, gain and timbre is appropriate, especially for LDC's, where it's difficult to calibrate the capsules in their head baskets. DPA seem to "match" by checking FR magnitude and phase plots, noise and sensitivity to within a tolerance.
http://www.dpamicrophones.com/en/products.aspx?c=Item&ca tegory=186&item=24005