There are some things manufacturers do not want to tell you about matching pairs
of microphones. Among these things, they will not tell you that Studio Projects is perhaps the only company who matches pairs for free.
There are many variables in the manufacturing process of microphone capsules.
Capsules generally have a loose sensitivity spec of +/- 2db as a result of these variables, so
the difference between the minimum and maximum spec can be 4dB. This happens due to
slight differences in the back plate, the tension of the Mylar film, the capacitor
of the capsule, or even the internal Mic pre-amplifier.
The sensitivity of Studio Projects mics are +/-2dB. The sensitivity difference of other well known brand Mics...well some are +/-1.5dB, some are +/-1 dB,
and some are +/-2dB.
So even very well known manufacturers have this same issue to deal with,
so the question
is...what to do with it?
When you test a capsule's sensitivity using a B&K measuring device, they are
accurate between about +/-0.5dB. This is very good for measuring, and even when
companies used to match pairs, they can't get that close. That is why most companies
no longer match pairs. Studio Projects can build and make mics with a +/-0.5 dB sensitivity
difference, but the price would be double, and the idea is make a good "affordable" mic that
is up to the task of competing with the expensive mics. So fine, no problem, but the problem is
one mic can be 4dB difference than another one.
One way Studio Projects found to resolve the problem was to split tested capsules into
sensitivity classes, and code them with a colored dot sticker.