Topic: Do preamp bodies effect dB matching on switachable capsule systems?

[tgakidis]

Just wonder when matching caps does the preamp come into play or not?  In other words do the preamps need to matched also?

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Just wonder when matching caps does the preamp come into play or not?  In other words do the preamps need to matched also?

preamp as in 460 body or preamp as in Grace?

[tgakidis]

Just wonder when matching caps does the preamp come into play or not?  In other words do the preamps need to matched also?

preamp as in 460 body or preamp as in Grace?

Bodies...

[guysonic]

Not just an issue with switchable capsules, but all matched mic's sensitivity (output signal level) can be affected by the preamplifier's loading characteristic in an unequal fashion.  Mics are usually calibrated with a particular loading that may or may not track at a different applied preamp load. 

Also, the preamp's tracking (or mistracking) of the level knob or dual knob adjustments made during a recording is often a concern if in other than full up maximum. 

Any mid-range adjustment of single/dual knob settings can be off by several dB getting most inaccurate toward the bottom of the adjustment range. 

The exception are those preamplifier designs using true stepped ranges with resistor ladder switch design keeping better than .1 dB accuracy regardless of chosen setting positions. This is the way I design my preamps to function.

Only way to know is to test your mics with your preamp at various settings to see what happens to mic match verses knob settings.

[DSatz]

I think some of the vocabulary here is causing confusion. There's a paradox in the conventional terminology for condenser microphones: The amplifier is the part of the microphone containing the circuitry--and the output of that microphone amplifier is connected to the input of what is called a microphone preamplifier! Go figure.

Anyway, the question as I understand it is about modular microphone systems with interchangeable capsules. Amplifiers from the first-rate manufacturers all have essentially identical frequency response but slight variations in gain. Those variations are typically less (on average) than the typical variations in capsule sensitivity (on average).

Take for example a pair of microphones in which the capsules have a 0.75 dB difference in sensitivity while the amplifiers have an 0.5 dB difference in gain. If you put the more sensitive capsule on the amplifier that has the higher gain, the difference in sensitivity between the two complete microphones will be 1.25 dB. If you swap the capsules, the two complete microphones will have a difference of only 0.25 dB in sensitivity. So that can definitely be worth paying attention to.

Unfortunately most manufacturers don't tell you the precise sensitivity or gain of the individual capsules and amplifiers that you buy, but if you can measure it yourself, you can optimize the combinations of capsules and amplifiers.

--best regards

[tgakidis]

Thanks David, I knew you would shed some light on my question.