<<So my recommendation is basically that, if your intention is to record
infrasound then a transformer coupled preamp is not the way to go. >>
I can't speak to sub-audio frequencies specifically, but it is worth
noting that the studio preamps most prized for their massive low end
response are the Neve 1073/1081/31105 series designs, all of which are
transformer coupled on the input & output, as well as adding another
transformer when switching in the EQ circuit. My conclusion then would
be not to suspect transformers generically in explaining a low end
rolloff.
I'm surprised to hear that the Countryman B3 measured flat down to
20Hz, as the intended application for these is vocal reinforcement in
PA systems, where low end response is not only not required but
detrimental in terms of controlling feedback. I use the Countryman
Isomax omni mics extensively in reinforcing the Kronos Quartet
concerts & I generally always need to add boeuf in the 80-120Hz region
on the Isomax mounted on the cello, since the mic is a bit light in
that region.
Scott Fraser
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