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Soundhaspriority · Guest

The mike pres in the Tascam FireWire desks, models FW-1884 and FW-1082, are
susceptible to damage if a phantom powered mike is plugged/unplugged while
phantom power is active. It has been suggested that the reason for the
vulnerability is the omission of a coupling capacitor at the input to the
preamp IC.

Tascam does not supply a schematic for this product. If I determine the p/n
of the IC, would it suffice to break the connection directly after the 6.8K
phantom resistors, and splice a cap at that point? If it's a classic op-amp
circuit, there should be nothing at the input terminal of the chip except
the mike signal, but I'm asking in case there are other connections at that
point that are peculiar to this app.

If the cap is too large, the protective value against inrush current will be
lost. What is a good value that won't compromise LF response while providing
protection? Is it obtainable via a single polystyrene?

Bob Morein
Dresher, PA
(215) 646-4894