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Definition of "equitek":

Equitek is CAD’s name for a unique microphone amplifier circuit design.

The original Equitek circuit, found in the 1990s-era E-100, E-200, and E-300 microphones as well as the revised e100² and e300², employed opamps rather than transformers or transistors in the output stage. This was done to avoid the “inherently nonlinear” behavior of output circuits with twin output transistors, which are difficult to match precisely.

The drawback to op-amps is their high current draw. Standard 48V phantom power is insufficient to power these output ICs (such as TI’s OPA2107) during transients. Therefore, CAD reengineered the power supply to feed the high-current op-amps in the Equitek output circuit: P48 was used to trickle-charge two built-in rechargeable (NiCd or NiMH) 9V batteries, which in turn powered the amplifier circuit.

The next-generation Equitek circuit, such as found in the e60, retained the op-amps but did not require internal batteries. (CAD’s M179, although not named Equitek, employs a similar phantom-powered, no-battery op-amp output circuit — and requires true P48 power for best operation.)

With the release of the E100S in 2009, the Equitek name has evolved again, and in a sense come full-circle. The Equitek E100S has a full-differential design with 4 FETs on the input and two bipolar transistors (but no op-amps) on the output. The E100S does not have rechargeable batteries in the circuit, and is able to deliver full performance at low current draw.

So, the latest Equitek design reverts to discrete output transistors — and whatever nonlinearities they bring — in exchange for lower self-noise (3.7dBA!) and low current draw.

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side-address electret transformerless condenser opa2107 externally-biased end-address hpf large-diaphragm edge-terminated nickel-diaphragm lowest-noise pencil-mic detachable-capsule multipattern

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Find mics tagged 'equitek OR:'

side-address electret transformerless condenser opa2107 externally-biased end-address hpf large-diaphragm edge-terminated nickel-diaphragm lowest-noise pencil-mic detachable-capsule multipattern

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Mics tagged: equitek

	CAD Audio E-100 Supercardioid Condenser Microphone side-address, electret, transformerless, condenser, opa2107, equitek
	CAD Audio equitek e60 Cardioid Condenser Microphone externally-biased, transformerless, end-address, condenser, hpf, equitek
	CAD Audio E100S Supercardioid Condenser Microphone side-address, large-diaphragm, externally-biased, transformerless, edge-terminated, nickel-diaphragm, equitek, lowest-noise
	CAD Audio equitek e70 Detachable-Capsule Pencil Condenser Microphone pencil-mic, transformerless, detachable-capsule, condenser, hpf, equitek
	CAD Audio e3002 Multi-Pattern Condenser Microphone side-address, large-diaphragm, externally-biased, multipattern, transformerless, condenser, hpf, equitek
	CAD Audio e1002 Supercardioid Condenser Microphone side-address, electret, transformerless, condenser, hpf, opa2107, equitek