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Additional Products & Services


Old Bird 21c upgrade (from pre-2017 model to pre-July-2020 model) - $100 USD

(replace bucket, interior base, pyramid & mic element - includes replacement of plastic & cloth covers)


Old Bird 21c check up and maintenance - $25 USD

(test mic & cables; replace plastic and cloth covers)


Acrylic pyramid with mounted microphone element - $40 USD

(useful to have in reserve for quick replacement/repair of damaged mic element)


Replacement microphone element with leads for Old Bird 21c (pre-July-2020 model) - $25 USD

(the Knowles EK23132 microphone element that has previously used been used in the 21c mic is out of production. We have a limited stock still available. We recommend the PUI AOM-5024L-HD-R, which requires a additional 2.2 k metal foil resistor and a 0.1 uF ceramic capacitor, as a replacement - this mic element is similar to the Knowles, perhaps with a bit better signal-to-noise ratio)


Knowles EK23029 microphone element with leads - $25 USD

(limited supply available; for 2000-2020 DIY mic design)



Contact Bill at ear2sky at oldbird dot org to make purchase and shipping arrangements.

Payment can be made via personal check or PayPal.