Is the Marantz powered with a two prong AC to DC power supply, or is it also grounded? It might be worth trying to ground the Marantz recorder housing to house ground. I had a similar problem with a home stereo system and the 21c OldBird flowerpot mic. Grounded the stereo to house ground and the 60Hz noise vanished. Just a thought and worth a try...
Good luck!! Sincerely, Chris T-H Sent from my iPhone On Sep 19, 2018, at 19:14, Wim van Dam <wim.van....@gmail.com<mailto:wim.van....@gmail.com>> wrote: [I'm not sure if this newsgroup is still alive, but here goes.] This week I finally installed my OldBird 21c microphone and I'm having some noise issues. In my setting I use a Marantz solid state recorder for my recordings. When I power this recorder with its standard AA batteries, things are fine but it does not allow me to record for more than a few hours. When I use AC power for the recorder instead, a lot of noise shows up at 1500Hz, 1620Hz, 1740Hz, 1860Hz, etc. Likely this has to do with the fact that the recorder and the OB21c microphone use the same AC outlet. What is the best solution to this problem? Thanks Wim van Dam Solvang, CA, USA -- NFC-L List Info: Welcome and Basics<http://www.northeastbirding.com/NFC_WELCOME> Rules and Information<http://www.northeastbirding.com/NFC_RULES> Subscribe, Configuration and Leave<http://www.northeastbirding.com/NFC-L_SubscribeConfigurationLeave.htm> Archives: The Mail Archive<http://www.mail-archive.com/nfc-l@cornell.edu/maillist.html> Surfbirds<http://www.surfbirds.com/birdingmail/Group/NFC-L> Birding.ABA.Org<http://birding.aba.org/maillist/NFC> Please submit your observations to eBird<http://ebird.org/content/ebird/>! -- -- NFC-L List Info: Welcome and Basics � http://www.northeastbirding.com/NFC_WELCOME Rules and Information � http://www.northeastbirding.com/NFC_RULES Subscribe, Configuration and Leave � http://www.northeastbirding.com/NFC-L_SubscribeConfigurationLeave.htm Archives: The Mail Archive � http://www.mail-archive.com/nfc-l@cornell.edu/maillist.html Surfbirds � http://www.surfbirds.com/birdingmail/Group/NFC-L Birding.ABA.Org � http://birding.aba.org/maillist/NFC Please submit your observations to eBird! ��http://ebird.org/content/ebird/ --
