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What microphone should i get if i want to record tuba duets and low brass ensembles? Im going to be playing pedal tones from time to time so id like a microphone that could pick that low of a frequency up and it not sound horrid. Im currently using my Samsung Galaxy S21+ so the microphone for brass music is sub-par at best.

I looked at same. Best is to contact a specialist online retailer and ask the question. Give them your situation, audio setup skills, typical venue, and your budget. They should give you some options.

more info here: viewtopic.php?p=717145#p717145

I had the privilege of discussing this question with legendary recording engineers Al Schmitt (may he rest in peace) and Elliot Scheiner. After some deep discussion on the matter, they recommended the Shure Beta 52 kick drum mic. It's big and heavy and needs to be mounted on a stand over the horn, but really has a punch and doesn't drop the low end.

If you need something to mount on the horn, another highly regarded engineer, Eric Schilling, thought I'd do well with the newer generation of Shure clip-on horn mics.

(I have no affiliation with Shure!)

Zoom H1 or H2 could be your answer, a huge improvement on a phone’s built in microphone, not too expensive and easy to use.