Marty Mcfly

While playing "Johnny B. Goode" at the Enchantment Under the Sea dance, Marty sings into an American Microphone Company DR 330. This is clearly visible in the video below:

https://youtu.be/S1i5coU-0_Q?t=54

Compare with the link here: http://www.coutant.org/american/

Note that the DR 330 is visibly indistinguishable from the R 331 and DR 332. The only difference between these mics is polar pattern. The DR 330 was switchable, the R 331 was bi-directional only, and the DR 332 was cardiod only. Since Marty is using this mic on-stage, we can assume it is either a DR 330 switched to cardiod, or a DR 332. Since Marvin Berry's band had the Cadillac of guitars, along with a real Cadillac (in which Marty was locked in the trunk), we can assume they would have the Cadillac of American Microphone Company mics, which was the DR 330. Conjecture? Maybe.

American Microphone Company was also based in Pasadena, California, making it readily available in Hill Valley, CA. A spec sheet for this family of mics from countant.org is dated 11/15/50. Thus, it is period correct for the 1955 dance, unlike Marty's ES-345 guitar.