I have only seen 8 ohm speakers in any modern radio, but it seems like I have seen some 6ohm in some old 23 channel radios. You should be safe with 8 ohm or higher, but with reduced output the higher the speaker rating.
I thought I'd share my experience. I'll say it again, I'm so impressed with the sound coming out of either the $12 or $29. Anyone looking to improve the reception of their recive should buy one. Especially if their using antiques like myself. What a terrific improvement.Hi,
Not sure where you're going, but for just an external speaker, I use this one.
Mounted it facing me under the dash and it is markedly better than the radios and cuts through road noise well!
I use a JBL two-way speaker (has woofer, tweeter, and crossover), and it will 'blow the doors off' of any speaker that is supposed to be used for radio. A fuller range speaker system like that seems to make less hash and more clear, natural, full sounding receive - IMO . . .