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It's always a good idea to take measurements of diy speakers to look for any problems, but if you don't have a measurement microphone then a basic frequency sweep can identify really obvious problems (mainly resonances). So Yea, try both speakers, sweep the frequency (mainly low frequencies) and see if it becomes unexpectedly loud at certain frequencies.
I use this app for Android (well, normally I use REW for pc and a measurement microphone) https://play.google.com/store/apps/details?id=com.jm.android.frequencygenerator