Heads up on polarity testers and crossover slopes.

[Taxed1]

Just a heads up people. I just finished installing a new component set. I made sure it was all wired properly, positive to positive and negative to negative. I wanted to double check everything with free polarity tester app from the iOS store. The new components all tested fine but my existing subs were showing as reversed. I was stumped. I double checked everything. I can physically follow the wires out of the amp into the back of the sub. I even tried with a 9v battery & it’s wired correctly. Then I noticed that the polarity tester app sends a thump around 90-120hz. Then I realized I am using a low pass crossover of 60hz with a -24dB slope. I forgot that when using that slope the polarity switches 360 degrees at the end giving me a false reading on the tester. As soon as I dropped the slope to -12db the tester said I was good. So yeah, all that for nothing wired wrong. What’s your favorite slope?

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[Doxquzme Premium Member]

LR on midbass and tweeters, usually 24 db depending on the drivers and integration goal and the RTA once set up. For subs, usually 12, sometimes 18, sometimes 24. All of them are unique to specific setups/configurations. Open cabin or trunk? Ideally the sum of the crossover points is equal or flat, that is the goal for initial tuning. Running the drivers out of phase is not necessarily a bad thing either. 24 db is more common on the top end of the subwoofer cross inn open cabins versus maybe a 12 to 18 in a trunk, again as much environmental as anything. You could have just reversed the phase on the output via tha amplifer if the amp has that option which many do. Or, could have left the 24 db in place and reversed the speaker input wires too. So now that you have it all "in-phase", does it sound right?

 

[Taxed1]

LR on midbass and tweeters, usually 24 db depending on the drivers and integration goal and the RTA once set up. For subs, usually 12, sometimes 18, sometimes 24. All of them are unique to specific setups/configurations. Open cabin or trunk? Ideally the sum of the crossover points is equal or flat, that is the goal for initial tuning. Running the drivers out of phase is not necessarily a bad thing either. 24 db is more common on the top end of the subwoofer cross inn open cabins versus maybe a 12 to 18 in a trunk, again as much environmental as anything. You could have just reversed the phase on the output via tha mpliferif the amp has that option which many do. Or, could have left the 24 db in place and reversed the speaker input wires too. So now that you have it all "in-phase", does it sound right?

Thanks for the input. I run the subs in the trunk in a sedan. Sealed off from trunk, subs facing into cabin. It’s an SPL build.

 

[winkychevelle 10+ year member]

12db is usually 180° out of phase if used left and right. 24db makes the full 360° phase change when running left and right.

This is mathematically at least. Differences in distance from the listener and reflections mess with the reader

When using the handheld polarity testers you're only supposed to check the speakers one at a time and you don't even need crossovers to do so.