TrueAlert Help?

Today I received a Simplex 4903-9425 (4-wire, not addressable or SmartSync) TrueAlert. I was able to get the strobe working fine, but when I try to run the horn, it’s really quiet. You can see what I’m talking about in this video:

Am I doing something wrong, or is this thing just broken?

It sounds like the horn is picking up the charging circuit on the strobe. Are you sure you have the polarity correct, the NAC is functional, and you are using 24 VDC Filtered? I see you have a 4004… If you’ve checked all this, then you have a busted horn. Don’t toss it though, it’s still useful as a remote strobe.

Also, I moved this to Fire Alarm Technical.