elk 45 siren making suming sound when on stand by


I have an elk-45 siren connected to my elk m1 board on the out 2 connector. I also have an elk73 speaker connected to out 1 connector. The 45 siren makes wining sound when on standby, is this normal?
I also have an elk-71 echo siren, where do I connect this one since out 1 and out 2 is used?
I think the out 2 just support 1 amp and the elk 45 draw 1.2 by alone.
Try just one of the 2200's that comes with the panel for the regular zone supervision - I'm almost positive that's what I have on mine right now.  The supervisory voltage is enough to cause a low siren sound.
I too am experiencing a high pitched humming noise from the ELF-150RT SIREN I just installed on output 2 (programmed for voltage out).  It's a continuous high pitched sound (low volume) that is heard.   Does this indicate a flaw with the siren, miswiring, or are you saying this can be remedied with resistors?  I did a search on resistors and sirens, and the threads that came up were unrelated to this problem. 
This is due to the supervisory voltage on that output - the resistor will solve it without hurting anything.  Put the resister between the + and - while keeping the siren hooked up properly.
Here's a 6yr old thread I was pointed to that has the official Elk answer in it too (Spanky):
I will say that after I played with the siren originally installed in my house, I decided I wanted to go with a speaker instead - it may not sounds like much, but I like that it fixes this issue, while also allowing the indoor and outdoor siren to be in sync (the inside one will cut out to make voice announcements too, then go back to the siren) - it makes the siren clearer and less jumbled.
Thanks, I finally found the thread.  I will try the resistors, and then based on the result determine which way I should go.  I appreciate the help!
After rethinking this issue, placing a resistor across the terminals eliminates the supervision of the siren.  Consequently if it's later disconnected - the control wouldn't inform me of this, and would eliminate a critical safety feature. So either I live with a humm, or install a speaker instead.  From everything I've read, the speaker sounds like a better way to go.  Thanks for your help on this issue.
Did you test this?
Also, I'm pretty sure I connected some piezo screamers to Output 2 without a resistor and did not get any hum, maybe that would be another option?
I haven't played with any of this stuff in a few years and my mind is a bit rusty on this subject! :)
Oh yeah,  I tested your solution- and you were right :excl:   With  one resistor the hum was barely audible.  And as I was placing the resistor across the terminals, I realized that if one of the wires to the siren was cut, the resistor would make it undetectible to the control.  I think I will try a piezo - thanks for the suggestion.  I didn't detect any rust - and again, I really appreciate your help! :)  -Thanks again.
I think if the wires were cut and the resistor were present it'd still present as a trouble at the panel, but I haven't tested to be absolute.