Hmm About Hum

[Samsquatch]

Will there always be a low level 120Hz hum at the speaker? If I put my ear right up the both channel speakers I hear it. Just cured up a louder left channel hum by re flowing some joints and just noticed the barely audible bit now.

Cheers

[Paul Birkeland]

Hum we generally refer to as 60Hz noise and buzz 120Hz noise.  On a Stereomour II with the DC filament upgrade and the SR driver upgrade, it's entirely possible that there still may be a little residual 120Hz noise with your ear next to your speakers, especially if they are sensitive speakers.  If you listen to a 120Hz tone and a 60hz tone separately, which are you hearing from your speakers?

[Samsquatch]

It's the 120Hz noise if I compare with an internet test tone. The speakers I have are rated at 93dB. I'll put  it down as residual and carry on. I have yet to install the SR upgrade and want to make sure the 'Mour is working spot on.

As always, thanks for the quick and knowledgeable help!

[Paul Birkeland]

The SR upgrade may knock it down a little bit.  Some noise at the speaker terminals isn't particularly surprising from a zero feed back amp, but sometimes 120Hz buzz can indicate a loose power supply cap (or two).  If you have the same amount of noise in both channels, I wouldn't sweat it.

[Deke609]

@Samsquatch - do you in fact have the DC Filament upgrade installed?  Using headphones, I never heard hum in either of my fully upgraded SII's. But I did hear a bit of hum before the DC Fil upgrade.

cheers, Derek

[Karl5150]

+1 on the DC upgrade knocking down the 120Hz buzz. (I'm as guilty as the next guy of sticking my ear right next to the driver.)
I also always had an audible hum from my diy subs, using the high-level inputs of a couple of 250W PE plate amps wired directly from the SII. At the same time as I installed the DC upgrade I brought my new speakers in. With cheaper 100W PE plate amps there is virtually no hum. Same wires, same A/C cords, and same Monster power strip. (It is plugged in to an outlet one earlier, but the same circuit as the previous incarnation) I'm going to chalk it up to the magic of DC.
Karl