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Two SWR SM-400S questions

Discussion in 'Amps and Cabs [BG]' started by tornadobass, Mar 28, 2004.

  1. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    I'm bringing out my SWR SM-400S amp after a few months and had a couple of questions:

    * Once the fan comes on, it stays on for quite awhile. I just finished playing the amp until the fan switched on (bridge mode into 8 ohm
    Goliath II cab). It took 11 minutes...no playing during that time...until the fan went off. The amp is in a rack and it has one full open space above the amp. Is this usual? I'm wondering in part because the fan sensor went bad last fall and I had it replaced...want to be sure it's working right.

    * The amp requires quite a bit of gain before the clip light starts to flash. With moderate EQ and enhancer at 1 o'clock, I need to turn up the gain to about 3 o'clock with my Jazz bass pickups full on before the light flashes at my usual playing level. Is this where you're setting the gain for passive instruments?

    Thanks for your ideas...it's a nice amp, but these two things seemed a bit unusual.
  2. from my experience the sm 400s preamps tend to take alot of input before they clip. As for as the fan my 350x fan stays on for a while :p
  3. atldeadhead


    Jun 17, 2002
    On my SM500, which is pretty much a 400s, once my fan comes on it does not go off until I turn off the amp. Other than the fan being a touch on the noisy side, I don't think it will hurt anything by remaining on.
  4. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Thanks to both of you...it sounds like everything's as it should be. I'll look forward to the amp returning to a life of gigging.
  5. Joe BassPlayer

    Joe BassPlayer Supporting Member

    Aug 18, 2002
    Everything sounds normal to me. I've owned 1 SM-400 and 2 SM-400s amps. The 400s that I currently own had a bias problem when I purchased it (new) and the Fan stayed on all of the time. Typically if once the fan comes on it never shuts off (after idling for several minutes) the amp probably needs the bias adjusted. You can check this by turning on the amp (with no input), if after several minutes the front panel gets extremely hot (and typically the fan would come on) you have a bias problem.
    Sounds like your fan eventually turns off. No need to worry.
    Also, what you described when setting the input sensitvity is normal.
  6. on my sm-400 i can crank the gain up really high until it starts to clip, swr kicks ass.

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