SWR SM400S Crossover problem

Discussion in 'Amps and Cabs [BG]' started by snoopyjc, Oct 5, 2003.

  1. Ever since I bought my SWR SM400S (basically the same as an SM500) used on eBay, the crossover hasn't worked. Here is the wierd part - if I tap the signal from the "left" and "right" line outputs, then I can clearly hear the highs in one channel and the lows in the other channel. The stereo/mono switch also determines if those line outputs contain the same signal, or the high/low split. The crossover frequency knob functions properly in the Line outputs when the switch is set to "stereo".

    Here is the strange part: on the Speaker outputs, the signal is the same (full-range) on both Left and Right - the Balance control adjusts the AMOUNT of signal, but the crossover frequency knob has no effect. Wierd, huh?

    Any clues?

  2. ihixulu

    ihixulu Supporting Member

    Mar 31, 2000
    South Shore MA
    The stereo/mono switch controls how the power amps are engaged, it has nothing to do with the crossover unit directly. If you switch it to mono it means you should use the bridged output; with the switch in stereo you use the 1/4" outputs labelled left and right.

    The proper way to use the crossover with the SM400/400S is to set the poweramps to stereo, run a cable from the hi out of the crossover to one of the stereo effect returns and the low out to the other. Now the highs are sent to one power amp and the lows to the other.

    The balance control on the 400/S is more akin to the balance control on a stereo than anything else, raising or lowering the level of one channel vs. the other. It is not an active tone control.
  3. Aha!! Well, that explains why it wasn't working!!! I've had this amp about a YEAR now, and I always thought this feature was BROKEN (based on how my Hartke worked)!

    However, this will keep me from using my tuner (with MUTE option) in the effects loop, though, because it's MONO!

    Thanks for the info!

  4. Last night before my gig, I did the "rewire" job and hooked the "Hi" preamp output to the "Left" effects return, and the "Lo" preamp output to the "Right" effects return.

    I was quite surprised, however, when the amp would NOT make a sound!!! I know there is signal on those outputs, because I use them to mix 2 channels to my ear monitors.

    The only way I could get the amp to make ANY sound was to turn the bass's volume control to "10", in which case it only made a "farting" noise!!

    Obvously, I quickly had to rewire it back where I previously had it!

    Oh well. So much for having a crossover that works!

    What the hay???

    --joe http://www.pieceofcandi.com/
  5. gnome01


    Oct 30, 2001
    Bronx NY, USA
    hmm, while were on the subject, I've noticed something funny on my SM400. The DI provides the straight, uncolored signal in direct mode that it's supposed to, but in line mode the output is extremely weak, even with the gain and master all the way up. I tried using it at a recording session, and could only get signal to the board in direct mode. This is definately not normal because most line outs on SWR amps make mixers explode!
  6. ihixulu

    ihixulu Supporting Member

    Mar 31, 2000
    South Shore MA
    Hey Snoopy Joe,

    How were your speakers hooked up? What position was the power amp assign switch set to?

    The behavior you're desribing is very strange. Maybe the amp is broken... mine certainly doesn't behave so badly.
  7. Amp was set to stereo mode.

    Left speaker output to my Eden 1x10Coaxial, and Right speaker output to my Acme subwoofer.

    Have you tried this?

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