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active bass into passive input

Discussion in 'Amps and Cabs [BG]' started by flamer, Jan 20, 2003.

  1. flamer


    Oct 18, 2002
    swindon, england
    Thought i'd get all my questions in whilst i have access to a computer that actually lets me post!

    I have just got an ashdown abm500 amp, is it ok to put an active bass through the passive input?
    The output on my rbx seems extremely similar to that of my passive precision and doesn't seem to register too well through the active input.

    just wanted to check i wouldn't damage anything if i did this.

    hope this makes sense!
  2. Petebass


    Dec 22, 2002
    QLD Australia
    Should be ok provided you watch for clipping. The only difference between the "Active" and "Passive" inputs on most amps is that the "Active" input is padded to compensate for the hotter output of the active bass. For some reason they seem to pad it at 20db but I reckon 5db would be enough. That's why a lot of people do what you're suggesting and plug the active bass into the passive input, but ride the gain control to avoid clipping.
  3. amper


    Dec 4, 2002
    Actually, the amount of padding seems to depend on the unit. I have one amp that pads -6dB and one that pads -14dB, although I have seen many that pad -20dB. Also, there are some I've seen that pad even more (like mic preamps)--up to -40dB or more.

    But the bottom line is, go ahead and plug it in. In fact, SWR even recommends that you use the passive input on the 'Stella, even going so far as to label it a passive/active input. The only reason to use the active input is if you're distorting too much when using the "passive" input. Otherwise, you're just throwing away gain and/or adding another attenuation stage to your signal path.