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Active switch equals low volume

Discussion in 'Basses [BG]' started by steve5224, Dec 3, 2012.

  1. Noob question, but I have a 4x10 swr with 750x head and whenever I plug my bass to the active side the volume is lower than if I were to place it in the passive. Why is that? I have an active ibanez 755 5 string.
  2. kander


    Feb 3, 2007
    An active bass has a preamp that boosts the strength of the signal coming out of your bass. When you plug an active bass into the passive input your signal will usually start to distort at moderate levels. This is why there is an active input: plugging your bass into this input will not cause distortion.
  3. Ewo

    Ewo a/k/a Steve Cooper Supporting Member

    Apr 2, 2008
    Huntington WV
    The active/passive thing, on the input of an amp, refers to the gain of the preamp.

    The passive input (or switch in the passive position) gives more gain in the preamp. The active input (or switch in the active position) gives less. Sometimes you'll see a switch for a pad; this works works the same as active.

    This feature matches the amp's input to the signal coming from the bass. A passive bass has a lower signal, so the preamp needs more gain. An active bass has a hotter signal, so the preamp needs less gain.

    The idea is that you want to match the preamp gain to the signal level of your bass. (Edit: for the reason kander mentioned, above.)
  4. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Yeah, the active input is usually attenuated 12 to 15 dB to avoid overdriving the input buffer or preamp in the amp.
  5. Baird6869

    Baird6869 RIP Gord Downey. A True Canadian Icon. Supporting Member

    I rarely run any bass into the active input (or have the active switch engaged).

    Rarely, a 18v bass may be hot enough to warrant this, but rarely.
  6. darkstorm


    Oct 13, 2009
    Most "active" inputs cut the signal to much imo. A good bass amps passive input can handle active basses quite well. Only the low grade ones as I call em, cant.
  7. JTE


    Mar 12, 2008
    Central Illinois, USA
    Most active bass preamps don't boost much, unless you run all the EQ at full boost. The active circuits generally are there for the additional EQ they offer and to reduce the impedance related signal degradation.

    Because most active instruments do NOT have significant additional gain compared to most passive basses, the presence or absence of an active pad is meaningless. That active input simply pads down the signal from the bass before it getsnto the first gain stage. The only reason to use the pad is if you're overdriving the input with your normal settings.

    And be clear, the passive input doesn't boost anything. The active input is generally simply resistors to cut the voltage. Don't usevit unless your typical settings cause the preamp to distort.

  8. Brad Johnson

    Brad Johnson Supporting Member

    Mar 8, 2000
    Gaithersburg, Md
    Same here. I even run my Bart NTMB equipped basses with the internal gain turned up in most passive inputs without issue.

    If the active bass is audibly overdriving the passive input, THEN try the active or padded input. That's my m.o.
  9. chadds


    Mar 18, 2000
    Use the passive input. ;);)
  10. P Town

    P Town

    Dec 7, 2011
    I have an active bass, (Fender Am Dlx P) with an 18 volt upply, and I find that it works fine in the regular input of my Ampeg PF 500. I never use the padded input.
  11. devilman666


    Apr 23, 2011
    manchester nh
    I owed the same rig and bass . Def us the passive pre gain at like 11 o clock .
  12. Basically +1, but to be a little more clear, these 'active/passive' input pads are mislabeled and therefore confusing. WAY back in the day, the early active circuits mostly had a boost baked into their voicing, so the amp manufacturers used the shorthand 'active/passive' to indicate, as you say, a hot or not hot input signal.

    These days, there are super hot overwound pickups that can put out huge, hot passive signals, and most many active circuits have no volume boost built in and/or have internal trim pots that allow you to set the active singal at parity with the passive output of the bass when bypassing the preamp.

    So, unless the OP has VERY aggressive technique, or an unusually hot output bass, there would be no reason to add the extra circuitry and gain reduction of an 'active' switch or input with any bass.
  13. Ric5

    Ric5 Supporting Member Commercial User

    Jan 29, 2008
    I convert 4 string Rickenbackers to 5 string basses.
    It is designed that way for really hot preamps so the amp won't distort.

    I play active basses and I plug into the passive input.
  14. Again, just to be clear, those active inputs are designed for extremely hot basses, passive or active. The only two instruments I've ever had to use the 'active' input/pad position with were the passive Reverend basses, and my buffered Rob Allen piezo loaded instrument (active) which both put out HUGE signals to the preamp.

    The key here is that in the very rare occasions where you have to turn the gain control so low on the preamp that it is hard to adjust, and/or the input clip light continues to light at very low gain settings, the 'active' (or on some amps, the -10db or -15db switch) will help. For the other 99% of situations, the passive input will actually sound a bit more open, due to that one less capacitor or whatever hitting your signal.
  15. I have only active basses, and switch between using my active/passive switch. I was told not to use it, to run everything as passive, which did make it louder, but I noticed that produced a lot of hiss from the amp, similar to a high gain guitar. That's not what I wanted, so I used the pad, and the hiss was gone. On another bass, however, I use the passive setting because it's a relatively quiet bass compared to my other two. It needs the passive circuitry to keep volume. It doesn't hiss, and I don't have to radically change my EQ or gain staging to get the sound I like.

    So overall, I'd say try both. If one sounds off, use the other. My gut tells me that when I replace the preamp on my "quiet" bass, it'll no longer be quiet and I'll use the active pad on all basses. Only time will tell.
  16. Wallace320

    Wallace320 Commercial User

    Mar 19, 2012
    Milan, Italy
    I play mostly passive basses, or active/passive in passive mode
    But then again I hit very hard and my pedalboard (and head equalizer) work to let me through a dual active downtuned seven string guitar attack, so I play at no more than 9 o'clock for both volume and gain, and still I can clip: I'm sometimes forced to switch the active filter on even when playin' passive

    When I play active only basses (Peavey Cirrus, Ibanez ATK) I surely use the active pad
    And if I can, more volume than gain so that I get more bottom

  17. It's a common misconception to assume active basses have a higher output. Some do. Many don't.
    The inputs in the amp should have been labelled as "normal" and "attenuated" or something along those lines. Then you choose which one to use based on the output of your bass, not whether it's active or passive.

    I normally use the passive input, when I have a choice, and just adjust preamp gain as necessary. I don't have any bass with crazy output. Even the G&L L2000 is ok... that's my "loudest" bass... in passive mode.
  18. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    My Sadowsky Modern 5-24s are the only basses I have that are too hot to run into the passive input on most of my amps.