Active or passive input?

Discussion in 'Amps and Cabs [BG]' started by Wolle, Dec 5, 2007.

  1. Wolle

    Wolle Guest

    Dec 5, 2007
    Hello guys.
    New to this forum :)

    I have a Hartke model 3500 amp.

    What are the differences between the passive and active input?

  2. billfitzmaurice

    billfitzmaurice Guest Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Passive has higher gain for use with passive pickup instruments.
  3. Asa Samuel

    Asa Samuel Guest

    Apr 9, 2007
    Cornwall, UK.
    Active has a lower gain for use with active instruments.
  4. Purple Haze

    Purple Haze Guest

    Apr 16, 2001
    Northern Ireland
    What this guy says.

    Basically you plug passive basses into the passive input, and active basses into the active input.

    This used to confuse me when I started out too as I didnt realise that you could buy basses that took batteries!
  5. Wolle

    Wolle Guest

    Dec 5, 2007
    So would anything happen if i used my active bass in the passive input? Because my active input seems to be broken :(
  6. Active inputs are padded down so that instruments with extreme hot output levels don't overdrive the input stage of you amp. The labels 'active and passive' don't really correspond to basses with or without preamps, since some passive instruments can have much higher output levels than many active instruments.

    If general, you should always us the 'passive' input on an amp. This is the purest input to your preamp. Only use the 'active' input if you need that extra circuitry to reduce a very hot signal. Again, this has NOTHING to do with the fact that your bass may have a preamp in it or not.

    Also, many times a bass with a preamp will have a trim pot inside the cavity to adjust the output. It's always better to adjust the output of these types of circuits so that they optimally drive the passive input rather than setting them so hot that you have to use the active input.
  7. Wolle

    Wolle Guest

    Dec 5, 2007
    What is a hot output level or a hot signal?
  8. It's the level of signal that actually comes out of the jack of your bass guitar. If you ever have the chance to compare a few different basses, if you plug each one into an amp and keep the amp's gain and volume control the same, you will notice that some basses are louder than others. This is because the actual signal coming out of various basses is either stronger or weaker, depending on the pickup design, and, if it's a bass with a preamp (i.e., a bass that uses a battery operated preamp that is built into the bass), how 'hot' the preamp is set.

    Sometimes, a bass's output (whether passive or with preamp) is so hot (i.e., strong) that it can actually overwhelm the input circuitry of your amp, causing distortion even at very low volumes, since it is actually distorting your system very early in the signal chain... at the input to the amp. In these VERY rare situations where the volume coming out of the bass is so strong, many amps have a secondary input, many times called 'active' that will apply a capacitor (or something of the sort) to actually reduce the output of the bass before it enters your amp.

    Again, it would be very unusual to have to use the active input. It won't hurt anything if you do, but the signal from your bass will be weakened and will pass through additional circuitry that you really don't need.

    No harm at all will come from using either type of input... it's just a matter of getting the optimal clean signal to the amp. In your case, my guess is you should be using the passive input anyway.

    Hope that makes sense.

    Edit: I really wish manufacturers would stop using the 'active' and 'passive' labels for these inputs... very misleading and confusing.
  9. Jeff A

    Jeff A

    Oct 22, 2005
    Well said.

    I have yet to play on an active bass that required me to use the "active" input.
  10. Wolle

    Wolle Guest

    Dec 5, 2007
    Wow nice answer :) I think i understand it now. But why isnt all basses then passive?
  11. I'm not sure what you are asking here? I'll try to answer if you clarify:)
  12. Wolle

    Wolle Guest

    Dec 5, 2007
    If you in almost every case should use the passive input anyways, why do some basses has a 9v battery inside?
  13. Ah.. this is the 'confusion' I was talking about in the 'edit' to my last post.

    The 'passive' input label really doesn't have anything to do with whether there is a battery in the bass or not. I believe this is a 'left over' and out of date way of labeling these inputs.

    I assume the ORIGINAL logic of these labels was that, many years ago when basses with battery preamps started to show up, they probably did have hotter (stronger) output than the old passive Fenders that were around at the time. So, the manufacturers used 'active' and 'passive' as a kind of short hand way of describing the two different inputs.

    Today, there are passive basses (like the Reverends) that have MUCH stronger output than most active basses, and also active basses (like the FBass) that have weaker output than even the old passive basses from many years ago.

    So... the best thing to do is to really ignore the 'active/passive' labels all together. The better way to think about it is:

    Passive Input... for all basses (active or passive) with output that isn't so hot as to cause distortion with the input gain control properly set.

    Active Input... for the RARE situation where a bass, whether active or passive (i.e., battery or not) has such a strong output that your amp distorts regardless of output volume even with the input gain knob set very low.

    One more complication.... a lot of this also has to do with how hard you play (i.e., the touch you use on your strings). If you have a very, very hard touch, and also if you pluck or pick close to the neck (which pumps more low end out of your instrument), you can actually really pump a lot of output from your bass. So, even with basses that have a 'normal' output (again, the vast majority of instruments), certain very aggressive playing styles might benefit from the 'active' (or padded down) input.


    Ps Welcome to Talkbass, by the way!
  14. Wolle

    Wolle Guest

    Dec 5, 2007
    i dont really see how this answers my question. Why isnt all basses just passive? Why are some active?
  15. ehque


    Jan 8, 2006
    Tone control (EQ) is a lot easier to implement with a active circuit than with a passive one, especially when you get above 2-band.
  16. Ah... I was still answering in the context of the amp input labels relative to type of bass. Sorry.

    There are a number of advantages having to do with pickup 'loading' on passive instruments, which cause changes in tone when you use longer cables, and also per the above post, the ability to have active tone controls (bass, treble, and sometimes midrange) right on your bass so you can adjust your tone right at the instrument.

    Nothing wrong with passive basses though.. some prefer them for that little bit more mid growl and grit you get, versus the wider, more 'hi fi' type response from most active circuits. The cool thing is that most on-board active preamps have 'passive' bypass switch which allows you to take the preamp out of the signal chain... hence making the bass 'passive' again. So, you have the 'best of both worlds' with those pre's IMO.

    There are actually true 'active' pickups that require the battery and circuitry to operate (like EMG pickups), but those are relatively rare. Most 'active' basses have passive pickups (identical to passive intruments) and just 'add' a battery operated preamp between the pickups and output jack of the instrument.
  17. Brad Johnson

    Brad Johnson Inactive

    Mar 8, 2000
    Gaithersburg, Md
    DR Strings

    All basses were passive, way back when. It basically means that there's no gain stage or preamplification happening on the actual bass. Some people still prefer no preamp or extra tone shaping in their instruments so they use passive instruments (no batteries or power cord).

    Back in the 70's some builders decided to include circuitry to boost the output of the instrument "in" the instrument. that required a power source, typically batteries but in some cases external power supplies. It caught on and that's where we are today. So why aren't all basses passive? Because some people prefer active.

    My suggestion is try each bass and decide on it's merits based on the actual bass, not what type it is. Other than that, you'll been provided a lot of useful information in this thread, if you can make sense of it.
  18. Purple Haze

    Purple Haze Guest

    Apr 16, 2001
    Northern Ireland
    hmmmmm, a few interesting points there KJung.

    So are you saying that I should use the passive input at all times? Does this make any kind of noticeable difference to your sound?

    I've always used the passive input for passive basses and active for active, just from fear of blowing my amp. I use an ashdown abm and i play quite hard, and even when using the active input I can easily go into the red of the input. Yes I do adjust my gains to correct this, but I just didnt want to use the passive input incase I blew the thing up.

    Im definately gonna have a play around later 2nite to see if theres any kind of noticeable difference in the tone.
  19. You won't do any harm either way. I actually have found that the 'non padded' input does sound better, even after setting the gain to equalizethe volume when A/Bing the two inputs. The slightly hotter signal and, I assume, the fact that the signal is not passing through that 'reduction circuitry' always sounded better to me. Again, it won't change your life or anything.

    Again... it all has to do with the output level of the bass, not the existence of a preamp. There is no advantage to padding down a moderate level signal that I know of.

    IMO and IME:)
  20. Purple Haze

    Purple Haze Guest

    Apr 16, 2001
    Northern Ireland

    What your saying does actually make sense, the less things the signal goes through, the better its gonna sound.