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DI box necessary with active bass?

Discussion in 'Recording Gear and Equipment [BG]' started by suicas, Apr 19, 2004.


  1. suicas

    suicas

    Mar 12, 2004
    UK
    Title pretty much says it all, but is a DI box necessary for recording bass to PC if the bass has active pickups?

    In addition, will running the bass directly through some effects pedals have the same effect as running it through a DI box?
     
  2. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    The issue here is the strength of the signal. Generally speaking a bass, active or passive, won't have a strong enough output to send a decent strength signal to the recording software. You need some sort of pre-amp to boost the signal's voltage. Some soundcards have the pre-amp built in nowdays, but most don't, so you'll need a pre-amp somewhere in the signal chain.

    A standard DI won't boost your signal . A DI will split the signal in 2 so you can send an unbalanced line to your amp and a balanced line to the desk. Balanced signals maintain their strength over long distances but they don't necessarily get any stronger. Ideally you'd need a DI like a Countryman, Sansamp, or MRX which has a preamp section as well.

    Effects can sometimes make do as pre-amps. I did a recording las night using only a bass and a graphic EQ, then straight into the PC (I was too lazy to go downstairs and set it all up properly). It wasn't great but it worked.
     
  3. I would not disagree with Petebass' comments on signal levels, but the other issue is impedance matching, and an active bass is much easier to work with than a passive.

    A passive bass needs to feed into a hi-Z circuit, otherwise the impedance mismatch will act like a treble cut. A standard DI is a passive device (a transformer) and is not hi-Z. An active bass, an active DI, or a pedal when it is in circuit, will all give you the hi-Z buffer that you need betweeen the pickup and the PC, but bear in mind that a pedal on bypass will normally not give you the buffer effect, but will still be hanging on your line, dragging down your input impedance.

    If your amp has a line out, or an effects loop, you could use that part of circuit to give you the extra gain you need.
     
  4. dTune

    dTune

    Feb 28, 2004
    Finland
    An easy way is to get the Zoom 506 (?) effects pedal. It has a built-in preamp and a couple of useable effecs and a lot of useless stuff too. Plus it's quite cheap...

    I'm not sure if it was 506 that was meant for bass, but to my knowledge the guitar and bass Zooms don't have anything different in them. I've used a 505 (Guitar) for PC recordings, and have no complaints. Though the sound quality isn't necessarily the best imaginable, and there's a lot of buzzing, it's good for home use. Depends on the program used.

    Of course there are probably many other similar pedals that do the same thing.
     
  5. I heard that the 506/7 was quite noisy, so I went for the Zoom BFX 708. I use it more as a drum machine and tuner during practice than as an effects unit during performance, but it is quiet enough to take on-stage.
     
  6. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Mine was noisy, until I worked out that it doesn't like using a shared power supply. So now I daisy chain all my other pedals, but the Zoom gets a power supply on it's own. Problem solved.

    I honestly didn't know that. No wonder passive basses I've recorded with always sound muddy and dark.
     
  7. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Some active pickups are hotter than others. The Bartolini soapbars in my Roscoe are really hot, and the active preamp will output something like 6 volts peak to peak. That's plenty to run straight into the board, and it's a low impedance output so there shouldn't be any hum problems. I regularly run active basses straight into the board, or from the line out of a small Walter Woods head. A very few of them are too quiet to run straight through, in which case the preamp is a good idea (or if you're using a DI into the board, you're probably using the board's built-in mic pre anyway).
     
  8. Droog

    Droog

    Aug 14, 2003
    PDX
    Nobody has mention a pretty important part of a DI. Yes it does give you a balanced signal, but more importantly its a mic level signal, not instrument level. Giving you the ability to amplify your signal to line level byways of a mic pre.

    So to stir the kettle a bit more, what is the level of an active pickup. Nonsqtr says some are hotter than others and have balanced outs, but at what level? Mic, instrument, or line? I have little experiance with actives so I am not sure, but it is important to know, concerning the original question. If its a balanced mic or line level, then no DI needed, just jack into corresponding input. If its still instrument level then yeah get a DI and nock it down to to Mic level.

    Not as a rule. There are lots of active DI's out there. Countryman, Summit, Avalon etc.....
     
  9. My understanding of electronics suggests to me that a balanced pickup will only stay balanced if you connect it to a three pole (TRS jack) and feed that directly into a hi-Z balanced input. Any buffer electronics in the bass are likely to be unbalanced, but may have a balanced driver-chip on the output.

    Most mixer mic inputs are lo-Z, and most mixer balanced line inputs are only about 10-20K ohms, so in either case, you will lose top end if you plug a passive bass straight into a mixer.

    The advantage of a balanced mic level input is that it rejects hum, due to being balanced, so that you can use long signal cable lengths. If you do not need the long cable length, then dropping your signal from instrument level (~100mv) to mic level (~2mv) does not make a lot of sense. You would do better to stay unbalanced, and use a hi-Z preamp.
     
  10. Droog

    Droog

    Aug 14, 2003
    PDX
    Yeah, if you plug unbal. hi-z into a balanced line input you will loose the top end (and more), but the point of a DI is to balance and correct the impedence of your HI-Z so as to not loose the top end (or any other end for that matter). Now I have used some pretty chep DI's, that sound like crap, but a good DI (especially active ones) sound great.

    It makes sense if you would rather use a mic-preamp instead of a instrument pre-amp. Which if you are recording is fairly practical.

    Here is an idea. Next time you go to record split your bass signal two ways. Run one directly to the line input, then run the other to a DI and mic pre. Record both signals. The results should speak for them selves. If it sounds good, it is good.
     
  11. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    The application is recording bass to PC, right? So we're talking about a sound card input that's probably at +4 dBm (high line level) or -10 dBm (low line level). And I'm guessing that either way it would have an "ordinary" impedance like 10k or something.

    I agree that it wouldn't be a good idea to plug a passive bass directly in. Probably wouldn't be loud enough anyway, but if it was you'd still have impedance problems and it wouldn't sound very good.

    But most active basses have very low impedance unbalanced outputs, like somewhere around 100 ohms or so. So there wouldn't be any impedance problems plugging the bass directly into the sound card. The only issue would be whether the signal level is high enough. If your sound card has a -10 level input, it probably will be, for most active basses. With a hot one like my Roscoe, you can even go straight into a +4 input and it'll work fine, but not all active basses are that loud.

    Most people use a POD or a SABDDI or something like that, for this purpose. You could use a stompbox to amplify the signal, maybe use the "gain" control on the footpedal to provide a little boost, that would work.

    What kind of sound card is it?
     
  12. suicas

    suicas

    Mar 12, 2004
    UK
    Soundcard is a midiman delta 66 (http://www.portlandmusiccompany.com/delta66.html)
    My bass is a Dean Edge 4 with EMG HZ active pickups I believe, if that's any help.

    Soundcard has a setting to let me change the line level between +4 dBm and -10 dBm.

    Don't suppose any of you know of a good guide to get started in all this? I'd never even considered or heard of most of the things mentioned in this thread before (Hi-Z, impedance matching and the like).

    Thanks for the advice so far though!
     
  13. Sound on Sound is a good magazine on recording and PA technique/gear etc.

    If you search on 'recording bass' it comes up with things like this (one of several).
    http://www.soundonsound.com/sos/mar....htm?session=79028e6f637146966f8ed24154829c4d

    Hope it helps.
     
  14. davesisk

    davesisk

    Aug 30, 2004
    Raleigh, NC
    I'd suggest a MXR M80 or Tech21 Sansamp Bass Driver/DI. Both of these are footpedals that have have bass preamps, tube emulation circuitry, and EQ's built in. Both of these sound fantastic. I have the M80, and it sounds more like a tube preamp than the tube preamp in my SWR SM-900 head does. Go figure. :eek: You might find yourself liking it so much that you decide to run it through your live rig...it's that good. The M80, IMHO, sounds better than the Sansamp, and it's quieter and cheaper ($120). Regardless, either of these will be worlds better than a bass multiFX pedal.

    HTH,
    Dave
     
  15. setisan

    setisan

    Sep 28, 2004
    i'm currently changing the emg active pickup system in my Fender P to a passive config because i use a zoom 506 for a preamp, no need to have such a hot signal from the emgs going into yet another preamp (i like dynamic dryness in my bass sounds)