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Why bother with actives on a bass.

Discussion in 'Pickups & Electronics [BG]' started by Rockin John, Apr 26, 2001.

  1. Having just read Fleabass89's thread, " Can you put active pickups on a passive bass." I thought I'd get some opinion on the question of, 'Why bother with actives at all?'

    Having built basses with passive pups + active EQs and add-on actives for passive pup basses I am, in retrospect, not sure why actives are necessary at all. As a (quite mediocre) bass player, I feel I can get a fair tonal range from my Squier P + very old HH combo: as much tonal range as I need at any rate.

    Bassists normally pass their active EQ bass into the amp which also has an active EQ of, usually, much more sophistication than the bass. So, if the bass has a passive pup, then it's signal is EQed twice. Rickbass1 mentioned that actives are often regarded as too coloured or muddy and I think the double EQing is the reason.

    Now, if the output of an active bass is fed directly into a slave amplifier rather than a normal head (say) then the basses EQ = the whole rig's EQ (my actives ran 775mV into 600 Ohms so I know it can be done!!). In that case actives are justified, I think, because the player has the tone controls at his/her fingertips. But how many players use such a set up?

    Are actives really useful...I mean, really useful...or is it more of a marketing ploy to screw a load more bucks from us bassists?

    Or am I totally missing the point?

    Rockin John
  2. I prefer passive basses, but I've owned active basses before, and I can think of a couple of reasons why people like active pickups and preamps. The obvious one is tone shaping. Some people like to tweak their tone a lot. Having an active preamp on your bass allows you to shape your tone at the instrument, and get closer to using your amp strictly for amplification.
    Another reason is headroom. If you have a 9V or 18V preamp on your bass, you're sending a stronger signal to your amp. Some people think active basses "cut" better.
    I like to find one tone and leave it, and I also think a good passive bass sits better in the mix, but that's just me.
  3. Rockinjc


    Dec 17, 1999
    I don't think that active basses necessarily have more useable output than passive basses. My hotrod P-Bass is totally passive and puts out enough juice with the volume knobs wide open to overdrive most any bass amp. My J-Bass drives hard enough with no battery. I own a P-Bass with 18 Volt EMGs in it and it does sound nice, but you have to unplug it to keep the batteries from wasting away, same goes for my chandler baritone guitar.

    There are enough passive pickup options to get all kinds of tones. Especially if you know how to use your fingers, the best tone devices of all. I say if a bass gets a decent sound, let it be and keep the fingers on the strings instead of the knobs. It gets the job done just as well.

  4. Very interesting thus far.

    Not sure I agree with you, Dave, on the headroom matter. Having available headroom does not in itself achieve anything because the amp (head, combo, etc) only has a certain sensitivity. That is, X mVolts in = X Watts out. Above that, plus a bit perhaps, the amp overdrives anyway so, unless the player specifically wants that sound, all the headroom is potentially wasted.

    The business of amplyfying certain parts of the bass' signal with active EQs will produce quite high voltage swings so there, headroom is needed. But they can be turned down with the volume pot, anyway.

    What a shame, JC, that your P doesn't have jack-in switching. On the 18 Volt basses I built (many moons ago) I used switching jack sockets so that the batts were totally disconneceted when the jack was out of the bass.

    Passive basses seem to rule so far, and I agree with that.

  5. John, I was thinking that if you send a stronger signal to the amp, then you don't have to turn the amp up as far, and you're getting more of the sound of the bass. But, I'm probably wrong. There must be a reason people go for 18V preamps in their basses.
    I'm a passive bass guy, anyway.
    Rockinjc is right.. a lot of passive pickups are very hot. When I turn my Reverend Rumblefish all the way up, I have to back way off the gain on my amp to avoid clipping.
  6. Hi Dave.

    Yeh, the reason for 18 Volts is quite simple, really.

    First off, 9 Volts isn't really enough for reasons I'll explain soon. As 9V batteries are physically quite small that's really the only alternative for the next step up in voltage: use 2, 9 Volt batts.

    9 Volts isn't enough because of the characteristics of most of the common op-amps (the amplifier chips) used in the actives. They won't allow output voltages to swing within about 1.5 volts of both the supply rails depending on type, etc [an oversimplification]. A 9 volt batt would usually be set up to supply the actives with + and -4.5 volts. Subtracting 1.5V from each 4.5V gives a max voltage swing of + and - 3 Volts = 6 Volts. And that's when the battery's brand new.

    Consider, then, actives that amplify a 1 Volt bass note by x10: 1 Volt peak to peak is easily obtainable from a passive pup. The required output would be 1x10=10Volts. But we've only got a maximum of 6 Volts. Result= gross distortion. The situation becomes much worse when the batt wears down, of course.

    As you can perhaps see, an 18 Volt supply (+ and - 9 Volts) will easily accomodate our theoretical 10 Volt signal. The sum here gives 15 Volts available: (9-1.5)x2=15. The batt voltage can fall to about 6.5 Volts each before the 10 Volt signal becomes a problem again: (6.5x2)-(1.5x2)=10.

    Does that explain it, Dave, or have I just confused you further.

    Best regards.

  7. To quote Chevy Chase as President Gerald Ford: "I was told there would be no math!"
    Seriously, John, I understand what you're saying. I like my passive basses.. I figure, I've got a tube preamp built into my amp, and 12 bands of EQ, plus Bass, Treble and the Aural Enhancer if I need it.
  8. rickbass

    rickbass Supporting Member

    John - if I may add a little more confusion ;) you might also add "when the battery's brand new... AND is a premium brand." 9 volt batteries are actually like six 1.6 batteries (approx.) linked to together. The mumbo jumbo that "links" these batteries is one reason why premium brands command premium prices. As I understand it, their output is truer and they don't decline in perfomance so markedly over time.

    Bottomline, using cheap batteries is pennywise and pound foolish.

    I'm getting ready to send in some details on a custom on which I have spec'd a 27V system. I'll see what the luthier has to say about that, (but I have details on how it's done). It may not work out, because as on one of my basses with a push/pull volume control for active/passive, the active mode is simply too hot for some uses.
  9. Good morning Rickbass1. My reply takes the thing a shade off thread, but what the heck....(only kidding, Moderator).

    You are quite right. The quality of the battery is important for the best performance. I was assuming the use of Alkaline batteries at least. Zinc carbon and zinc chloride types would not, I suggest, be suitable.

    Battery technology is complex: well above my understanding. But manufacturers will usually supply data books which usually contain discharge curves. I've usually used alkaline types and found them fine. They lasted months of occasional use with my design of onboard actives. Doubtless anyone who gigs regularly would (should?) replace batts before each gig - and carry a spare set with them!!

    Lithium Manganese Dioxide batts have a very flat discharge curve. If you could afford those (approx £8 to £9 each) then they're better still.

    Many amp chips these days run at very low currents and a good onboard active designs will use such devices for obvious reasons. Also, these days, many types of amp chips will swing to within a few milivolts of each supply rail thus allowing a much greater swing (almost the entire batt voltage).

    27 Volts, Rickbass1. Goodness me. You should have absolutely no problem with that provided you've got room for three batteries. Electronically, most amp chips will stand 30 Volts across them so there shouldn't be a problem there. If the luthier uses chips that only need a single supply voltage it will simplify the on - off switching. If he uses dual supply chips then why not consider Doing what I did? I got hold of double pole changeover switching jack sockets and wired the + and - rails through that: jack plug inserted = batts connecteded; jack removed = batts disconnected. I felt I couldn't trust myself to remember to switch the darned thing off!!!!

    Hope that helps.

  10. rickbass

    rickbass Supporting Member

    rockin - What can I say? It's the American way, faster, bigger, louder, let's see how fast this sumbitch can go!!!!

    I know I have to check with the pup manufacturer to make sure theirs can handle 27V and not fry the preamp. Plus, the body will have to be larger so I don't end up with a hollowed-out shell.

    The name of this particular game is transient response. More power = more headroom, more headroom = a signal not peaking out easily.

    In the end result, on basses I've read about where it's been tried, they report more crispness, more snap, better low end "bloom." I have basses with the fuller, rounder, tone. This should be different.

    I imagine the difference isn't as significant as the step up to 18V from 9V, (law of diminishing returns, AGAIN, :rolleyes: , like wattage and decibels). But I can easily remember when a lot of people thought 9V was the end of the story.

    Thanks for the info about amp chips. I printed it off to mention to the builder.

    Bottomline, I'm not going to have it done just because more is better. I'll always take a single pickup, simple bass with one great tone than some multiple-pickup job with 25 mediocre tones.
  11. Tsal


    Jan 28, 2000
    Finland, EU
    I can see where this is going. Soon, we'll have something like large cellphone batteries installed onboard with a small hole next to controls for recharging plug.

    Well, that would eventually come cheaper than buying a set of 9Vs every month.
  12. rickbass

    rickbass Supporting Member

    Shoot, Tsal, now you've got me thinking...that car of mine doesn't really need that battery while it's parked in the driveway, does it? ;)
  13. Any way one could make an adaptor and plug a bass into the wall? 120 Volts good enough?! :D
  14. Damn, Tsal, that's a good idea!! Maybe we could even build a cell phone into the bass for quickly setting up gigs.


    Though the cell-bettery idea does have merrit.

    Rock on
  15. isn't the Lightwave system powered by something approaching that?

    Jonas Hellborg's old Status signature bass had four battery, 36v actives. he said that lower voltage circuits don't allow the effect of "digging in" on a passive bass (presumably meaning unwanted compression of the signal).

    I'm not really a fan of active circuitry- I like high mids in my bass sound, and active circuitry tends to emphasise the lows and highs.
  16. Well folks.

    Interesting. You're perhaps right, Rickbass1. Us Brits, you see, tend to be a touch more conservative in life. However, as the other guys on this thread kinda like hiking the voltage, over this side of the pond, we can plug into a whopping 230 Volts (LOL). Oh, Gawd, hope nobody takes that seriously. DON'T DO IT FOLKS.....ONLY KIDDING.

    Rickbass1, I used (the now old) Texas Instruments' chips, TLO64 / '074 in Quad packages. Only about 600 microamps /amplifier. I had about 12 individual amps onboard giving a total current of about 7ish milliamps: not a great deal, eh, for alkaline cells @18 volts. Admittedly my design is at least 12 years old now.

    Can't see the prob with 27 Volts and the pups. Assuming the pups are passive, just put a capacitor in series. But you knew that anyway.

    Best regards.

  17. Nino Valenti

    Nino Valenti Supporting Member Commercial User

    Feb 2, 2001
    Staten Island NYC
    Builder: Valenti Basses
    Why have a bass w/passive pick-ups?

    Mast of my basses are active, most w/EMG 18V electronics. I love it. I have a 79 P-bass w/passive Duncan 1/4lb P/J's. Sounds great!!!! Every bass is going to have a different setting on an amp to get a desiralbe sound. So to say you're EQing your EQ all depends on how your using your EQ. (Try saying that 10 times fast) At this point in my life I'm happy w/EMG's & heavy Spector basses. MAybe in a few years I'll start playing something lighter & passive.
  18. mchildree

    mchildree Supporting Member

    Sep 4, 2000
    Add me to the list of players who prefers the sound of passives. If I had to keep just one bass and sell the rest, I'd retain my Lakland with the 3-band Bart setup just because it offers the most versatility (versatility that I rarely need, but it's nice to have). I play my passive bass most of the time, though, in situations where I can "set it and forget it".

    Funny...I've always had a bass with active eq so that I can adjust easily and get it "just right" in the mix. As Dave said, though....passive basses just usually do that anyway, without the tweaking. I'm not crazy about the noise sometimes, though.
  19. Err, Rickbass1, sorry. I quoted the wrong numbers for the Texas amp chips.

    The correct numbers are:

    TLO61 for single chips and TLO64 for quads.


  20. Mike.. I'm sure you know this, but DiMarzio, among others, makes some nice humbucking J pickups that eliminate noise altogether. I've got an Ultra Jazz in my Carl Thompson, and a set of DP123s in my MIM Jazz.. they're great. And silent!

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