Converting 9v to 18v

Discussion in 'Pickups & Electronics [BG]' started by BassicRob, Aug 5, 2001.

  1. BassicRob


    Mar 28, 2001
    Massapequa, NY
    I know i've seen this on here before, but can't seem to find it. When converting the active electronics from 9v to 18v, all that is required is soldering another 9v connector to the board, right? This can be done without damaging the electronics? I was thinking about doing this to my Spector NS5cr because it seems like a simple upgrade.Is this correct, or are more mods needed?
  2. rickbass

    rickbass Supporting Member

    I was looking at going from 18V to 27V and the article I saw about it mentions all you have to do for either conversion is, "the modification for the voltage step-up is simple: just connect an extra battery harness in series with the one already in the system.....find the battery harness' negative wire (black) and unsolder it from the output jack."

    "Next, connect it to the positive, (red or white) wire of the added harness and solder the negative wire of the new harness back on the respective output-jack lug....". Plug your batteries back in and you're in business.

    Of course, this is all done unplugged and assumes you have room routed for the added battery. And a guy at Guitar Villa mentioned the above procedure wasn't quite the case for a 27V system.
  3. Bob Gollihur

    Bob Gollihur

    Mar 22, 2000
    New Joisey Shore
    Big Cheese Emeritus: Gollihur Music
    My son put up a page explaining how to do the 9v to 18v upgrade. You can even do it using an extra battery connector so you don't have to modify the bass' electronics.

    However, not all are capable of handling the 18v upgrade, which can potentially be fatal to some preamps.
  4. The difficulty is, making sure you get the Zero Volts (0V) connection correct when adding the extra battery.

    Single battery systems usually artifically create the 0V rail to bias the amp chips. That's usually arranged to be half the battery voltage @ whatever it's state of charge. That means, as far as the chips are concerned, they're running @ + and - 4.5 volts @ full battery voltage = 9 Volts total. This 0V point is usually connected directly to signal ground: that is the shield of the guitar lead, the bridge, the strings, etc.

    Two battery systems usually use 0V rail as the connection point of the two batteries. From the chips' perspective that's + and - 9 Volts = 18 volts total @ full batts voltage. This 0V point is connected likewise to the previous case.

    Rick's 3 battery system is more likely to be arranged as per a 1 battery system than a 2 battery system.

    Depending on the actives' design you might or might not be able to simply solder the two batteries' connection point to the signal ground. Well, of course you can always do it, but the trick is to do it without generating loads of smoke from the chips!!!

    Another difficulty with adding an extra battery is that you've got to switch it - well, them both , of course - when removing the jack from the bass. That's more difficult than it sounds if you want it done automatically: if you've an on/off switch on the bass for the purpose, then it's likely to be somewhat easier.

    You also need to figure whether or not the chips can handle the extra potential across them. Frankly, these days, that's really not likely to be a problem.

    Finally, I suggest having a word with an electronics man if you can. It might just save you an expensive bill if it all goes wrong.

    Hope that helps.

    Rockin John
  5. rickbass

    rickbass Supporting Member

    Just to let you know - I think I may have to save the 27V system for another bass. If I understand correctly, (and that's a real, "if"), the Basslines MM pickup and the Bartolini soapbar I've bought for the luthier to put on the bass are an active and a passive pickup, respectively.

    I was originally going all Bartolini, which at first glance, didn't seem to be a problem. Guitar Villa said that because both Bartolini pickups are passive, 27V shouldn't cause any problems. So, I infer from that statement, actives ARE a problem.

    Moreover, I originally was going to use a Bartolini NTMB preamp and I guess this was another snag. They said the preamp's IC's (??) have a +9V and a -9V supply and the voltages have to be equal but opposite polarity or else the output is "highly distorted." And Bart doesn't guarantee or warranty their products if the supply voltage the specify is exceeded.

    After 3 months, this bass still isn't ready for the saw due, (now), to wood hassles. :rolleyes: So, I don't want to delay it even more by spec'ing a component mismatch.
  6. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    The first part is true, to get 18V you simply add a second battery in series.

    The second part really depends on the circuit. All EMG circuits are designed to handle 18V, but I'm sure plenty of active systems out there will smoke if you run them at 18V.

    Check with the manufacturer before you do anything.
  7. BassicRob


    Mar 28, 2001
    Massapequa, NY
    Thanks for the input, you may have saved me a few bucks :)

    But I did some research and this is what i found. This was taken from EMG's website regarding the Active EQ:
    "All the BT family circuits come prewired for easy installation and includes all required hardware including a matched set of black knobs. The systems are set up for 9V operation off a single battery (including pickups) but can be optionally operated with 18V for additional clean headroom." (

    And they say all their p/u's can handle up to 27v, but 18v is maximum recommended voltage.

    However, I don't recall offhand exactly what Spector uses, only that the p/u's are EMG-45DCs. I am assuming the EQ is the BT model because it only has the 2 bands, bass and tone. Then I saw the sweepable mids module, and I love my mids. But now I am getting in over my head :)

    I am going to take a close look at the board when I can and see what happens.

    BTW - Where's Nino or RAM? Haven't they done this before?? At least they can sacrifice one of their many Spectors and still have another to fall back on :p
  8. Rick.

    I'll think on this. Just returned from a week @ coast so haven't got electronics head on yet.

  9. rickbass

    rickbass Supporting Member

    Thanks, John. To me, a custom is the only real opportunity to experiment, so I thought, "Let's see if 27V rocks any harder, escpecially in the studio."

    I remember when no one was thiniking more than 9V and when you would have been locked away if you ever suggested a 10" speaker for bass. And look what happened there. But time may prove an 18V may be all that's really needed.
  10. I've heard that cheaper pre-amps get detroyed by doing this. I have a Yamaha RBX765 and was wondering if this mod would damage my bass.
  11. oddentity

    oddentity Supporting Member

    Nov 20, 2000
    Rick, weren't you after Lane Poors for your DP a while back?

    There's a set of soapbars on eBay right now...
  12. Hi Rick.

    OK. Here goes.

    First off, I'm @ a real disadvantage because I know[U[absolutely nothing[U\]about the workings or circuits of either add-on preamps or active pups.

    However, I can offer what is just one possible circuit that could be used to generate the + and - 9 Volts that the pups want, from the 27 Volt battery voltage that you've got for the actives.
  13. Shoot.

    That last post wasn't really supposed to have happened like that. Let's hope it works a bit better this time.

    I was going to attach a circuit diagram, too.

    If it's actually readable then I suggest you ask the pup and active people whether they think it'd be OK with their circuit. If so the you might like to consider having it built and fitting it to your bass. If you can't get it built then I'll build it for you and mail it to US.

  14. Double shoot.

    Still no circuit.

    Hmmmmmmmmmmmm m m m m m m m
  15. You see, guys, this is a classic case of me opening my mouth before engaging my brain........(and that's irrespective of the missing circuit diagram)!

    So I reckon I'll start over, as they say.

    Rick, from a signal point of view it would be absolutely pointless running active pups into (say) a 27 Volt preamp, if headroom is the main reason for wanting to do it. I guess, therefore, from that perspective, Guitar Villa are partially correct in what they say. The actives in the pup would clip the signal before the active preamp so making the extra voltage headroom totally wasted. If you had to go active and passive, I'd put the active nearer the bridge because the output will be lower because string excursion is smaller and the passive nearer the neck for opposite reasons.

    Good passive pups with a 27 Volt preamp might well sound superb, provided it's gain isn't that high. Bear in mind, though, that the circuits in the head (or whatever) are likely to clip the signal unless they're supplied with @ least 27 Volts. Preamp chips - yes, ICs - in a solid state head might be run on + and - 15 Volts and a good tube head would have correspondingly high preamp voltages.

    I've probably gotten thing wrong about + and - 9 Volts and 27 Volts but I'll still post the circuit if I can find out how to do it. Somebody might be able to make use of it.

    Generally speaking, ICs like to have their outputs set up (biased) to about half supply voltage. That way you get the best possible voltage swing from them. If the output's set up to be nearer one supply rail or the other they'll distort (clip the signal) more quickly so there's, in effect, less voltage swing available. So, yes, generally speaking, equal an opposite supply rails.

    BassicRob. What you need to do is get the part numbers from the ICs on your board. If we can identify what they are there's every chance of discovering what supply voltage they'll tollerate.

  16. Has anybody ever tried this mod (18v) with the Ibanez EQB III electronics (ergodyne edb 605)? I'm not too afraid of damaging any ICs, but I'd prefer not to have any trouble at all!
  17. OK. One last shot @ posting this circuit diagram.
  18. BassicRob


    Mar 28, 2001
    Massapequa, NY
    Here's the good news. There are no IC's. Its only two circut boards on two of the pots. One has a jumper pad with two dip switches on it which leads me to wonder what thats for.

    The labeling on the boards state "EMG Inc." on one and "BT Rev-A" on the other, which confirms it is indeed the EMG BT system, which they describe as an Active Bass and Treble Module. I'm assuming then that there is no active preamp, only an active 2-band EQ, and being there are no IC's, I should not have to worry about blowing anything out.

    Am I correct in saying this? Or at least partly?
  19. phunky345


    Jun 20, 2000
    Missoula, MT
    I play a 765, too, and I was wondering the same thing. Cause the pre-amp in my Yamaha does seem kinda cheap, since it has just a 2-band eq and it makes all sorts of fuzzy noises. I wanna get a bartolini or aguilar preamp sometime.
  20. rickbass

    rickbass Supporting Member

    odd - Finally got back here! Thanks for kindly thinking of me!! You're a good man.

    I had email correspondence with that seller before the auction started when I got wind of his Poors. I'm have a 5'er built but the size of those suitcases put me off. I thought, "I doubt having too much magnet, in terms of width, would be detrimental. But it would be nice if this turns out looking like a bass with pickups, instead of, pickups with a little bass surrounding them." Especially considering the months I spent trying to find wood that was exceptional looking but subordinate to tonal considerations.