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9, 18, & 27 Volt Onboard preamps. What's the difference?

Discussion in 'Pickups & Electronics [BG]' started by Mario Lewis, Feb 15, 2003.

  1. Mario Lewis

    Mario Lewis Supporting Member

    Jul 6, 2001
    Clinton, MD
    Is it more headroom? Quicker response time? One's better than the other?

    Your preference?

  2. hujo


    Apr 18, 2001
    Stockholm, Sweden
    It's a headroom issue... Sometimes a preamp can sound a bit muffled and maybe a wee bit distorted if you crank a couple of the controls, and adding more voltage is supposed to clean things up.
  3. chucko58


    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    IMHO: If designed properly, and powered by a fresh battery, a 9 volt preamp should have all the headroom most players ever need. Some preamps are marginal even with a good battery; a low battery will squash the sound of even the best preamp.

    An 18 volt preamp is easier to design, and offers more headroom even with low batteries - but at the expense of having to replace two batteries instead of one. And most will have shorter battery life.

    If you're plugged into the "passive" (or unlabeled) input of an amp, the headroom limit is usually the input of the amp. Even a 9 volt preamp can overdrive many amps' input stages - in fact, some high output passive pickups can do it without any help. Think about that before you crank up the gain on a preamp!

    There should be no reason a bass player should ever need more than an 18 volt preamp. If you're recording or going direct into the PA, a 27 volt preamp may have some advantages, but it's overkill if you're going through an amp first.
  4. rojo412

    rojo412 Walnut is fun! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    I put another battery into my modulus q5 with a dual P5 configuration. The difference was awesome, especially since the added cost for better headroom was about $4 and about 10 minutes of actual work (including soldering iron warmup). It now runs at 18 volts and despite having to change 2 batteries next time, I think about it this way: EMG's need a new battery about 1x every 6 months (if that). If you have 2 batteries, you spend $8 every 6 months. If someone said that you could improve the sound of your bass for $20, would you do it? I would! The added cost per year is $8 (if you use 9v and replace twice). It's the lowest price upgrade available and it works. Why WOULDN'T you do it? There are no negative problems associated with it and if you really get maxed out by spending $8 more per year, then it's easy to switch back.
  5. huh:confused:
  6. rojo412

    rojo412 Walnut is fun! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    I'm sorry! That's the only way I could describe it!

    The upgrade is easy to do yourself if you can solder. The costs:
    Battery Clip: $2 at Radio Shack (it's the thing the battery terminals attach to)
    Batteries: $8 at Medic Drug Store (2 pack of 9v Energizer Long Life)
    Labor: cut 1 wire (negative lead from existing clip to jack), strip the ends, attach new battery clip (between the 2 ends that you cut and stripped) and you now run 18v. Most guitar techs may charge about $15 for this, but it's SO EASY.
  7. I put an 18 volt pre in an old Peavey Fury .

    I don't see the problem with any active pre amps , if you buy rechargeable batteries .
  8. RevGroove

    RevGroove Commercial User

    Jul 21, 2002
    Burlington ON Canada
    Manager, Account Services: Long & McQuade Ltd. (Burlington); MTD Kingston Basses International Emerging Artist; Bartolini Electronics Emerging Artist
    Hey Chucko, both my basses sounded great before I did the upgrade, but after installing the second battery in each, they both sounded even better...I didn't need it, but it sure gave an extra boost tone wise! I think if your bass has no tone and you have to do something to get better tone, then yeh, there's something wrong...but if you take a great sounding instrument and make it sound even better, then why not?:bassist:
  9. Nato


    Jun 2, 2002
    Okay how would you go about making a 9 volt into a 18 volt. Would you just add another battery and wire it to the same place or what?
  10. rojo412

    rojo412 Walnut is fun! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Yep. It's just splicing another battery clip into the loop. if you were to cut the Negative (blk) lead to the jack, just splice neg to pos, then neg to neg. Very easy.
  11. Wouldn't you need to change the preamp in the bass?

    Surely if you change from 9V to 18V, you're doubling the voltage that's going through it, and that'd fry it, yeah?
  12. rojo412

    rojo412 Walnut is fun! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    It's actually less common than you would think. 18v isn't really that much. Also, I BELIEVE that the 9V preamps "clip" because the signal coming from the pickups is overdriving them if you pluck really hard. It then tries to output that, only to be limited by the 9V limit of output (like a "bottleneck" effect). If you put more power behind the pre, hit the string really hard, the signal can be translated better... or something like that (where's Rob Turner when you need him?)

    BTW, on a search for a Status, I spotted a Signature Series one that was 36V!!!
  13. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    When I lived in my native Scotland, a friend of mine (James Finnigan) was the bass player for the band Hue & Cry. He had a Vigier 4 string which ran on power supply only! This was 1990. Sounded great, had the whole Vigier presets system but talk about restricting your movement onstage!
  14. GFOS


    Dec 27, 2002
    Athens, Alabama
    You might want to check with the manufacturer of whatever pre amp and pickups you have. I talked to the guys at EMG before upgrading my Q5 to 18v, and they said that their stuff was designed to handle up to 27v. I made a cool little harness with three battery clips that I just plugged into the existing clip. That way I didn't alter the original and can change back to 9v in a matter of a few minutes with no soldering.
  15. rojo412

    rojo412 Walnut is fun! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    That's a sweet idea!!! I didn't even think of that! You used 2 terminals and sent the 3rd set to the existing unit, correct? It works okay, too?

    If you have an 18V system and want to just run on 9 (assuming that it would function), you can bridge the second battery terminal (pos to neg) and it should run on one. Not that anyone would, but if you didn't want to alter the bass.
  16. rojo412

    rojo412 Walnut is fun! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Here's a pic of the harness. In fairness, it is more work than just adding a new terminal, but it's not much work in total.