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Is it a do-it yourself job, installing a OBP-1 pre-amp in a Fender Marcus Bass?

Discussion in 'Pickups & Electronics [BG]' started by Bobbo 77', Nov 26, 2005.


  1. Compadres',
    Is it a tech job, or has anybody out there ever installed a Aguilar OBP-1 pre-amp by themselves? Now, I can solder, but is this a delicate job? I'd like to put the pre in my Fender Marcus bass. Bass Bros., chime in!

    Bobbo 77"
     
  2. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    it's pretty simple as far as preamps go.
    Just curious, what are you looking for out of this upgrade?
     
  3. David,
    Thank's for the reply back.

    Well, to me, the weak link in this Bass is the Fender Pre-amp. I've read that it's suppose to mimmic Marcus' Bart pre. Now the only thing that I'd like to hear out of this Bass is a less sterile treble, it is really HARSH, and a tighter low end. But, it sound's pretty darn good! I know I can never duplicate THAT tone, but the Aguilar and the J-retro are what I'd like to hear out of this bass. It feel's great, but it could use a upgraded pre.

    Thank's,
    Bobbo 77'
     
  4. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    ok, was just wondering. You know the obp-1 preamp is boost only like the fender preamp, right? If you feel the treble is harsh, maybe consider getting either an obp-1 plus tone control, or preamp with cut/boost eq such as aguilar obp-2 or bart 2 band.
     
  5. David,
    Question. I'd imagine the Aggie is a Better sounding Pre, it seems everyone that I've read that's used these say they are "Transparent", I thinking more "Hi-Fi" sounding. I heard a clip of a OBP-1 and I dug the tone. But my question to you, can you use the OBP-2 with the same wiring scheme, V/V/B/T? Hows the Bart sound?

    Bobbo 77'
     
  6. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    You do know that on the marcus, bass and treble are boost only, right? It seems that if you are saying "the trebles are too harsh, and the bass is too muddy" you might not. Try setting both preamp controls to "0" or fully counter-clockwise. Maybe boost the bass 10% or so, but not really more than that. Maybe even try it with the preamp off, to see if you like that.

    FWIW, I ended up removing the preamp entirely from my Marcus Miller, and wiring it V/B/passive tone. I really dig it this way.
     
  7. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    yes, you can use the obp-2 with the same wiring.
    Are you feeling the sound of the bass is too bright in general, even when you don't boost the treble?
    As I said, and just to be sure, the preamp is boost only so when the bass/treble knobs are at standard midway positions that means the treble and bass are being boosted 50%.

    The Aguilar preamps are more transparent IMO, that is with eq flat they don't affect the sound. Bart preamps are good too, but the off the shelf ones seem to have a slight dampening of the high end - I guess this is to reduce noise.
     
  8. Dan and David,
    Thank's for all the suggestion's.

    Yes, the cutting of freqencies makes MUCH more sense, and going with the OBP-2 seem's to be the ticket. Now, fella's, do the Bart's have a tone closer to what a Marcus pre Should sound like? Or is the Aggie a good enough choice?

    Thank's,
    Bobbo 77"
     
  9. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    You still haven't answered my question. How does it sound when you turn both preamp knobs ALL the way down (counter clockwise)? This is the "flat" setting on this bass.
     
  10. IMO...stay away from the OB-2 if you are going after the Marcus thing... that 6.5k treble center frequency is not optimal for an old school slap sound IMO... the OB-1 would work out better... and as suggested above, a passive tone control would greatly help tame the treble when you don't need it.
     
  11. Dan,
    Cutting back both the Bass and treble knobs help tame the Freq.s that are harsh (Treb). I doing as you suggested, and I kinda dig it. Low end is'nt as boomy, and it really helps the harsh top end. Thanks to KJung for your help also.

    Bobbo 77"
     
  12. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    No problem. Fender's website states that the preamp is boost/cut, but it is, in reality, boost only. Therefore, many people set the two preamp controls about halfway, thinking they've got the preamp set flat when, in reality, they're applying a very heavy boost to the lows and the highs. No wonder it sounds muddy and harsh. Turning it down to more reasonable levels (when I had that pream, I always had treble turned ALL the way flat, and bass bumped from anywhere to 0-3, and no more) will give you a much better sound. You'll get the same effect by flipping the switch to bypass the preamp.

    I ended up liking the sound of the preamp bypassed better then the preamp on, even when it was set totally flat. There seemed to be "something" about the midrange. I couldn't tell you what it was, but it was certainly audible. So I removed my preamp entirely, and replaced it with a B/V/T setup. I love this bass, now.
     
  13. Dan 1099
    I was under the asumption that it was Cut/Booost. And, I was running the bass half-or a notch more, and the treble less than halfway. No wonder it just was'nt right. And I dig it passive also, for old 70's style Funk.

    Question. Did you do that Tommy Thompson quick fix passive re-wire mod? It's suppose to make that switch "True Passive"

    Sorry for the late response before!

    Bobbo 77"
     
  14. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    No, i didn't do that. My bass was true bypass already. I believe Fender upgraded the wiring several times throughout the life of the MM bass. In some early MMs, the preamp was "on" whether the bass was plugged in or not. If the switch was on, the preamp was on. This lead to quickly drained batteries. I know Fender addressed this problem. As far as the switch "just turning the preamp flat," that may have been the case at some point, but mine was certainly wired from the factory as true bypass. I could hear a definite difference between the preamp on and set flat vs. the preamp off. Also, my bass worked in passive mode with no battery. That's a dead giveaway, right there, to test if your bass is true bypass or not, remove the battery, and play the bass. It should make no (or very very little) noise with the preamp engaged, and should work normally in the bypass position.
     
  15. Dan 1099,
    Question, when in the passive mode, do your tone control's work? I believe that's one of the big complaints about the Marcus, is that when in passive mode, you can't use the tone controls. Mine is a 2004, and the tone controls only work in active mode.

    The reason I asked about the "True Bypass" was that there was a Bassist/guitarist named Tommy Thompson who was posting on both Talk-Bass and Harmony Central with different wiring/tone and volume pot arrangements for the Marcus.

    Bobbo 77'
     
  16. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    No, those tone pots do not work in passive mode. They are the primary function of the preamp. The only tone controls you have on that bass in passive mode are the volumes, and your fingers. Not that that's bad. I played for about 6 months withouth ever taking that bass out of passive mode. Eventually, I decided that I was using the preamp so little, that I might as well get rid of it. So I wired it all up so that it would work just like a traditional passive jazz bass. I can no longer boost bass or treble, but with the passive tone knob, I can cut treble.

    I know who Tommy is. Try the test I suggested. Remove the battery, and play. If you get normal sound in passive mode, then your bass has all the wiring mods that Tommy did, right from the factory.
     
  17. 1099,
    Yes, you KNOW your stuff! Just checked out my Marcus without battery and yes, it's wired correctly. I thought that without the use of the tone controls it would have to be wired to use them. Like you said, Just use the Finger's! I'm also diggin' that passive mode more, and got fooled when I thought I had it active! Any more tip's?

    Bobbo 77"
     
  18. Dan1099

    Dan1099 Dumbing My Process Down

    Aug 7, 2004
    Michigan
    When I had the preamp in mine, I liked to keep it in passive 90% of the time, but leave the bass contol boosted about 30%, so that when I played a ballad or something, I could flip it into active for a nice fat sound. Then, I also really like how it responds to D'Addario XLs and a medium action.

    Also, if you're into that vibe, 70s style jazz basses with flatwounds can be really sweet sounding. Check out the new Ben Folds cd for a good example of this. If I were in a more laid back band, I'd be all over this.

    I installed Dunlop straploks on mine, too. I reccomend it. I also fully shielded mine when I did the passive configuration. I reccomend that unless you have a good idea about how electronics, etc. work, you leave this for a tech, or at least have someone help you out with it.
     
  19. In my Valenti #002 I have the Aguilar OBP-1 preamp and I miss to cut treble.
    Therefore I think I will install a vintage tone control.

    But the Bass boost in the obp-1 preamp sounds really big and natural.