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Bypassing the active EQ on a Spector Euro

Discussion in 'Pickups & Electronics [BG]' started by eukatheude, Aug 10, 2012.


  1. Hi, i have a Spector Euro 5 with the stock tonepump on and EMG 40 DC's. I want to install a switch so i can bypass the tonepump and have the signal straight from the EMGs. Apparently it's possible since on Aguilar's site there's a schematic (page 3) for that, based on their OPB1 circuit which is a common tonepump replacement. The problem is that the wiring there doesn't make much sense to me, since the EQ is connected no matter the position of the switch. More importantly, on page 3 the output from the volume pots is on the center connector, while on the others (and on my bass) is on the right. With some digging i found this post on the EMG user forums, of which i have made a crude drawing:
    [​IMG]

    And this seems the right way to me, but i'm definitely no expert - this is my first electronics mod, aside from the easy 18v circuit upgrade. What do you guys think?
     
  2. mazdah

    mazdah

    Jan 29, 2010
    Kalisz, Poland
    My friend did that few weeks ago, he has push/pull volume pot installed which activates the preamp. I'll ask him and I'll let you know.
     
  3. Thanks! I was thinking of using a push/pull pot too, but i'm afraid those are quite a bit pricey compared to a switch, and i'm quite a bit broke.
     
  4. Still need an opinion. Anyone?
     
  5. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    That is how you wire a bypass switch.

    Is the volume pot before the preamp? If it isn't, then you need to change the wiring. if the volume pot is after the preamp, it will be a low value like 25k-50k. That wont work with a passive setup.
     
  6. Hey everyone, sorry i disappeared but i've been on vacation.

    The cable from the pickup goes to the center thingy on the pot, then from the right thingy (with the pot upside down) goes to the preamp. A black wire on the left goes into the preamp too, but i think that's ground, so i think it's before the preamp. Both pots are 25k
     
  7. Bump, still need help chaps.
     
  8. Hello? Any input would be gratly appreciated. I'm a total noob to this stuff and i don't want to mess up anything.
     
  9. grendle

    grendle

    Mar 4, 2011
    Central FL
    The vol pot (s) run through the pre and the pre also shares power with the pups. To do that your gonna have to splice into the power and the vol pot (s) and reroute the output to the jack. It's do able but kind of a pita. Why do you want to bypass the pre?
     
  10. The power is not an issue, i don't mind having the pre being power even while i'm playing with it turned off. I want to turn it off because more tonal options = more... better :D
     
  11. Stealth

    Stealth

    Feb 5, 2008
    Zagreb, Croatia
    If you mean the schematic on page three of the OBP guide, look closer. In the up position, the cyan (volume) goes to blue (OBP input), and green (OBP output) goes to purple (output jack). In the down position, the cyan goes to purple (straight from volume to output jack), the blue goes to black (shutting off the preamp's input) and the green is unconnected (so there's no output from the preamp whatsoever).

    With a single pickup, or a blend-volume, the output's taken from the center lug because that way the pot doesn't change the pickup's impedance (and thus tone). On the other hand, if you had a pot for each of your pickups and turned one pickup down, you'd kill both pickup's outputs because both pickup's outputs would get "drained" through the closed volume pot to the ground. That's why your bass takes the output from the right lug, so you can dial down each of them independently without affecting the other.

    The pot's definitely before the preamp. I was about to comment on the 25k value, but then I remembered those are EMG active pickups.
     
  12. grendle

    grendle

    Mar 4, 2011
    Central FL
    Best bet is to run wiring to half the new pot like a std install without the pre, then wire the other half like its the std volume pot for the pre. PS. The pump absolutely kills wired for 18v , and turn the trim pot down to about 3. Some prefer it to the haz (myself included) run that way. They usually come set way too hot from the factory. The sweet spot is usually around 3-4 depending on your amp and how much you want to drive it. But the bypass is a neat idea I guess.
     
  13. Thanks for the answers! So, basically both wirings are right?

    What do you mean by "kills" wired? I've kept it fairly high, i'd guess around 5-6 for a while and had not many issues, though i must say i don't have a 'real' amp - just a 15w little thingy and i mostly play striaght to my computer. It does clip a lot, but i can keep things under control by not using the bass boost and keeping pups volumes low.
     
  14. grendle

    grendle

    Mar 4, 2011
    Central FL
    Kills as in sounds awesome. If you turn the pump down a little more you can run the bass and treb both boosted full, with no clipping issues. At 9v the pump clips a little with the attack like the haz does, but the haz has more complexity in the mids with less bottom end. At 18v the pump the pump doesn't clip on the attack, and it gives the emg's more headroom and fidelity. The bottom end is more solid / clean and you can hear the edges of the notes better. The pump also has more and cleaner low end on tap than the haz. When you turn down the pump you can bring all of that into play (at full boost), you can also dial it up to hit the sweetspot on a tube pre nicely.

    For finger players the haz (usa 9v) is the way to go , for a pick the pump is better imo. The 18v mod takes about 10 min and is easily reversible ( 3, 9v clips from rat shack and you don't have to alter the stock wiring)

    There's a lot hiding in the pump but they are usually wicked hot from the factory and most people are too quick to swap them out . Awesome sounding and very overlooked pre.
     
  15. Already did the 18v mod, it sounds great though i did notice an increase in output and therefore distortion when playing on the computer. The TP sounds great but i'd swap it for something with both boost and cut and midrange control.
     
  16. grendle

    grendle

    Mar 4, 2011
    Central FL
    The pump is both boost and cut ( -4-+15). No mids though , but that's the Spector trick ( the mid boost inherent in the circuit). The pots just don't have a center detent which is no big deal. Most run them both full boost or just dialed back slightly from there. Put them where they sound good , pull the knobs off and put them back on pointing to a refrence point on the bass. Dial the pump back till you can run the bass wide open (full boost) without clipping the puter (or clipping it as much as you want) and you should be good to go. Just my .02
     
  17. Yup i know it boosts and cuts, i mean something that boosts and cuts at the same level (ie. +15 /-15). The midrange might be a design decision but i'd still love to be able to tweak it. I agree on the "put them where they sound good", don't really need a center detent. I tried dialing back the pump as you said, but i prefer the tone i get out of it when it's more open. I remember Patrick Stern saying that around 6-7 you get a very USA pre sound. Anyway i don't want to bypass it because i don't like it, i just like to have the most possible options, and sometimes i love me some good passive sound. I've actually been considering putting a J pickup between the two soapbars, but that would fill the control cavity even more than it is now (and with the second battery it's pretty much cramped) and i don't think i want to route it or put on a second output.
     
  18. grendle

    grendle

    Mar 4, 2011
    Central FL
    Yeah JP likes his a little hotter. If you want to hear all the available pre's check out Lima guys posts on sound cloud. He has all the pre's in almost all the different configs on there with pretty much the same riff so you can hear the differences. You do realize that bypassing the pre won't make the emg's passive or make them sound that way. Sounds like a cool I idea though.
     
  19. That's interesting, do you have a link?

    I know it won't sound like a P bass, it's still going to sound like a Spector with EMGs but nevertheless it's another tone options, and i love having tons of tone options! And since i have to change a pot anyway (one of the two outer thingies where the knobs are fixed is broken, i've had it covered in electrical tape for years now) so might as well get a push-pull one.
     
  20. grendle

    grendle

    Mar 4, 2011
    Central FL
    Phone won't let me post a link from the app. Go to sound cloud and search limaguy. Or hop over to the Spector thread and look there. Good stuff.
     

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