Active and Passive combo/possibly fake emg's

graver555 · #1 11-16-2012, 08:24 PM

Well I have an Ibanez EX series bass that I picked up a few years ago. The owner said that he replaced the neck (p-style) with active emg's. He had left the original passive bridge pup (jazz style) in it. Well when I played with it for awhile and quickly noticed the the input jack was shot. Well I didnt know how to solder at the time so I took it to a freinds and he got it in. We also noticed that the last person while knowing how to wire it looked like couldnt solder so he redid most of the connections.

How the bass is curently wired is one volume pot and one tone pot. The last pot on the right only has the bridge ground going to it its not hooked up to anything else. Now I get some signal from the passive one if I remove the battery but its not happy about it and very low power. I want to be able to blend the two together but Im not getting enough from the bridge pup. (Im also not certain if its totally functional. It only has volume without the batt across all the strings if the tone knobs in certain places or it only has volume on two strings, or this could be the pot) Is there a way to use both pickups? If not whats the best way to switch between them if the battery goes dead.

Now I also question the legitimency of these pickups. From what I found online all new emg's have detachable wireing. After a little more digging I found the old ones are hardwired but have seriel numbers and other marking on the back but these dont. Considereing the hack job on the wireing and the fact that there is no preamp in the body I am not confident that these are the real deal.

One more thing, I also have a squire p bass. Would it work to swap around the pups in these guitars, makeing the p bass active and the Ibanez all passive with a v/b/t knob configuration? Holy cow long post sorry.

line6man · #2 11-16-2012, 08:34 PM

You're not getting any output from the bridge pickup because you have a low impedance pickup running parallel to it. There is no way to mix a low impedance active pickup with a medium/high impedance passive pickup without buffering the passive pickup to reduce its output impedance.

graver555 · #3 11-16-2012, 08:47 PM

so when I take the battery out is it just the little bit thats makeing it through the circuitry? Because its faint to the point I have to turn my little practice amp all the way up to hear over my strings themselves.

line6man · #4 11-16-2012, 08:59 PM

Quote:

Originally Posted by graver555

so when I take the battery out is it just the little bit thats makeing it through the circuitry? Because its faint to the point I have to turn my little practice amp all the way up to hear over my strings themselves.

The output impedance of the active pickup increases when you remove the battery. That being said, the DC resistance of most EMGs is about 60k. If you have a 25k pot in there, and a 1M input impedance, that makes ~17.64k Ohms against the passive pickup. That is ridiculously low, which explains the low volume. If you had a 500k volume, 1M input impedance, and no load from the other pickup, you would have ~499.75k Ohms.

danomite64 · #5 11-16-2012, 09:08 PM

FWIW, I've owned several sets of the older EMG pickups and don't recall ever seeing serial numbers.

graver555 · #6 11-16-2012, 09:15 PM

I think I need to do more research on impedance as I am still quite confused by it. So should I just leave the passive pup in as decoration then since I wont be getting much from it? Or can I use the third unused pot somehow as a selector switch in case my battery runs out? Bridge if its all the way one way, neck if its the other way? Im always scared my battery will run out in a show and the type of playing Im doing wouldnt give me time to switch batteries.
Or would it be better to swap them out with the p basses pickups and make it all passive. I mostly like either a dark tone or a piano like tone depending on music so I dont think I need the real hot active output in the firstplace.

graver555 · #7 11-16-2012, 09:17 PM

Quote:

Originally Posted by danomite64

FWIW, I've owned several sets of the older EMG pickups and don't recall ever seeing serial numbers.

So in your opinion do these look legit? Sorry I tried posting pics of the front but I could only get 2 in the first. Here it is.

line6man · #8 11-16-2012, 09:26 PM

Quote:

Originally Posted by graver555

I think I need to do more research on impedance as I am still quite confused by it. So should I just leave the passive pup in as decoration then since I wont be getting much from it? Or can I use the third unused pot somehow as a selector switch in case my battery runs out? Bridge if its all the way one way, neck if its the other way? Im always scared my battery will run out in a show and the type of playing Im doing wouldnt give me time to switch batteries.
Or would it be better to swap them out with the p basses pickups and make it all passive. I mostly like either a dark tone or a piano like tone depending on music so I dont think I need the real hot active output in the firstplace.

Do what you want with the passive pickup. It's not hurting anything to be there.

Selector switches of any sort would require the use of a switch, not a pot. There is the option to use a pickup selector switch, however.

Worrying about battery life is being paranoid. The current consumption of most EMGs is only 85uA. Less than a tenth of what a discrete transistor-based preamp would draw, and still enough for thousands of hours of use from a standard 500mAh 9V battery.

line6man · #9 11-16-2012, 09:27 PM

Quote:

Originally Posted by graver555

So in your opinion do these look legit? Sorry I tried posting pics of the front but I could only get 2 in the first. Here it is.

Why wouldn't they be? It's unlikely anyone would have EMG casings on hand to make pickups with.

graver555 · #10 11-16-2012, 09:40 PM

Quote:

Originally Posted by line6man

Worrying about battery life is being paranoid. The current consumption of most EMGs is only 85uA. Less than a tenth of what a discrete transistor-based preamp would draw, and still enough for thousands of hours of use from a standard 500mAh 9V battery.

Well that makes me feel alot better about that. Yea I guess I have been a bit paranoid about it. So since there is no onboard preamp is there one inside the pickups themselves?

line6man · #11 11-16-2012, 09:47 PM

Quote:

Originally Posted by graver555

Well that makes me feel alot better about that. Yea I guess I have been a bit paranoid about it. So since there is no onboard preamp is there one inside the pickups themselves?

Yes, EMGs have an internal opamp-based buffer circuit.

walterw · #12 11-16-2012, 10:48 PM

relax, you have real (older) EMG pickups.

they will not mix with passive pickups; they take over, so you don't hear the passive pickup at all.

yanking them for another straight-up P bass and putting a passive P into this one makes sense.

graver555 · #13 11-17-2012, 11:01 PM

Quote:

Originally Posted by walterw

yanking them for another straight-up P bass and putting a passive P into this one makes sense.

Yea the more I think about it the more I like that idea. Just reserved about messing with the p as it was my first bass and I know I can rely on it. I was also thinking of the trick where you take a cheaper bass like this one and pulling the frets out to since Im modifying it. Possibly painting headstock black also. I want to put better bridges on them also but dont have the money and not sure if it would be worth it at that point or just buy another bass. Then again I would be moding that in a year to......