Mixing actives and passives

[wilsonic]

Has anyone had good luck mixing active pickups with passive? I have an EMG 85 in the bridge of my guitar and tried installing a Seymour Duncan P-rail humbucker in the neck. I tried calling SD about this and they didn't advise it, but the EMG site says it can be done.

I have the correct pots installed for each, but have very low output on the p-rail. I have 2 push/pulls for the neck volume and tone for switching the p-rail sounds.

Am I wasting my time or can it be done a better way?

Thanks.

[JohnH]

It should be possible to get each to work seperately, but if you try to mix them by connecting their outputs together, then the active will dominate because it is lower impedance.

So I think you need an active buffer to balance things out and stop one from fighting the other. Theres a couple of ways it could be used. Take a look at this scheme, using small active circuit and a pot to blend two active pickups on an acoustic, but I believe the circuit would also work blending active with passive:

guitarnuts2.proboards.com/index.cgi?board=schem&action=display&thread=4595

If you did not want a blend pot, the same principles could be designed around a 3 position toggle switch instead.

What sort of controls will you want to have in terms of volume and tone pots, selector switches etc?

John

[wilsonic]

I have a 3-way switch on the guitar. I'm not worried about blending the 2 pickups in the middle position of the 3-way. I just want to be able to use each pickup independently. The problem is that the EMG is about 10 times louder than the Seymour, and using the push/pull pots to switch between coils on the Seymour doesn't seem to do much of anything.

I'm just wondering if I'm missing something here.

[JohnH]

each seperate coil on a neck Hb often sounds very similar. What is your push/pull switch intended to do?

But if its a single coil to full humbucker switch, it should make a significant change, so if it doesnt then it may indicate some wiring problem, that may also explain the big volume difference with the bridge pup

John

[wilsonic]

Hey JohnH, this is what I want to acheive, but just with the neck pickup. The bridge is active and I'm not concerned at the moment about the middle 3-way postition.

www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=2_prails_1v_1t_tspp

I think I missed something. I think I may have wired the volume incorrectly, but I'm not sure as the diagram is for two pickups. How would I wire the black lead from the pickup? That might be the problem.

[JohnH]

I'd suggest wiring it exactly as in that diagram, just omit the bridge pickup. Then you should get the variations for the neck that the two pp switches provide. Once that works you could swap wires to put the neck volume pot before the toggle switch, so you can bring in the active bridge pickup.

John

[wilsonic]

Well I did that and I think everythings working as it should. I'm getting some hum and noise though. When I touch the pots, the hum decreases.

With the EMGs you are suppose to disconnect the bridge ground wire. Should I reconnect the bridge ground to the neck pickup?

[JohnH]

hi wilsonic - i dont know why they would not want the bridge grounded. I would expect best noise results if the bridge and all pot cases are grounded - i suggest trying that.

[wilsonic]

Thanks John, I'll do that.

[sumgai]

willy,

Jan 6, 2010 17:16:54 GMT -5 wilsonic said:

With the EMGs you are suppose to disconnect the bridge ground wire. Should I reconnect the bridge ground to the neck pickup?

Not quite. Connect the bridge ground wire directly to the output jack's ground tab. If the Neck pickup's ground goes there too, fine and dandy, but going the direct route means one less connection (solder joint) to worry about possibly going bad.

EMG espouses the disconnection for safety reasons only. They feel that if your pickups are not humming, then there's no need to "ground" the strings with your body, because there's no hum to reduce/kill/cancel/whatever. Thus, you can eliminate your chances of getting a shock from improperly grounded electrical devices by cutting this wire.

Yeah, sure.... and would you like to buy this lovely ocean-front property I just happen to have for sale, Mr. Emg? It's in beautiful downtown Gila, Arizona, just a stone's throw from all the best resorts - I swear!

Speaking from a safety standpoint, no bridge wire would be a nice thing, but realistically?.... it ain't gonna happen. Bottom line. 'Struth!

HTH



sumgai

[wilsonic]

Well I reconnected the bridge ground and got rid of the hum. I guess now that I can truely hear the pickup, I'm not convinced I have it hooked up correctly.

It seems like the highs are a little piercing and there doesn't seem to be a drastic difference in the sounds when switching between them ( individual coils, series, parallel). For the type of pickup it is, I would have guessed it would have more difference in the sounds. One coil is a P-90, the other a rail single coil, together a humbucker.

I seem to be missing that full, fat tone it is advertised as having in the humbucker and P-90 modes.

[sydsbluesky]

Hmm... I'm still planning on trying this soon with the Les Paul. Good stuff, guys.

And yeah, the first time I wired up with EMGs I tried leaving the bridge ground off, and it was awful. I'm not sure what EMG is smoking when they say that.

I know of a guy that used an EMG afterburner on the passive to match it up before sending it out to meet with the other pup. Worked well for him, or so he says... But I never mix neck and bridge either. Just don't like it.