Classic Stack noise help

[Emarcey]

Hi all.
I'm newly registered but been outside-looking-in for a long time.

I have a Classic Stack STK-4 in the bridge of one of my strats with 2 Fender Custom Shop Fat 50's SC's in the middle (RWRP) & neck.
I'm getting a little bit of hum in position 1 (w/ bridge only) and then more in pos 2 (B/M) (this is what's baffling, right???). Position 3 normal amount for SC middle, pos 4 (M/N) QUIET AS!, pos 5 normal amount.

I should note that I have done a bridge tone control mod and a comprehensive shielding mod as per the GuitarNuts.com site.

I can't for the life of me figure out why the mini HB is causing hum in pos 2.
I have reversed the black & white wires off the 4 conductor lead as per the SD wiring instructions that came with the Classic Stack.

Any insight would be appreciated.

ps: one thing worth mentioning is the bare wire is tied in to the ground along with the white wire. I read somewhere that others have left the bare wire disconnected. It doesn't seem to me that that would make a difference though. Any thoughts?

Thanks,
Mick

 

[DrNewcenstein]

Re: Classic Stack noise help

Not sure why you'd swap the black and white. Usually if the other 2 pickups are Fenders, you'd swap the Duncan's Green and Black (Black to ground and green to hot), leaving the red and white either in their split location or taped off and soldered together.

If you're getting more hum in position 2, I'd say you've got it wired to split the CS in that position, which would add the noise of both pickups together.

In position 4, the two Fenders are working together in series to cancel the hum.

 

[Emarcey]

Re: Classic Stack noise help

Thanks Dr.
The wiring instructions that came w/ the STK-4 specifically note to switch the black & white leads if being installed in conjunction with Fender pups. Also with the STK-4, there is no green wire. It's a 4 conductor lead with: black, white, red, bare. The red is cut & taped.
What you said about pos 2 has got me thinking though... I might try switching the black & white, but I think I think I did that when I initially installed the HB and it made the tone nasally and thin because it was out of phase. Anyway, I'll try it tomorrow and see.
Thanks again.

 

[frankfalbo]

Re: Classic Stack noise help

Couple things: first I wouldn't refer to the STK-S4 as having 4-conductor. It is 3-conductor with shield. Just like full sized humbuckers are 4-conductor plus shield, and we don't call them 5-conductor.

Next, inverting phase on the STK-S4 was the right thing to do, but I may suggest reversing it and reversing the phase of the other two Fender pickups instead. The reason you hear hum in position 4 is because the middle pickup is a single coil and the bridge pickup is a humbucker. You need to auto-split to the top coil if you plan to cancel hum with the middle pickup. This, however can only be done if they are reverse polarity from one another. I can't remember if they are. A call to Customer Service should help. They should know. The auto-split only works if the STK-S4 is wired to stock phase. Otherwise you'd be splitting to the bottom coil which is not picking up proper audio.

 

[uOpt]

Re: Classic Stack noise help

The bare wire (which connects the shield in the wire and the baseplate of the pickup) must be grounded, regardless of which other color is wired to ground.

 

[Emarcey]

Re: Classic Stack noise help

Thanks guys!
I had considered switching the polarity of the Fender pups but only as a punt, not because I actually know what I'm doing! I know just enough to be dangerous sometimes!
I hadn't thought it through enough as to first switching the leads on STK-4 back to standard though. Duh! Of course!!
I'll try and get through to Customer Service @ Fender, but I live in Australia and haven't dealt with Fender AU before. If I have to ring Fender USA, it's bit of a pita with the time difference. We'll see how we go & I'll swap all the pup leads over and see what happens.
Thanks for your input.
If anyone else has ideas, I'm still open...

Cheers,
Mick