EMG 81 & 89 wiring HELP needed!

[Devotee]

Hi all, i've been lurking around the forum for a while now but this is my first post here.

I'm looking to wire up an 89 (neck) and 81 (bridge) with a 25K push/pull pot as a master volume (and for coil tapping the 89) and a 3-way toggleswitch along with a Neutrik locking jack in my recently restored/rebuilt/modified Kelly. I contacted EMG directly and a helpful dude called Rick sent me the diagram below:



The p/p pot should be wired up like so:



So i wired it up as in the above diagrams and the pups are selected correctly according to the switch and the coil tap works fine but for some reason there are several other serious issues:

- The pot isn't acting like a volume pot, it's acting more like a tone pot (i think) in reverse (i.e.: turning it clockwise decreases the treble and turning it counterclockwise increases); essentially think lefty tone pot.
- There's a horrible scratching/buzzing noise whenever i turn the knob.
- There's an annoying buzz when i touch the pot, switch, jack and EMG 81 (bridge pup) which leads me to believe that something isn't grounded right even though i followed the diagram to a T.

I've wired it up and rewired it and checked my connections plenty of times and can't seem to find anything wrong, what's the deal? Can somebody help me figure this out, what should be a relatively straightforward wiring job is driving me nuts! :think:

[Cygnus X1]

Did you accidentally get a reverse taper pot?

[Devotee]

I thought about that. I got it from Ebay: http://tinyurl.com/39x2tey.
Either way, if i did it wouldn't bother me so much. What's bothering me is the noise!

[maggo]

I had the same problems years ago with this combination (EMG81/89).

I also had a ground problem, everything was loud/noisy when touching the pot and metal parts on that guitar. I soldered the area new, where all cables came together for ground and that helped.

About that scratching noise when turning the knob..i think while you did the soldering, that tin solder has flown inside the pot which causes the noise..that was at least the reason in my case.. I had to buy a new push/pull pot which i didn't...i removed those f***ing Emgs and sold them.

[DonP]

I think you have some wires reversed on the lugs of the pots, or you have wires touching each other. It's a busy connection, make sure stuff isn't crossed up.

[bratfink]

The noise is grounding. Make sure you have a clean earth for everything. Also make sure you didn't accidentally get some solder in a place you didn't want it.

By any chance are both pickups live all the time? Therefore when you bleed off the volume it only takes out the bridge pickup leaving the neck pickup on full vol. That would give the impression of a tone cut. Tap the pickups with something metal at both extremes of the pot and see if they respond. In either case, back to the drawing board.

[Devotee]

Thanks for all the help guys, it's greatly appreciated.

maggo, i really considered doing what you did but i just like the brightness and clarity EMGs have to offer, so i'll try what bratfink suggested tomorrow.

[Newc]

See that little wire on the push-pull that goes to the center lug of the pot in the close-up view? Remove it and send it to the 3-way instead like it shows in the bigger diagram.

[maggo]

I didn't want you to sell them, too That wasn't what i wanted to say with my post. I liked the clean sound of the emgs very and the possibility to split the emg89, but i went with passive pu's after all..
Many luck for fixing that problem!!

Thanks for all the help guys, it's greatly appreciated.

maggo, i really considered doing what you did but i just like the brightness and clarity EMGs have to offer, so i'll try what bratfink suggested tomorrow.

[Devotee]

I noticed that the pot itself is a B25K pot. This one is a replacement, the original is an A25K pot. After some quick searching i discovered that A (alpha) potentiometers are linear (audio tapered) and B (beta) pots are logarithmic. What that means i have no clue but does this have anything to do with the fact that it's not working right? If so, i guess i have to order another one...

I'm getting really frustrated with this whole thing and will probably end up taking it to some local luthier to see if he can fix it.

Another thing, anyone on this forum know where i can get a custom control cavity cover made? Nothing fancy, just a simple black plastic/aluminium cover made traced from a paper template.

[Hellbat]

You have it backwards. Logarithmic taper is an audio taper. Linear pots are for non-audio use. The reason for this is because sound pressure is non-linear. Each 3db of SPL is approximately double as loud as the 3db before it. The taper of the pots will have ZERO bearing on hum style noise, it's just an indicator of how the resistance changes when turning the shaft.

[Devotee]

You have it backwards. Logarithmic taper is an audio taper. Linear pots are for non-audio use. The reason for this is because sound pressure is non-linear. Each 3db of SPL is approximately double as loud as the 3db before it. The taper of the pots will have ZERO bearing on hum style noise, it's just an indicator of how the resistance changes when turning the shaft.

Thanks for clearing that up. I know that the taper will have no bearing on the noise, but after checking it again today i'm beginning to think some solder might have got into the pot. Then i did some research on A vs B potentiometers and realised that i probably have the wrong pot; hence the lack of change in volume when the shaft is turned.