MEC Passive J pickup hum

BassMike · #1 09-23-2010, 01:09 AM

Guitar Info:
Corvette Standard, 5-string
Natural Oil finish
Bubinga body
Ovangkol neck
Chrome hardware

Produced: 14/10/2003

Has the original passive MEC pickups. It has recently developed a wicked hum. Changing circuits within my house does not help, in fact hum is still there in a completely different building with different amp/cab/cable combo than at home - I don't think it is coming from the environment. Touching the strings/bridge/pickups has no effect on reducing or increasing hum. A quick perusal of wiring in cavity, and gentle "wiggling" of wires has little to no effect. Soloing in either the bridge or neck pickup has no effect. Pickups mixed together also has no effect on hum - it's there no matter what I do - except for one thing…

The hum is greatly reduced and virtually eliminated when I change the orientation of the bass relative to the amp/speaker, the hum seems most reduced when 90 degrees to face of speakers.

From my limited knowledge this seems to describe a "single coil hum pickup" problem.

My questions are:

Will cavity shielding with copper foil help? There seems to be mixed opinions on this.

Do these MEC passive pickups "wear out"? Will the hum increase as magnets and/or coils age and degrade over time?

Is the solution replacing the pickups?

Could there be an unseen or undetected wiring problem?

Please forgive me if this has been posted elsewhere in these forums, I did a cursory search but was unable to find any information on this topic. If you can point me to a thread where this has been covered I'd be most thankful.

If you can give me some advice on the best course of action, again, I'd be most grateful.

darkstorm · #2 09-23-2010, 08:59 PM

Mec pups hum worse then any Ive ever heard before. The ones in the basses with active eq dont because the active preamp kills the hum. But the passive warwicks with mecs hum worse then any other I know of. You can either replace them (best choice) or add a preamp that removes the hum.

BassMike · #3 09-25-2010, 12:29 AM

Thanks for the advice DS, anybody else care to weigh in?

Chrisk-K · #4 09-25-2010, 07:13 AM

I used to own a Corvette Standard and it hummed a lot.

Why does active EQ remove hum?

Shakin-Slim · #5 09-25-2010, 07:21 AM

I'd say replace the pups. An all passive Warwick is a beautiful beast

SGD Lutherie · #6 09-25-2010, 02:01 PM

Quote:

Originally Posted by darkstorm

The ones in the basses with active eq dont because the active preamp kills the hum.

Preamps don't get rid of hum. Those pickups are hum-canceling.

Quote:

It has recently developed a wicked hum.

If it just started, you need to check the wiring. A ground is probably broken.

BassMike · #7 09-25-2010, 04:35 PM

It always had a bit of hum, but I think it's gotten worse as of late. I'm going to go have a closer look at the wiring this weekend, once the "honey-do" list is a little shorter.

I'm also thinking now that I'd like to replace the pup's - Bart's seem to be a leading choice.

Has anyone else done this? What pup's did you use? I think I'd like to keep it passive, unless someone can convince me otherwise.

Rick Auricchio · #8 09-25-2010, 06:18 PM

I hated the hum in my fretless Corvette Standard. Replaced the MECs with DiMarzio Model J pups and haven't looked back. No other changes to the controls. The Js sound just fine in that bass.

darkstorm · #9 09-26-2010, 01:10 AM

SGD Lutherie...> O Ok, I thought the active corvettes and passive ones used the same mec jazz pups. They look the same. My active one didnt hum but all the passive ones I tried hummed a lot.

levis76 · #10 09-26-2010, 08:21 AM

+1 for checking your ground wiring, if you don't have some knowledge of electronics, take it to a tech and ask him to give it a once over.

I have a 'vette 4 string that had the same MEC passive p'ups and they were quite noisy from the day I got it. I replaced them with a set of Bartolinis, never looked back. Sold the MECs to some kid who put 'em in an SX. Everybody Happy!!

BTW, that is a beautiful grain pattern!! My wife stopped and stared over my shoulder and commented that mine didn't look like that!! The grain on mine is a bit darker and has a straight pattern.

maguire · #11 10-08-2011, 04:08 PM

I know its an old thread but I wanted to concur for anyone else stumbling on this thread. I just got an 06 passive 5 string corvette standard (MEC J Passive) and the pickups hum like crazy.

Some specific details about the hum:
1. Hum increases as tone knob is turned clockwise and decreases as it is turned counterclockwise.
2. The hum decreases when I orient the pickups at a 90 degree angle to the amp. If they are directly facing the amp the hum is loudest.

If I replace the pickups I will report the outcome here.

Very happy to find this thread - i was worried about the bass (which I bought used).

maguire · #12 11-07-2011, 11:14 PM

I replaced the MEC's with a set of Bartolini 5 string J pickups - much better.

Then I decided to go all out and added the Bartolini 3.3 preamp.

Amazing! The amount of tone variation I can dial is shocking and the sound is hum-free! I'm going to have a lot of fun with these electronics.

Recommend to replace the MEC's on a Corvette standard.