Minimizing hum on a 4003

jnbass · Post by **jnbass** » Mon Apr 11, 2005 8:07 am

Bob-

the paint was easier than the foil.

Of course if you like all the cryptic writing in the RIC cavity this method is out.

The foil on the scratchplate had the most dramatic change in noise level.

m_cuffa · Post by **m_cuffa** » Mon Apr 11, 2005 8:57 am

If I'm not mistaken doesn't shielding only eliminate electro-STATIC noise? I.e. the the kind of noise that goes away when you touch the strings... I'm not having a problem with that.. the hum I'm getting seems to be electro-magnetic, i.e. due to the single coil pickups... which is why Jeff's solution seems like a really good (and ingenius) one.

johnhall · Post by **johnhall** » Mon Apr 11, 2005 9:25 am

Electrostatic noise comes from neon or flourescent lamps, dimmers, switching power supplies such as you find in a computer, or other source which have a spark, high frequency, or high voltage component.

Electromagnetic noise is generally limited to transformers such as in your amp, motors or non-electric dimmers (which can also be a source of electrostic noise)- typically anything with a large set of coils. You're less likely to run into such a source in a playing environment with the exception of the amp.

The most important thing, which I've said many times, is to avoid ground loops. If you do the foil trick, for example, you need to cut holes around the pots and switch and arrange things so there's only one point of connection to ground. Shielding is more black art than science so there are no absolutes but ground loops usually cause more problems than no shielding at all.

rictified · Post by **rictified** » Mon Apr 11, 2005 11:08 am

All I know is that when I was done the difference was dramatic (running stereo that is), I had been getting terrible neon noise which I believe has a transformer in it as they run at a very high voltage and I had to aim the bass at them to get any noise and the noise window was very narrow after shielding.
I'm not saying I could put a bass on top of my SVT which has huge transformers in it, but I have never had any trouble from that with or without shielding unless I was almost right on top of it and I mean less than two ft. away, way too close to play comfortably. I don't think electromagnetic noise is a big factor unless you are playing in a power station. I haven't had any excessive noise problems with a Ric since I've run mono for more than ten years now, maybe you have a grounding problem in your bass.

atomic_punk · Post by **atomic_punk** » Mon Apr 11, 2005 11:23 am

Neon is a big problem for my guitar player in a lot of the clubs we play, we have to turn it off or else his single-coil pickups get some nasty hum. I keep telling him, another excuse to buy a Les Paul, but he just won't listen!

His cavity is shielded to the max, as well.

rictified · Post by **rictified** » Mon Apr 11, 2005 12:22 pm

I always shut them off too.
I like Les Pauls also, you don't see them much anymore, I wonder if the price has anything to do with that?

rickinroma · Post by **rickinroma** » Mon Apr 11, 2005 8:10 pm

I noticed that my brand new 4003BBoy has plenty of annoying hum when I play close to the amp while my V63 has no hum at all...is that normal?

cheyenne · Post by **cheyenne** » Tue Apr 12, 2005 12:16 am

I sometimes pick up hum from my amps cooling fan. Which dosent run all the time. Took me a while to figure that on out.

m_cuffa · Post by **m_cuffa** » Tue Apr 12, 2005 4:16 am

I noticed my new 4003 (bought in 2003) hums a little
more than my brother's '84 4003 - I think it
has something to do with the new high-gain pickups
on mine rather than a grounding problem - it's usually not sooo bad. I suspect
that maybe my lead guitarist's amp may have had something to do with it
last saturday - he was WAY too loud - maybe generating too much power? That all said.. after mulling over the options - I don't think I will do a shielding job - I don't have the expertise to do it myself and I won't trust anyone touching my baby's private parts. Same goes for the mute pickup though this seems a little less drastic. I'm considering buying a noise gate pedal, though. Anyone have any experience with those?

jwr2 · Post by **jwr2** » Tue Apr 12, 2005 4:50 am

The room my band rehearses in has a dimmer switch for the lights ... this really increases the hum ... so when I play a 4003 I use a noise gate ... and when I use a 4004 it is just quiet ...

rictified · Post by **rictified** » Tue Apr 12, 2005 10:56 am

Transformer hum only goes a couple of feet from your average amp, just move away from it. An amp's volume has not a lot to do with how much noise the transformer would generate I wouldn't think any way. An SVT has about the biggest transformers of any amp I can think of (35-40 lbs. and generates the biggest magnetic field) and I only pick it up if I am just about sitting on the amp, it has never been a problem.
Fransesco your V63's treble pickup is covered with a grounded cover (horseshoe) which is much thicker than the covers on 4003's so it shields the pickup much better and the treble pickup usually is much noisier than the neck pickup. When I took off the horseshoes from my V63's they got a lot noisier.

jps · Post by **jps** » Tue Apr 12, 2005 11:33 am

Rick Turner has an excellent tutorial on this subject in Jim Robert's American Basses book.

gareth · Post by **gareth** » Mon Apr 18, 2005 10:27 am

My 4003 used to be nice and quiet, with just a little hum. Then, over time, it developed a hum that became almost a roar, and actually renders the bass almost unplayable at times. I have taken it all apart, checked grounds, removed all sources of interference from the area, and used another bass to act as a reference on the amp, which is a Trace Elliot setup. I guess the next step is to try the copper shielding mentioned above.

When the hum goes away though, it's the sweetest, most punchy bass I've ever owned.

rictified · Post by **rictified** » Mon Apr 18, 2005 11:19 am

You have a problem someplace, hum doesn't slowly develop over time unless you have a slowly corroding ground or connection which would be easy to overlook, check all your connections with an ohm meter. Basses do two things hum and buzz, 99% is buzz.

jwr2 · Post by **jwr2** » Mon Apr 18, 2005 12:17 pm

How to minimize hum on your 4003 ....

...

...

teach it the words!!!