Adventures in shielding

[fergs40]

I know there will be many on here who have done this a hundred times and more, but as it's my first go I wanted to share - please pass on if not of interest!

 

My motivation for this was sparked by @Jean-Luc Pickguard's NBD about his Rick 4003, and the subsequent discussion about shielding it. So I acquired some copper tape and rather than jumping straight into disassembling my Rick, as a first experiment I set about my 1987 Thunder 1A. This is still 100% original, including the 18v preamp, but my goodness was it noisy!

 

It probably took me about an hour to complete the job. It was surprisingly straightforward to cut out strips of tape and manipulate them into place. I had the odd piece tear when I was smoothing it down, but it was easy enough to patch. I'd read some warnings about the sharp edges of the tape being a bit hazardous, but I was either sufficiently careful or lucky and survived without injury. I did the inside of the pickup rout (discovering that a younger me had almost pulled one of the mounting studs out of the body in a ham-fisted attempt to lower the pickup), the inside of the cavity and the inside of the rear cover (which has the preamp mounted to it). I put everything back together and, not really expecting very much, plugged in.

 

The difference was night and day - the bass has gone from a handy receiver for local taxis to almost completely silent, even with the active circuit at the extremes of its settings. Previously the active circuit was so noisy I just avoided using it, but no longer!

 

I was so flushed with success I decided to do my Vigier Excess at the same time as fitting the new preamp (see other thread). I'm not sure the difference with the Vigier was quite as noticeable - it already had shielding paint and it's still a bit buzzy sitting in front of the computer (despite having a hum cancelling circuit). Equally I believe the pickups in these are perhaps more prone to noise than some, the sacrifice being reasonable for the excellent tones they produce.

 

Anyway. there you are - a simple job with a satisfying result (and no slugs harmed). I'm afraid I was so engrossed I forgot to take much in the way of photos, but here are the couple I did take (one each of the Westone and Vigier).

 

 

 

[Hellzero]

By the way, did you ground all the cavities after shielding them with copper?

[Jean-Luc Pickguard]

Good job!

[fergs40]

1 hour ago, Hellzero said:

By the way, did you ground all the cavities after shielding them with copper?

Not specifically. On both basses I reckon the control cavities are grounded due to the jack sockets touching the copper.

The Westone had a grounding wire in the pickup rout already (though on reflection it’s a mystery why, as there was no shielding in there?), so that is definitely connected to the control cavity and thus to ground.
 

On the Vigier, however, the pickup rout shielding isn’t connected to anything - there was nothing obvious on the pickups to connect it to (and frankly I wasn’t about to start soldering anything on to my irreplaceable pickups), and running additional grounding wires along the same route as the pickup wires was too much effort…maybe another day.

 

But perhaps some explanation for why the job seems to have been less effective on the Vigier?

Edited January 8 by fergs40
Cursed grammar

[Hellzero]

If you don't ground the pickup cavities, then what you did there is totally useless as the sensed electronic parasites won't be grounded and will pass in the signal through the pickups.

 

Furthermore, your own body will still act as the more powerful antenna around and you'll still have your free taxi radio turned on...

 

Simply solder a wire from the pickup cavities to the copper of the preamp cavities and everything will become dead silent, especially your Vigier with the amazing Benedetti single coil pickups (that I know very well as my Leduc basses are equipped with Benedetti-Leduc single coil pickups with a third hum-cancelling "pickup" à la Alembic).

[fergs40]

3 hours ago, Hellzero said:

If you don't ground the pickup cavities, then what you did there is totally useless as the sensed electronic parasites won't be grounded and will pass in the signal through the pickups.

 

Furthermore, your own body will still act as the more powerful antenna around and you'll still have your free taxi radio turned on...

 

Simply solder a wire from the pickup cavities to the copper of the preamp cavities and everything will become dead silent, especially your Vigier with the amazing Benedetti single coil pickups (that I know very well as my Leduc basses are equipped with Benedetti-Leduc single coil pickups with a third hum-cancelling "pickup" à la Alembic).

Well that certainly makes a lot of sense, and explains why the Westone job was more effective than the Vigier one. I shall return to the Vigier at some point and add a couple of wires. Ta!