Jazz Shielding Pictorial (Big Images Warning)

[Lyle Caldwell]

Originally Posted by mike_odonovan

I want to incorporate this shielding system into a preamp setup.
Should the the grounds from the pickups still be the only ones soldered the control cavity?
and all other grounds ie. volume pots and preamp grounds to the jack?
why do have to ground the bridge?

To be 100% true to star grounding, I should have run all the ground wires to the ground lug in the control plate. I've done that in the past, but found no difference doing the partial star ground like in the photos. The reason I prefer the pictured method is the control plate lifts up easily with only two wires connected, plus there are only two wires bundled up in the cavity. Just neater and easier, and it has the same benefits of "complete" star grounding. Note that even this way, each component only has one possible path to ground, so there can be no loops.

Plus, I ground the lugs of each pot individually to the output jack (could be the ground lug in the cavity) for two reasons:

1) If they are grounded to the body of the pot and the pot becomes loose the signal will cut out. This way, the signal will never cut out.

2) The pot never gets superheated, which is more a concern with the little stacked pot than with the big CTS pots, but it can be more of a concern depending on one's soldering skills/equipment. For example, it's hard to quickly get a good solder joint on a pot if you have a 20W or 30W iron. It's not all that easy with a 40W. But any of these irons (I prefer 35W for guitar/bass work) can solder wires to lugs.

Also, since this is a traditional Jazz, the control plate is separate and is conductive. On an instrument that's rear-routed with no plate, I'd have everything lined with foil, the pots grounded to the foil, and have every ground wire run to a ground lug screwed into the cavity.

As to your specific needs, I'd need to know which preamp before I could give specific advice.

And last, no, you don't need to ground the bridge at all when the instrument is properly shielded and star-grounded. It makes no difference whether you're touching the bridge/strings or not- it's equally quiet. I grounded it because I didn't want it flopping around in the cavity and I didn't want to remove it, just in case I ever wanted to use it in the future. Totally optional once everything else is done.

[Lyle Caldwell]

Originally Posted by mike_odonovan

also if using paint should i solder a wire from the control plate the shield?
with the paint i don't think i could get the copper edges touching the control plate effect.

Well, there would be two ways to do it. Either have some paint come over the cavity edge just like the foil does or run a wire from the output jack negative lug to the ground lug in the cavity. I chose the strip just because it was easiest and resulted in one less wire.

[mike_odonovan]

thanks lyle!
i'm learnin

here's a diagram of the preamp i will be puttin in and the push/pull pot i am addding on.

http://www.bartolini.net/instruction...b/ntmb918f.htm

http://www.bartolini.net/1_wirngs/ppapsw_n.htm

should all the grounds that would go on the back of pots still go to the jack?
and what about those pramp grounds?

[Lyle Caldwell]

The volume and blend and stacked pot ground lugs should be connected to a shared ground- I would use a grounding lug screwed to the cavity wall. The preamp grounds would also go to the grounding lug. The Treble, Mid, and Bass pots should be left alone - don't modify the stock Bart wiring. Then just run a wire from the grounding lug to the sleeve lug on the output jack and make sure the cavity shielding is not touching the output jack at all. If you can't avoid having the jack contact the shielding, then make sure you have 0 ohms of resistance between the sleeve lug of the output jack and the shielding and the grounding lug, in which case you don't need the wire between the grouding lug and the output jack. Either wire or shield, but not both.

[BassManPatsFan]

hey man great stuff, good job!

I just recently installed a set of dimarzio model js in my warwick and i have the pickups grounded to teh back of the pots, but I'm getting a very faint hum when I don't touch any of the metal on the bass, so I think I wanna try the complete star grounding on my bass. My question is where do i find a ground lug, and how do I go about attaching all of the ground wires to it?

can i ground the tone capacitor to this ground lug too?

thanks so much!
-Alex

[Minger]

0.o

I never thought of grounding the tone pot, would that work ? Because the more I turn the tone pot up the more hum I get, and vice versa...0.o

[adrian480]

My sheild work:

[Lyle Caldwell]

Originally Posted by BassManPatsFan

hey man great stuff, good job!

I just recently installed a set of dimarzio model js in my warwick and i have the pickups grounded to teh back of the pots, but I'm getting a very faint hum when I don't touch any of the metal on the bass, so I think I wanna try the complete star grounding on my bass. My question is where do i find a ground lug, and how do I go about attaching all of the ground wires to it?

can i ground the tone capacitor to this ground lug too?

thanks so much!
-Alex

I got the ground lug at a hardware store. They sell them in various sizes for different gauges of wire. They're designed to crimp a single wire, so just buy one large enough to hold however many ground wires you'll use. You can also get them at Autozone and other car parts stores.

Scroll down to Ring Terminal Crimped Connectors and look at the images directly above to see what the crimped part looks like. Mine doesn't have the sleeve over the crimp.

I attached them to the lug by stripping about 1/2" of the insulation off each ground wire, then twisting the ground wires together, then tinning the twisted wires. Then I put the (now one big) wire in the sleeve of the ground lug, then partially crimped the sleeve, then soldered the sleeve to the shared wire. Then I screwed the lug through the coppper shield to the cavity wall, first drilling a pilot hole so I didn't split the wood.

You can ground the tone cap to the lug, certainly, but I wouldn't recommend it in a top-routed bass with a control plate, as it would put a lot of pressure on the cap leads when you opened it up. In that case, solder the cap to the output jack or to the back of a pot. In a rear-routed bass where nothing will move, sure, solder the cap to the ground lug if you want.

[Lyle Caldwell]

Originally Posted by Minger

0.o

I never thought of grounding the tone pot, would that work ? Because the more I turn the tone pot up the more hum I get, and vice versa...0.o

No, that just means you have a high frequency hum (probably from single coils) in your bass, and as you turn the tone pot down, you're hearing few of the high frequencies in the hum. If your tone rolls off as you turn down the tone pot then your tone pot is already grounded. You'd need to shield the bass to lose the hum.

[Lyle Caldwell]

Originally Posted by adrian480

My sheild work:

Adrian,

That's looking great. Two suggestions:

1) You might want to shorten the ground leads in the control cavity so they don't bunch up under the controls. Leave a little slack for future adjustments, but keep it as neat as you can.

2) Your control cavity ground goes over the edge of the route all around. But that can leave you open to a ground loop if one screw of the control plate is a little looser than the others. In that case, there would be more than one path to ground, and you could get hum. In practice, it's better to only have the copper shield overlap the control cavity in one spot like in the pictorial.

But it's a very neat job overall!

[Audiophage]

Originally Posted by Lyle Caldwell

I would say carefull desolder and remove the original pots and control plate, in case you ever want to sell to a collector. Buy new pots, control plate, knobs, etc. Then try to do it yourself. The advantage of copper shielding over shielding paint is that you can remove it if needed. So you won't screw your bass up.

And if it all collapses on you, you can always take it to a pro, but your mistakes wouldn't have ruined the original pots.

Ok, cool. I'm not planning on ever giving this bass up to a collector, just so you know.

I'm first going to try it on my GSR to get a feel for things. I noticed that your wiring diagram is slightly different from my bass. Mine has 2 volumes(neck and bridge) and tone. Do you have any diagrams for this type of setup?

[Minger]

His was oringally the same I think, but he rewrired it.

V/B/T

I'm going to do that sooner or later

[Lyle Caldwell]

Originally Posted by Audiophage

Ok, cool. I'm not planning on ever giving this bass up to a collector, just so you know.

I'm first going to try it on my GSR to get a feel for things. I noticed that your wiring diagram is slightly different from my bass. Mine has 2 volumes(neck and bridge) and tone. Do you have any diagrams for this type of setup?

There are a bunch out there. Fender has them, Seymour Duncan, etc. Just run the ground lugs on each pot and the pickup ground wires to a common ground point as in the pictorial instead of grounding them to the pot cases.

[BassManPatsFan]

Originally Posted by Lyle Caldwell

I got the ground lug at a hardware store. They sell them in various sizes for different gauges of wire. They're designed to crimp a single wire, so just buy one large enough to hold however many ground wires you'll use. You can also get them at Autozone and other car parts stores.

Scroll down to Ring Terminal Crimped Connectors and look at the images directly above to see what the crimped part looks like. Mine doesn't have the sleeve over the crimp.

I attached them to the lug by stripping about 1/2" of the insulation off each ground wire, then twisting the ground wires together, then tinning the twisted wires. Then I put the (now one big) wire in the sleeve of the ground lug, then partially crimped the sleeve, then soldered the sleeve to the shared wire. Then I screwed the lug through the coppper shield to the cavity wall, first drilling a pilot hole so I didn't split the wood.

You can ground the tone cap to the lug, certainly, but I wouldn't recommend it in a top-routed bass with a control plate, as it would put a lot of pressure on the cap leads when you opened it up. In that case, solder the cap to the output jack or to the back of a pot. In a rear-routed bass where nothing will move, sure, solder the cap to the ground lug if you want.

thanks so much, man!

you rock! keep up the good work!
-Alex

[Funky Doctor]

Ok, here's my problem,

I just shielded my entire control cavity and pickups routs, 0 ohms between any 2 points, or any point and the ground terminal on the jack. I have an Aguilar OBP-3 in here and when I plug it in I get some serious buzz/hum. I have NO idea what is going on. It worked fine before without the shielding with a bit of buzz when the bass was facing in certain directions, now it is just nuts. Any help?

[Lyle Caldwell]

James,
I'd double and triple check the OBP wiring - if you reversed positive and negative on it at any point, or didn't connect the OBP ground to the shielding, you'll get lots of noise. Can you post a photo of your wiring?

[Modern Growl]

Lyle,
I'm actually a little suprised that you didn't shield the pickup themselves... any thoughts as to why you didn't?

[Lyle Caldwell]

Originally Posted by Modern Growl

Lyle,
I'm actually a little suprised that you didn't shield the pickup themselves... any thoughts as to why you didn't?

I did shield the pickup cavities, just not the inside of the pickup covers.

Two reasons....

First, shielding the covers of a single coil pickup can reduce the top end, and it still won't completely eliminate 60 cycle hum.

Second, I knew that I would be replacing the single coils with humcancelling pickups, so even if there wasn't a downside to shielding the covers, it would have been a waste in my situation.

I went with the Sadowskys after researching everything. Maybe the Nordstrands and Fralins sound better, but with my playing ability, not $150 better. <g>

I'd like to point out that shielding the instrument is still beneficial even with humcancelling pickups, as noise can be introduced to the signal at any point between the pickups and the output jack. Shielding isn't something you only need with singlecoils.

[Modern Growl]

Originally Posted by Lyle Caldwell

I did shield the pickup cavities, just not the inside of the pickup covers.

Two reasons....

First, shielding the covers of a single coil pickup can reduce the top end, and it still won't completely eliminate 60 cycle hum.

Second, I knew that I would be replacing the single coils with humcancelling pickups, so even if there wasn't a downside to shielding the covers, it would have been a waste in my situation.

I went with the Sadowskys after researching everything. Maybe the Nordstrands and Fralins sound better, but with my playing ability, not $150 better. <g>

I'd like to point out that shielding the instrument is still beneficial even with humcancelling pickups, as noise can be introduced to the signal at any point between the pickups and the output jack. Shielding isn't something you only need with singlecoils.

Thanks for the info.
quick question though. Why would you soder the wall to the floor of the cavities if the copper is already touching, or making the connection between the wall and cavity floor? whats the deal? seems redundant, but i'm probably wrong.

also

isn't shielding the pup cavity going to reduce some top end as well, being its so close the the coil? or does the shielding have to be like...... right next to the coil to reduce top end?

[Eric1977]

Truly awesome thread! Thanks for this!!