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Jazz Shielding Pictorial (Big Images Warning)

#541
Stuggi said:
Thanks mate, I'll add the missing pics today or tomorrow, maybe rework the PDF a bit. Would it be a good idea to add an appendix or two on grounding and audio signal theory?
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No problem! I would say anything contributed to the doc would be good as long as it didn't grow to be too big to be as useful as it is now. Maybe some topical stuff, but not too much detail. Just enough to understand the principles and goals, without necessarily getting into the specific science behind it. I would think that would serve the most people best.

Anyway, keep the thread updated, at least I'm curious what you come up with. :)
 
#546
Do note that you could create a ground loop (basically you need to think of it as a map, if you start at Point A, and you can go back to Point A without going back the way you came you have a ground loop) by dotting it in several places. Personally I just make a blob in a corner of the cavity and check the resistance (it should be around 0 Ohms). This way you form the pieces into a long conductor, and then you ground it to the jack at one end.

Then again, I don't think that dotting in several places would induce that much humming, but it's good practice to star ground as even a copper foil has a bit of resistance.

EDIT: I meant to say one dot between every 2 pieces, all pieces should connect to a previously grounded piece of course. :D
 
#547
Vic said:
No problem! I would say anything contributed to the doc would be good as long as it didn't grow to be too big to be as useful as it is now. Maybe some topical stuff, but not too much detail. Just enough to understand the principles and goals, without necessarily getting into the specific science behind it. I would think that would serve the most people best.

Anyway, keep the thread updated, at least I'm curious what you come up with. :)
Click to expand...

Yeah, nothing with a lot of physics and stuff, just a simple intro into star grounding with maybe an short explanation of why it's a good idea, but definitely no "the series resistance between different case ground points and their impact on the 50/60 Hz hum induced by alternating magnetic fields in the surroundings of mains wiring". :D
 
#548
Do you have to have a copper foil tunnel through the tunnel that goes up to the bridge for the grounding just like lyle did a tunnel from the control cavity to the pickup cavity? The tunnel seems way too small to the birdge to get any foil in there and it doesn't seem like it'd do anything.
 
#549
paf77 said:
Do you have to have a copper foil tunnel through the tunnel that goes up to the bridge for the grounding just like lyle did a tunnel from the control cavity to the pickup cavity? The tunnel seems way too small to the birdge to get any foil in there and it doesn't seem like it'd do anything.
Click to expand...
No, because the only thing that goes there is the ground wire. Lyle wrapped the wires from the pickup routes because SIGNALS passed through there. :)
 
#550
Yes, you don't need a shield for cables carrying ground. An easier way to shield the pickup signals are to use a coaxial cable, with a wire mesh around it as the ground conductor so shield the pickup cables, but both methods work. A third way is to use a 2 strand shielded cable, so you ground the shield and the pickup ground independently, which IMHO is the best way to do it, this way you're sure that the pickup ground is a really good one, and you have a good shield and ground conductor for the pickup cavity shielding. Just make sure that the pickup ground and shielding ground don't short out in the pickup cavity if you go this way, as then you get one of those nasty ground loops.
 
#551
Stuggi said:
A third way is to use a 2 strand shielded cable, so you ground the shield and the pickup ground independently, which IMHO is the best way to do it, this way you're sure that the pickup ground is a really good one, and you have a good shield and ground conductor for the pickup cavity shielding. Just make sure that the pickup ground and shielding ground don't short out in the pickup cavity if you go this way, as then you get one of those nasty ground loops.
Click to expand...
This has actually been strongly debated by folks on this thread (including myself). While your comments make perfect sense from a purely electrical perspective, IMHO, they are moot in a bass guitar.

This is because the two grounds are effectively shorted at the jack anyway (there's only one ground and one signal in your guitar cord). I personally don't believe in ground loops internal to a bass guitar unless there's just an insane crazy rats nest of wiring in it. I strongly contend that you don't need to even consider separation if the grounding scheme uses sensible connections and wire lengths.

In fact, I even made the effort to create a ground loop using arguments from the other opinion, and was unable to hear any difference.
 
#553
Lyle Caldwell said:
There have been a lot of questions about shielding and star grounding, so maybe this will help someone.

Here's the schematic I came up with to do this with:

SchematicBVT.jpg


Any chance of getting the original post edited with links to the pictures that aren't broken? I'm about to do this to my p-bass special and it would be very helpful.

Thanks!
Click to expand...
 
#556
My little P-bass project. I'm hoping I did it right (the star grounding thing). I star grounded the isolated "studio" circuits my house, but never a bass. Seemed like the same idea. When I tested the foil shielding, I discovered that the conductive adhesive works, but I got measurably less resistance across the shielding foil after soldering the overlapping sheets together. I wrapped foil around a drill bit and shielded the pickup channels as well.

Side note. . . Bourns pots are very loose feeling and turn with little physical resistance, and I used 20 AWG silver coated teflon wire (only colors I found were white and white/blue). Don't know if that'll make any impact good or bad on tone.

Please comment if you see that I made any critical errors.

IMG_4161.jpg


IMG_4164.jpg


IMG_4166.jpg
 
#557
chunger said:
My little P-bass project. I'm hoping I did it right (the star grounding thing). I star grounded the isolated "studio" circuits my house, but never a bass. Seemed like the same idea. When I tested the foil shielding, I discovered that the conductive adhesive works, but I got measurably less resistance across the shielding foil after soldering the overlapping sheets together. I wrapped foil around a drill bit and shielded the pickup channels as well.

Side note. . . Bourns pots are very loose feeling and turn with little physical resistance, and I used 20 AWG silver coated teflon wire (only colors I found were white and white/blue). Don't know if that'll make any impact good or bad on tone.

Please comment if you see that I made any critical errors.

IMG_4161.jpg
Click to expand...
Nice work! The only critical error I see is owning that Twilight DVD
:bassist:
 

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