petros
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Post by petros on Apr 2, 2008 19:24:30 GMT -5
I was checking out this excellent article from the original Guitarnuts website but I can't find an answer to whether the cavity below the output jack needs to be shielded in the same manner you would the control cavity. I realize that the connection to the output jack is often made with a cable that is braided shield/ single conductor, but in my case the hole connecting to the adjacent cavity will only allow two thin wires through it.
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Post by newey on Apr 2, 2008 20:09:54 GMT -5
Petros-
This subject has been briefy discussed hereabouts, but not at any length. You'll find a few posts scattered about that discuss shielding the jack cavity if you do a search using those terms, and going back a few years.
The consensus seems to be that it's worthwhile to do if you're in there already.
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petros
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Post by petros on Apr 3, 2008 3:38:09 GMT -5
Thanks newey.
on Jan 25, 2008 sumgai said about shielding:
"The short run between a Strat's control cavity and the output jack, that's a questionable benefit, it's so short."
However, on Oct 8 2007 he said:
"You should shield all cavities that have anything to do with the signal...Most folks feel that doing the output jack's cavity is optional, due to the small cavity area involved. I, however, am of the opinion that wood does not stop electromagnetic hum, so if one does not shield that area too, then one has left an opening for hum/buzz to get into the circuitry, and therefore the guitar won't be at it's most quiet."
----I'm assuming if I was able to use shielded cable it wouldn't be as critical, but since I can't I'll shield the cavity with copper adhesive tape. The copper tape at the output jack cavity should be connected to the shielding at the adjacent cavity, yes?
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Post by newey on Apr 3, 2008 4:26:56 GMT -5
Petros-
Yes, the jack cavity shielding would need to be electrically continuous with the rest of the shielding in order for it to have any effect. This could be via a wire. If you use shielding paint, you can also use a cotton swab to coat the inside of the hole from the control cavity to the jack cavity- I've heard of that being done, never done so myself, so YMMV.
Your other option is to enlarge the hole so you can get a shielded cable through there.
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Post by ashcatlt on Apr 3, 2008 7:02:08 GMT -5
...or use a smaller shielded cable!
Since the shielding in the jack cavity will contact the jackplate, it should be connected to your other shielding by way of the ground wire coming from the contol cavity. Keep in mind also, that this jackplate is on the "wrong side" of the safety capacitor (if it exists).
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Post by D2o on Apr 3, 2008 12:39:01 GMT -5
Good call, Ash
Personally, I like and employ Wolf's (past) idea of rigid telephone wire. I can't say enough good things about that idea.
Also, I am not sold on the need for shielded cable.
Most of it is already shielded by the QTB shielding, and I don't recall having read anything from anyone here where they offer any hard data that it is particularly beneficial (not that it would hurt).
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Post by sumgai on Apr 3, 2008 14:44:13 GMT -5
Dan, No, there is no hard data available, AFAIK, that shows just how much reduction in noise is realized from using shielded wire versus twisted pair. petros, The same thing goes here, no hard data on how much reduction in noise is realized from shielding the jack cavity. So, further discussion is in order.......... I believe that somewhere on these pages, I once said "95% is good enough, shielding the jack cavity probably won't get you that remaining 5%", or some such. That's most likely true, but I'm operating from gut feel here, not hard data! I also base some of my observations on the effort required to do the mod. If you're already in there............ If you are wanting to open up only the jack cavity for just this job, then you have to weigh the possible benefits versus the time and effort. Me, I wouldn't do it, but that's based on past experience. I shielded the jack cavity on all of my previous Strats, but the current one's jack cavity is unshielded. In the locations where I play, I don't perceive that this guitar is any more noisy than my previous one(s). But that's just me, your mileage may vary. And as ash points out, if you add the safety capacitor mentioned on the original GuitarNuts site, then the jack is on the wrong (unprotected) side of that cap. Not much you can do about that, short of installing an insulated jack. Most folks don't bother with that expense and trouble, for obvious reasons. And I'd also use the twisted pair, instead of shielded cable. Again, in this case (a very short run), the extra effort and expense probably isn't gonna pay off, to get that last 1 or 2%. Oh, and nice shielding job! HTH sumgai
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petros
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Post by petros on Apr 3, 2008 19:42:03 GMT -5
Thanks for the replies. I got a conflict though with the typical star grounding design. If only the signal grounds are attached to the star washer, then the washer should be insulated and doesn't attach to the copper of the cavity (which is the "chassis" ground), yes? The original guitarnuts instructions here don't say anything about attaching the star to anything and to isolate the connection. However, here is an example of star grounding where the design indicates running a wire from the star washer to the inside of the pickup cavity: www.alloutput.com/Wiring/HSH_wiring_layout_1.pdfThe star washer should remain isolated, yes?
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Post by newey on Apr 3, 2008 20:08:59 GMT -5
Petros-
It goes on the shaft of one of the pots, and thus is in contact with the pickguard shielding, as per the original scheme. However, you can attach all grounding points to the cavity also, via a screw/ ring connector.
Either way, your signal ground and shield ground do meet up at some point. You isolate the star up to the point of grounding so as to avoid inadvertent contact with other connections.
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petros
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Post by petros on Apr 3, 2008 21:19:53 GMT -5
AH!
I just realized now that the safety cap in the drawing from the guitarnuts article is the connection between the star washer and the volume pot, and the pot touches the shielding. I have too many wiring diagrams I keep referring to for the sake of looking for consistency! I see now that you can do it both ways--either at the volume pot with the safety cap or connecting a seperate wire from the star washer.
Thanks for clearing that up, newey.
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petros
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Post by petros on Apr 4, 2008 10:57:23 GMT -5
Introducing the J-file. It's actually a type of round coping saw blade that can cut in all directions. I snipped off one end of the blade and bent it so it could slip into the existing hole and fit between the two cavities. Works like a flexible rat tail file. Now a shielded cable can fit through easily. (I think I'm becoming a guitar nut. )
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Post by D2o on Apr 4, 2008 12:32:03 GMT -5
Introducing the J-file. It's actually a type of round coping saw blade that can cut in all directions. ..... (I think I'm becoming a guitar nut. ) Now that's intuinventionitive thinking, petros! I have the same blade, and wouldn't have thought of that. Yes, how does it feel knowing that you are soon-2-b-certifiably-nutz! ;D
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Post by sumgai on Apr 4, 2008 12:57:14 GMT -5
Dan, It oughtta feel pretty good - I just plus one'd him! ;D
sumgai
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