Mickguard Posted October 16, 2005 Report Share Posted October 16, 2005 I'm trying to fit a metal pickguard over a P90 --the P90 doesn't have its cover --I've drilled holes in the guard for the P90's poles. It looks great. But. The P90 doesn't seem at all compatible --the entire pickguard starts sounding like a pickup --and the pickup sounds like crap. A huge drop in volume and especially a dramatic loss of tone. The other pickups sound as normal with the pickguard --so why is the P90 incompatible? Better still, what can I do to make it work? I have a piece of copper shielding there. I've tried cutting a piece of plastic to place between the metal and the P90 -- no result. I suppose I could expose the P90 entirely (and replace the cover), but it won't look the same. Anyway, I know that there are chrome covers for P90s --why do they work? Quote Link to comment Share on other sites More sharing options...
thegarehanman Posted October 16, 2005 Report Share Posted October 16, 2005 Wait...you're fitting the pickguard "over" the P90? So I imagine this pickguard is grounded since it's metal, right? If that's the case, then you're putting a ground signal in between the magnetic field of your P90 and your strings...than can't be good. Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 16, 2005 Author Report Share Posted October 16, 2005 Wait...you're fitting the pickguard "over" the P90? So I imagine this pickguard is grounded since it's metal, right? If that's the case, then you're putting a ground signal in between the magnetic field of your P90 and your strings...than can't be good. ← It ain't good, I can say that much The pickup's grounded-- I imagine the pickguard gets grounded once it touches the pickup? Maybe this is a case where there's a double ground --because the pickguard is also touching a second, grounded pickup? Suppose I remove the ground from the P90 (or attach that directly to the pickguard)? Quote Link to comment Share on other sites More sharing options...
thegarehanman Posted October 16, 2005 Report Share Posted October 16, 2005 Is there any way you could cut holes in the pickguard so the polepieces stick out. That would function just like a pickup with a metal cover. Ordinarily, it's be ok to have the ground there, but I'm thinking that perhaps the combination of the ground signal and the (relatively) large gap between the pickup and strings is the culprit. I can't say this with all certainty though, so take it with a grain of salt. It'd be nice if lovekraft would chime in right now. Quote Link to comment Share on other sites More sharing options...
Daniel Sorbera Posted October 16, 2005 Report Share Posted October 16, 2005 Try ungrounding the pickguard. Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 16, 2005 Author Report Share Posted October 16, 2005 I should point out that this is on my telecaster. The pickguard itself isn't grounded, but it's touching the bridge plate and the neck pickup, both of which are metal and both of which are grounded to the volume pot. The P90 is also grounded to the volume pot. Neither the bridge nor the neck pickup lose their tone, only the P90. Quote Link to comment Share on other sites More sharing options...
thegarehanman Posted October 16, 2005 Report Share Posted October 16, 2005 try ungrounding the pickguard Nooo, you think? Do I hear an echo? That idea is to be inferred from what I said. However, it looks like ungrouding the pickguard could be more difficult than it seems. Idch, didn't you have a plastic pickguard on that tele before? Didn't that work fine? If that's the case, then your answer is pretty blatent. Both the bridge and neck pickups are not covered by the pickguard, correct? Once again, if the answer is "yes," then I think the answer to your problem may be staring you in the face. peace, russ Quote Link to comment Share on other sites More sharing options...
Daniel Sorbera Posted October 16, 2005 Report Share Posted October 16, 2005 try ungrounding the pickguard Nooo, you think? Do I hear an echo? ← Yes I know. In his post above mine it looked like mabye he still diddn't get that he needed to unground his pickguard... Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 16, 2005 Author Report Share Posted October 16, 2005 Not so fast, bub... I drilled holes in the guard for the pole pieces --they stick through, they're fairly close to the strings, they don't touch the pickguard. I had a wooden pickguard on there before --that covered the P90 completely (about 1 mm of wood above the pickup itself), the sound came through just fine. I'll play around with it some more tomorrow, in the meantime maybe some of the resident electronics gurus will wake up...I'm willing to bet this is pretty simple. In the meantime, I'll just play a different guitar Quote Link to comment Share on other sites More sharing options...
thegarehanman Posted October 16, 2005 Report Share Posted October 16, 2005 I'd PM lovekraft. I don't know if he checks the Tech Area section, so he might not see this. I don't know what else it could be(other than the ground). hmmmm Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 16, 2005 Author Report Share Posted October 16, 2005 try ungrounding the pickguard Nooo, you think? Do I hear an echo? ← Yes I know. In his post above mine it looked like mabye he still diddn't get that he needed to unground his pickguard... ← The question is how is the pickguard being grounded and what do I need to do to 'unground' it --because I haven't attached a wire to it or anything like that. Hmm, should I wrap the underside in insulation tape? Quote Link to comment Share on other sites More sharing options...
thegarehanman Posted October 16, 2005 Report Share Posted October 16, 2005 Assuming that's the problem, you'd have to find every piece of metal that's grounded that's touching the pickguard and cover that area so they don't make electrical contact any more. I'd say electrical tape would work for this. Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 16, 2005 Author Report Share Posted October 16, 2005 Assuming that's the problem, you'd have to find every piece of metal that's grounded that's touching the pickguard and cover that area so they don't make electrical contact any more. I'd say electrical tape would work for this. ← Okay, that's along the lines of what I've been thinking. The pickguard's worth the hassle though --when I get this problem sorted out, I'll post pictures for sure. Quote Link to comment Share on other sites More sharing options...
crafty Posted October 16, 2005 Report Share Posted October 16, 2005 If the pickguard is ferrous metal, it's probably messing with the magnetic field from the bar magnet. If you lift the ground off the pickguard that'll probably just induce hum into the system. What is the pickguard made out of? Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 16, 2005 Author Report Share Posted October 16, 2005 If the pickguard is ferrous metal, it's probably messing with the magnetic field from the bar magnet. If you lift the ground off the pickguard that'll probably just induce hum into the system. What is the pickguard made out of? ← Jeez, that's a good question...I cut it from a bunch of rusted old shelving....so if it's screwing with the pickups, does that mean it's hopeless? Why doesn't it mess with the other pickups? Quote Link to comment Share on other sites More sharing options...
Southpa Posted October 16, 2005 Report Share Posted October 16, 2005 (edited) I was going to suggest the same, seeing that the problem is unique to the P-90. The P-90 pickup covers more area than normal single coils. Perhaps its wide, squat shape is more reactive to the mild steel in such close proximity? The effect could also exist in regular sized single coils but just not as noticeable, I couldn't say. To eliminate the grounding theory try insulating the pickguard from all other components. ie. pickup mounts, bridge plate (its also grounded thru the bridge pup). Check with a multimeter as you go by touching the pickguard and output jack ground. When you have totally isolated the 'guard and your P-90 is still sounding bad then the most reasonable conclusion is that the excess metal is playing havoc with the pickup's electromagnetics. If the pup works fine then allow only ONE path to ground for the pickguard. The most obvious might be its contact with the bridge plate. Edited October 16, 2005 by Southpa Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 16, 2005 Author Report Share Posted October 16, 2005 The neck pickup has a similar effect, in that the pickguard becomes microphonic. But the sound of the neck pickup doesn't change. Tomorrow I'm going to cut a new piece of the same metal so that it only fits over the pickup and doesn't touch anything else. That'll help isolate the problem I figure. The pickguard touches against the bridge plate --could that be the problem? Maybe it's grounding out by touching that? But I'm correct in thinking that I've seen metal pickguards before, so there's no reason why this can't work, right? Quote Link to comment Share on other sites More sharing options...
lovekraft Posted October 16, 2005 Report Share Posted October 16, 2005 This is just my "best guess" on this situation, and I'm no electromagnetics engineer, but using any magnetic material is likely to cause you some grief, because it's going to reshape the magnetic field of the pickup - it's quite possible that the wider coil on the P90 is influenced more radically than the single simply because of its width. FWIW, I've seen aluminum, brass and even solid copper used as pickguards, but I can't remember ever seeing an iron/steel one. I also sincerely doubt that grounding the pickguard has much to do with your problems, since they appear to be magnetic in nature, but as I said earlier, this ain't my area of expertise, so take all this with a big block of salt! Sorry I can't be more help. You might PM or email RG - IINM, he's a transformer designer in real life, and probably knows more about magnetics than the rest of us together! Quote Link to comment Share on other sites More sharing options...
jnewman Posted October 16, 2005 Report Share Posted October 16, 2005 (edited) Here's just my guess. The traditional singlecoils are both entirely through the pickguard (no metal over the tops), and have magnetic pole pieces, so the "important" part of the magnetic field mostly comes out of the top of the pole pieces, and the responding field from the strings goes straight through the coil without anything blocking it. The P-90 is covered over the top except for the pole pieces, which in a P-90 are just steel slugs - they have a bar magnet under the pup like a humbucker. So you're blocking some of the magnetic field from the magnet by having the metal over some of the magnet (even though the pole pieces aren't covered), and you're blocking some of the magnetic field from the strings, which can't reach the interior of the coil because a good portion of the coil is covered by the metal pickguard. I'd bet if you actually uncovered the P-90 (so that it's installed like the single coils) it'd work fine, or that if you just drilled pole piece holes for the single coils instead of through-mounting them as you did with the P-90 you'd have pretty much the same problem. Edited October 16, 2005 by jnewman Quote Link to comment Share on other sites More sharing options...
crafty Posted October 16, 2005 Report Share Posted October 16, 2005 (edited) Email Bill Lawrence, he'd be able to tell you for sure, but my money's on the steel pickguard screwing with the magnetic field. Keep in mind that the polepieces aren't designed to pick up all of the string's vibrations--they simply help focus the broader field. It would also explain why the pickguard is microphonic on the neck pickup. You're inducing a vibration into a magnetic field and the pickup is going to pick that up the same way it picks up the string vibrations. This is why pickup covers are not made out of steel. Edited October 16, 2005 by crafty Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 17, 2005 Author Report Share Posted October 17, 2005 Okay, yes, it's looking like a fatal incompatibility... It's definitely not the grounding --this morning I taped off all the edges, including the parts that actually touch the P90. So there's no metal touching metal anywhere. Still screws up the P90. I also took a very small piece of the same metal and set it so it touched the pickup, the control plate and the bridge plate --no effect on the P90. (because there's not enough metal there to screw with the P90s magnetic field, I figure) Of course, now that I understand a little more about the P90s construction vs the other pickups (thanks guys! ) it makes perfect sense... It's a very pretty pickguard, but it'll have to go! (boot!) Back to the drawing board... in the meantime, I've developed a new idea while trying to find a workaround...don't know if I'll use it for this guitar, but it's a good one. Now, I need to find a different type of metal...hmmm...zinc? Quote Link to comment Share on other sites More sharing options...
Southpa Posted October 17, 2005 Report Share Posted October 17, 2005 (edited) Thats why the first 2 guitars I built have pickguards made from stainless steel. There is NO interaction between magnets and stainless. I used commercial grade 16 ga. scrap stainless, the type made for appliances etc. I sand it with 120, 180, 320, 600, 800, 1200, 1500, 2000 and finally 2500 grit paper. Then polish with 6 micron, 2 micron and finally 1/4 micron diamond grit polish. Comes out like a mirror! Edited October 17, 2005 by Southpa Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 17, 2005 Author Report Share Posted October 17, 2005 Thats why the first 2 guitars I built have pickguards made from stainless steel. ← Yeah, but stainless steel doesn't rust Quote Link to comment Share on other sites More sharing options...
Southpa Posted October 17, 2005 Report Share Posted October 17, 2005 Yeah, but stainless steel doesn't rust Isn't that good? Whats your point? Quote Link to comment Share on other sites More sharing options...
Mickguard Posted October 17, 2005 Author Report Share Posted October 17, 2005 Yeah, but stainless steel doesn't rust Isn't that good? Whats your point? ← (click me I get bigger ) It looks even better on the guitar. So if there's any way to save this one, I want to go for it...even if it means giving up the P90.... Quote Link to comment Share on other sites More sharing options...
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