markdavid Posted May 1, 2016 Share Posted May 1, 2016 Hi all, i have fitted a quarter pound bridge pickup in a p j bass , sounds fine seems to work as it should etc however when i used a screwdriver to tap the pickups when i have the bridge pickup on but the volume for the neck pickup turned off i still got a faint sound from tapping the neck pickup with the screwdriver,it is much quieter than the sound from tapping the bridge pickup with the screwdriver, i am guessing something is up ? What do you think? Quote Link to comment Share on other sites More sharing options...
Manton Customs Posted May 1, 2016 Share Posted May 1, 2016 (edited) It could be that either you've cooked the volume pot, or the first lug that gets grounded to the pot casing is not making contact anymore (via the lug itself or short wire). So check the lug first . Edited May 1, 2016 by Manton Customs Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 1, 2016 Author Share Posted May 1, 2016 (edited) [quote name='Manton Customs' timestamp='1462111348' post='3040333'] It could be that either you've cooked the volume pot, or the first lug that gets grounded to the pot casing is not making contact anymore (via the lug itself or short wire). So check the lug first . [/quote]Thanks, both volumes seem to be working so i think it must be the lug, i have checked the solder joints and they all look ok albeit a bit messy soldering wise so am a bit baffled Edited May 1, 2016 by markdavid Quote Link to comment Share on other sites More sharing options...
Grangur Posted May 1, 2016 Share Posted May 1, 2016 [quote name='markdavid' timestamp='1462112347' post='3040339'] Thanks, both volumes seem to be working so i think it must be the lug, i have checked the solder joints and they all look ok albeit a bit messy soldering wise [/quote] If the soldering is messy make sure there are no stray wire threads or spikes of solder shorting anything. Also if there is a foil backing to the pickguard, make sure nothing is shorting to the foil that shouldn't be doing so. Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 1, 2016 Author Share Posted May 1, 2016 Thanks,if i am getting sound from the p pickup when the p vol is turned down and the bridge pickup is turned up then it would be the wiring for the p pickup that i would need to check wouldnt it? Quote Link to comment Share on other sites More sharing options...
luckydog Posted May 2, 2016 Share Posted May 2, 2016 Before ripping wiring apart, try tapping the offending pickup with a plastic pen or something that isn't ferrous metal ? It's just possible perhaps that the magnets interact between the two J and P pickups, and this is what you are hearing picked up in whichever one is on ? LD Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 3, 2016 Author Share Posted May 3, 2016 Hi, has just occurred to me that the scratch-plate is metal, instead of grounding to the back of the volume pot can I just wedge the ground wire between the scratch-plate and use the scratch-plate to ground the volume pot for the p pickup? Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 3, 2016 Author Share Posted May 3, 2016 (edited) [quote name='markdavid' timestamp='1462267694' post='3041505'] Hi, has just occurred to me that the scratch-plate is metal, instead of grounding to the back of the volume pot can I just wedge the ground wire between the scratch-plate and use the scratch-plate to ground the volume pot for the p pickup? [/quote] Looking into this a bit it seems like this might be a bad idea as the ground for the bridge pickup is grounded to the bridge pickup volume , would this create a Ground Loop ? [url="https://en.wikipedia.org/wiki/Ground_loop_(electricity"]https://en.wikipedia...op_(electricity[/url]) I assume this would be ok as long as I ground both volumes to the metal scratch-plate ? Edited May 3, 2016 by markdavid Quote Link to comment Share on other sites More sharing options...
Ghost_Bass Posted May 3, 2016 Share Posted May 3, 2016 (edited) All grounds must be connected together. Doesn't mather how or where you do this. You an have each pickup grounding on it's volume pot but you need to connect both grounds using a wire solder to each pot casing at each end. With both volumes turned down can you still hear the tapping? Could it be that what you're hearing isn't really from the neck pickup but from the bridge pickup er... picking up (sorry) the tap on the the neck one? The magnet has a big pull and when you get a metal object close it pulls it with a considerable force and the resulting bang will resonate through the bass and can be picked up by the other pickup (sorry again). Edited May 3, 2016 by Ghost_Bass Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 3, 2016 Author Share Posted May 3, 2016 [quote name='Ghost_Bass' timestamp='1462269101' post='3041516'] All grounds must be connected together. Doesn't mather how or where you do this. You an have each pickup grounding on it's volume pot but you need to connect both grounds using a wire solder to each pot casing at each end. With both volumes turned down can you still hear the tapping? Could it be that what you're hearing isn't really from the neck pickup but from the bridge pickup er... picking up (sorry) the tap on the the neck one? The magnet has a big pull and when you get a metal object close it pulls it with a considerable force and the resulting bang will resonate through the bass and can be picked up by the other pickup (sorry again). [/quote] Thanks, with both volumes turned down i cannot hear the tapping ,also i have tried tapping the bridge pickup with only the neck pickup voume on and it does not pickup the bridge pickup Quote Link to comment Share on other sites More sharing options...
Ghost_Bass Posted May 3, 2016 Share Posted May 3, 2016 Post a picture of the wiring, if you can. Quote Link to comment Share on other sites More sharing options...
KiOgon Posted May 3, 2016 Share Posted May 3, 2016 @markdavid - basically I think you're worrying too much - the SD 1/4lb P - pick up is most likely sensing the tapping on the other pick up & creating an output. The J bridge pick up will not have the same sensitivity so won't react to the P being tapped. If you want to test that, completely remove the pick ups from their mountings so there is no mechanical contact between them & try again. IMO - IME etc.etc. John Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 3, 2016 Author Share Posted May 3, 2016 (edited) [quote name='KiOgon' timestamp='1462271710' post='3041556'] @markdavid - basically I think you're worrying too much - the SD 1/4lb P - pick up is most likely sensing the tapping on the other pick up & creating an output. The J bridge pick up will not have the same sensitivity so won't react to the P being tapped. If you want to test that, completely remove the pick ups from their mountings so there is no mechanical contact between them & try again. IMO - IME etc.etc. John [/quote] Sorry I should have been more specific about the pickups , the neck pickup is stock and the bridge pickup is the Seymour duncan quarter pound pickup , I chose a high output bridge pickup to balance out the volume difference between neck and bridge Do you think that the above would still apply? Edited May 3, 2016 by markdavid Quote Link to comment Share on other sites More sharing options...
Ghost_Bass Posted May 3, 2016 Share Posted May 3, 2016 [quote name='KiOgon' timestamp='1462271710' post='3041556'] @markdavid - basically I think you're worrying too much (...) [/quote] +1 So, the main questions that remain unasked. How does the bass sound? Do you like the tone? Does it have any humming or RF noise? Will you be playing it live using a screwdriver as a pick? Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 3, 2016 Author Share Posted May 3, 2016 [quote name='Ghost_Bass' timestamp='1462273507' post='3041576'] +1 So, the main questions that remain unasked. How does the bass sound? Do you like the tone? Does it have any humming or RF noise? Will you be playing it live using a screwdriver as a pick? [/quote] Thanks, yes the bass sounds good,the bridge pickup on its own still sounds like a bridge pickup should so i guess the bleeding through of the neck pickup is not affecting the tone so maybe i am worrying too much about this Quote Link to comment Share on other sites More sharing options...
KiOgon Posted May 3, 2016 Share Posted May 3, 2016 [quote name='markdavid' timestamp='1462272115' post='3041561'] Sorry I should have been more specific about the pickups , the neck pickup is stock and the bridge pickup is the Seymour duncan quarter pound pickup , I chose a high output bridge pickup to balance out the volume difference between neck and bridge Do you think that the above would still apply? [/quote]Apologies I misread the original post. Yes still applies - the P pick up is most likely a sensitive beast - do the isolation test Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 3, 2016 Author Share Posted May 3, 2016 [quote name='KiOgon' timestamp='1462274796' post='3041594'] Apologies I misread the original post. Yes still applies - the P pick up is most likely a sensitive beast - do the isolation test [/quote] Ok thanks, so to do the isolation test I unscrew the pickups from the body of the bass and move them as far away from each other as possible? Quote Link to comment Share on other sites More sharing options...
Ghost_Bass Posted May 3, 2016 Share Posted May 3, 2016 [quote name='markdavid' timestamp='1462275157' post='3041608'] Ok thanks, so to do the isolation test I unscrew the pickups from the body of the bass and move them as far away from each other as possible? [/quote] I'm guessing that you just need to have the pickup detatched from the body so that it doesn't[u] pick up/transmit (depending of the tested PU)[/u] any vibrations from/to the bass. It's easier if you remove the strings first. Hold each pickup with your hand carfully so that you don't pull the wire too much and test each with the screwdriver. If the tapping is still noticeable it's because your volume pot is knackered and doesn't fully cut your sound or something in the wiring isn't connected as it should. Quote Link to comment Share on other sites More sharing options...
markdavid Posted May 4, 2016 Author Share Posted May 4, 2016 Have had gas for a Seymour Duncan SPB-1 Vintage for P bass pickup as I think the Quarter pound J and the SPB-1 together could have some interesting tonal possibilities, also would be good to use the P pickup soloed for old school motown like tones so have ordered an SPB-1. Anyway I digress way too much, I will do the isolation test when I receive and fit the new pickup. Quote Link to comment Share on other sites More sharing options...
luckydog Posted May 5, 2016 Share Posted May 5, 2016 Hhmmm, if it sounds good and works as it should I'm not seeing the prob here.....for all we know you've stumbled on something wonderful and unique in terms of pickup interaction that is custom to you...... Someone's law says if you muck about with something long enough it will break........! HTH! LD Quote Link to comment Share on other sites More sharing options...
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