| Author | Message | ||
| fdeeptone
Junior Username: fdeeptone Post Number: 39 Registered: 3-2009 |
Posted on Thursday, May 27, 2010 - 9:42 am: -------------------------------------------------------------------------------- Well i started a new thread in hopes to get some information. I took my spoiler electronics out and had them inspected by a local tech,all the soldering is good and the companants checked out. I put it all together again and still it seems to be a grounding issue. if i touch the jack going into the bass the noise stops. Could this be as simple as repainitng the cacity with conductive paint? And if so would i ue aluminum or nickel? thanks in advance for any help adriaan Moderator Username: adriaan Post Number: 2495 Registered: 6-2002 Posted on Thursday, May 27, 2010 - 9:51 am: -------------------------------------------------------------------------------- Since it changes when you touch the jack, did you try with different cables? Or the same cable with a different instrument? fdeeptone Junior Username: fdeeptone Post Number: 38 Registered: 3-2009 Posted on Thursday, May 27, 2010 - 10:31 am: -------------------------------------------------------------------------------- yes I have tried different cables different basses. It only happens with the spoiler, I can actually ground it with my body, just touching the wood. If someone else touches the jack while im holding the bass they dont ground it, but if i touch the jack while holding the bass it grounds. | ||
| mica
Moderator Username: mica Post Number: 6758 Registered: 6-2000 |
On early Spoilers, it's possible to plug the pickups in upside down. So if you unplug the pickups, rotate the connector 180 degrees and reconnect, your hum might go away. Try it out and let me know what you find. | ||
| fdeeptone
Junior Username: fdeeptone Post Number: 40 Registered: 3-2009 |
Hi Mica, First of all thank you for taking the time to reply  The spoiler is an 1982 but the connectors for the pups will only go on one way. if you turn them over they wont seat all the way down. Is it possible that that i am losing ground from the silver paint? I placed a meter on the painted area in several places and recieved varied readings. | ||
| fdeeptone
Junior Username: fdeeptone Post Number: 41 Registered: 3-2009 |
Oh somthing else i noticed at practice tonight, The low pass filter plays a big part in the volume of the noise, If I turn it about halfway down the noise isnt too bad but if i turn it up it is very loud. | ||
| dfung60
Senior Member Username: dfung60 Post Number: 427 Registered: 5-2002 |
I think the problem you have here is that there's a ground connection between the bridge and the common ground in the control cavity that's not connected. You might have missed this when reassembling the electronics. Alembics shouldn't need this as much as something like a traditional Jazz Bass, but it's common for the bridge and strings to be connected to the electrical ground. When connected this way, when you touch the strings, your body becomes part of the ground plane as well. Since you're a big bag of non-conductive water (no offense intended), your body makes a fairly good shield. There's probably a wire that runs from the conductive paint or the EQ board to the base of the bridge that makes you part of the circuit. If you left either end of that wire disconnected, you'll get buzz like you describe. When you touch the shell of your cable, your hand is making the ground connection and you're part of the shield. When somebody else touches the cable they're part of the shielding now, but they're not close enough to the pickups to held reduce the noise. The interference you're picking up has some high-frequency components. That's why turning down the tone control reduces the level of the noise - it's just filtering the noise out along with your instrument's treble. The reason that this is a little odd is that your Spoiler has hum-cancelling pickups, so it shouldn't be all that noisy (vs. something like a Strat that has true single-coil pickups). The Alembic folks can confirm whether there's supposed to be a bridge ground wire. The grounded bridge helps noise, but you do need to be a bit careful. If any of the outlets on stage are wired backward, if there are any 2-prong AC cords, or if there are any 3-prong to 2-prong adapters, then there's a shock hazard with the grounded bridge. For instrument amplifiers, signal ground also equals electrical ground and if your polarity is reversed with regard to anything else on stage, the current will flow though YOU. That'w unpleasant if you're in the US and could be fatal if you're in Europe with 230VAC mains. David Fung | ||
| mica
Moderator Username: mica Post Number: 6769 Registered: 6-2000 |
There is no ground wire to the bridge on Alembic instruments. Try this troubleshooting and get back with us. Put the bass face down on a table while it's plugged in. Move your hand closer and farther away from the backplate. Come close and touch the backplate too. Do you hear any difference in the buzz? Ok, now flip the bass over and do the same hand approach test over the controls. Get in really close again and touch the wood between the knobs. Do you hear any difference in the buzz? Reach between the strings and touch the pickups. Do you hear any difference in the buzz? Also, share a picture of the inside of the cavity. I'm not sure you have the original backplate, it doesn't look quite right to me. Is the inside of the backplate shielded? The shielding inside the Spoiler is silver conductive paint. Unless it's been breached or painted over, it should conduct just as well as it did in 1982. It doesn't break down over time. But seeing an image will help evaluate what is going on. You've got some homework to do! | ||
| fdeeptone
Junior Username: fdeeptone Post Number: 42 Registered: 3-2009 |
Thank you David, Thank you Mica, I will post a picture tomorrow of the cavity. Ill run the tests tonight. The shield is coated in silver and I beleive it is the correct shield. This just started recently for no apparent reason. Ill have more information tommorrow. Thanks for your input! | ||
| fdeeptone
Junior Username: fdeeptone Post Number: 43 Registered: 3-2009 |
Well i did my homework here are the results. If i move my hand close and then away from the backingplate no change in sound. Bit of crackling when i touched the backing plate but it was only secured with 2 screws at the time due to constantly having to remove the back plate. turning the bass over and testing the controls no real response to speak of. when reaching in between the strings and touching the pups it seems to get louder but it also seems to get louder as my hands approach the strings. Touching the strings,bridge,tuners, all increase the noise.touchiing the guitar input jack instantly grounds and no sound. I have added a link with some pics of the electronics and wiring.I hope my tests give some clue as to what the problem is. here is the link. http://cid-065b7782ed48fdec.skydrive.live.com/browse.aspx/instruments?uc=6&isFromRichUpload=1 | ||
| fdeeptone
Junior Username: fdeeptone Post Number: 44 Registered: 3-2009 |
I guess i will just send the electronics to alembic and see if you can find anything wrong with them. I just stripped the bass down today for refinishing. if the above test gives a clue as to the problem your input would be appreciated. |
