Guest lime Posted September 6, 2003 Report Share Posted September 6, 2003 right, my guitar squeals, i put my finger on the metal plate with the volume knobs on and it stops the squealing (mostly). i therefore deduced that my guitar is picking up oscilations, and i need to put a decoupling capacitor across the source (pickups) am i right or am i drastically wrong? if so, around what size capacitor shall i experiment with? Quote Link to comment Share on other sites More sharing options...
Alex Posted September 6, 2003 Report Share Posted September 6, 2003 I had a similar problem with my guitar, and had to rewire it because the live wire exposed and soldered really badly. I'd check the wiring. Decoupling capacitors are only typically used in DC circuits I think. Z=1/jwC and all that malarkey. Quote Link to comment Share on other sites More sharing options...
soundian Posted September 7, 2003 Report Share Posted September 7, 2003 Yup, sounds like bad wiring. That's certainly the first avenue to explore. Cheapest to fix and the likeliest. Bad earths are a very common problem.You seem to be earthing it when you touch the metal plate, which is probably in electrical contact with your volume and tone pots. Does it do the same when you touch the stings as well? Quote Link to comment Share on other sites More sharing options...
Guest lime Posted September 7, 2003 Report Share Posted September 7, 2003 well, bad earthing was my first theory, i checked the wiring and there was some bad connections, re-soldered them, thing is, i cant see any connections to the metal plate witht he pots on, which is why i changed my theory to picking up wobulations (it happened on a regular basis in the labs last eyar when i did electronics, but we had a scope, a little easier to fualt find with an oscilly)) and its cured by using a decoupling capacitor, i cant see why adding in the impedance of the capacitor would make any difference, am i wrong? im going to maplin to buy some tubes and a set of capacitors, ill experiment after iv resolered all the wiring. i think the strings do effect it aswell, and the plate that the strings are attached to aswell, but strings to lesser extent. Quote Link to comment Share on other sites More sharing options...
Guest lime Posted September 7, 2003 Report Share Posted September 7, 2003 iv got another possible solution - , nothing guitar related turns out, "(Note... the high pitched ringing sound your amp usually makes is not parasitic oscillation. It is a microphonic preamp tube, a problem that is far more common. Here's how to tell the difference: pull the guitar cord out of the input jack. Turn it up really loud and smack it. Does it make the amp ring more or stop rInging? Yes? Then reach around back and tap on each preamp tube individually. The one that makes the sound needs to be replaced.) " Quote Link to comment Share on other sites More sharing options...
David Posted September 7, 2003 Report Share Posted September 7, 2003 if its a cheap guitar it couls be a microphonic pickup, that would need replacing or wax potting to stopDavid Quote Link to comment Share on other sites More sharing options...
Guest lime Posted September 7, 2003 Report Share Posted September 7, 2003 it is,,,i ordered new pots and switch selector, gonna re-wire the whole thing with new parts and see what happens, otherwise itll be new pickups, i havean open coil and a closed coil, squire tele, which one dya reckon is the offender? Quote Link to comment Share on other sites More sharing options...
soundian Posted September 8, 2003 Report Share Posted September 8, 2003 Originally posted by lime it is,,,i ordered new pots and switch selector, gonna re-wire the whole thing with new parts and see what happens, otherwise itll be new pickups, i havean open coil and a closed coil, squire tele, which one dya reckon is the offender? How did you come to that conclusion. And surely if you change pickups, the squealing will stop if it's ONE microphonic pickup. I'm not ruling out both, or there being more than one problem. Quote Link to comment Share on other sites More sharing options...
Guest lime Posted September 8, 2003 Report Share Posted September 8, 2003 i didnt really come to any conclusion, i just got fed up and decided to gut the bastard. Quote Link to comment Share on other sites More sharing options...
Alex Posted September 15, 2003 Report Share Posted September 15, 2003 I'd just ground it properly. Quote Link to comment Share on other sites More sharing options...
GraemeC Posted September 15, 2003 Report Share Posted September 15, 2003 Originally posted by Alex I'd just ground it properly. I think you're right, but how deep in the ground? Quote Link to comment Share on other sites More sharing options...
GraemeC Posted September 16, 2003 Report Share Posted September 16, 2003 Originally posted by lime right, my guitar squeals, i put my finger on the metal plate with the volume knobs on and it stops the squealing (mostly). i therefore deduced that my guitar is picking up oscilations, and i need to put a decoupling capacitor across the source (pickups) am i right or am i drastically wrong? if so, around what size capacitor shall i experiment with? Ok my tuppence worth.......Guitars are very very simple peices of kit...they usually make noises for one of two reasons.1. they are fitted with single coil pickups and are being effected by other electrical equipment (strip lights are the worst)2. Poor earthing, which is your problem, if you think about it, you are acting as the earth when you touch the control plate.If you check the earth wire that runs from a pot to the bridge you will find it has a dry solder joint or its not contacting the bridge very well. Quote Link to comment Share on other sites More sharing options...
Guest lime Posted September 16, 2003 Report Share Posted September 16, 2003 as i said, i got fed up, ordered new pots and pickup selector, and took all the old bastards out.note. it no longer has a standard wiring, it may not even have a correct wiring.second note. why do they solder wires on to the back of the pots? is it just because theres not enough room in one solder tag? furthermore, theres no wirerunning from the bridge to any pot now. i just took a small wire, connected it from the bridge to the earth connection on the bridge pickup, which im sure is a much more efficient way to do things, but who knows, im probably wrong. Quote Link to comment Share on other sites More sharing options...
soundian Posted September 16, 2003 Report Share Posted September 16, 2003 Originally posted by lime as i said, i got fed up, ordered new pots and pickup selector, and took all the old bastards out.note. it no longer has a standard wiring, it may not even have a correct wiring.second note. why do they solder wires on to the back of the pots? is it just because theres not enough room in one solder tag? furthermore, theres no wirerunning from the bridge to any pot now. i just took a small wire, connected it from the bridge to the earth connection on the bridge pickup, which im sure is a much more efficient way to do things, but who knows, im probably wrong. Now your strings aren't earthed. And the wires on the back of the pots are the earth. Quote Link to comment Share on other sites More sharing options...
Guest lime Posted September 16, 2003 Report Share Posted September 16, 2003 my strings are earthed, they are connected to the earth connection on the pickup, which is all one node (earth). i know the connections on the back of the pots are earth, i made it that way, they are connected to the earth connection from the jack (the real earth conenction). originally i didnt bother with the back of the pots, cos i thoguht ti just made a mess and was pointless, but i guessed there was probably a good reason for it, but probably not as iv thought about it more.as i said before, why do they solder them to the back of the pots?the only reason i can think is there isnt enough room for all the wires in the earth solder tag. Quote Link to comment Share on other sites More sharing options...
Guest lime Posted September 16, 2003 Report Share Posted September 16, 2003 in any case, im pretty sure my guitars fine now, im going to sheild the inside of it though, might aswell go the full hog now that its all in peices and before i put strings back on it.anyway, turns out its the valves that need changed in my amp, which i suspected all along, but am too poor. Quote Link to comment Share on other sites More sharing options...
Rob Karloff Posted September 18, 2003 Report Share Posted September 18, 2003 The case of a potentiometer is it's ground (or Earth) connection. That is why the wires run to them and onto the ground connection of your jack plug.If you're re-wiring or re-fitting a guitar out, the best way to do it is to run black earth wire from each individual component direct to the earth on the jackplug. E.g. a wire from the bridge to the jack, a wire from Pot #1 to the jack, a wire from Pot #2 to the jack, etc. That way, each component has it's own ground connection and should earth better overall. Also worth doing is lining the inside of your control cutout with tinfoil and connecting this to the ground terminal too. It helps trap RF and electrical hum and channel it to earth. Also worth doing is swapping out your mono jack-plug on your amp and guitar for a much more sturdy, reliable XLR setup. The advantage is that you then have shielded guitar cabling, you can daisy-chain as many mic leads together as you need for total length, and the plug will be less likely to come out your guitar mid-performance. It's simple to then make a short bridge lead so you can hook up to a regular guitar lead, and another bridge lead to allow players with a regular lead to still plug into your XLR input amp. Quote Link to comment Share on other sites More sharing options...
Guest lime Posted September 18, 2003 Report Share Posted September 18, 2003 i disagree with your single wire to ground for every component theory, it seems like it would 1. create a mess inside the guitar, making fualt finding harder 2. make unecessary soldering aswell as a waste of wire.im also sceptical about your "casing of the pots being ground", there are 3 terminals on all potentiometers, and one is usually ground, it woudlnt make sense to have 4 terminals on the pot, and one of them be the casing.....however, if you are SURE, im quite willing to believe you. (i studied electronics last year you see, and iv never come across an arangement of attaching wires to the back of pots, as i said before, the only reason i could think of was that they needed a place to bundle a load of wires together and the sodler tag was too small.)i intend to sheild the inside of my guitar while im at it, but with copper tape if i can find it, failing that itl be tin foil, i replaced the jack, but not with xlr, although il bare it in mind, cheers. Quote Link to comment Share on other sites More sharing options...
soundian Posted September 18, 2003 Report Share Posted September 18, 2003 Originally posted by Rob Karloff Also worth doing is swapping out your mono jack-plug on your amp and guitar for a much more sturdy, reliable XLR setup. The advantage is that you then have shielded guitar cabling, you can daisy-chain as many mic leads together as you need for total length, and the plug will be less likely to come out your guitar mid-performance. It's simple to then make a short bridge lead so you can hook up to a regular guitar lead, and another bridge lead to allow players with a regular lead to still plug into your XLR input amp. I have to disagree. 1) No advantage in signal quality. A long lead will still be unbalanced. Guitar leads are shielded and work better with a capacitance sheath to further sheild against RF. 2) Just get a long lead, more connections equals more chances of a fuck up. 3) Loop the jack through your guitar strap and through the handle of your amp. They don't come out often then. 4) The cables you would have to make would involve more connections and, more importantly, in-line jack sockets; possibly the most unreliable connector around ( although Neutrik are, as ever, reliable and expensive). Since these cables are not standard, you'd better carry spares or be pretty nifty with a soldering iron mid gig. 5) People forget to bring/pack away cables. This happens disturbingly often. Quote Link to comment Share on other sites More sharing options...
badger Posted September 25, 2003 Report Share Posted September 25, 2003 although netrik do manufacture a nice locking surface mount jack socket which would be rather better than just looping the cable through the strap. If only all guitar manufacturers would actuall spend some money at the imoprtant parts I think I'm gonna get a spell checker for my fingers Quote Link to comment Share on other sites More sharing options...
soundian Posted September 26, 2003 Report Share Posted September 26, 2003 Originally posted by badger although netrik do manufacture a nice locking surface mount jack socket which would be rather better than just looping the cable through the strap. If only all guitar manufacturers would actuall spend some money at the imoprtant parts I think I'm gonna get a spell checker for my fingers I never knew they did a surface mount locking thing. Cool. Jacks do suffer from the lack of lock, but you need good technical knowledge to do it otherwise. Don't worry Badger, this forum has it's very own spellchecker, it just takes him a while. Quote Link to comment Share on other sites More sharing options...
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