Osiris Posted December 30, 2013 Share Posted December 30, 2013 Hi folks, I’m after some advice, please. I’m currently renovating an old Ibanez bass and have removed the original P/J pickups and pre-amp and plan to replace them with just a passive P pickup to keep things simple. What I would like to do, if possible, is wire the pup to a volume pot and then straight to the output. (I don’t tend to use passive tone controls as I prefer to make tonal changes via the amp or by adjusting my technique). [indent=1]o Is it even possible to do this?[/indent] [indent=1]o Do I need to have a tone control in the circuit?[/indent] [indent=1]o Presumably this will give the full range signal from the pickup? i.e. as if the tone pot was wide open?[/indent] [indent=1]o Would I need a capacitor or resistor in the circuit or can that be omitted too?[/indent] [indent=1]o Would doing so have any adverse effect on the tone?[/indent] Assuming that the above is feasible does anyone have (or can they point me in the direction of) an appropriate wiring diagram, please? Any advice, guidance, words of wisdom much appreciated, Cheers, Sid. Quote Link to comment Share on other sites More sharing options...
KiOgon Posted December 30, 2013 Share Posted December 30, 2013 Yes you can wire direct to the jack socket or to volume pot then jack - no need for anything else - no cap or resistor. The effect will be like having tone control fully clockwise with a normal circuit. All you need is the hot wire from pick up to tag 1 on volume pot, output to jack socket from tag 2 (centre) & black wire from pick up to tag 3 & pot body & centre of jack socket. Hope that's clear enough? Cheerz, John Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 30, 2013 Share Posted December 30, 2013 Removing the tone control from the standard passive P-Bass circuit is simple, it's a simple potentiometer and capacitor wired across the signal and earth that bleeds more treble off to earth as the you turn the control to "0". If you don't want ir simply leave out the components and wire the output of the volume pot directly to the output jack. This may actually give a slightly brighter sound than with the tone control on full treble as even in their position on a standard pot some of the high frequencies will still be going to earth through the control. If you want to replicate the sound of the control in the circuit but on minimum treble cut simply replace the tone pot with a resistor of the same value. Quote Link to comment Share on other sites More sharing options...
Osiris Posted December 31, 2013 Author Share Posted December 31, 2013 Thanks for the help, guys. John, a couple of further questions if I may;[list] [*]The hot wire from the pickup is presumably the white one??? [*]Shouldn't there also be an earth wire somewhere (the one that connects to the underside of the bridge?) If so, where does the other end of it go? [/list] Cheers, Sid. Quote Link to comment Share on other sites More sharing options...
KiOgon Posted December 31, 2013 Share Posted December 31, 2013 Yes the white is hot in the majority of 2 wire standard pups, the black is earth & the bridge ground goes to the same place as the black - to the pot body or to the jack socket centre. HTH, John Quote Link to comment Share on other sites More sharing options...
Osiris Posted January 2, 2014 Author Share Posted January 2, 2014 Cheers for the clarification, John. I'll get my welding torch out at the weekend and see what happens ...... Quote Link to comment Share on other sites More sharing options...
dannybuoy Posted January 2, 2014 Share Posted January 2, 2014 I'm not sure if just removing the tone pot well have the same effect, but I tried a toggle switch to bypass both the volume and tone pots in my P Bass once, and it made it sound way brighter - too much in fact, I preferred the sound of it stock. Quote Link to comment Share on other sites More sharing options...
BigRedX Posted January 2, 2014 Share Posted January 2, 2014 [quote name='dannybuoy' timestamp='1388667718' post='2324515'] I'm not sure if just removing the tone pot well have the same effect, but I tried a toggle switch to bypass both the volume and tone pots in my P Bass once, and it made it sound way brighter - too much in fact, I preferred the sound of it stock. [/quote] As I said in my previous post even with the passive tone control set at minimum treble cut some of the high frequencies still bleed through to earth (unless you use a pot that goes into open circuit at the point where it would normally be maximum resistance. Which is why I suggested that the OP could replace the tone pot with a resistor of the same value connected to the capacitor, if removing the components completely resulted in too bright a sound. Quote Link to comment Share on other sites More sharing options...
Osiris Posted January 5, 2014 Author Share Posted January 5, 2014 Thanks for the word for wisdom people. I've just finished wiring the bass up - direct from the volume pot to the output with no [color=#282828][font=helvetica, arial, sans-serif]resistor/capacitor[/font][/color] - and all sounds great through my little 30 watt practice amp. Not tried it through my gig rig yet but if things do sound a bit too bright for my tastes then I'll try wiring a [color=#282828][font=helvetica, arial, sans-serif]resistor [/font][/color]into the circuit. Cheers, Sid. Quote Link to comment Share on other sites More sharing options...
BigRedX Posted January 5, 2014 Share Posted January 5, 2014 [quote name='Osiris' timestamp='1388921379' post='2327571'] Thanks for the word for wisdom people. I've just finished wiring the bass up - direct from the volume pot to the output with no [color=#282828][font=helvetica, arial, sans-serif]resistor/capacitor[/font][/color] - and all sounds great through my little 30 watt practice amp. Not tried it through my gig rig yet but if things do sound a bit too bright for my tastes then I'll try wiring a [color=#282828][font=helvetica, arial, sans-serif]resistor [/font][/color]into the circuit. Cheers, Sid. [/quote] You need the capacitor as well. Resistor of the same value as the pot it's replacing in series with the capacitor wired across the signal and earth. Quote Link to comment Share on other sites More sharing options...
Maude Posted January 5, 2014 Share Posted January 5, 2014 I'm no electrical whizz but my understanding on the way it's being explained is that the tone control is essentially a variable resistor. If wiring the P/U direct to the ouput, either via the volume control or not, is too bright then put everything back as it was and replace just the tone control with a resistor of the same value. I also assume if you like the tone of your bass somewhere between 'fully up' or fully down', as mine seems to have a real sweet spot so to speak, then you could replace the control with a resistor having a value somewhere inbetween the 'fully up' or 'fully down' values on the tone control. I assume it's possible to get a reading of the tone control when it's in that sweet spot so you know what resistor will achieve this 'tone'. Is this correct? I don't want to do this, just interested. Quote Link to comment Share on other sites More sharing options...
Grangur Posted January 6, 2014 Share Posted January 6, 2014 [quote name='Maude' timestamp='1388934919' post='2327773'] I'm no electrical whizz but my understanding on the way it's being explained is that the tone control is essentially a variable resistor. If wiring the P/U direct to the ouput, either via the volume control or not, is too bright then put everything back as it was and replace just the tone control with a resistor of the same value. I also assume if you like the tone of your bass somewhere between 'fully up' or fully down', as mine seems to have a real sweet spot so to speak, then you could replace the control with a resistor having a value somewhere inbetween the 'fully up' or 'fully down' values on the tone control. I assume it's possible to get a reading of the tone control when it's in that sweet spot so you know what resistor will achieve this 'tone'. Is this correct? I don't want to do this, just interested. [/quote] You're thinking on the right lines, but the tone at the output jack is determined by fixing a capacitor between the two terminals. The capacitor changes tbe tone by leaking some high frequency signals (treble signals) to earth. You get to control the sound by using a varible resistor to increase the resistance to current able to flow through the capacitor. So if you're fitting a tone control you need both a capacitor AND a regulating resistor. You're right that the variable resistor can be replaced with a combination of 2 fixed value resistors. The reason why it has to be 2 resistors is that electrc current will always take the easiest route. So if you simply put a resistor in series with the capacitor all the current will go straight to your jack and pass the capacitor by. So if you want the effect of a VR being at the halfway sweet spot. Then you will need to use 2x 125 ohm resistors. Quote Link to comment Share on other sites More sharing options...
BigRedX Posted January 6, 2014 Share Posted January 6, 2014 You don't need to resistors to replace the tone control, because on the normal passive tone circuit the other end of the potentiometer isn't connected to anything. Quote Link to comment Share on other sites More sharing options...
Grangur Posted January 7, 2014 Share Posted January 7, 2014 [quote name='BigRedX' timestamp='1389025008' post='2328947'] You don't need to resistors to replace the tone control, because on the normal passive tone circuit the other end of the potentiometer isn't connected to anything. [/quote] I stand corrected - thanks. I wrote that without checking. I'm surprised it works without, but I guess the potential divider circuit uses the impedance of the amp circuit to make it work. Thanks BRX Quote Link to comment Share on other sites More sharing options...
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