goonieman Posted July 30, 2015 Share Posted July 30, 2015 Hi All, I just installed in a Spector Tonepump into my 2 x humbucker bass using this diagram: http://michalik.cz/images/pdf/bp-4_2volume_rev2_en.pdf Only I used a 250K vol pot, and added the ground from the bridge assembly into the ground on the jack (where the brown wire goes). I gut this intermittent 'whine' when boosting the treble pot:, FYI: [color=#333333][font=Verdana, Arial, sans-serif]• Powered by 9V battery[/font][/color] [color=#333333][font=Verdana, Arial, sans-serif]• Current consumption 1,2mA[/font][/color] [color=#333333][font=Verdana, Arial, sans-serif]• Battery lifetime cca 420 hours, when using quality alkaline ones up to 1000 hours.[/font][/color] [color=#333333][font=Verdana, Arial, sans-serif]• Gain +12dB[/font][/color] [color=#333333][font=Verdana, Arial, sans-serif]• Tone controls:[/font][/color] [color=#333333][font=Verdana, Arial, sans-serif]• Bass: +14dB/-4dB @55Hz[/font][/color] [color=#333333][font=Verdana, Arial, sans-serif]• Treble: +14dB/-12dB @6,5kHz[/font][/color] [color=#333333][font=Verdana, Arial, sans-serif]I reckon its battery related because the 'whine' reduces and drifts when I move the battery around the compartment. Should the battery be shielded?[/font][/color] [color=#333333][font=Verdana, Arial, sans-serif]thx[/font][/color] Quote Link to comment Share on other sites More sharing options...
HowieBass Posted July 30, 2015 Share Posted July 30, 2015 I've never heard of a battery being the cause of electromagnetic interference - though if you're moving the battery about that probably means you're also moving bundles of wires about with the possibility of movement at poorly made connections maybe? Looking at Tonepump wiring diagrams I see that some suggest using 250K volume pots and some (including the BP-4 module that your diagram indicates) say use 500K - are you sure the 250K pots are ok? This assumes you've got passive humbuckers too. Quote Link to comment Share on other sites More sharing options...
hubrad Posted July 30, 2015 Share Posted July 30, 2015 More likely there's something in the vicinity which is causing the previously imperceptible whine, and the treble boost is enhancing it. The battery could well alter the pattern by which it's being picked up. All kinds of things can cause electromagnetic interference.. cabling, lighting, transformers, mobile phones.. you name it! Tried switching things off to see if anything in the house is the cause? Quote Link to comment Share on other sites More sharing options...
goonieman Posted July 30, 2015 Author Share Posted July 30, 2015 [quote name='HowieBass' timestamp='1438269716' post='2833100'] I've never heard of a battery being the cause of electromagnetic interference - though if you're moving the battery about that probably means you're also moving bundles of wires about with the possibility of movement at poorly made connections maybe? Looking at Tonepump wiring diagrams I see that some suggest using 250K volume pots and some (including the BP-4 module that your diagram indicates) say use 500K - are you sure the 250K pots are ok? This assumes you've got passive humbuckers too. [/quote] I would have thought that 500k would bring out the higher spectrum even more? I have MEC passive soapbar pups. It's odd, because my passive single coil MECs on my warwick corvette with glokenklang pre are totally silent! I've emailed the designer of the tonepump, so i guess i'll wait to hear back. thanks Quote Link to comment Share on other sites More sharing options...
Thunderbird Posted July 30, 2015 Share Posted July 30, 2015 As a rule active basses do use 500k pots Quote Link to comment Share on other sites More sharing options...
goonieman Posted July 30, 2015 Author Share Posted July 30, 2015 hmmm... but they're passive pups, into an active preamp? Anyway, they work well: not muddy on the full setting. Just the right amount of treble... Quote Link to comment Share on other sites More sharing options...
HowieBass Posted July 30, 2015 Share Posted July 30, 2015 Humbuckers usually take 500K pots but if you've enough treble and you like the sound then stick with the 250K. How well is the bass shielded? I'm just wondering if the high pitched whine when you boost the treble is evidence of interference that needs screening out. Quote Link to comment Share on other sites More sharing options...
goonieman Posted July 31, 2015 Author Share Posted July 31, 2015 yeah, I guess some copper shielding is required. The cavity is painted in conductive paint - but not exceptionally well. Quote Link to comment Share on other sites More sharing options...
mrn1989 Posted October 22, 2015 Share Posted October 22, 2015 Ive had this with the East J Preamp with the Treble boost engaged Quote Link to comment Share on other sites More sharing options...
Norris Posted October 22, 2015 Share Posted October 22, 2015 [quote name='goonieman' timestamp='1438341715' post='2833696'] yeah, I guess some copper shielding is required. The cavity is painted in conductive paint - but not exceptionally well. [/quote] Quite probably this Quote Link to comment Share on other sites More sharing options...
iiipopes Posted October 22, 2015 Share Posted October 22, 2015 If the pickup is passive and is controlled before the signal enters the preamp, then sometimes the higher value pots are used, as the pickups are essentially functioning in passive mode. By not wiring the bass exactly according to the schematic, you may have introduced a loop that caused the preamp to become unstable and induced oscillation. Quote Link to comment Share on other sites More sharing options...
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