B.Flat Posted January 22, 2013 Share Posted January 22, 2013 Hi everybody. I suppose I am living up to the male stereotype by admitting I can't find the sweet spot! That aside, when positioning a pickup, where is the "sweet spot" ? it under a node of the vibrating string (harmonic) where the string movement is the least, or is it between nodes where the string movement is at its maximum ? I am aiming to fix a Seymour Duncan SCPB-3 to my bass. I have located the harmonic nodes equivalent to those found on frets 31/3, 4 & 5. What advice does anyone have on this? All advice gratefully received but if I don't get any replies I am going to ring RELATE and SAMARITANS, in that order ! Whilst on the subject of my project could anyone provide me with a wiring schematic to allow the use of two passive pickups with the Seymour Duncan STC-2P preamp but then switchable to just one of the pickups in passive mode (i.e.the preamp removed from circuit). Hope that makes sense. All suggestions gratefully received. Brian Flat Quote Link to comment Share on other sites More sharing options...
LukeFRC Posted January 22, 2013 Share Posted January 22, 2013 Which sweet spot? The P bass sweet spot or the Musicman sweetspot? My suggestion - either tune it by ear to where sounds best... or let Leo do that for you and just copy his pickup placements Quote Link to comment Share on other sites More sharing options...
BigRedX Posted January 22, 2013 Share Posted January 22, 2013 [quote name='LukeFRC' timestamp='1358859425' post='1946076'] Which sweet spot? The P bass sweet spot or the Musicman sweetspot? My suggestion - either tune it by ear to where sounds best... or let Leo do that for you and just copy his pickup placements [/quote] This. The actual harmonic "sweet-spot" moves every time you fret a note, so unless you are going to only play open strings then it's useless. Quote Link to comment Share on other sites More sharing options...
ikay Posted January 22, 2013 Share Posted January 22, 2013 Here are some measurements for industry standard sweet spots (measured from the centre of the 12th fret to the centre of the polepieces) MM Stringray 5 - 332mm neck coil / 356mm bridge coil Fender Jazz (60s spacing) - 277mm neck / 367mm bridge Fender Jazz (70s spacing) - 277mm neck / 377mm bridge Fender Precision - 281mm G D coil / 309mm A E coil Quote Link to comment Share on other sites More sharing options...
B.Flat Posted January 22, 2013 Author Share Posted January 22, 2013 Thanks LukeFRC, BigRedX & iKay for your replies, especially to you iKay for the measurements. I don't soppose anyone out there with a '51 PB single coil could tell me if my estimate of 250mm from twelfth fret centre to pole piece centre is correct? Still interested in ideas for wiring to remove STC-2P from circuit. B.Flat Quote Link to comment Share on other sites More sharing options...
iiipopes Posted January 24, 2013 Share Posted January 24, 2013 (edited) Trying to run a bass with both a hi-z and lo-z (active) simultaneously is not usually a good idea. There are those basses which have passive as the "backup" for active if a battery goes down, but batteries are so cheap and plentiful, and thankfully most manufacturers make battery compartments accessible, so it should not be an issue. It should be an either-or, not both. One signal will override the other, and not get a good blend. Detail: most Fender-style passive hi-z pickups use 250kohm volume and tone controls for the proper circuit "loading." By contrast, EMG's classic active pickups use 25kohm controls. The EMG website used to have a manual (I don't know if it still does) that gave all the reasons why this is a bad idea. The issue is deciding whether or not to make the entire bass active or passive, and then what pickups. I personally do not like single coil pickups due to the noise. If a SC P-style pickup is desired, I'd get one of the end-to-end, or "split coil" pickups like Lindy Fralin makes. Moreover, since this style pickup is made on what is essentially the same as a Telecaster bobbin, it has a larger flange and mounting requirements. It is not as straight forward as mounting a Precision or Jazz pickup. I would rethink your project from scratch. By the way: the traditional placement of a single coil precision pickup is just about a pickup's width upstream from a Jazz neck pickup. Rickenbacker pickups are on the double octave and triple octave nodes, with the 4003 "one-inch" neck position a little more downstream than the double octave node. Edited January 24, 2013 by iiipopes Quote Link to comment Share on other sites More sharing options...
B.Flat Posted January 30, 2013 Author Share Posted January 30, 2013 Thanks iiipopes, that all makes good sense. However I never intended to use active/passive simultaneously. My objective was to wire a bass with active Stingray-style sounds, switchable to a completely passive '51 P.Bass set-up. I had the STC2P in the drawer, and a Fender Vol/Tone stacked pot. So the idea was to use an SD SBM4a for the stingray side of things and the SCPB3 for the Pbass side. However, as the STC2P has a balance control I thought a third alternative would be to use both pickups with the active circuit, then, if I could sort out the wiring, use a switch to completely remove the active circuit & the SBM4a, simultaneously switching the SCPB3 to the passive pots and the output socket (the active circuit being disconnected from the output socket) Obviously this is all achievable but the question is could the switching be achieved a lever switch or would a rotary be required to perform all the making & breaking of different circuits? Still open to advice. Brian Quote Link to comment Share on other sites More sharing options...
iiipopes Posted January 31, 2013 Share Posted January 31, 2013 Go active. You get the effect of a passive '51P by turning the treble knob down a number or two on the preamp and setting the bass knob "flat," to emulate the "loading" that 250kohm pots and a .1 mfd tone capacitor do in the original circuit. I can see how having a bass with a '51P pickup in its traditional position and a MM pickup in its traditional position would be a versatile bass. But wire it straightforward with both pickups going into the preamp conventionally, either with a volume knob on each or a master volume and blend, then through the tone stack and out. The more you wire, the more there is a chance something will go wrong at at gig. Especially with bass, the simpler is usually the better. And since you have a noise reducing pickup in the MM, I still would go with a "split coil" '51P pickup. Quote Link to comment Share on other sites More sharing options...
B.Flat Posted February 1, 2013 Author Share Posted February 1, 2013 Thank you once again iiipopes, good advice & a bit more knowledge to store in my old grey matter! Can I ask you a final question? I have an S'ray 2 band preamp in my drawer. Do you think I would do better to use this with the MM pickup, use the SCPB3 with a Fender 250/500k tone/vol. concentric pot & just use a toggle (DPDT) to switch either (not both) to the output jack? I would be grateful for your thought on that set-up. B.F Quote Link to comment Share on other sites More sharing options...
iiipopes Posted February 3, 2013 Share Posted February 3, 2013 Either/or would solve the override problem, but it would create two others: 1) the inevitable "pop" that would occur switching the active in or out, and 2) equalizing the output so that there was not a large volume drop between the two circuits. If you're absolutely set on having both passive and active, the only real solution is to have two output jacks and two amp/speaker setups so that each pickup has its own discrete signal path. I still would recommend the more conventional approach. After gigging bass and experimenting with wiring schemes of all kinds on both guitar and bass since the summer of 1976, I can wire anything for a bass for any purpose. But on my own custom fanned fret bass that is the main instrument I gig regularly with, it's still just P-J V-V-T wiring, with only a couple of tweaks: [url="http://basschat.co.uk/topic/174777-and-now-for-something-completely-different-in-a-pj/page__hl__%22fanned+fret%22__fromsearch__1"]http://basschat.co.uk/topic/174777-and-now-for-something-completely-different-in-a-pj/page__hl__%22fanned+fret%22__fromsearch__1[/url] That said, on my Ibanez SRA305 5-string I have for those songs that require it, it has the Ibanez "Phat II" control, which is their version of the EMG EXB (probably even the same unit under license), which for what I play is a very versatile control that raises bass and treble and cuts mids simultaneously, like a variable "vintage-to-modern" or "variable-slap" knob. The reason I mention this particular control is that my Ibanez SRA305 has two of the EMG HZ passive pickups, wired V-V-T, then into this control. It has unity gain, so using this control may also be an option to get the tonal range you are looking for. Quote Link to comment Share on other sites More sharing options...
B.Flat Posted February 3, 2013 Author Share Posted February 3, 2013 [font=lucida sans unicode, lucida grande, sans-serif]The penny has just dropped (if that expression means anything in Southwest Missouri! If not substitute "I’ve seen the light"!)[/font] [font=lucida sans unicode, lucida grande, sans-serif]I only want this configuration in one bass to save having two. (A little known or understood affliction called "reverse G.A.S, or RGAS, as it is known to the medical profession.)[/font] [font=lucida sans unicode, lucida grande, sans-serif]Ergo your two output jacks suggestion. Perfect, all I have to do is plug into the gig-appropriate socket, Q.E.D.[/font] [i][font=lucida sans unicode, lucida grande, sans-serif]Oh what a twisted web we weave.[/font][/i] [font=lucida sans unicode, lucida grande, sans-serif]Thanks iiipopes,[/font] [font=lucida sans unicode, lucida grande, sans-serif]Rock n'Roll Mamma On A Saturday Night![/font] Quote Link to comment Share on other sites More sharing options...
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