I recently acquired a passive jazz bass which I fell in love with the second I plugged in and played it.
Its a 60s style passive pickup fretless Fender Jazz, specifically a Jaco signature model. It sounds absolutely amazing plugged straight into an amp or DI. I would however like to install a preamp to give it more output and less noise in live settings without having to run both pickups at once to effectively cancel noise.
The problem is - no back cavity space for a preamp, let alone a battery. The front cavity is small, but could contain a small EMG preamp keeping the stock Vol-Vol-Tone control scheme. Routing a separate cavity is absolutely out of the question. Any ideas for a way to add a battery without mutilating the body?
I have another jazz bass with passive pickups which I used external power over a TRS cable to run the preamp. I just want to keep it simpler on this new one.
Its a 60s style passive pickup fretless Fender Jazz, specifically a Jaco signature model. It sounds absolutely amazing plugged straight into an amp or DI. I would however like to install a preamp to give it more output and less noise in live settings without having to run both pickups at once to effectively cancel noise.
The problem is - no back cavity space for a preamp, let alone a battery. The front cavity is small, but could contain a small EMG preamp keeping the stock Vol-Vol-Tone control scheme. Routing a separate cavity is absolutely out of the question. Any ideas for a way to add a battery without mutilating the body?
I have another jazz bass with passive pickups which I used external power over a TRS cable to run the preamp. I just want to keep it simpler on this new one.
Attachments
9 V "Phantom power" and coupling caps at both wire ends? Not sure how that would impact sound and plug-in-boom, however...
Adding a buffer/preamp will do absolutely nothing for lower noise (the classic single-coil mains hum).
@stv I used the ring (R) contact on a TRS cable to power the preamp. No coupling cap was needed.
I run my other bass this way through my pedal board with an inline female - female 1/4" junction box to inject the preamp DC voltage, which is carried to the bass via the ring contact on a TRS cable. The preamp buffers the output so the cable capacitance doesn't affect the tone or act microphonic due to the higher passive pickup impedance. It lowers noise on stage when lighting dimmer control packs are close by.
The pickup cavity usually gets more copper tape shielding added along with the control cavity on most of my basses and I also add a bridge string ground. This cuts down on most of the noise, but sometimes it doesn't do enough. The noise gets worse when the strings aren't being touched and only one pickup is used. I sometimes use just either the neck or bridge pickup separately, which doesn't allow the other reverse phase pickup to cancel hum. I do not want to change pickups, as these have a very specific sound which I dont want to mess with.
I've previously tried smaller lithium batteries to power a buffer or preamp, but the battery life is short.
I run my other bass this way through my pedal board with an inline female - female 1/4" junction box to inject the preamp DC voltage, which is carried to the bass via the ring contact on a TRS cable. The preamp buffers the output so the cable capacitance doesn't affect the tone or act microphonic due to the higher passive pickup impedance. It lowers noise on stage when lighting dimmer control packs are close by.
The pickup cavity usually gets more copper tape shielding added along with the control cavity on most of my basses and I also add a bridge string ground. This cuts down on most of the noise, but sometimes it doesn't do enough. The noise gets worse when the strings aren't being touched and only one pickup is used. I sometimes use just either the neck or bridge pickup separately, which doesn't allow the other reverse phase pickup to cancel hum. I do not want to change pickups, as these have a very specific sound which I dont want to mess with.
I've previously tried smaller lithium batteries to power a buffer or preamp, but the battery life is short.
There's two sources. One is magnetic, and running both pickups with the winding reverse-connected will cancel it like a humbucker, but the real solution for running only one single-coil pickup is to stay well away from anything with a power transformer. If you move or rotate and the hum goes up and down with your position, the hum is magnetic. There may be "stacked humbucker" pickups for bass, but they may have a different tone.
The other is electrostatic, also easily picked up by a guitar or bass due to the pickups being such a high impedance. If the hum reduces or stops when you touch the strings or metal of the output jack, that's electrostatic. Fortunately this can be fixed by adding shielding (the usual roll of wide copper tape with adhesive on one side, put in the back and walls of all cavities) and connecting it to ground at the jack or controls
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If you add a preamp at the bass, it may sound different due to the lack of cable capacitance of the usual long cord no longer reducing the tone or resonating with the pickup inductance. You could likely add a capacitor equal to cable capacitance before the preamp to fix that.
Technically they can be, but there's so much history here, most of it having to do with wanting these instruments to "sound just like they did in the 1950s/1960s/1970s."
There was a "Recording Les Paul" model that Gibson made, had low impedance humbucker pickups and balanced output (even an XLR connector), had a flat (!) frequency response, but didn't sell well because it "didn't sound right."
A fender passive jazz bass and precision bass have magnetically out of phase pickup windings to cancel hum. On a jazz bass this feature isn't operational when only one pickup is turned up.
On a precision bass, the pickup consists of 2 separate pickup coils staggered next to each other wound magnetically out of phase, but in phase electrically, so only the hum picked up is canceled out.
@benb The humbucking les paul guitar sound is more midrange focused as opposed to single coils most fenders used. I'd characterize it as a British type of tone. The single coil Fender sound is tighter and has more focused low end. It also has that twangy sound embraced by most older country music. Telecasters were even more twangy in character and sounded a bit thinner than Stratocasters. Telecasters have their place, but need to be EQed carefully to not dominate the mix and bite off your ears.
The instruments pickup location on the body in relation to the bridge and neck makes a huge difference in tone, both on guitars and basses. Humbuckers used on a bass have much less low end punch than single coils, especially when used in the bridge position. I've had other basses with Bartolini jazz type soap bar humbucking pickups. These sounded very midrange focused and thinner in the bridge position, much more so than the single coil bridge PUs on Fender jazz basses.
You can get close to a precision bass sound just by using the neck pickup on a jazz bass, but it doesn't have the drive a real precision bass has with its humbucking pickup alone.
On a fretless jazz bass like mine, the single coil bridge pickup is where most of that magic fretless sound comes from. Fretless precision basses have a more upright acoustic bass sound. Thats a very specific, unique type of tone. Music Man basses have a completely different tone thanks to the one big single humbucking bridge PU. This type of bass with a fretless fingerboard sounds amazing. My most frequently played bass is a Music Man fretless with a maple finger board and only one split winding humbucking PU close to the bridge.
I have an Ibanez 5 string with Bartolini humbuckers in both positions. It has various selectable winding taps on both pickups to get a wide variety of tones. I bought it for this reason, being the bass I would grab first to take on most gigs. It has a very quiet 18V preamp with sweepable EQs, making it useful playing live. It doesn't however have that vintage Fender fretless sound needed for playing jazz.
The instruments pickup location on the body in relation to the bridge and neck makes a huge difference in tone, both on guitars and basses. Humbuckers used on a bass have much less low end punch than single coils, especially when used in the bridge position. I've had other basses with Bartolini jazz type soap bar humbucking pickups. These sounded very midrange focused and thinner in the bridge position, much more so than the single coil bridge PUs on Fender jazz basses.
You can get close to a precision bass sound just by using the neck pickup on a jazz bass, but it doesn't have the drive a real precision bass has with its humbucking pickup alone.
On a fretless jazz bass like mine, the single coil bridge pickup is where most of that magic fretless sound comes from. Fretless precision basses have a more upright acoustic bass sound. Thats a very specific, unique type of tone. Music Man basses have a completely different tone thanks to the one big single humbucking bridge PU. This type of bass with a fretless fingerboard sounds amazing. My most frequently played bass is a Music Man fretless with a maple finger board and only one split winding humbucking PU close to the bridge.
I have an Ibanez 5 string with Bartolini humbuckers in both positions. It has various selectable winding taps on both pickups to get a wide variety of tones. I bought it for this reason, being the bass I would grab first to take on most gigs. It has a very quiet 18V preamp with sweepable EQs, making it useful playing live. It doesn't however have that vintage Fender fretless sound needed for playing jazz.
The only solution to magnetic hum interference is to use some sort of humbucking scheme
- classic dual coil humbucker in JB format
- stacked humbucker in JB format
- Preci-type split coil PU but in JB format
- standard single-coil with large external low-impedance humbucking coil (which needs to be located somewhere, usually it can go under a pickguard or in the control compartment when large enough)
A work-around is standard SC with strong small neodymium magnet and narrow/short coil geometry, that maximizes signal output vs hum pickup (loop area matters).
This is a strong indication that the shielding isn't working as intended. You need 100% coverage everywhere (Faraday cage) including the pickups themselves -- which is usually the hard part unless they have removable covers. Pickup shielding should ideally avoid strong eddy current paths which complicates things but with copper foil the required open-loop petal pattern is not too hard to do. When unshielded, another thing one can do (often neglected, though) is providing a shield connection to the magnets/pole-pieces (if they are conductive, that is) and the proper winding direction (outermost layer should be the GND side).
When all things fall in place, no need to "ground" and touch the strings -- the effect of which basically is just an additional weak shield formed by your body (belly, mostly ;-)
Super capacitors could be an option as they are available in small and flat form factors and many voltages, for example Kyocera SCM: https://datasheets.kyocera-avx.com/AVX-SCM.pdf
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As for bass talk, Fenders (P and JB) have their place but a good G&L L-Series does everything they do, just better**)
G&L's often have preamps and that's the first thing I rip out as it is useless for me. The full shield job is much more important.
**) Offering dual humbuckers (in the L-2000) with fully accessible individual coils, they also can be modded further to allow for virtually several dozens of different pickup coil selections (and those "OMG"-modes) with no addtional switches or controls, so not butchering the instrument.
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As for that, different strokes for different folks. While the classic Jaco fretless tone is well known and immediately recognized by musicians and non-musicians alike, I personally sort of hate it -- but I'm more a rocker than a jazzer and mostly play "power bass" with pick and substantial palm muting on the attacks. Fretless is more a thing of comfort and flexibility for me.
The main reason I dont want to mess with the tone of my FL jazz is the bridge pickup has decent low end balance to it, which is not so typical. Most JBs have very thin sounding bridge PUs, but mine doesn't at all. On my other FL jazz basses I have to blend in a bit of the neck PU to fill in the low end. This isn't the case on this Jaco signature model. Its built to 1963 specs. You have to pull the neck to adjust the truss rod, which has the traditional slotted screw head. The body has a very thin clear finish on it to not kill too much tone. They built them properly in those days and it shows in the functionality as well as the sound. Along with that come the quirks, most of which are good ones.
Yes, the G&L stuff is idefinitely mproved Music Man. I also don't like the older active preamps in the MM, but its part of the character. I listened to alot of tracks with Pino Palladino on them, so that makes me more of an 80s pop guy, but also like his work with the John Mayer trio playing a P bass. He even played on NIN albums, so he's extremely versatile.
Nick Karn from Japan played a fretless and he's another favorite of mine. Yes, the Jaco thing has been overplayed for alot of us, but being a jazz guy I totally love the sound. He influenced alot of guys later on, like Marcus Miller and Anthony Jackson, which I listen to alot. They played on so many albums and most people don't realize this. Im definitely more of a Funk, Soul and Fusion guy, but not the excessively noodly stuff.
I do also like prog rock and even some Iron Maiden. Steve Harris is an animal. Unfortunately alot of harder rock pushes the bass in the corner and turns it into unidentified mush on most recordings. The older Van Halen records literally had non existent bass and kick in them. They mixed those horribly IMO. The older Zeppelin music was great. JPJ is an amazing musician. The recordings on the other hand were terrible. You can tell they were done with alot of Jimmy Page influence. Very hard to listen to more than a few songs at a time.
Yes, the G&L stuff is idefinitely mproved Music Man. I also don't like the older active preamps in the MM, but its part of the character. I listened to alot of tracks with Pino Palladino on them, so that makes me more of an 80s pop guy, but also like his work with the John Mayer trio playing a P bass. He even played on NIN albums, so he's extremely versatile.
Nick Karn from Japan played a fretless and he's another favorite of mine. Yes, the Jaco thing has been overplayed for alot of us, but being a jazz guy I totally love the sound. He influenced alot of guys later on, like Marcus Miller and Anthony Jackson, which I listen to alot. They played on so many albums and most people don't realize this. Im definitely more of a Funk, Soul and Fusion guy, but not the excessively noodly stuff.
I do also like prog rock and even some Iron Maiden. Steve Harris is an animal. Unfortunately alot of harder rock pushes the bass in the corner and turns it into unidentified mush on most recordings. The older Van Halen records literally had non existent bass and kick in them. They mixed those horribly IMO. The older Zeppelin music was great. JPJ is an amazing musician. The recordings on the other hand were terrible. You can tell they were done with alot of Jimmy Page influence. Very hard to listen to more than a few songs at a time.
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@KSTR Those "supercaps" you mention - don't they only come in very low voltage ratings ie 3V or so? I don't think there's enough capacitance to power a 9V preamp which draws a few mA. A single 9V usually lasts around 20 - 30 hrs before it starts to sound distorted and clipping on the louder, lower notes.
I run some of my basses at 18V for less distortion playing harder on the low B and E. The hotter MM humbuckers can distort on the lowest notes with just 9V on the preamp. I had a newer 4 string MM with the alnico PU, which would often break up playing the low E on louder tracks. I didn't realize it until in one session, the engineer said something about it. We were both surprised about that. I had to scramble to find a solution, otherwise a bandaid would have been to lower the PU height, which hurt the tone alot.
I fixed the distortion by changing the 16V caps on the preamp board to 25V and adding another battery in series. They ran TL062 op amps in the newer Ernie Ball MM models, so the chip could handle the extra voltage. The hotter pickup lowered preamp noise, but it caused the other issue above.
Normally I would record with a passive bass, but sometimes needed the MM sound, being the producer wanted it. A passive bass has no battery, so it doesn't hiss but it needs a really good high impedance DI with selectable lnput loading.
I run some of my basses at 18V for less distortion playing harder on the low B and E. The hotter MM humbuckers can distort on the lowest notes with just 9V on the preamp. I had a newer 4 string MM with the alnico PU, which would often break up playing the low E on louder tracks. I didn't realize it until in one session, the engineer said something about it. We were both surprised about that. I had to scramble to find a solution, otherwise a bandaid would have been to lower the PU height, which hurt the tone alot.
I fixed the distortion by changing the 16V caps on the preamp board to 25V and adding another battery in series. They ran TL062 op amps in the newer Ernie Ball MM models, so the chip could handle the extra voltage. The hotter pickup lowered preamp noise, but it caused the other issue above.
Normally I would record with a passive bass, but sometimes needed the MM sound, being the producer wanted it. A passive bass has no battery, so it doesn't hiss but it needs a really good high impedance DI with selectable lnput loading.
In the past, there were only low voltage super caps but today there are modules with higher voltages like 9V or 12V.
A preamp that draws several mA is not up to date IMHO. With today's opamps like TI's OPA205 it is no problem to design a good preamp/buffer with goods specs like large bandwidth, low noise, less than 0.25mA supply current and high supply voltage (>12V). With 4 or 5 CR2450 Lithium cells (for 12V/15V) at 620mAh capacity you'd have a service life of at least 2000hrs.
I understand there are options to reduce current draw and other battery formats. I usually prefer EMG preamps, which are either built into pickuos as buffers or (in my case) separate buffers connected behind the passive PUs and tone bleed circuit. I'm not planning to build my own buffer circuit, as I don't have the time to do so. I'd rather use a tried and true buffer/preamp from a company like EMG. I just need a battery format which is easy to service and compact enough with sufficient battery life. CR2450 is an option with the appropriate holder setup. There's barely enough room for larger potentiometers, so the EMG modules with integrated buffers are small enough to install in the stock, unmodified location. At this point I just need something with similar capacity of a 9V battery and the size small enough to fit in the cavity without modifying it.
That means it will have the same occupied volume but needs to have a different form factor to accommodate the six 1.5V cells it is comprised of.
You may want to check here what sizes are available. The simplest equivalent of one 9V would be 6 AAAA cells. The problem is that the packaging/shell of a battery takes up more percentage of total volume the smaller the battery is and the more its shape deviates from a sphere. Plus you need some kind of holder or other way to contact a bunch of individual cells.
You could carefully hack a 9V block and re-layout the geometrical arrangement so that it fits, taking care that the connection welds don't brake: https://blog.xkcd.com/2007/08/20/testing-the-9v-battery-hack-or-assault-on-battery/
John East's J-Retro preamps were specifically designed to be drop-ins without modifying the cavity: https://www.east-uk.com/product/j-retro-01/?v=79cba1185463.
Not sure about availability in the US but if you're willing to pay for shipping I'm sure you could get them from the source.
Not sure about availability in the US but if you're willing to pay for shipping I'm sure you could get them from the source.
Three CR2030 cells would be closer to the typical capacity of a 9V, but if three CR2450 will fit, all the better. How much space are we talking here? Dimensions would help