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spiritwalker

Aqua Marine

Posts: 3,641 Member Since: 14/02/2011

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Mar 20 17 8:58 PM

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A young musician has come to me for help upgrading his Mexican Jazz bass that he's had for 12 years. You know, emotional attachment.

So this stock bass makes a lot of noise unless he turns the treble down, and buzzes when you take you hands off the strings.
Not a bit of shielding in the cavities.
The pots probably could be replaced and the tiny cap in there at the same time.
The bridge is causing problems as it's rusted and the allen screws are stripped.

So what would you suggest for pickups and a bridge?
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weedywet

Ruby Baby

Posts: 5,791 Member Since:20/01/2011

#1 [url]

Mar 20 17 9:35 PM

BadAss 2 bridge. 
And I'd put either Duncan Antiquity II (if you want 'faithful') or Status Graphite (if you want better) pickups. 

...if it were me. 

 

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soapfoot

Ruby Baby

Posts: 7,162 Member Since:04/02/2011

#6 [url]

Mar 21 17 7:32 AM

Make sure the strings are grounded. There's a ground wire that goes from the electronics cavity to the bridge. It often breaks, and this can cause some of what you're talking about re: "noise when you take your hands off the strings."

I would replace all electronics-- some good pickups (the Antiquities WW mentioned are fine; there are other very good pickups out there, too). Replace pots with CTS or another good brand; often the higher quality pots are designed to fit imperial-mesaurement hole sizes, so if your J should happen to be metric, the holes might have to be enlarged slightly. A nice new jack, finally-- Switchcraft brand, preferably.

brad allen williams

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gregdixon

Gold Finger

Posts: 472 Member Since:30/01/2011

#7 [url]

Mar 22 17 4:48 AM

Be careful with the Mexican Jazz pickups. For a long time they used two that were the same size. I can't remember when they changed it. Early '00s I think, but am not sure.

Jazz basses always need a lot of shielding, but it's definitely worth the effort. A lot of the Mex instruments are quite good, once you upgrade the pickups and hardware too.

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soapfoot

Ruby Baby

Posts: 7,162 Member Since:04/02/2011

#8 [url]

Mar 22 17 8:18 AM

Someone with more electronics knowledge than me can school me, perhaps--

It's interesting to me to read that people find that shielding control cavities helps with hum in single coil pickup systems. For high frequency interference, this makes sense to me.

But I've never personally found it to help with radiated 60 Hz hum, and can't understand the mechanism behind how a foil shield (as opposed to a high-permeability shield like Mu-metal) could have a significant benefit at hum frequencies, particularly when the pickup coils themselves are mostly not going to be shielded. What am I missing?

Thanks in advance!

brad allen williams

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zmix

Aqua Marine

Posts: 3,982 Member Since:20/01/2011

#9 [url]

Mar 22 17 8:57 AM

soapfoot wrote:
Someone with more electronics knowledge than me can school me, perhaps--

It's interesting to me to read that people find that shielding control cavities helps with hum in single coil pickup systems. For high frequency interference, this makes sense to me.

But I've never personally found it to help with radiated 60 Hz hum, and can't understand the mechanism behind how a foil shield (as opposed to a high-permeability shield like Mu-metal) could have a significant benefit at hum frequencies, particularly when the pickup coils themselves are mostly not going to be shielded. What am I missing?

Thanks in advance!

You are correct, shielding the control cavity isn't going to stop the primary source of hum, which is the enormous coils of wire specifically designed to be sensitive to electromagnetic interference  aka "the pickups".

RF noise can be reduced by shielding,  and in Fender guitars where the wires themselves are not shielded this *may* help...

The Jazzmaster I owned had a soldered, solid brass shield in the entire rout, it was no less hummy than any other Fender, certainly..

Guitars are fairly high impedance environments, so they are susceptible to interference.  I noticed that in cold, dry weather, brushing my hand on the pickguard of my Telecaster produced a lot of static, it sounds like a Geiger counter..!  If I were to coat the bottom surface of the pickguard with a conductive material this would dissipate the static charge and reduce that noise.
Lower resistance pots would help too.. (this one has the 1966 1MΩ tone and volume pots).

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soapfoot

Ruby Baby

Posts: 7,162 Member Since:04/02/2011

#10 [url]

Mar 22 17 10:38 AM

Yeah, the jazzmaster is a great example. All of the originals had not only the big brass shielding tubs all throughout the cavity, but a shielding plate below the pickguard as well, to complete a total faraday cage around all electronics...

save, of course, for those massive wide, flat coils.

Which were like antennae for magnetically radiated hum, making the jazzmaster one of the most notoriously noisy guitars ever in mass production.

You make a great point, too, that I had overlooked-- all Gibsons have braid-shielded wire throughout, from the pickup leads all the way to the output jack. From the factory, the coils themselves are also shielded with metal covers... though nobody seems to complain about (and I've never noticed) any noise penalty from removing those covers, as is common practice (obviously the common mode rejection of the humbucking coil would help with a lot, anyhow).

brad allen williams

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maarvold

Aqua Marine

Posts: 3,011 Member Since:23/01/2011

#11 [url]

Mar 22 17 2:24 PM

soapfoot wrote:
...nobody seems to complain about (and I've never noticed) any noise penalty from removing those covers, as is common practice (obviously the common mode rejection of the humbucking coil would help with a lot, anyhow).

 
When I took the covers off my humbuckers, I think I remember a slightly higher noise floor: enough that I bought some commercially-available nickel-plated covers I found with the tops cut out, but not enough to inspire me to get them 'reliced' and install them, although I will probably do it eventually.  

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seth

Ruby Baby

Posts: 5,527 Member Since:26/01/2011

#13 [url]

Mar 24 17 6:58 AM

Admittedly I'm prejudiced, but to me the sound of a good jazz bass is both pickups all the way up and the tone either all the way up or down. A passive Fender, a good one anyway, gives you a lot of options for sounds using just your hands. It takes a lot of work to learn how to get the sounds out of it, but if you put the work in it can be very rewarding. Any sort of active electronics or humbucking pickups take away some of those options from under your hands which is why I don't have any basses with active electronics or humbucking pickups. If the passive sound is not what you want, a Fender is probably not the best option.

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gustav

Silverado

Posts: 97 Member Since:12/02/2011

#14 [url]

Mar 25 17 11:07 AM

I have worked on two older MIM Jazz Basses. They had the same size pickups and were not reverse polarity and reverse magnets to each other for humbucking when both were at equal volume.
One I installed CS60s(needed to open up the pickguard and body route to fit the pickups) the other I reversed the magnets and wiring of one of the pickups and wax potted the pickups in 20% beeswax 80% paraffin. I am not 100% sure what the wax potting does but it does seem to take some of the edge from ceramic magnet steel pole piece pickups. The wax has different dielectric constant than air(so it changes the pickui capacitance) and also damps microphonics. The stock controls and tone cap were fine. I also twist the signal wires and shorten wires if possable and sometimes adjust the grounding wires.

Gustav

Last Edited By: gustav Mar 25 17 11:11 AM. Edited 1 time.

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zmix

Aqua Marine

Posts: 3,982 Member Since:20/01/2011

#15 [url]

Mar 30 17 7:37 AM

soapfoot wrote:
Yeah, the jazzmaster is a great example. All of the originals had not only the big brass shielding tubs all throughout the cavity, but a shielding plate below the pickguard as well, to complete a total faraday cage around all electronics...

save, of course, for those massive wide, flat coils.

Which were like antennae for magnetically radiated hum, making the jazzmaster one of the most notoriously noisy guitars ever in mass production.

You make a great point, too, that I had overlooked-- all Gibsons have braid-shielded wire throughout, from the pickup leads all the way to the output jack. From the factory, the coils themselves are also shielded with metal covers... though nobody seems to complain about (and I've never noticed) any noise penalty from removing those covers, as is common practice (obviously the common mode rejection of the humbucking coil would help with a lot, anyhow).
I have been rethinking the importance of electrostatic shielding in 2017.  

 I was playing my Telecaster late at night through a test rig I have set up to evaluate DSP based amp simulators,  wearing headphones,  and at one point I was possessed to *remove* the bridge cover (shock and horror) suddenly I was invaded by hum...  put the cover back on, silence.. (The  Telecaster Neck pickup has a permanent cover and is as quiet as the bridge pickup when the cover is in place).  

I looked around and realized that most of the power supplies on at  the time were Switchmode Power Supplies (all of the "real" gear was off for the night) ...  SPS have very weak 60Hz EM radiation, but can generate harmonics, especially those that have poor PCF.    

The only thing that Leo Fender encountered in the 1950s  that was similar to the sort of EMI and RFI we have today would have been Neon lighting (you can read references to it in old interviews with guitarists in the 50s-80s), but he prepared us for the modern world with those covers...

Last Edited By: zmix Mar 30 17 7:40 AM. Edited 1 time.

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injured ear

Silverado

Posts: 79 Member Since:20/02/2012

#16 [url]

Mar 30 17 9:19 AM

I have a ca 1999 Mexi Jazz bass. I replaced the stock pickups with Dimarzio Ultra-Jazz model. They didn't fit without some routing out of the body of the bass. One issue I didn't know about was that the string spacing/pole piece spacing wouldn't match up with the stock bridge. The front pickup was way off, and I wound up with inconsistent string-to-string volume.
Eventually I removed the pickguard and screwed in the front pickup in at a slight angle to get the string spacing correct across the pole pieces.
The pole pieces are not adjustable in height, so I wound up taping some washers to the pole pieces under the A and D strings and *finally* I have even string-to-string volume across the bass.

It was a science project and the bass has no resale value, but it's a good player now with great sound. I think the pickups/strings/strap are worth more than the bass.

-Greg

Greg Thompson

www.injured-ear.com

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tb av

Platinum Blonde

Posts: 1,151 Member Since:24/04/2011

#17 [url]

Apr 4 17 1:34 PM

So what brand / gauge strings do you guys recommend?

I am trying to build myself a Jazz Bass. I'm trying to build a lightweight bass that is basically fun to play... hopefully. I have a Kramer P/J copy and have some pretty heavy I think flat wounds on it but I've played a few Jazz in the stores and they play a lot easier.

So far I've been collecting parts and have found a lightweight body. I found a Badass II, an Antiquity II Neck pu, I have a bound maple neck coming from China.

Any thoughts on Sperzel Tremlock Bass tuners. I love Tremlock for guitar and though I would go with them. Otherwise I think I would get the ones recommended above.

So I need strings ... and I'm not a real big string changer so if one type/brand has more longevity than another that helps.

so Strings, Pots, Caps, Nut(the neck may have a nut and was pictured with tuners but who knows, it's a China deal) , Strap Lock and a bridge pu is all I have left to find. I have a wiring diagram around here somewhere that just says Jaco wiring. Would that be good to go with? Or consider some different values for pots/caps? Been trying to find everything as blem, sale, etc. and so far had good luck. The neck has been the most expensive adn I hope it's nice. Otherwise it will end up on eBay and I'll keep looking.

A friend of mine was concerned about the light body. It's that Palowina stuff. He said it might end up neck heavy. I have some large sheets of 3/8" brass. If it doesn't balance well would anyone see an issue with me routing under the bridge and placing what would be a Badass backer plate. BAII screws to 3/8" brass which screws to body. I suppose I could stack two if needed.

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soapfoot

Ruby Baby

Posts: 7,162 Member Since:04/02/2011

#18 [url]

Apr 4 17 2:37 PM

for strings-- that's just personal preference.

I like pure nickel wound strings for roundwounds (there are several decent makes), and I like LaBella flatwounds.

I recommend STAYING AWAY from "coated" strings.

brad allen williams

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weedywet

Ruby Baby

Posts: 5,791 Member Since:20/01/2011

#19 [url]

Apr 4 17 6:02 PM

I'm a LaBella user for almost everything (endorser: full disclosure)

type depends on the sound be you're after. 

I personally like roundwounds to sound really alive. Which translates to NEW

So, for me, if you say long lasting that implies flats. 

I am a big fan, when not using rounds, of nylon tapewounds. They get that deep thumps McCartney like sound and they're comfortable to play. 

http://www.labella.com/products/750n-black-nylon-tape-light-50-105/

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seth.lucasmicrophone

Tin Man

Posts: 28 Member Since:03/10/2013

#20 [url]

Apr 4 17 7:23 PM

I use Dean Markely Super Rounds, Medium Light .045-.105, and have for thirty-odd years. The sets are consistent string-to-string, which was a big problem for me with Rotos. I'd buy three sets and two of them would have dead low E strings. As Bill said, no roundwounds stay bright for long and in the days of slapping I'd change them every week or so, depending on how busy I was. These days I don't need them to sound as bright, so I'll change them before record dates as needed. I use the same strings on my fretless bass and my five-string. I have a couple of other basses with flatwounds, and I don't really have a preference because I don't use them enough. LaBellas have always been good, and I have Pyramids on one bass. They sound excellent.

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