Phase question

bklynbass

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For years my 68 Starfire II sounded terrible when both pickups were on all the way...no bottom end, nasal, anemic, butt tone. No big deal as I usually just used the front pickup anyway. If I rolled off the back pickup just a hair, the bottom end jumped back out and sounded like 90% neck/10% bridge - cool, but I never really got to really hear or use the back pickup with the front. Fred Hammon had told me that they were probably wired out of phase (like a jazz bass out of the shop), I guess so they would hum-cancel. I don't love the sound of both jazz bass pickups on all the way but this was about 100 times worse, I assume because the immense output of the Bi-Sonics canceling each other out made the sound that much worse when they were out of phase

Having no hum is useless to me if it's making the sound so terrible so a few months ago I finally got around to wiring them IN phase - I just reversed the wires on one of the pickups. And now I can hear what I was missing since I got the bass 9 years ago...there's a whole other sonic dimension to the bass now. All things being equal I think I still prefer the sound of the front pickup soloed but it's a much more versatile bass now (particularly for playing live) and with both pickups working I'm getting great new overdriven sounds...I also realized that Jack probably had his dialed in like this a lot of the time.

So my questions are - has anybody else had this experience with their two pickup Guilds, and did Guild intentionally wire the pickups out of phase? Or did someone just hook them up the wrong way at some point? Just curious.
 

fronobulax

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Interesting. AFAIK my JS II came from the factory wired in phase but beyond that I can't help you. My Starfire is a Starfire I :wink:
 

jte

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First, the Jazz Bass PUPs aren't wired out of phase, they've got reverse polarity. That way they get the full frequency response (less the very very short wave lengths that are exactly equal to the distance between the poles on the two PUPs), but have the humbucking effect.

Wiring Jazz Bass PUPs out of phase (reversing the hot and ground) is a MUCH different sound than the reverse wrap/reverse polarity that they have. It's much like what you describe your bass sounding like- anytime both PUPs have the same volume, the bottom end disappears and it's a thin, nasal honk.

It definitely sounds like your PUPs are out of phase, and it's probably not how they were supposed to be wired from the factory. All the dual PUP Guilds I've played were in phase.

John
 

fronobulax

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jte said:
First, the Jazz Bass PUPs aren't wired out of phase, they've got reverse polarity.

What's the difference? I've never messed with PU wiring but in every other case I have encountered with two wires they are effectively the same thing. Thanks.
 

bklynbass

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According to the Wikipedia page on Jazz Basses:

"Having both pickups cranked up at full volume produces the classic scooped, out of phase "growling" sound which many players - such as Marcus Miller and Will Lee - use for slap bass playing. This sound is the product of certain frequencies from both pickups being out of phase and cancelling each other, leaving a "scoop" on the midrange. This is similar to what happens on some guitars when you blend the sounds from two different pickups, such as the Fender Stratocaster. Perhaps this is why in recent years it has become quite popular to add an active on-board EQ with a special "phase" switch on Jazz-style basses."

And from http://www.bass-guitar-info.com/pickup_wiring.html

"Pickup wiring is one of those items that is worth knowing, especially if your bass has two pickups or split type pickups.  Most pickups are wired in parallel configuration to the output jack. 

 There are some important things here to note.  First, the pickups are actually out of phase.  When both pickups on a Jazz bass are turn up full on, the pickups cancel out any hum that may be in the area.  If you use one coil only, it will be in single coil mode, and you can pick up hum."
 

mellowgerman

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As stated above, being wired out of phase and cancelling hum are two completely different things. The wiki page is incorrect in saying "out of phase" but that doesn't surprise me since literally anyone can write a wiki page and small things like that get overlooked.
My friend has a 1964 Starfire III that came out of the factory wired out of phase... we always assumed it was on purpose though because we installed a 5-way pickup/phase selector switch and the out-of-phase parallel setting sounded best to our ears -- an edgy cutting sound that works great for lead. Still out of phase rarely works well for bass. I've installed phase switches on several of my basses (including a fretless jazz that I had, another reason I know jazz's are not wired out of phase innitially) and it was more of a fun thing to mess around with maybe for the intro of a song or something along those lines.
 

bklynbass

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Cool, I have no idea what I'm talking about, that's why I brought the issue here...I've always been told, perhaps erroneously, that humbucking pickups (and I assumed, hum-canceling single coils) are wired out of phase, whether parallel or in series. At least that's what Dan Erlewine's book says.

What I can tell you is that before I reversed the wires on one of my pickups (putting them in phase or not) they definitely hum-canceled when both were full-on and now they don't, though like I said it sounds 1000x better now.

Perhaps there's a total pro luthier/Guild guru out there who can set us all straight? :D
 

jte

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Wiring single coil pickups with reversed wrap and reversed polarity is how you get rid of hum without strangling all the lows and low mids. It's not the same as wiring the PUPs out of phase, but it's similar. If you reverse the hot and ground connection of one PUP on a typical Jazz bass, you'll hear a much more pronounced low end drop off, and that's what out of phase means.

John
 

bklynbass

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That makes sense... And since my starfire's old hagstrom pickups are probably not RWRP, they won't hum cancel unless they're out of phase, I presume?
 

fronobulax

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jte said:
If you reverse the hot and ground connection of one PUP on a typical Jazz bass, you'll hear a much more pronounced low end drop off, and that's what out of phase means.
That's what I thought reversed polarity was. Yet above you speak as if reversed polarity and "phase" are different. Would/could you clarify, please? Thanks.
 

mgod

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This conversation is getting very messy.

RWRP DOES mean the pickups are out of phase in certain respects; that's what reverse polarity means.

There are a lot of schemes for hum canceling, but AFAIK all of them involve putting two signals (or more) electrically out of phase with each other. If I remember right its called "differential mode rejection" wiring. Alembic uses it in their instruments: the dummy pickup in the middle picks up hum as the signal pickups do, but is out of phase and adjustable on the back of the instrument.

The old GD Wall O' Sound used a similar concept for the vocals (two mics wired OoP into a combiner box: one sung into, one not, to reject the the sound coming in from behind the singers).
 

fronobulax

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mgod said:
RWRP DOES mean the pickups are out of phase in certain respects; that's what reverse polarity means.

Thanks. Every so often something happens that makes me think "everything I know is wrong". I think in this case there are subtle nuances I am missing but my basic concepts are sound. Part of my problem stems from knowing enough practical electronics to assemble a Heathkit computer but not design an analog circuit, plus serious professional experience in digital signal processing.

Should we take a lead from the Owner Review threads and start one for Starfire basses?
 

mgod

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From RT:

"Actually, the pickups are NOT out of phase in the electrical sense as you've flipped the magnet (for 180 degrees phase shift) and also the coil via reverse wind (for another 180 degrees of phase shift), so electrically, the pickups are now in phase, but the coils which sense hum (the magnets don't) are out of phase.

"That does not change the other issue which is that just like microphones, if you have two or more separated by some distance, there will be harmonics (for microphones: frequencies) at which they're out of phase.

"And then there's the whole issue of coil loading...

"But given how much work I have in front of me, that's as much as I can write 'til after NAMM...

RT"
 

bklynbass

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Thanks for going to the source.

I have four Bi-Sonics between my two Guild basses and now I guess I need to figure out if they can be arranged in RWRP pairs or not so they can eliminate hum without sounding choked.
 

mgod

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If you play them simultaneously facing each other, I'm sure you'll find a hum-canceling position.
 

mellowgerman

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Sort of interesting note to make... on my Fender Mellostang bass, when I have the dark star and dimarzio model one (single coil mode) both on full, they just happen to cancel out hum almost perfectly without being out of phase. Crazy coincidence, but I'm not complaining :)
 

mellowgerman

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bluzman said:
Once you got the pups right, change the cap to a .1 oil/ paper. One of the best and cheapest mods I've ever done to a bass.

any chance you could elaborate a bit on this?
 

bluzman

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mellowgerman said:
bluzman said:
Once you got the pups right, change the cap to a .1 oil/ paper. One of the best and cheapest mods I've ever done to a bass.

any chance you could elaborate a bit on this?

Surely... :D

The tone caps stock appear to be .05 uf. If you change them to .1uf it lets less treble come through.
To my ears the .1 uf caps give a richer feel to the bass tones. If you don't like the .1uf buy a couple of .047uf
and you can put it back to what it was but the oil filled make a difference... at least to my ears.
You can get them anywhere on the internet, but the link below has them for fair prices (still a little high),
but some places charge enormously for caps. While you will never see 600Volts in a bass guitar circuit,
the higher voltage oil caps are a good thing. All I can say is I love what it has done to my basses and I turned
on a few touring players to these and they love what it did too. I think it's worth the money and the effort.
Better than Orange Drops in my opinion too.

This link is for the Vitamin T... Some places have the Sprague Vitamin Q

http://www.mojotone.com/amp-parts/Vitam ... d-1uF-600V

Starfire_Bass_II.jpg


http://www.stewmac.com/freeinfo/w101-tonecontrol.html
 
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