More than one pickup, or "I don't know what I'm doing"

[richardjmorgan]

Being the main gear/sound nerd (something of a best of a bad bunch scenario) in the band I play guitar (boooooo) in, I was having a play around with our bassist's stuff yesterday in practice to try and get a better sound out of it, and was wondering if those of you a bit more clued up on bass stuff could help explain something to me.

He has an Epi bolt-on Thunderbird, with (what I assume, from a bit of informed fiddling) separate volume pots for the bridge and neck (well, middle-ish but it's the nearest of two to the neck) pickups, and a master tone. I found that I seemed to get a sound that came out both louder and punchier by rolling the bridge volume off to a little over half way than with it on full. Now this seems oddly counterintuitive to me, as I'd have thought 1. the two pickups both on max volume would have more output than any other option; 2. the more bridge pickup there was going into the amp, the "tighter" the sound would be.

I've only ever used basses with single, p-style pickups in more or less the usual place, so i wondered if there was some sort of explanation for this that I've overlooked, whether my ears are playing tricks on me, or whether there's something strange afoot with this particular bass and I need to get my soldering iron out.

Edited April 10, 2013 by richardjmorgan

[danthevan]

I would agree with your assumptions on volume and say there is a dodgy pot there, but I know nothing about anything when it comes to knobs on basses other than everything ive used gets louder when turned clockwise

[Machines]

Having 2 pickups with a large gap between them produces a scooped sound and a perceived drop in volume of the mids.

[neepheid]

On most of the 2 pickup basses I've played, having both pickups on is the "mellowest" sound - they seem to cancel each other out in certain frequencies. The exception was a Guild B402-A I had - both pickups together was the loveliest sound and they seemed to have this natural "chorus" sound to them, like they were singing in unison rather than competing. Can't really explain it better than that.

I use one or the other, usually neck.

[discreet]

[quote name='Machines' timestamp='1365586631' post='2041313']
Having 2 pickups with a large gap between them produces a scooped sound and a perceived drop in volume of the mids.
[/quote]

This. Both pups at max vol tend to work against each other somewhat.

[jezzaboy]

On a T bird, turn the neck pickup up full and turn that pesky bridge pickup down completely.

The neck pickup alone is enough for me. It kicks a*s!

[richardjmorgan]

[quote name='jezzaboy' timestamp='1365591283' post='2041399']
On a T bird, turn the neck pickup up full and turn that pesky bridge pickup down completely.

The neck pickup alone is enough for me. It kicks a*s!
[/quote]
I actually found dialling in a bit of the bridge (somewhere between about 4-6/10) gave us what we were after - seemed to add a bit of extra attack to what we were getting from the neck (which, of the two soloed out, I agree was the better sounding)

[richardjmorgan]

[quote name='discreet' timestamp='1365590891' post='2041391']
This. Both pups at max vol tend to work against each other somewhat.
[/quote] Ah, ok. Is there a particular technical reason for this? It's not a phenomenon I've ever encountered on any of my 2 pickup guitars.

[Machines]

[quote name='richardjmorgan' timestamp='1365592704' post='2041427']
Ah, ok. Is there a particular technical reason for this? It's not a phenomenon I've ever encountered on any of my 2 pickup guitars.
[/quote]

It is the same principal on a Les Paul but since you have twangy trebly string and the Human ear is more sensitive in this frequency range you won't notice.

Edited April 10, 2013 by Machines

[richardjmorgan]

[quote name='Machines' timestamp='1365593076' post='2041433']
It is the same principal on a Les Paul but since you have twangy trebly string and the Human ear is more sensitive in this frequency range you won't notice.
[/quote]
Ah, ok, so it's a mixture of actual technical reason and me having stupid ears then!

[EssentialTension]

This is common.

On a two pickup Jazz bass there's a sweet spot (although not everyone will agree it's sweet) with the neck pickup on 100% and the bridge pickup rolled off to about 75%.

[BOD2]

It's more noticeable on a Strat. The "in between" pickup selections (bridge + middle, or middle + neck) are thinner than each pickup on its own.

Each pickup, due to its position relative to the strings, "hears" a different combination of harmonics. With two pickups selected you get a mix of the two sets of harmonics and some combine while others cancel out.

[ead]

It's called phase cancellation I think, and it's due to the relative positions of the pickups and the vibrating string.

See the article here: http://barefacedbass.com/uploads/BGM61%20Dec2010.pdf

[richardjmorgan]

[quote name='ead' timestamp='1365594999' post='2041487']
It's called phase cancellation I think, and it's due to the relative positions of the pickups and the vibrating string.

See the article here: [url="http://barefacedbass.com/uploads/BGM61%20Dec2010.pdf"]http://barefacedbass...1%20Dec2010.pdf[/url]
[/quote]
Interesting stuff, cheers for the link!

[drTStingray]

If you have an active bass with a 3 band (or 4 band is even better) EQ, you can counter the issue by boosting the mids and holding back the bass a little. Works well on a Stingray HH.

[iiipopes]

[quote name='richardjmorgan' timestamp='1365583657' post='2041253']
Being the main gear/sound nerd (something of a best of a bad bunch scenario) in the band I play guitar (boooooo) in, I was having a play around with our bassist's stuff yesterday in practice to try and get a better sound out of it, and was wondering if those of you a bit more clued up on bass stuff could help explain something to me.

He has an Epi bolt-on Thunderbird, with (what I assume, from a bit of informed fiddling) separate volume pots for the bridge and neck (well, middle-ish but it's the nearest of two to the neck) pickups, and a master tone. I found that I seemed to get a sound that came out both louder and punchier by rolling the bridge volume off to a little over half way than with it on full. Now this seems oddly counterintuitive to me, as I'd have thought 1. the two pickups both on max volume would have more output than any other option; 2. the more bridge pickup there was going into the amp, the "tighter" the sound would be.

I've only ever used basses with single, p-style pickups in more or less the usual place, so i wondered if there was some sort of explanation for this that I've overlooked, whether my ears are playing tricks on me, or whether there's something strange afoot with this particular bass and I need to get my soldering iron out.
[/quote]
This is normal. It's a combination of impedance drop with both pickups in parallel, and some comb filtering from the different phasing of the overtones sampled in different positions. I solve the matter on passive J-basses and P/J basses by putting a .01 mfd capacitor inline from the bridge pickup hot lead to the bridge pickup volume control. Since there isn't that much fundamental to the signal in the bridge position, it doesn't affect the tone significantly, and it eliminates the dropout. The tradeoff is that there is the slightest bit less volume to the bridge pickup, kind of like a permanent volume roll-off to about 8 1/2. I first noticed this myself in 1981 on the 1975 J-bass I had then.

Edited April 10, 2013 by iiipopes

[richardjmorgan]

[quote name='iiipopes' timestamp='1365604647' post='2041699']
This is normal. It's a combination of impedance drop with both pickups in parallel, and some comb filtering from the different phasing of the overtones sampled in different positions. I solve the matter on passive J-basses and P/J basses by putting a .01 mfd capacitor inline from the bridge pickup hot lead to the bridge pickup volume control. Since there isn't that much fundamental to the signal in the bridge position, it doesn't affect the tone significantly, and it eliminates the dropout. The tradeoff is that there is the slightest bit less volume to the bridge pickup, kind of like a permanent volume roll-off to about 8 1/2. I first noticed this myself in 1981 on the 1975 J-bass I had then.
[/quote]
Interesting. Might have to see if he'll let me give this a try!

[stingrayPete1977]

I've never really got on with multiple pickup basses partly because of this, when its good its very good though.

[Lfalex v1.1]

Anyone who favours single pickups, don't accidentally buy a Warwick Fortress Masterman... It'll confuse the hell out of you!

[stingrayPete1977]

I get confused with the tone pot on a p bass going what sounds like the opposite way to my ears!

[Jono Bolton]

[quote name='EssentialTension' timestamp='1365593496' post='2041446']
This is common.

On a two pickup Jazz bass there's a sweet spot (although not everyone will agree it's sweet) with the neck pickup on 100% and the bridge pickup rolled off to about 75%.
[/quote]

This. With both pickups turned up on my Jazz there's a distinct drop in volume, and rolling back one of the pots brings it up again, although I prefer 100% bridge and 75% neck

[karlfer]

So what's the script with active bass, 4 controls, vol, pan, bass, treble?

[richardjmorgan]

[quote name='karlfer' timestamp='1365663063' post='2042410']
So what's the script with active bass, 4 controls, vol, pan, bass, treble?
[/quote]
No clue. As we've established, I'm out of my depth with more than one passive pickup!

[RandomBass]

[quote name='stingrayPete1977' timestamp='1365620782' post='2042016']
I get confused with the tone pot on a p bass going what sounds like the opposite way to my ears!
[/quote]

Have you tried facing the other direction?

[Lfalex v1.1]

[quote name='karlfer' timestamp='1365663063' post='2042410']
So what's the script with active bass, 4 controls, vol, pan, bass, treble?
[/quote]
Adjust to taste.
But feel for those with 3-band, 4-band and anything with frequency AND level controls/ filters...