Centre toggle position = lower volume .... why?

[Oz_Greg]

.
Ok,

Why does my Rick 4001 (fitted with a high gain and HB1) put out less volume when the toggle switch is in the centre position and both neck and bridge volumes are set to maximum?
If I back the pot off on either of the pickups a little the combined volume rises to a level you would expect, but in that centre spot it is noticably reduced when compared to individual pickup volume levels (ie toggle up or down).

I've been told this is typical of these, and 4003 basses.
I'm not happy with "typical", I want to fix it! Has anyone addressed this issue before and come up with a solution?

Just a thought ...... Would a suitable diode on each wire going to the jacks prevent any signal fighting the other if this is the problem?

Greg

[Tigger]

I have a couple of customised V63s, Greg, with additional Hi-Gain between neck toaster and bridge horseshoe, controlled with individual selector switches. Each pick-up is set to a height that balances for output level with the other pick-ups (which required replacement of the original horseshoes), and all pick-up selections are nice and consistent for level, whether single pick-up, any two, or all three. What you're describing is characteristic of an out-of-phase situation, so have you tried reversing the wires of one pick-up relative to the other to see what happens?

[cassius987]

Why does my Rick 4001 (fitted with a high gain and HB1) put out less volume when the toggle switch is in the centre position and both neck and bridge volumes are set to maximum?
If I back the pot off on either of the pickups a little the combined volume rises to a level you would expect, but in that centre spot it is noticably reduced when compared to individual pickup volume levels (ie toggle up or down).

Go grab a Jazz Bass or any other two-pickup bass. It does the exact same thing, getting louder if you dial one pickup back a little. It's not the same as RWRP, which has no effect on sound other than to remove external noise picked up equally by the coils. However RWRP also relies on equal gain levels to work.

The effect you are hearing is not a flaw or bad wiring--this is what happens when you put two pickups' signals into the mono output at roughly equal gain (based on the volume pots). If you turn the volume of one or the other down, the signals don't compete at the same gain and one can basically resume the role it would have had if you had soloed it so the sound is bigger while the other basically becomes "icing on the cake". Same thing happens when you use a 0.0047 microfarad cap on the bridge pickup--the result is largely the neck pickup signal soloed with a little extra top from the bridge pickup, because the signals are no longer in parallel phases. And this also one of the reasons Ric-O-Sound seems to make each pickup sound better even though you can hear them both and even send them to the same amp with the right setup.

The physics behind this basically amounts to a phenomenon called comb filtering. The pickups are generating waves that are slightly out of phase with each other not in time but in space, as I understand it to be a result of pickup placement, and that results in some frequencies getting overall added to or subtracted from. This phenomenon is even more severe if you run 3 pickups at once (I should know).

Just a thought ...... Would a suitable diode on each wire going to the jacks prevent any signal fighting the other if this is the problem?

That would have no effect if you modified both signals equally, however a large capacitor (0.1 microfarad or bigger) on just one of the two pickups would put them perpendicular to each other above Fc with regards to phase, and so you would not have any appreciable comb filtering and no detectable signal loss from the cap. Since you have a setup that does not rely on RWRP and you don't seem to like this phenomenon this could be a good solution to you. I think you may like the comb filtering sound a little more with two similar pickups, but I understand that two dissimilar pickups can sound very weird with this phenomenon and the result is not always good.

[antonius]

And this also one of the reasons Ric-O-Sound seems to make each pickup sound better even though you can hear them both and even send them to the same amp with the right setup.

This is interesting. So if I use a stereo male - mono female adapter to enable me to use a normal guitar cable plugged into the Ric-O-Sound output will I get a very different sound to the usual plugging of my cable into the mono output? Will the character of each pickup be enhanced or sound different by doing this or will I get the same sort of sound I get using the mono output?

[cjj]

Joshua's pretty much got it there.

When you add 2 signals you always have the potential for comb filtering. If the signals are complex (not a single sine wave) you almost certainly get filtering. Here's what happens to cause that. Say you take 2 signals that are both 1 volt AC signals meaning they alternate positive and negative 1 volt each way. If, when you mix them, one goes to +1 volt at the same time the other goes to -1 volt, adding +1 to -1 gives you 0, and no output. If you turn one signal down a bit, say to 1/2 volt, then you'll get +1 added to -1/2 which leaves 1/2 volt so, magically, the volume goes up!

Now, on a multipickup guitar, you have fairly complex signals with lots of different frequencies and even the same frequency from 2 different pickup positions on the string will have phase differences in the waveforms. When you add them together, you will get some of those cancellations.

Adding a capacitor in line with a pickup will change this, not eliminate it. A signal going through a capacitor undergoes a phase shift, so now, instead of +1 adding to -1, one of the signals is shifted a bit and doesn't hit -1 at the same time the other hits +1 so you get the same effect as turning the volume of one down a bit. You're still getting cancellations, just not the same cancellations...

[cjj]

And this also one of the reasons Ric-O-Sound seems to make each pickup sound better even though you can hear them both and even send them to the same amp with the right setup.

This is interesting. So if I use a stereo male - mono female adapter to enable me to use a normal guitar cable plugged into the Ric-O-Sound output will I get a very different sound to the usual plugging of my cable into the mono output? Will each pickup sound 'better' or different by doing this?

No, the signals will still add the same way as they do in the switch. Now, if you run the 2 pickups into separate amps, you won't get the cancellations. If you use 2 separate preamps and mix into a single power amp you may get the cancellations depending on how much phase shift you get in your amps (they all have some phase shift that varies due to design and a lot of other factors.

And again, mixing signals will ALWAYS cause some cancellations since not everything is going positive at the same time as everything else. This will even happen in the AIR with signals coming from separate speakers! Speakers move in and out (positive and negative) to create sound. If one goes out when the other goes in, the air doesn't get moved as much as it would if both were "in phase" (this is why you should pay attention to the + & - speaker leads)...

[antonius]

Thanks for the explanation CJ.

[cassius987]

CJ, thanks for filling in the gaps, and it was educational for me too.

[coolhandjjl]

This should be a Sticky! I've read numerous posts from Joshua on this, he does explain it the best regarding a two pickup bass where both pups are same or similar.

Regarding the OP using a humbucker and a single coil, he should try to reverse the polarity on one of them as a test, but I have found that when using two pickups that are vastly different, the results are unpredictable. Often, the one with the higher windings has to be dialed down to balance out if you want them to mix 50/50.

[iiipopes]

I have even gone so far as to put a .01 inline capacitor in the bridge position of basses with a "J" bridge pickup in order to eliminate the dropout as much as possible. There's not much fundamental signal anyway at that position, and it really cleans up the combined tone.

Aside for those who also play guitar: this is also one reason why humbuckers sound different than single coils (wider "aperture"), and one reason why a guitar two humbuckers in the middle position has a "sweet" tone.

Wiring of two different kinds of pickups can be a chore. When I did my custom fanned fret bass with a Rick humbucker in the P position and a DiMarzio UltraJazz in the J bridge position, I had to go through all the permutations of wiring the DiMarzio to get the proper electrical and magnetic alignment for the pickups to work together.

[johnallg]

Regarding the OP using a humbucker and a single coil, he should try to reverse the polarity on one of them as a test, ........

What Ian and John said. Reverse the HB1.

[8mileshigher]

Good stuff ! Very educational thread here.

[Oz_Greg]

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Wow, what a forum!

Thank you all for the responses. (You were right to suggest this Dane!)

Greg

[coolhandjjl]

.....however a large capacitor (0.1 microfarad or bigger) on just one of the two pickups would put them perpendicular to each other above Fc with regards to phase, and so you would not have any appreciable comb filtering and no detectable signal loss from the cap......

I have even gone so far as to put a .01 inline capacitor in the bridge position of basses with a "J" bridge pickup in order to eliminate the dropout as much as possible. There's not much fundamental signal anyway at that position, and it really cleans up the combined tone.......

For future reference, if one wants to isolate the pups, which cap is better, a .1 or a .01?

[cassius987]

0.01 is probably more than adequate. 0.1 will simply have a lower Fc and further assures you lose none of your signal--if that's what you're after. Sticking the cap on the bridge pickup, like Scott said, is the other way to be safe.