cassius987 wrote:A Jazz Bass or any other two-pickup bass will do the same thing your 4004 is doing. It's called comb filtering, and it happens when equal level signals are slightly out of phase with each other so some frequencies get cut and others boosted. In nearly every case what you hear is a mid scoop; same as a Jazz Bass. It's totally normal. The effect can be defeated by putting a cap or resistor in series with one of the signals (for different reasons), or just by sending one of the signals even a little to ground as is observed with the VVT wiring. The Roscoe Beck bass uses a resistor in series, so there are no impedance or tonal changes, just an overall dip in one pickup's output allowing the other to "rise to the top" and the full signal comes through again.
I _like_ the effect, personally. Depending on the tune, of course.
Is the effect limited to basses primarily? None of my two-pickup guitars do this, which is (I suppose) why I found it surprising initially.
Last edited by Kingbreaker on Thu Mar 28, 2013 7:26 am, edited 1 time in total.
cassius987 wrote:A Jazz Bass or any other two-pickup bass will do the same thing your 4004 is doing. It's called comb filtering, and it happens when equal level signals are slightly out of phase with each other so some frequencies get cut and others boosted. In nearly every case what you hear is a mid scoop; same as a Jazz Bass. It's totally normal. The effect can be defeated by putting a cap or resistor in series with one of the signals (for different reasons), or just by sending one of the signals even a little to ground as is observed with the VVT wiring. The Roscoe Beck bass uses a resistor in series, so there are no impedance or tonal changes, just an overall dip in one pickup's output allowing the other to "rise to the top" and the full signal comes through again.
What took you so long to get here! I was going to explain this in simpler terms but I knew you'd do a much better job of it.
Kingbreaker wrote:Is the effect limited to basses primarily? None of my two-pickup guitars do this, which is (I suppose) why I found it surprising initially.
I would think it happens with guitars, too, although the higher frequencies make it harder to discern the comb filtering. Pickup spacing has a much to do with the strength of the filtering, also.
Kingbreaker wrote:Is the effect limited to basses primarily? None of my two-pickup guitars do this, which is (I suppose) why I found it surprising initially.
I would think it happens with guitars, too, although the higher frequencies make it harder to discern the comb filtering. Pickup spacing has a much to do with the strength of the filtering, also.
So. . . the wide spacing of the bass pickups --> greater phase delay --> more pronounced effect? On a 4005 it must be very strong if that's the case.
cassius987 wrote:A Jazz Bass or any other two-pickup bass will do the same thing your 4004 is doing. It's called comb filtering, and it happens when equal level signals are slightly out of phase with each other so some frequencies get cut and others boosted. In nearly every case what you hear is a mid scoop; same as a Jazz Bass. It's totally normal. The effect can be defeated by putting a cap or resistor in series with one of the signals (for different reasons), or just by sending one of the signals even a little to ground as is observed with the VVT wiring. The Roscoe Beck bass uses a resistor in series, so there are no impedance or tonal changes, just an overall dip in one pickup's output allowing the other to "rise to the top" and the full signal comes through again.
What took you so long to get here! I was going to explain this in simpler terms but I knew you'd do a much better job of it.
Thanks Jeff!
jps wrote:
Kingbreaker wrote:Is the effect limited to basses primarily? None of my two-pickup guitars do this, which is (I suppose) why I found it surprising initially.
I would think it happens with guitars, too, although the higher frequencies make it harder to discern the comb filtering. Pickup spacing has a much to do with the strength of the filtering, also.
I agree, it's probably the frequencies being filtered that are less noticeable on the guitar. Although I believe I have heard this effect on an SG once, and I thought it was pretty common on classically wired Strats too but don't remember for sure.
Kingbreaker wrote:
jps wrote:
Kingbreaker wrote:Is the effect limited to basses primarily? None of my two-pickup guitars do this, which is (I suppose) why I found it surprising initially.
I would think it happens with guitars, too, although the higher frequencies make it harder to discern the comb filtering. Pickup spacing has a much to do with the strength of the filtering, also.
So. . . the wide spacing of the bass pickups --> greater phase delay --> more pronounced effect? On a 4005 it must be very strong if that's the case.
The effect may be more or less pronounced but the frequencies filtered are also going to change and may lead to how noticeable the effect is or isn't. Notably, the 4004 has wider spacing than the 4003.
Very sharp looking bass 
I was going to explain this in simpler terms but I knew you'd do a much better job of it. 
