Ideal bass pickup height

[vulcan_creedler]

I'm sure it's been discussed before, and I've seen the odd reference in various threads, but I'm wondering on what is the ideal spacing between the pickup and the strings.

The reason I ask, is that I think this could be one of the reasons why I cannot get 2 HB1's (of different vintages) to work well together on my '88 4003. I've tried switching the phase on one of them to no avail. Whether in or out of phase, the combined sound is a lot quieter.

Kind of clutching at straws, but maybe it is a physical setup issue? Generally - I get the pickups as close as possible to the strings, at the same time, keeping their relative volumes similar. On my old 4001, I actually changed out the 4 sets of domed nuts/bolts on the neck pickup, for a set with the heads ground virtually flat, just to get a bit more height from that higain.

but back to my question: Is as close as physically possible best, or is thee a "sweet spot" level some way below the strings?

GT

[woodyng]

I never actually measure the heights,but on 2-pickup basses I always have the rear pickup raised to where i can get some finger contact with the pickup,and usually tend to recess the forward pickup to the point of it's upper edge being just slightly above the pickguard. It tends to even out the relative volumes that way.

[clementc3]

You might be experiencing "comb filtering". Do an advanced search on that phrase; there is a brief explanation here:

viewtopic.php?f=2&t=408759&p=794385&hil ... ng#p794385

[Captain Bob]

FWIW...... a good starting point might be 3/32" with open strings. One must be careful to avoid a 'wolf tone'. If the bass starts sounding like a sitar, particularly in the upper register of the neck, the magnets are too close to the strings.
My 4003 sports both a toaster and HS. The toaster has one rubber donut on the adjustment screws, and I run this pup at 8/64" from the bottom of the open E string. Without mentioning 128th's, the G string is slightly closer. For this, I use volume with consistent attack to adjust it as needed, to match the E string volume.

The HS is around 10 or 12/64" (I'm not home and able to visit my notes or measure). BUT, its measured from the base of the HS pup to the underside of the E and G with a machinist's scale, not the individual pole pieces. This is do to the upper HS arms interfering with the scale. Once dialed in with volume on that pup between the E and G, I then utilize the pup selector on each individual pup to ensure equal volume between the bass and treble pups themselves. The bass sounds great.

It's kind of like biasing matched set of power tubes on an amp. One would like to see equal negative voltage on the plates, equivilent Ik, and exact percentage of wattage output.

When I first received the bass (4003 Snowglo) it was still in its shipping box. Just exploring the factory setup before I started my own work to dial the bass in, the HS pup was so high that as I went fret by fret on each string, up the neck I was getting wolf tones above the 15th fret or so.

Hope that provides some insight.

Cheers