Rickenbacker 4004 problems

[Mick Bailey]

I've got a 4004 in for investigation. The owner thought he had a pickup issue but I've eliminated this. Whilst I'm familiar with dead-sounding guitars and dead-spots on the neck, I've never really experienced this as an overt problem - usually quite subtle.

But this bass is the definition of the problem; an A played on the low E string is way lower in volume than the open A string, by a country mile. Alternating between the fretted A and B played on the bottom string is like two different guitars - similar to engaging a boost pedal. The A has a much shorter sustain and is properly dead.

Apart from a very high nut and consequently high action I can't see anything wrong. No fret buzz, mechanical interference, loose bridge or anything else I can see.

Any thoughts?

[tedmich]

Pickup too close? A few dead spots on a couple frets for specific strings are expected and usually respond to minor truss rod adjustments, or in bad cases lighter tuners can help but your description sounds too extreme (strings aren't dead I hope!) I'd play with PU height! Ricks are supposed to sound too loud and sharp EVERYWHERE!

[Justin Thomas]

Maybe this is too easy and I hope I'm not insulting anyone with this suggestion
When's the last time the strings got changed? Is there a divet on the underside of the string? I'm the only bass player I know who changes their strings more than once every few years... but it sounds like you tried all the obvious.

Justin

[Mick Bailey]

No insult taken, though the strings are good and there are no fret problems. The pickups had already been adjusted right down by the owner and experimenting with height didn't give any improvement. I wondered if adjusting the truss rod may be beneficial - though the neck relief is good as it stands. I'll try this - maybe a slight 1/8th turn or so. Perhaps this in conjunction witha guage change.

As an update I put a contact pickup on the body (with the pickups set as low as they'll go) and the results are the same. As you'd also expect, the instrument also has issues acoustically, with the same notes sounding dead unamplified.

[tedmich]

The body pickup is a good control, it certainly sounds like some destructive resonance although this is usually just a couple fretted notes and this description sounds more global. I'd only trust the strings is they performed differently on a different bass but see if the truss rods help. You could also try a (temporary) weight on the peg head to see if you could shift the resonance, although going lighter is usually preferred...owners not gonna go for that probably.

[bbsailor]

No insult taken, though the strings are good and there are no fret problems. The pickups had already been adjusted right down by the owner and experimenting with height didn't give any improvement. I wondered if adjusting the truss rod may be beneficial - though the neck relief is good as it stands. I'll try this - maybe a slight 1/8th turn or so. Perhaps this in conjunction witha guage change.

As an update I put a contact pickup on the body (with the pickups set as low as they'll go) and the results are the same. As you'd also expect, the instrument also has issues acoustically, with the same notes sounding dead unamplified.

Mike,

Try putting the bass on a hard surface on it's back. Secure the head area to the hard surface with a bungi cord. Measure the distance from the middle of the neck back to the hard surface. Place a block of wood a little thicker than the measured distance under the middle of the neck to damp any neck vibrations and see if the dead notes change, shift or are eliminated.

Joseph J. Rogowski

[Mick Bailey]

Hi Joseph,

Just placing the bass on the benchtop resting the head on a block is enough to dramatically improve things. Blocking the centre of the neck eliminates the problem entirely. I also tried Tedmich's suggestion and used a G-glamp to add some weight and this also is beneficial, but I think the weight needs to be trimmed just right to shift the resonance. I also experimented with a single-band compressor and this gave an instant improvement and completely 'fixed' the problem, but it would need a dual-band or selectable unit to give the best results.

[David King]

It's a Rick, it has a spaghetti neck, what was this fellow expecting? You're sure the fingerboard is firmly glued on, that the frets are tight in their slots and that the truss rods aren't rattling inside the neck? Does the nut fit in it's ledge without rocking or showing a gap under the middle?
There are all manner of passive and active resonance treatments if someone wants to throw money at the problem. I'd try putting lead plugs under the face dots. One of the easier fixes is to glue an aluminum plate to the back of the headstock with an elastomeric glue. 3M reusable mounting tape is a cheap and quick way to start. Cut holes in the aluminum where the tuners go in such a way that the tuners don't touch the plate at all. The softer and rubberier the glue the better. The stuff they use to glue the magnetic business cards of ambulance chasing lawyers to the yellow pages cover would be ideal if you could find it.

[Mick Bailey]

Well, I 've been all over this instrument and can't see anything loose or rattling. The only thing I don't like is the nut is cut a little too high for my taste, but nothing extreme. I had a bass many years ago where the answer was to cut a shaped piece of type-metal (from the hot-metal days of newspapers) and stick it to the back of the headstock with double-sided carpet tape.

I wonder if changing string gauge and therefore neck tension may help?

[David King]

You could read up on dampening systems and see if it makes any sense in the context of a guitar neck.
Passive and active vibration isolation systems - Theory
One of my favorites is the semi-passive piezo feedback loop. This was used to treat structural resonance in bridges. You apply a piezo electric patch to each side of the member that's vibrating and then connect the patches together out of phase. As the member starts to bend in one direction it flexes the piezo crystal on one patch into compression generating a DC voltage which is fed directly into the opposing patch causing it in turn to try to flex in the opposite direction momentarily stiffening the system and damping out the movement. You could achieve the same thing using strong magnets and eddy currents. An active version of this would have an amplifier in the feedback loop so that the voltage might be doubled or tripled to speed up the damping process.

Examples using ISODAMP C-1002 elastomeric compound...
E-A-R Specialty Composites

A slab of Dragon Plate stuck on the back of the neck with said isodamp C-1002 might be a very effective solution but it would also be butt-ugly to the owner.

If I were going to anything with this neck I'd probably pop the fingerboard off and install some steel or carbon fiber stiffening rods between the truss rods. Just replacing the bubinga fingerboard with an ebony one would make a world of difference in terms of the stiffness.