minimizing (eliminating?) dead spot

Discussion in 'Luthier's Corner' started by Jim Breece, May 20, 2007.

  1. I've been looking all over for you guys. Just checked all the threads, didn't see this addressed:
    Has anybody found any secrets for minimizing or eliminating the dead spot around C# on the G string? Here are some things I can eliminate:
    1 scale, at least 32"-35"
    2 fingerboard and neck wood, at least maple, mahogany, wenge, rosewoods, ebony, pau ferro and phenolic
    3 one or two trussrods, single or double action
    4 bolt on, set neck, neck through construction
    5 straight or tilted headstock
    My observations have been that a good bass has it most noticeably at the C#, getting better very quickly in either direction, a bad bass is fuzzy from A to E. My Hohner Steinberger knockoff seems to have it more an octave up, but chopping off all the extra wood on a P bass headstock focused the dead spot but didn't eliminate it or change its pitch. I believe my upright even has a smidgen of it. A stiff neck with a chunky shape seems to be the best answer but it still seems like there should be a way around it. I think the fundamental is about 155 Hz, no? Seems like the fundamental and first harmonic die off quickly but the higher harmonics continue to sustain. Enlighten me, oh gurus.
  2. The things that I've found to help the most with minimizing deadspots are laminating very stiff woods (purpleheart, padauk, bubinga, etc) and using carbon fiber bars.
  3. Jazz Ad

    Jazz Ad Mi la ré sol

    It's mostly a Fender style issue. Eliminating 4 in-line tuners seems to be the most efficient way.
    No design is completely immune to dead spots though. Sometimes it just happens.
    Oh and just to be an annoying know-it-all, the fundamental IS the first harmonic.
  4. Rodent

    Rodent A Killer Pickup Line™ Commercial User

    Dec 20, 2004
    Upper Left Corner (Seattle)
    Player-Builder-Founder: Honey Badger Pickups & Regenerate Guitar Works
    I have had great success in significantly reducing (in most cases it's almost completely eliminating) deadspots by installing threaded steel inserts in the neck and utilizing stainless steel machine screws. I know that there have been numerous threads (nyuk, nyuk) on this topic - if you can't find one of them, make sure you have your search looking back beyond just a few weeks. I believe I even posted a small tutorial as part of a larger work on customizing a pre-finished parts bass (Tele '51P 5-string)

    I know not all here would agree to this being such a significant solution ... but I only write of what I have directly experienced first-hand on many, many Fender and Fender-style necks.

    all the best,

  5. I don't know about deadspots...

    but I'll tell you this...last week I gave my 4 neckplate screws a good tightening on my inexpensive Yamaha...In addition, the 5 screws in the bridge also, needed a nip up...(I do this once or twice a year)

    now, I don't know about deadspots...but the acoustic sound of the bass immediately became significantly louder...

    I played the bass in Church last night (like I do a couple of times a month), and I was getting all the tones I wanted from the bass, from deep P thump up to
    jazz bark.

    This is true, even though strings are quite dead on this bass (I've had them on for about 6 months now)...they're overdue for a good alcohol bath (yes, it DOES work).
  6. ehque


    Jan 8, 2006
    none of this problem on my Zon.
  7. Musiclogic

    Musiclogic Commercial User

    Aug 6, 2005
    Southwest Michigan
    Owner/Builder: HJC Customs USA, The Cool Lute, C G O
    I think Ritter addressed this in a good way(maybe even a bit of overkill) by adding mass at the heel block with the 1000 screw attachment(slight's only 10). I just sent out two Ritters that I did some work on, and there was no deadspots.
  8. ahh, interesting. So how would one achieve something similar in a neckthrough or set neck?
  9. I have never run into a dead spot on a neck through bass.

  10. ehque


    Jan 8, 2006
    sink useless bolts into the neck? :D
  11. Thanks much for the input. I'll search through older threads. I agree Fender style headstocks and bolt-on necks show it the most, but the deadspot was there in my Rick 4001, 76 Tbird, a Spector I played on a session and the neck through 5 string I just completed. With due repect to all the neck through folks, are you sure you haven't just been working around that weak spot so long it no longer registers? The underlying question for me is also how so many instruments that vary so much in design, materials and construction all display the same trait at pretty much the same frequency. Anyway, thanks to all for the good info and I'll look forward to hearing more.
  12. Rodent

    Rodent A Killer Pickup Line™ Commercial User

    Dec 20, 2004
    Upper Left Corner (Seattle)
    Player-Builder-Founder: Honey Badger Pickups & Regenerate Guitar Works
    A recent build I did originally was to be without the threaded inserts. When I played the 5th and 7th frets on the G-string, the note was almost immediately dead. Later that day I installed the threaded inserts, installed the neck, and re-strung ... +90% of the deadspots are gone. You can tell there is a little weakness in the sustain of the fundimental as it decays about 10% faster than any other note on any other string. This is now a very playable instrument in these otherwise dead positions.

    In my books, this is quite a remarkable and simple solution to a common issue that plagues 34" scale bolt-on basses.

    all the best,

  13. rodent,

    based on this, what you are saying is that a slight weakness in the neck-body joint can absorb some frequencies, thus causing the dreaded "deadspot"...

    i believe that this is entirely possible, and by using the threaded inserts, you are increasing the joint tension tremendously (Hambone would probably be able to tell you just "how" strong that is).

    at any rate, based on my recent observations, I do not doubt your findings at all...

    IMO...if the acoustic volume of an instrument can increase by increasing neck-body joint strength, then the "dampening" affect of this joint must be real. And all acoustic dampening is frequency-sensitive in one degree or another.

    another thing that really affects deadspots on a neck is truss-rod tension...(again, it has to do with "dampening").

    I think from what everyone has said, that the following can be surmised:
    "the more the bass is able to vibrate as one complete, untinterrupted mass, the less chance there is of the bass having deadspots...or more accurately, the lesser the degree of the deadspots"
  14. Musiclogic

    Musiclogic Commercial User

    Aug 6, 2005
    Southwest Michigan
    Owner/Builder: HJC Customs USA, The Cool Lute, C G O
    I have never had a problem with dead spots in my neck throughs or set necks, but Alembic had an approach they used for quite some time, using Brass blocks to add mass under their bridges. I think this might be a way to add mass to the neck to promote possible dead spot relief, also using good dense woods really works well. eg. bubinga, purpleheart, granadillo, ebonies and rosewoods. I think any dense carrier of sound will promote even sound and help to quell dead spots, but this is just my opinion, and I believe that other factors such as gluing, and hardware can make a discernable difference too.
  15. Suburban


    Jan 15, 2001
    lower mid Sweden
    It's all about adding stiffness and reduce weight, of the entire backbone, from bottom string anchor to top string anchor.
    So, just chop off the headstock and glue some alu plate all the way to the bottom strap knob, and you'll be fine! wonder why I never thought about that before...
  16. ehque


    Jan 8, 2006
    perhaps its an amp issue or a ear issue?
  17. Musiclogic

    Musiclogic Commercial User

    Aug 6, 2005
    Southwest Michigan
    Owner/Builder: HJC Customs USA, The Cool Lute, C G O
    or perhaps it's a personal taste issue and available stock issue.....LOL
  18. lefty007


    Jan 19, 2004
    Miami, FL
    Roger Sadowsky addressed this problem by making the headstock thicker. I had a 2002 (?) Sadowsky that indeed had a bad deadspot (which didn't really bother me, though) and I later had a newer one (2003 and on?) with the thicker headstock that had no deadspots whatsoever.
  19. pilotjones


    Nov 8, 2001
    I had a neck-thru 4-string with a 7th fret wolf tone (jumped up an octave). It had a 2+2 tuner arrangement, but it was still a fairly large headstock, and no CF stiffeners.
  20. Fingerz


    Jan 21, 2008
    I'm very interested in this subject, as a player of 34" and 35" bolt on necks, I have a MIJ 75 Reissue jazz (3 bolt) with no dead spot issues whatsoever. I imagine this is down to the inherent resonance between the 2 pieces of wood presenting no audible dead spots/sympathetic resonance within the western tempered scale, I'm sure there are some in the gaps!

    However, that 7th fret on the G string is such a common zone. I am now in the process of designing and building an instrument, and would like to investigate this subject. I know one luthier who believes inserting Carbon rods can open up the neck to certain issues as you are creating interruptions in the grain/more cavities, which I can relate to, and again, I've experienced dead spots on basses with these inserts. I wonder if anyone has ever tried, or there is any point, in inserting a smaller carbon rod, on the treble side of the neck around the 5th-7th fret area (and an inch or so either side), or whether the issue lies in other areas?

    It also seems logical to me that in effecting the resonance of the neck you are likely to 'shift' dead spots around.

    That's a long question, granted.. I will appreciate any views to add to the experiences already expressed above...

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