Pearson Instruments #12

Discussion in 'Luthier's Corner' started by Brad_Pearson, Jan 25, 2021.


  1. Hey guys, just thought I would share some pics of my latest bass. I think I'll document the next one in more detail for a full build thread. Here are the specs

    Alder body
    Interesting flamed maple top
    Black accent veneer
    Red oak neck
    Pau fero fretboard
    35" scale
    18mm Hipshot
    20" radius
    Hipshot ultralight tuners with drop A
    EMG P pickups
    BQC system with additional passive tone
    Dunlop flush straplocks
    Small stainless steel frets
    Luminlay

    Just some of my own observations:
    As much as I love the cleanliness of a one piece neck, I really don't like the flat headstock and string retainers on a 6 string (Dig it on 4's, not sure about 5's yet). My bandsaw only has a 4" depth, so scarf joints with ears will be my new headstock approach.

    Heres the final product on my FB page


    A few posts back you can see some progress shots
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    Any feedback or thoughts are very welcome! Thanks for checking out my bass guys!

    -Brad


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    Last edited: Feb 16, 2021
  2. ciwi

    ciwi

    Jun 2, 2010
    This is super beautiful! It looks very comfy. Something about the body contour lines just make it want to nestle into the player.
    (also those bridges are great. Make string changes soooo easy)
     
  3. Unable to see for fb or ig
     
  4. Rôckhewer

    Rôckhewer Supporting Member Commercial User

    Feb 28, 2015
    Phoenix, Arizona
    Owner/Builder- RockHewer Custom Guitars LLC
    Yeah...do that. We like to follow along.
    This is gorgeous. :thumbsup::thumbsup:
    Post big pictures
     
    Beej and TrustRod like this.
  5. KB5

    KB5

    Sep 28, 2012
    I'm curious about the truss rod wheel placement. I've never seen the adjustment placed so far from the end of the neck. I guess on a traditional 19 fret bass it would be in the normal spot. I'm interested in how the additional neck length changes the dynamics of the truss rod action. I'm probably wrong but I would think that a rod placed that way would change the position of maximum relief on the neck. At approx what fret does that put the maximum relief? Was there a specific design goal that required that placement? Does the end result require any changes to the setup procedure and what is the net effect on playability if any? Thanks.
     

  6. *Edit* I realize how long that answer below is so the the short answer is, it puts the relief in neck where I want it*Edit*

    Ok get ready.

    My theory, based on reshaping and constantly refining the camber on my double bass fingerboard, is that the ideal relief in a fingerboard is NOT a perfectly elliptical curve but rather, a gradual increase as you move toward the nut.

    Heres how I've come to this conclusion, and later I'll explain my experiment to see if I can develop a more predictable way to achieve it with a truss rod, and ultimately, why.

    As I tried to achieve a lower, but still clean playing string height on my upright bass, where I have total control of every part of the curve, the traditional gradual curve presented a problem. The end of the board furthest of the nut, had to curve up, as more relief was carved into the middle. This curve would cause more string/board interaction (buzz) above the Bb on the G string (generally). It also limited how much dynamic range could be achieved with the right had because I physically couldn't get enough finger under the string. Same thing happens on an acoustic guitar when the neck-to-body join area of the neck ramps up drastically. For years, luthiers have compensated for this with fallaway.


    Lets take a second to think about what happens to the witness point (Where the string leaves the finger or fret) when relief is introduced into the fretboard: In the lower frets, the angle at which the string leaves the fret becomes more obtuse, allowing the string more room to vibrate, because the next highest fret is now slightly lower than the fret being played. Hence why when your low frets buzz, you add relief by loosening the truss rod. Now think about that angle once you pass the apex of the curve (generally, around the 8th-12th fret but that varies a LOT). The angle becomes more acute, and the frets above the note being played are closer to the string and more likely to buzz. Now, of course, your string hight gets higher as you move toward the higher frets which is why, most of the time, the traditional amount of upward curve at the higher frets, isn't a problem. But what if you want to have the ability to get your strings lower? Or, as in my case, Have a medium string height but the room to dig in with a heavy hand when you want it?

    Now think about how a string moves. Obviously, lower notes vibrate in a slower, wider pattern, further accentuated by the fact the the string is longer. As a string gets shorter, from being fretted at higher positions, it doesn't move as much.

    With all this in mind, I wanted to experiment with a neck that stays perfectly flat above the 12th fret, and only curves up gradually toward the nut. The experiment here, was to put the middle of the truss rod (theoretically, where the apex of the curve should be) closer to the 8th fret of the neck. My thought was that the lower area of the neck, being thiner both in width and thickness, would be pulled up more easily than the thicker, stiffer upper area of the neck if the end of the truss rod was moved away from the neck heel.

    It turned out, there was a slight bump around the truss rod wheel after being strung up for a day, easily fixed with a fret level.

    My next experiment will be with stiffening the neck only at the upper end, and possibly using a shorter truss rod. Its a slow process since I am JUST a musician, I took math essentials until grade 10 and have no background in physics. Just trial and error over years of working on instruments.

    My ultimate goal is to build a bass that is SO user friendly that the common player will never need to see a professional to have it setup. Like a Civic from the 90's, so easy to work on, anyone that wants to, can do it. Hence why I've chosen stainless frets, a zero fret, and a wheel style truss rod. The hardest thing to adjust on my basses is the bridge, every parameter of which is easily done with only an Allen key and a Phillips screwdriver. I also use stainless steel cap head bolts for the pickups, they don't strip like the normal pickup height screws can.

    My first bass was sold to me with a warped neck, and since I couldn't afford, or was I really aware of lessons, no one told me otherwise so thought it was normal, but just not adjusted correctly so I spent forever trying to make this thing playable. As a young player, it was discouraging to say the least. I don't ever want to put an instrument out into the world that will cause that level of frustration, ever. Simply not acceptable.

    Apologies for the long-winded answer for the simple question of "why is the truss rod there?". I guess the short answer is "because I wanted it there".
     
  7. I'm planning a six string fretless for myself for the next build. Not sure exactly what the truss rod experiment will be on that one but I'll document it.

    I should add. The problem I am trying to solve is so unbelievably minor, most people don't even realize its there. I guess I'm really just experimenting to satisfy my own curiosity. I don't believe a bass with a traditional truss rod setup is inferior. However I've never liked truss rods that are hard to access, or, under a cover. What happens when you get to a gig late and the place is hot and dry and your neck straightens out and the notes you are actually being paid for all buzz. "hang on guys I need to find two different tools and have to remove and replace a cover, and loosen and remove my A string, then put it all back together then we can start". With a truss rod wheel, you grab your multi tool, or if your desperate, bend a damn dinner fork, make the adjustment, and get back to work.

    Jaco knew this and ditched his pickguard so he could adjust his neck easily as needed. I heard a story once that he kept the wrench on his amp and sometimes even tweaked his neck in the middle of tunes. Ive never seen it, but if anyone would do something like that, it would be Jaco.

    Ok now I'm just ranting, but, It is my thread :p thanks for the kind words everyone!
     
    Tim Barber and KB5 like this.

  8. I like to have a stool handy to sit with the body while I carve. I just keep taking away wood until it feels right. When its on my right knee it needs to wrap around the right side of my ribcage.

    And ya the Hipshot B style bridge is the bees knees!
     
  9. LM Bass

    LM Bass

    Jul 19, 2002
    Vancouver, BC
    This one looks so great Brad! Congratulations. I look forward to the fretless coming up next.
     
    Brad_Pearson likes this.
  10. KB5

    KB5

    Sep 28, 2012
    Thanks for the great explanation. I get what you are trying to do and had a feeling that you were trying to move the apex of the bend. The best innovation comes from ignoring preconceived norms.
     
  11. wraub

    wraub

    Apr 9, 2004
    ennui, az
    Same.

     
    bobdabilder likes this.
  12. Primary

    Primary TB Assistant

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