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Neck Block

Discussion in 'Setup & Repair [DB]' started by farmerdude, Jan 14, 2002.


  1. I owned a bass that I really liked (when played pizz) and I noticed that the width of the neck block was shorter than normal. This bass had almost no distance between the body and the finger board unlike this one...
    [​IMG]

    The bass had low tension and sounded great with gut. It did not however sound that well arco. (no matter the string) Do slight changes to this distance have significant impact on tone, tension, etc or do you get the same effect by adjusting the bridge height?
     
  2. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    A higher neck-set allows you to effectively raise the strings, thereby putting more tension on the bass. This has gotten pretty radical over the last 25 years or so, I guess. Shank tells me that there has been a lot of basses caving in with all the extra tension.

    I've noticed that ply basses tend to have a lower neck-set and / or less angle. Likely a CYA move by the producers of fine plywood instruments. It's nice in a sense, though, as ply basses tend to play a lot looser as a result.
     
  3. So the 3 points of angle are?
    1. neck set
    2. saddle
    3. bridge

    The bridge is only to fine tune, the other 2 points have the most impact on tension? So if I raise the saddle does it have any other impact than lower tension? In other words, should I do this? I assume this would have negative effect on arco but with this bass its ok. (sorry, I'm thinking our loud here)
     
  4. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    JEEEEEEEEEEEFFFFFFFFFFFFFFFFFFF!!!!!

    :)

    I don't have a lot of answers on all of this angle biz, just some anecdotal evidence that is likely all wrong. Let's see if Mr. Bollbach will field this one.
     
  5. Thanks for your input Ray.

    all-together-now
    JEEEEEEEEEEEFFFFFFFFFFFFFFFFFFF!!!!!
     
  6. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    unfortunately i'm up to my eyeballs in poop. I will put my .02 cents in but can't right now.
    jeff
     
  7. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    Yes, neck resets have changed greatly in recent times. One reason is that by pulling the neck further from the body one gets easier access to the upper regions of the bass. Another is that it DECREASES the tension on the instrument. I've seen hundreds of neck resets done this way and in what seems to be 99% of them-the players are thrilled with improvements to tone and playability. There may be basses out there with tops caving in but it is not because of a general elevating of necks. Whatever increases the angle over the bridge-towards 180 degrees vs. 90 will lessen the tension. This can be accomplished by raising the tailpiece. One way to do this is raising the saddle. How much improvement you will get is hard to say but I recommend trying it. It's not irreversable.
     
  8. This saddle raising business sounds interesting. Any tips on how to proceed before I go improvising. (like I always do.)
     
  9. Chasarms

    Chasarms Casual Observer

    May 24, 2001
    Bettendorf, IA USA

    I see old plywoods at the BG festivals all the time that have a thick piece of leather, or even a piece doubled, and laid over the saddle and then the tailgut run over the leather.

    I always thought it was to keep the cable from buggering up the saddle, but maybe it is to raise the height? Two thick pieces of leather would get you nearly a 1/4". Would that be enough to make a difference?

    It didn't dampen the tone as far as I could tell, but we are talking plywood kays.

    Chas
     
  10. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    Wellspal, where have you been my old worthy adversary? You need to post more.

    There are basically three ways to raise the saddle. Raised saddles first became popular at the advent of metal strings. The initial attempts were a simple steel rectangle with a lip at the upper edge. This was screwed into the end block thru the ribs. While this was a very effective way of accomplishing the task it raised issues because it involved drilling holes into the bass[albeit in an inconspicuous place both cosmetically and structurally]. The solution was worse. A wood block was fitted so that it mortised in to the existing slot and cantilevered out onto the top plate. This enabled you to get height without the saddle toppling. There are two big problems with this method. One, is that the wood part that extends over the top clamps down on the top and denting or distortion of the top is inevitable. Secondly, and worse is that this clamping results in an inability of the top to move in this area[climatically speaking] and cracks often result. The third way of raising the saddle is to extend the footprint on the saddle into the top in order to prevent it from toppling over. This is effective in minor raisings but requires too much eating into the top for major raisings.
    Method #1 gets my vote for the least of evils. No one uses the steel plate thingie anymore and this mod is usually done with an exotic wood and can be attractive. The only real downside is that you need to drill one or two screw holes. There is no structural risk and if needed the holes can be pretty easily plugged up.
     
  11. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    Not to be argumentative, but are you certain of this? Picturing the neck moving directly forward and the height of the bridge being adjusted, the angle of the string on the neck side should remain the same while the angle on the tailpiece side should decrease (measured on the acute side), giving you a net of a bit more tension. A proportionately raised saddle would then compensate you back to a zero tension gain.
     
  12. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    Argumentative is OK, Ray-you're makin' me think. Certainly I'm certain of nothing. Uh... But like I said before, I have seen hundreds of neck sets[to higher elevation] and the "perceived tension" by the player always seems looser. Both with raising the saddle and without. I have no scientific way to measure the actual tension or perceived tension change. I just have my interpretation of the result and the players. Now mind you that most neck resets are not undertaken with a change in tension as being the paramount goal. If a player came in and complained of excessive tension, I would rarely suggest a reset. It is usually done in order to make an instrument more playable in the higher register or sometimes to correct a crooked neck which is a real problem. Many basses are quite difficult to negotiate over the shoulder-especially for smaller players[ I know-short people got no reason] Elevating the neck solves this problem handily. How much elavation? I shoot for this- I make my neck angle[the angle of the bottom of the heel gluing surface with the plane of the fingerboard] 87 degrees. the neck projection [top plate to underside of fingerboard] 38mm. This results in a bridge height of 6 3/4 -7in. depending on the arch. I like to shoot for 6 7/8.

    A higher bridge does not neccessarily translate to higher tension. I'm not sure but I think that part of this perception just comes from the suggestive aspect-the bridge is higher therefore the tension must be higher.
     
  13. Jeff, thanks for the kind words. I got too busy with some actual "WORK?!?" I hate when that happens.

    I did experiment with Chasarm's leather trick. (I think the kinkier members know what we're talking about here!) But seriously, this seemed to have little effect, if anything a bit of a muting effect. I do get the part about the neck and the tailpiece raising straight up from the body (NOT changing the BRIDGE HEIGHT or NECK ANGLE) will LESSEN the tension on the top. What I don't get is how less tension will improve the sound. After all when an adjustable bridge is cranked higher and higher, INCREASING the tension on the top, the sound improves alot.(at least on my 1999 plywood Englehardt S-9 Swingmaster) But hey, damn the logic. Let me just prove it to myself and I'll report back. How high would you recommend to start? !/4 inch? 1/2 inch? 1 inch? I'll hollow out the back of a dowel rod so it fits over my saddle effectively raising the tailpiece that much, I assume the tailgut will have to get longer also? At least the dowel will eliminate the softness factor of the leather experiment. I won't change the height of the bridge ofcourse.

    Just out of curiousity what is the tailpiece saddle called. You know, the part the strings are actually riding over. Couldn't this be raised also for the same effect? Is it normally glued in?

    BTW Jeff, I'm still planning on a thorough bridge comparison, solid vs. wood adjusters vs. aluminum adjusters of my own (which will be on this same bass for anyone that is interested.) Just as soon as I get the aluminum one either fabricated or bought. (which is taking forever.)
     
  14. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    I wasn't even considering perceived tension. I'm running on the notion that that more acute the angle of the strings over the bridge (measured on the bass side), the more pressure applied to the front of the bass. Bridge height has nothing to do with pressure on the front.

    So, if you had a zero degree angle (the strings theoretically pulling straight into the front of the bass), all of the tension to bring the string up to pitch would be on the front of the bass. A 180 degree angle (no bridge) would give you zero pressure on the front of the bass. Everything else falls in between somewhere. There are two angles made by the strings as the cross the bridge. There has to be some kind of formula that gives a proportion as to angle and downward (toward the front) force, and the total pressure on the front would be the sum of that formula applied to both of the angles. When the neck is brought forward, the neck/string angle will remain the same as long as the neck moves directly forward. The saddle hasn't moved, so the angle on the tailpiece side becomes more acute (and more acute quickly with bridge-height change because of the length of the tailpiece side of the triangle), thereby causing more pressure on the front of the bass.

    My math is weak, but I'm going to see if I can come up the formula that would describe angle v. downward force given the two angles. If someone wants to beat me to this, feel absolutely welcome!
     
  15. wow. we postd at the same time so I didn't read your response to Ray before that was written.
     
  16. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    OK. I think I might have it. I don't have the stuff around to test this out.

    A1 = 90 - acute angle on neck side of bridge
    A2 = 90 - acute angle on saddle side of bridge
    W = weight needed to draw the string to pitch

    W divided by 180 gives you the weight per degree of angle.

    A1 + A2 is the total downward angle.

    (A1 + A2) * W /180
     
  17. Actually we're talking about *force* to the top. All else being equal, raising the bridge will decrease the angle (from 180 deg.) applying more force to the table. Conversely, setting the neck further out from the top will increase the angle (towards 180 deg.) therefore lessening the resultant force to the table.
    Tilting the set of the neck forward will obviously increase the break angle and vise versa.


    Not sure how TB or peoples browsers do sub and superscript and I don't really know how to notate formulas in ASCII but here goes:
    Resultant force is equal to the square root of [(the sum of each component forces squared) plus twice the product of the component forces times the cosine of the included angle].
     
  18. Double wow. I feel like one of those little monk-men in the MC Esher print that are going up the stairs and down the stairs at the same time, passing each other but you can't tell who is going up and who is going down.

    I'll agree with Pete but the math part is way too confusing.

    If you raise the bridge either with those little wheel dealies or some pine shims from Home Depot you will INCREASE the tension on the TOP of the bass. I
    know this for sure as I just did my own scientific experiment to prove it. On a 4 foot long 1x6 board I attached a screw at each end representing the nut and the tail piece. To these scews I loosely attached a length of strong household string with a postage scale in the approximate bridge position of this mock bass. I took a 3/4x3/4 piece of wood and screwed a small screw into it. Representing an adjustable bridge. I put the "adjustable bridge" on top of the postage scale and tightened the string until the scale read 1oz. Then I raised the little screw just a half inch or so and put the string back on top of it. The scale now read more than 9oz. Nothing moved, no weight was added, only raising the string increased the scale reading.

    I need a cigarette. (oh yeah, I quit 10 years ago.)
     
  19. Actually the whole thing is the most elementary mechanics, and tests like this were done before Pythagoras and don't really need to be repeated. Your test however is flawed in that as you raised the "bridge" you also made the string more tense. On a string instrument, the string tension (pitch) would be constant.
     
  20. So Pete, just to be perfectly clear, what you are saying is as I raise the upper portion of my $175.00 wooden wheel bridge the tension or pitch as in pitch pipe is staying the same?