Sound Post

Discussion in 'Setup & Repair [DB]' started by JAS, Feb 19, 2002.

  1. JAS


    Jul 3, 2001
    where is the correct place for the sound post to go exactly? is there a basic rule for placement? i had a luthier adjust my bass and he moved the sound post pretty close to my right(looking straight at the bass) f hole. is this cool? he shortened the sound post so it could fit where he put it. it is also higher up than it was before. the bass sounds pretty good and feels pretty good too. does any one have any coments?
  2. pkr2


    Apr 28, 2000
    coastal N.C.
    What I have read in several different places suggests that it should be pretty close to being under the bridge foot.

    I would be a little concerned if it seems far enough away that it doesn't provide support to the top.

    If there are any hard and fast rules for setting a S.P. I havent been able to find them. I think that black magic and smoke figure into the formula someway.
  3. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    I have some info regarding the post on my website. Go to Rant, then to soundpost. It's not comprehensive but it may give you something to chew on. If you still have questions just ask again and I'd be happy to throw in another 2cents.
  4. Johnny L

    Johnny L

    Feb 14, 2002
    Victoria, TX
    I'm no luthier, but I've tapped the soundpost around on my bass, mostly for my own amusment, with this advice (Simandl lovers like me will dig this regimented soundpost placement method):

    About four years ago, I visited Robertson's in Albuquerque and spent some
    time with Dan, their super bass tech. He recommended that the SP be placed
    the same distance in from the G side F hole as the bass bar is from the E
    side F hole; then the SP should be 1/2 half its thickness below the bridge
    foot. I've been using this formula since then and very seldom do I have to
    change it. I put a piece of masking tape on the tip of my SP tool, trim the
    excess off and put a mark mark where the bass bar is; then I use that mark
    to place the SP from the G side.. You just have to estimate the the
    SPdistance ( about 3/8" ) below the bridge foot.

    Believe me , it works !!

    Bob Monroney
  5. Jim Dombrowski

    Jim Dombrowski Supporting Member

    Jan 16, 2002
    Colorado Springs, CO
    The February 2000 issue of Bass Player magazine has an excellent article about bridge and soundpost adjustments by David Gage.

    Jim Dombrowski
  6. JAS


    Jul 3, 2001
    o.k. i checked out gages site and paul's site too. they were helpfull, but i still have some questions. Does the soundpost being cut smaller and moved over about an inch and a half from the gstring f hole create a bassier sound? I also have my bridge just about on top of the sound post. It seems like since i brought the bass in it has a louder and bassier low end and less deffinition on some of the lower notes. (specifically on the a string) it also seems like the strings are not speeking as easilly and clearly as they did before when played arco.
  7. Would anyone care to share tips on fitting a new sound post?
  8. Sam Sherry

    Sam Sherry Inadvertent Microtonalist Supporting Member

    Sep 26, 2001
    Portland, ME
    Euphonic Audio "Player"
    JAS, this is one of those situations where the first two hundred are the toughest. Plus, it's entirely possible that the "sweet spot" for jazz pizz is not the same as for orchestral bowing.

    It's critical to have tools handy to grab and stand-up a "downed" post before you start -- you're all but guaranteed to flip it at some point if you move it around. I use: a) spike-end by paddle-end traditional soundpost setter -- this is a good tool for holding the bottom of the post in place while you move the top around with b) pliers-with-hole-in-middle type grabber; and c) extendable fingers for reaching the recalcitrant post when it rolls around on the back. At the minimum, two traditional-types are better then one: You can "hold" one end and wiggle the other.

    Finally, you can use a pencil taped to a ruler to mark the spot once you find it. That way, future experimentation can be quickly reversed, if necessary.

    Have fun!
  9. While we are on the subject of soundposts, it should also be noted that the hardness of the wood used for the soundpost can make a huge difference in the sound of an instrument. If you made ( two identical soundposts, one of very soft spruce and another of very hard spruce AND you could position each of them in exactly the same spot in an instrument (no - not at the same time), you would find that the soft post would tend to be dark while the hard post would tend to be bright. A good luthier will have a selection of blanks to choose from, and will know when to use a softer or harder post.
  10. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    My advice is DON’T DO IT! Sound post fitting is ounce for ounce one of the most difficult acts in lutherie. I don’t mean the act of getting the right sound-I simply mean just getting it to fit properly with no obvious gaps. It’s much more challenging than what is commonly believed. The interior contours of the plates are complex in their relationship. A well fit post moved a degree or two in its horizontal plane or vertical axis will then only be fitting on a point. Here’s where the danger is. [BTW-anyone who has read my SP rant may notice a bit of Department of Redundancy Dept. here-my apologies] Everyone always rails about the dangers of a tight post. [Partially to get you to come in every season!] I am not advocating a tightly fit post here but mind you, once the tension goes up-all posts are unbelievably tight-just try to move even a “loose” post under tension! A well fit post never damages the top but a poorly fit one does every time. Dents. [at least] It happens each time the post is moved-eventually leading to a generalized depression in the top plate which as it grows, makes each successive fitting more difficult.

    Fitting a post is so hard that many “professional luthiers” can’t seem to do it right. My bud Arnold and I regularly see horribly fit posts come in that were fit by pros in 5 minutes. So no offense guys- but how can we expect players with minimal experience to get it right when it is such a crucial element to a basses health? That being said I know you’re prolly gonna do it anyway, so I should stop ranting and put in my two cents. Previous advice from Bob and Samuel was good-mebbe I can add to it.

    As always the right tools are crucial. Believe it or not the most important tool is your lighting. For years I used a simple 15 watt bulb on the end of a wire---totally inadequate. You really need a lot of light in there-the difference between a shadow and a gap is quite hard to see. I use two lights. One, my favorite is called the sitelite and it was actually developed as a music stand light. It has a clip, a gooseneck, and a hooded halogen bulb. Take the hood off and drop it in a bass and its Yankee Stadium at night. It is available here- The other light is more directional and is like a very long flexible rod with a bulb at the end. I forget the name but it is available at . Using two lights may seem anal but it really is difficult to see inside a bass-especially while using a mirror.
    Samuel recommended the standard soundpost tools and these really are the best. Anyone who needs to know where to get these please let me know[just don’t have those addresses at hand right now]. But those tools are somewhat expensive and there are cheaper alternatives more commonly available.[though not as good] A telescoping mirror and a retractor[for grabbing the post] are available at any auto parts store. The retractor will need to be bent gently along its length in order for it to manipulate the post through the f-hole properly. You will also need something that can put leverage on the bottom of the post to help pull it up. A 3/8 in steel rod mebbe 15-20 inches long can be used here. Bend a small “L” into the bottom and curve the long length-you will need to experiment to get the right curve. This rod can also bang the post around handily. BTW it is a good idea to cover these tools with shrinktube or rubber paint in order to cut down on f-hole erosion. Another necessary tool is a feeler gauge to tell you exactly where the post is on the top. Most luthiers make these and they are quite simple. You will need a flexible piece of steel banding about 8 in. long. Bend it in half so it resembles your index finger touching the tip of your thumb. This can be inserted into the f-hole and as the bottom of the gauge corresponds to the top the soundpost can be traced revealing its position. Watch the varnish!

    The basic process to stand a fallen post would be as follows-stab the post with the standard post tool or grab it with the retractor about ¾ of the way to the top of the post. Remember to orient it so that when you stand the post the grain is perpendicular to the grain of the top plate. Put the post through the f-hole and place it so the bottom of the post is touching the back where you feel it should be and the top of the post is angled out towards the center of the bass. From this position you can lever the post up by pulling it towards you. Unfortunately, this basic process is somewhat akin to describing a heart transplant as first cut open the chest and cut the old heart out. Then put in the new one and sew it to all the places you cut before. Sew up the chest and apply electricity. That may be an exaggeration but not by too much.

    Fitting a new post is a whole ‘nother order of difficulty. First, you’ve got to get your blank down to fitting size. Use your old post length and cut the blank oversized from this 5-10 mm. The first tool I use in fitting after rough cutting is a small 4 in. stationary disk grinder. This is for gross fitting only. Use this to get the post to the point where you feel you could pull it upright with some muscle[don’t, of course]. Now it is time for fine fitting. The proper tools for this job are either a very sharp chisel or knife. That’s not a problem if you are adept at sharpening, but if you are not there is no way you can cut end-grain spruce with a dull tool. Sanding and filing tend to be very inaccurate and accuracy is crucial here. Perhaps the least of evils here would be a very fine diskgrinder-let’s say 180 grit or above. [better to learn to sharpen]
    Take the final fitting process very slowly. You may have to put the post in scores of times so try to be patient. BTW another trick to keep down the f-hole erosion is to take safe-release masking tape and line the hot parts of the f-hole with it. As far as where the post should go-generally it should stand centered with the treble foot and a little less than the diameter of the post back from it. The bassbar also should be centered on the bass foot but sometimes this is not the case. It should be checked and the post should reflect its symmetry[re centering]. The vertical angle of the post should be 90 degrees to the flat plane of the top plate-but this is not crucial. It could be off a few degrees and it wouldn’t matter-what does matter is that it fits. How far can you go in terms of varying from this position? Only so far before you start to compromise the structure of the top. I would say no further than two diameters of the post back from the bridge. As far as moving the post towards the f-hole-don’t let more than a ¼ of the post diameter travel past the outside edge of the treble bridge foot. Both these positions are extreme and I would never put a post in them-they just represent where I think structural problems[sinkage] may begin to occur.

    Well, this is very long but it is by no means comprehensive. It is just a hipshot of trying to cover all the bases here. If anyone has read this far and wishes for more detail please feel free to ask a detailed question. Hope this helps somebody-I know it did me [I had a need to be long winded].

  11. Jeff - Excellent!!!

    However, I think the the first sentence was the best advice. Fitting a post properly is not a job for the amateur. Over the past 40 years, I've fitted several hundred posts. I still consider myself lucky when I can accurately fit a post in less than an hour. I would guess that I end up fitting two or more posts before I get one right about 20% of the time.

    If you do insist on going it on your own, here's another tip. Wrap everything but the last inch or so of your store bought "S" style soundpost setter with a couple of layers of plastic electrical tape. This is just another way of preventing chips to the varnish around the f hole while you're trying to find the right place for your post to sit.
  12. Great advice in this thread. Best advice is, of course, take it to a pro. My excuse is I live on an island, and the nearest competent bass luthier is an airplane flight away. (Plus, I admit to being a tinkerer.)

    A trick I use is to glue little strips of paper, marked like rulers, around 3/4" away from the end of the post, one to to the north running horizontallyand one to the east running vertically, both on the top and bottom. More effective than the old pencil mark trick. At a certain position, I takes notes on both the location and my impressions of the sound, and then GENTLY ease the post one way or another and then write down what it sounds like in the new spot.

    Sometimes, especially if moving closer to the f-hole or closer to the bridge foot, I ease the strings off a bit before the move, and then tune back up to try the sound again. Painstaking, but I think I'm less likely to damage the plates this way. Gotta be careful of post falling down, though.

    Jeff Bollback, if I lived near you or one of your bretheren, I certainly wouldn't mess with this myself.
  13. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    New Mexico. USA
    Expanding on Jeff's excellent exposition (perhaps chapter 1 of a new book?): I think the most important info there were his warnings. Here's another: If a soundpost is set so one edge presses against the top, in line with the grain, and the bass takes a whack in the back (hey, I'm a poet, too), you're looking at a split top. Then you're looking at having your top off and a soundpost patch, a couple grand in repairs and loss of value. I agree with Jeff that many basses don't need Winter and Summer posts, but flatbacks generally do, because of the amount of back flex that changes with the climate. Jeff???...
  14. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    You are right sir! If the player feels that the bass is not responding as desired then certainly the post is a place to look and flatbacks do tend to show more movement. I just think that some luthiers tend to alarm players with the fear that a "tight" post is likely to lead to post cracks. It's a sales device to get people in the door. Some people are gifted in sales talent and they really should be selling vacuum cleaners. It doesn't help the situation to take a "tight" well fitting post-loosen it and have it fit like ****.
  15. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    New Mexico. USA
    You are right also, sir. I prefer the post stay up with the strings off when you move the bass to any position. But I must say I have seen some new basses where the post must have been installed in the summer, and then in winter, between the normal tightening and a little top settling, I have to knock that sucker out with a hammer, and it's made a bulge in the top! I tell my clients to have the post checked a several times in the first few years of a bass' life. Another thing--spruce is a very springy wood; often when you loosen strings the post falls right out, then fits perfectly a little while later. The top springs up in reaction to having the tension taken off; then settles back down. Either that, or these new close-up glasses I'm wearing...
  16. wannaplay


    Jan 30, 2012
    does the sound post diameter have any great effect on the tone or volume of the bass? i wonder if a larger diameter post would give more volume, since it has more mass. i have never had to stand one up yet, but my turn is coming someday!
    also, i don't ever hear of anyone making the F holes larger, what would that do to the sound quality and volume??

    i did thin out my neck, i have an englehardt supreme and the neck they have is the smallest in the industry,but it was still too hard for me to play those notes, so i got a vibrating sander and sanded the neck down. it worked for me! its even all the way down from the upper bend in the neck to the lower bend. what a world of difference!

    i also found the 3rd,5th,and 7th fret and marked with a stick on dot at 6 1/2",9 3/4",and 13 3/4" inches from the nut where it meets the fingerboard, respectfully. and i found out the distance from the nut to the bridge is 42".
    i also found out it is not so easy to move this thing!! got a van or pick-up, my car will let it sit next to me if i put the power seat back all the way and work the bass in just right!!
    i don't know a note, but i think i know where the notes are on the fingerboard, now i have to figure out what note the guitar player is playing. what i need is some fotos of what ur hands look like when ur playing a G, or A, or D, or F !!
    im learning! it takes time and practice! i'll get the hang of it someday! and hopefully soon! I wannaplay!
  17. wannaplay


    Jan 30, 2012
    Has anyone used a Sound Post Gauge? its like a inside caliper for the bass, and measures the distance from the inside of the back to the inside of front. its adjustable and in Traegers book(optimum sound) he suggests that the sound post have rounded ends (page 26, 3rd paragraph on the left). i just wonder about the diameter of the post??

    some basses even have a small nail in the front and rear to hold the soundpost in position so it won't fall and can't be moved accidently.
  18. eh_train

    eh_train Supporting Member Commercial User

    Jan 12, 2004
    Owner, Stand Up Guy Basses (Repair/Sell/Buy upright basses)
    Umm, I think that's the antithesis of luthiery practice.


    Paul (Eh_train)
  19. Jake deVilliers

    Jake deVilliers Commercial User

    May 24, 2006
    Crescent Beach, BC
    Owner of The Bass Spa, String Repairman at Long & McQuade Vancouver
    The title of your reply made me laugh out loud! :D
  20. Primary

    Primary TB Assistant

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