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Effect of String Height Adjustment on Amplified Sound

Discussion in 'Setup & Repair [DB]' started by Chris Fitzgerald, Jul 17, 2002.


  1. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    I'm not sure which forum this really belongs in, so I'll post it in Amps & Pickups and leave a direct in Setup in case our dueling luthiers would like to respond.

    I had a lesson yesterday with my teacher (an orchestra player) on the subject of thumb position. I was having trouble getting a sound up high with my thumb, so he asked if he could lower my strings to where he kept his (he's arco only, I'm pizz only). He changed the string height from slightly over 5mm(G) and 9mm (E) to dead on 4mm (G) and 7mm (E). The bass immediately became easier to play because of the relaxed tension, and to my great surprise, also had more sustain. I didn't notice any significant change in volume.

    Later that day I played a gig in a loud room with the bass (it's a gig I play every week). I noticed that my amplified sound didn't cut nearly as much as before, and I couldn't hear the attack nearly as much. My questions:

    * Has anybody else noticed anything similar after adjusting your string height? (There were some anomalies on the setup at the gig, so I can't be absolutely sure that it was an accurate test)

    * I'm using a K&K Double Bass Max (similar to an Underwood in that it fits in the bridge wings) and a Trinity mic. My thought before last night was that if anything would be affected, it would be the mic sound, but the adjustment seemed to affect the wing pickups more than the mic. If this is true, what is the cause of this? It doesn't make sense to my wee little mind.

    * What is considered a "Normal" string height range for jazz pizz? I loved the sound I was getting using Red Spiros on a carved bass with the pickups above, but I am also digging the added fluidity and sustain of the lower action as well. Is this one of those Catch-22 type of situations?

    * Last, what (if anything) can I do on the Pickup/Amp/EQ end of things to get some of that punch back without jacking the strings all the way back up? It's nice to be able to play in Thumb Position without severe pain.


    Sorry for the length of this...inquiring minds and all.
     
  2. Is it possible that the extra sustain you were hearing were overtones from increased fingerboard growl? I'd lay odds that from ten feet away, that effect would be a lot less noticeable. And that is the effect that your Trinity is conveying as well, less punch.

    FWIW, my string height (measured at the end of the fingerboard, from the bottom of the string to the fingerboard surface) is 12mm on the E, 10.5mm on the G. (about twice as high as yours). My fingerboard has very little relief.
    I'm using Velvet garbos, which have very even tension between strings
    I say go for the tone you want and work on that thumb callous.
     
  3. Nothing to add, except that I lowered my strings, too, for an extended gig that requires a lot of thumb-position arco stuff. I also noticed increased pizz sustain.

    However, when I took the bass to my regular Tuesday jazz gig (where I don't use an amp), my right hand had to work a LOT harder.

    Personally, given a tradeoff between sound and fluidity (especially thumb position), I'll take sound. I don't normally use thumb position enough to justify the tonal sacrifice.
     
  4. Chris,

    Lowering your action affected the sound of your bass which then in turn affected your amplified sound. Lowering the action generally increases sustain but softens the attack, in other words there's less ping on the front of the note. The ping is what cuts through. If you were to raise your action higher you'd notice the opposite effect, more ping in front, longer sustain, slower decay in back.

    Your rig only amplified the changes to the bass itself.
     
  5. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY

    Thanks, that's pretty much what I thought. I played a Quartet concert tonight in a recital hall (w/drums), and it was a little better, but I still miss a bit of that "ping". On the other hand, Craig (the guitarist I play with) says he really digs the fluidity of the sound like it is. I cranked it up about 3/4 of a turn after the gig, and I'll see how I like it.

    I had a couple of thoughts about this issue. First, I'm still unsure if it was the decrease in the height of the string or the decrease in tension which made the sound change so much (quite probably, it's a combination). If it was the tension issue, I might try out a set of the Spiro Starks (higher tension) but set them really low and see how I like it. I'm really digging the low string height.

    Does anybody have any insight into the whole height vs. tension issue?
     
  6. A while back I posted a diagram with the formula.
    I really doubt that is the factor in the tone though. Lowering the bridge by a couple millimeters changes the breakover angle only very slightly and therefore affects the force to the top proportionally.
     
  7. Sam Sherry

    Sam Sherry Inadvertent Microtonalist Supporting Member

    Sep 26, 2001
    Portland, ME
    Euphonic Audio "Player"
    It seems to me (Warning: the words "it seems to me" signify gusts of hot air unaffected by actual knowledge or perhaps even thought processes) that the volume changes because of tension and pressure on the top. The sustain changes because of the angle of the string to the board. The MUSIC changes because you have less work to do to cause the string to make contact with the board -- you don't have to push as FAR, even ignoring tension, so you can move around easier.

    I'm eager to hear how you make out with Starks.
     
  8. olivier

    olivier

    Dec 17, 1999
    Paris, France
    Piezzo cells are known to be rather sensitive to the pressure under which they operate. By releasing the tension on the string, you have dimished the pressure on the bridge/wing which transmits part of it to the pickup. Maybe some tweaking around with a used sax reed would restore your lost volume ?
     
  9. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    Me too. On one hand, the thought of any string that's even more "bridge cable-like" than the Spiro Orchs terrifies me, but the thought of that great punch and clarity with low action is VERY intriguing to say the least.

    Olivier,

    I wasn't aware that string tension had an effect on the tightness of wing pickups, but now that you mention it, it makes sense. I'll look into that, thanks!
     
  10. Chris,

    3/4 of turn is a lot. I notice a huge difference in 1/4, 1/2 is almost drastic.

    Also, I don't get how lowering the action actually reduces tension. Yes, the angle is less, but the strings then have to be tuned up (brought up to the right tension) to sound at the correct pitch. Is it possible that it only seems like less tension because the strings are closer to the board and don't have to be pushed down as far?
     
  11. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    I don't completely understand it either, but it makes sense in an intuitive kind of way about the whole downforce thing. Maybe if Pete can find that diagram he did a while back, he could link it here.
     
  12. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    Okay, after playing 3 gigs in as many nights after my strings were lowered, I have to say that I am NOT digging the change in sound AT ALL. Everything sounds too mushy, and the G sounds thin and gets buried when I try to solo. I'm going to try to raise them back up to near or at where they were later today. A question for the luthier types (or anyone who knows):

    I've been reading some of the old threads about string height, and the consensus seems to be that the adjusters on both side should be about equally extended, and the reason for this is to keep from cracking the bridge. Should I worry about detuning before trying to raise the adjusters a significant amount, or just go for it? Also, if I want my G string a little higher in relation to the E string, do I need to do this by reshaping the bridge, or can I go at least a little bit in this direction by using the adjusters and still not endanger my bridge too much?

    Also, I checked another old thread about strings, and THOMGUY reports that Spirocore Starks are only available for 4/4 basses. Does this mean I can't use them on a 3/4? (I posted the same question to Thomguy in the strings forum).

    Last, since everyone seems to feel that the sound difference is all about the bass and not about the amplification in this case, I'm moving this back to SETUP where it belongs.
     
  13. Sam Sherry

    Sam Sherry Inadvertent Microtonalist Supporting Member

    Sep 26, 2001
    Portland, ME
    Euphonic Audio "Player"
    All right, sir, step away from the bass . . . put the anvil down, sir . . . that's it . . .

    Yep, it's impossible to sustain a perfect balance of feel and sound on this infernal machine we're all involved with. You taste the sweet fruit of low action, and your sound turns to wet noodles. You put on bridge cables for volume and sound, and you have to stop playing before you hurt yourself. You find the absolute SWEET spot and the seasons change -- or, worse, a gust of wind blows your bass offstage and into the crowd. Good thing we do this for fun, eh?

    For what it's worth, since hanging around here, I've raised my action some (4.5/7.5 at the end of the board) and actually performed in public without an amplifier (damn, that air conditioner's loud).

    Enough kalanga. Tune down before raising the action.

    Happy hunting, Durrll . . .
     
  14. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    If you really want to hear your bass at its best, get those pickups out of the bridge wings! That gap is not meant to be bridged. Every string should have an open space between it and the top, if you draw a straight line down. This allows the bridge to flex in such a way that the bridge and top vibrations are "in phase". Wing pickups by nature have a mushy sound because they stiffen the whole bridge assembly. There's very little attack that comes through. As far as height, experiment acoustically, and when you find the bridge height that responds and sounds best to your ear, keep it there and play it...
     
  15. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    Unfortunately getting rid of the wing pickups is not an option, and oddly enough, the K&K Double Bass Max gives plenty of attack. I do have one more question about the bridge height though: Since I started this thread, I have raised my bridge back to where it was, and am once again happy with the sound. At least one member here has suggested that the loss of attack I experienced with the lower action was due more to the lower string height than the reduced tension. If I were to have the saddle raised a bit - giving me the same string height but slightly relaxed tension - would I likely experience the same loss of attack?
     
  16. Remember, only loosening the strings will relax their tension. (It also puts them out of tune).
    I have the feeling you mean raising the saddle so that less force is applied downward to the top. Some people swear this makes a string "feel" less tense, but I'm doubtful.
    First, the reason you felt that the string tension was relaxed when your bridge was lowered was because your action was lower - it simply was easier to push the string to the fingerboard.
    Second, your bridge was lowered 2.5mm. To reproduce the same breakover angle, the saddle could be raised 2.5mm. I doubt you would notice any difference in tone, and I'm certain you would not be able to feel a difference.
    Typically when a saddle is raised, it is usually raised around 20mm. This is the range where it makes a difference. It's done either to relieve some of the force of the bridge feet pressing down on the top of a delicate table, and/or because the bass speaks better with less force.