Question About Compensation For A Fretless Bass

[andy88]

Most likely only the experienced builders can help me with this one. I'm making a 32" scale fretless with fretlines and I want to use a fixed wooden bridge. This is the best example that came to mind:

http://www.ctbasses.com/picview.php?src=Ra...odyHUGEJuly.jpg

How would I calculate the compensation/ bridge angle for correct placement. I would use an adjustable bridge but I want to know what kind effect on the tone it will produce and I don't have enough room for a standard bridge. Also I don't know if it will affect the compensation but the strings will go through the body.

Thanks.

[GregP]

"Compensation" compensates for strings being pulled sharp by the action of fretting.

Fretless instruments do not need any compensation whatsoever. You compensate by putting your fingers in the right place. That Carl Thompson bass might be compensated with the assumption that the player will put his fingers on the marked lines. But in reality, there doesn't need to be any compensation-- you just have to understand that a true fretless player wouldn't even want those lines there because they understand that it's not condusive to intonating a note correctly.

If you look at other fretless instruments (violin, cello, contrabass) they don't have those lines. Players learn where their fingers need to go for correct intonation.

[andy88]

thanks GregP my sense of pitch isnt good enough yet to get it right without lines but when you mentioned the violin it triggered a thought. I feel kinda stupid since i have a violin (moveable bridge . . YAY) and should have thought about it. Ill go ahead and make the entire bass then string it up since it will be string thru i can then just leave the strings loose enough and move the bridge to the correct position.

Edited May 26, 2007 by andy88

[Primal]

Trust me, you will HAVE to use your ear. You can only use fret lines as a rough guide. It will NEVER be perfect (at the very least, it will even depend on the size of the tips of your fingers!).

[orgmorg]

Fretless basses may not need perfect bridge intonation, but you should get it close as possible. It does help, believe it or not. Especially when grabbing double stops up and down the neck.

Really, all you have to do with a movable wood bridge like you describe on a fretless, is start with it at 32" from the nut (your scale length), and move it back until the harmonic at the 12th "fret" and the open note are the same. You can use a tuner to do this. You may have to compromise a bit on a couple of the strings, since the bridge is not adjustable for each string, but you can play with it until you get a good balance.

[Primal]

like you describe on a fretless, is start with it at 32" from the nut (your scale length), and move it back until the harmonic at the 12th "fret" and the open note are the same. You can use a tuner to do this. You may have to compromise a bit on a couple of the strings, since the bridge is not adjustable for each string, but you can play with it until you get a good balance.

I don't think that is correct. You would have to compare the harmonic with the fretted note at the 12th "fret". The 12th fret harmonic and the open note will ALWAYS be the same. The easiest method would probably be to compare the physical location of the 12th fret harmonic on the string to the 12th fret marking. When the two are aligned, you got it. And actually, if you want to be more accurate, you would play the 19th fret harmonic and line it up with the 19th fret marker.

[GregP]

Indeed-- it's the FRETTED note and the harmonic that need to be compared. And since on a fretless you can fret wherever you want, not really any point to that.

Contrabass players (well, and violin, viola, cello, etc) play double-stops plenty, without having compensated bridges. Either the two fingers are slightly staggered, or the one "barring" finger is angled. When necessary. In many cases, it's "close enough for rock'n'roll" when playing certain kinds of phrases.

You can compensate if you really want to, but it's not typical for fretless instruments. As mentioned, the only real benefit is if you're going to slavishly follow the lines where there WOULD have been frets.

[orgmorg]

Oops, Greg and Primal are right on that. Not quite sure what I was thinking. I guess I was thinking back to when I set the bridge up on my fretless, and thought I remembered some trick I found for it. But no, as I recall, I did just compare the open string with the string stopped at the fret line. And yes, the open string and the middle harmonic are going to be the same... duh Sorry, brain fart.

Anyway, before I adjusted the bridge, I did notice it really sounded off, and had a hard time making the same intervals sound right at different positions on the neck, and now it feels/sounds better. But yes, this is probably largely due to me relying too much on the lines.

[erikbojerik]

In many cases, it's "close enough for rock'n'roll" when playing certain kinds of phrases.

Close enough for straight-ahead jazz for the last 40 years too, as far as I can tell.