Angle of rear face of bridge relative to the top

Steve Swan · #1 02-04-2011, 02:28 PM

Doublebass luthiers have differing opinions on the angle of the rear face of the bridge relative to the top. Many use 90 degrees, some prefer to bisect the two angled faces of the bridge and some others put it somewhere in between. I've even seen a few with an angle of less than 90 degress, with the rear face of the bridge tilted down a little toward the tail. What approach do you prefer to use and why?

Michael Eisenman · #2 02-04-2011, 03:34 PM

With the bridge feet centered on the f-hole nicks, I start mine at 90 and then adjust as needed until the octave harmonic and its fingered note match at the octave-dot position. Doesn't take much adjustment, if any.

forester · #3 02-04-2011, 05:06 PM

rear of foot at nicks,bridge canted back 2-3 degrees to center the cap over the nicks.
*utilitarian aproach to student plys'
*holds up well and seems to have less of a tendency to warp forward.
*why: i have been instructed to do so...and it does make sense for instruments that get little or too much attention from the instrumentalist!also, increased longevity when they sit @ pitch for extended periods of time.
normal disclaimer:

my old and enduring carved flatback:
split nicks, vert.90 degrees

**Matthew Tucker** · #4 02-04-2011, 06:04 PM

a bridge blank is cut out flat on a special bandsaw at the factory, so the feet and edges are cut perpendicular to one surface anyway. It is much simpler for the luthier to identify that "flat" face, place that side down, trim the feet roughly to size on their own bandsaw and do all the shaping work on the other face. Then you mount the bridge with the "worked" side facing the player. this means the flat back of the bridge will end up perpendicular to the top, unless you tilted the bridge when fitting the feet for some reason. Can't think of a good reason though.

Turnaround · #5 02-04-2011, 06:32 PM

Quote:

Originally Posted by Michael Eisenman

With the bridge feet centered on the f-hole nicks, I start mine at 90 and then adjust as needed until the octave harmonic and its fingered note match at the octave-dot position. Doesn't take much adjustment, if any.

Octave dot?

Michael Eisenman · #6 02-04-2011, 08:12 PM

Quote:

Originally Posted by Turnaround

Octave dot?

Yes, I admit to having two dots on the side of my fingerboard: one at third position and one at the octave. I've removed the rest, but these two come in handy. The octave is probably next to go.

Eric Hochberg · #7 02-04-2011, 09:25 PM

My luthier bisects the edge of the bridge and puts that line 90º to the edge of the C bout. I see many pictures of basses with the
underside of the bridge at 90º.

Jake deVilliers · #8 02-05-2011, 09:36 AM

I'm a little flexible on the 90 degree thing. Not all tops are really straight through that region so I take the overall posture into consideration. If I step back from the Bass Clamp and sight the bridge the correct stance is readily apparent.

I would prefer not to have the bridge too far forward as I'd have to leave the bridge a little fatter to strengthen it.

I start with the bridge centred on the f-nicks though.

AndreaVeneziani · #9 02-13-2013, 11:15 AM

I did some experiments about the bridge angle and it looks like the bridge (his lower side) slightly angle toward the fingerboard makes my bass sound better. There is a better response and bouncing of the string and also more bass to the sound. I don't know why, but setting the bridge at 90 degrees gives it a tension that doesn't make it sound well... I know this is not orthodox, do anyone else experienced this on his bass?

DoubleMIDI · #10 02-13-2013, 12:01 PM

Maybe the soundpost is too close to the bridge?

When angling the bridge to the fingerboard you lift the lower edge of the bridge feet and put more weight on the top part of the bridge feet. THat effectively moves the pressure away from the soundpost. But there might be other explanations and effects too.

AndreaVeneziani · #11 02-13-2013, 01:30 PM

Mmm actually it's possible, by too close you mean the soundpost should be moved a little bit down or too tight? I think it's probably too tight that might result in a similar effect? I will go to Gage and check, anyway right now the bass sounds and feel great...

**Matthew Tucker** · #12 02-13-2013, 03:53 PM

doubleMidi means, if you tilt the bridge towards the fingerboard to change the angle, the feet will lift at the back of the feet, making a gap. the feet will then only be touching at the front edge, and about 20mm further away from the soundpost position. It is this that could be changing your sound, not the angle.

DoubleMIDI · #13 02-13-2013, 05:10 PM

Thanks Matthew, that's what I meant.
It might also remove a very little bit of pressure (but not much) from the soundpost.

I didn't mean that the soundpost is too tight, but if (!) a little bit of pressure could be removed from the soundpost by angling the bridge towards the fingerboard, it also could mean the soundpost gets a little less tight that way.

But show your instrument to a luthier and explain what you found out and he will inspect your soundpost and probbly also some other things. Better than our guesses...

JoeyNaeger · #14 02-13-2013, 05:52 PM

I fit the bridge so the back is at 90 but then slightly arch the back surface by a millimeter.

AndreaVeneziani · #15 02-13-2013, 10:19 PM

Ok I see. Well the back of the bridge, at least looking at it it's not at 90 degrees, it really seems to be angled towards the fingerboard, but the feet are still in full contact with the top of the bass. Anyway i'll see what a luthier has to say, so far I am very happy with the sound and feel actually.

**Matthew Tucker** · #16 02-14-2013, 12:04 AM

i confess i still don't get that idea Joey. Doesnt change the breakover angle appreciably. how can it actually DO anything?

JoeyNaeger · #17 02-14-2013, 08:04 AM

For a given thickness of the crown, it leaves the heart a little thicker. It also helps keep the bridge from warping towards the tailpiece.

AndreaVeneziani · #18 02-14-2013, 08:53 AM

The thing is that i have adjustable bridge, so I can move the top part of the bridge without affecting to much the feet apparently. I guess it still should be at 90 degrees though...

JoeyNaeger · #19 02-14-2013, 03:44 PM

Having it stand any way other then how it was fitted will cause it to warp.

**Matthew Tucker** · #20 02-14-2013, 04:19 PM

two discussions going here sorry for the derail but ... my question is HOW does it stop the bridge warping? I can leave the heart thicker ... simply by leaving the heart thicker, and still get any crown thickness. despite all the oberlin discussion ... i just don't get it.

if its just a visual thing, well yes maybe ...

maybe i should chew on this bone offline!