Small changes make a big difference at the bridge

Please put your pickup/wiring discussions in the Electronics section; and put discussions about repair issues, including fixing errors in new instruments, in the Repairs section.

Small changes make a big difference at the bridge

Postby John Clifford » Sat Oct 20, 2018 6:54 pm

Never underestimate the importance of details at the bridge in bringing out the sound of an archtop!

I had originally made a two-piece adjustable ebony bridge for this guitar. I thought I’d done a good job with it. The strings all sounded cleanly, and the intonation was excellent. But I felt there was something lacking in the tone of the instrument. It lacked clarity and definition, and felt somewhat unresponsive. I attributed this to the sitka spruce top, and my carving and bracing work.

Then I decided to try making a one-piece bridge for it, again using ebony. When I first got it strung up with the new bridge, the action was a little high and the sound was . . . not that much different. This seemed to confirm my feelings about the top plate.

But THEN, I recut the top of the one-piece bridge to bring the action down, and I paid a LOT of attention to cutting the string slots, making sure they were angled back toward the tailpiece, and widened slightly in that direction, to ensure a clean break over the front edge of the bridge. When I brought the strings back up to tension, it sounded like a completely different instrument! Really open and “sparkly” on top with a solid, clean midrange. And significantly louder. My wife even remarked on the increased volume.

So the lesson is, the small things really matter at the bridge. It makes sense when you think about it. 100% of the sound energy of the instrument is transmitted from the tiny point at which the strings contact the bridge. The vibrations at that point are very low amplitude and very high impedance, so very small physical changes have a big impact. Also, for reasons I don't completely understand, high action seems to have a detrimental effect on tone - too bad for me, because I tend to like fairly high action.
Attachments
IMG_1256.JPG
IMG_1255.JPG
IMG_1254.JPG
IMG_1253.JPG
John Clifford
 
Posts: 108
Joined: Mon Dec 18, 2017 3:08 pm

Re: Small changes make a big difference at the bridge

Postby Brian Evans » Sun Oct 21, 2018 8:39 am

I agree. I've found that the lighter I can make the bridge, the better. The slots can be infinitesimal - only half string diameter, but definitely angled back towards the tailpiece. I try to split the angle towards the tailpiece so the string is supported by the full width of the saddle top. I am planning to experiment this winter with a spruce or redwood bridge, very light, perhaps hollow, with an ebony or bone saddle strip on top. Never experienced that with high action, but high action would contribute to a high break angle over the bridge, and I have found that reducing the break angle can be helpful. I seem to end up with 12 degrees or so. I also find that my acoustic archtops benefit from low tension, high mass strings and tuning down a step to D-D. In fact, I've about decided that E-E tuning is a hold-over from nylon/gut stringed classical guitars that should be done away with! :) Lovely guitar, BTW - beautiful!
Brian Evans
 
Posts: 718
Joined: Sat Aug 30, 2014 8:26 am
Location: Tatamagouche, Nova Scotia

Re: Small changes make a big difference at the bridge

Postby Alan Carruth » Sun Oct 21, 2018 12:05 pm

If the action change is enough to significantly alter the break angle/down bearing on the bridge I think that can alter the sound.

I once set up a guitar with a 'hook' type tailpiece that allowed for varying the contact point at the lower end. The tailpiece was 'L' shaped, with the leg of the L hooked down over the lower end of the top, and retained only with a light tailgut, since string tension served to hold it on. It was fairly easy to slack off the strings and slip in a pivot between the leg of the L and the side. The line the strings made behind the bridge pointed toward the pivot on the side, so they could effectively go 'through' the top, and there was no limit on the break angle.

At that time I didn't know as much about strings as I do now, and I bought into the notion that a higher break angle and more down bearing would produce more sound. Wrong. I started with the pivot up at the edge of the top and moved it down in steps. The sound really didn't change until, at a certain point, it just died. The change was sudden and repeatable: too much down pressure killed the sound.

Of course, at that time I didn't have the facilities to really measure things and find out what was going on. Since then I've come around to the notion that minimal break angle is probably better. I have to admit that while my model is probably better these days I don't have much more data backing up the current prejudice than the old one. It does seem to work, though....
Alan Carruth
 
Posts: 846
Joined: Sun Jan 15, 2012 1:11 pm

Re: Small changes make a big difference at the bridge

Postby John Clifford » Sun Oct 21, 2018 10:12 pm

Brian, what string gauge do you use for your D-D tuning?
John Clifford
 
Posts: 108
Joined: Mon Dec 18, 2017 3:08 pm

Re: Small changes make a big difference at the bridge

Postby Brian Evans » Mon Oct 22, 2018 9:43 pm

Usually regular light gauge acoustic, which seem to be .012-.052, but sometimes a "bluegrass" set which is .012 - .056. Depends on the guitar. I have never found a guitar yet that benefited from higher gauge strings, regardless of what the "archtop" guru's seem to say, but I do find that light gauge strings have some intonation and floppiness issues if they are tuned down too low.
Brian Evans
 
Posts: 718
Joined: Sat Aug 30, 2014 8:26 am
Location: Tatamagouche, Nova Scotia

Re: Small changes make a big difference at the bridge

Postby Eldon Howe » Wed Nov 21, 2018 4:39 pm

Are the tailpiece holes drilled all the way through the tailpiece?
I like that look with the D’Addario colors exposed.
Eldon Howe
 
Posts: 66
Joined: Thu Oct 29, 2015 11:23 am

Re: Small changes make a big difference at the bridge

Postby John Clifford » Sun Dec 02, 2018 11:32 pm

Sorry Eldon, I've been away for awhile. No, the holes don't go all the way through. They are just deep enough to hold the ball ends, and lined with brass tubing.
John Clifford
 
Posts: 108
Joined: Mon Dec 18, 2017 3:08 pm


Return to Archtop Guitars and Bass Guitars

Who is online

Users browsing this forum: No registered users and 2 guests

Your purchase from these sites helps support the MIMForum, but only if you start at the links below!!!
Amazon music     Amazon books     Amazon tools     Rockler tools     Office Depot    

The MIMF is a member-supported forum, please consider supporting us with a donation, thanks!
 • Book store • Tool store • Links •