Slotted bridges

BowynMadley

This is something new to me. In the last year or so I've ventured into the more boutique and higher ends of acoustic guitars having bought an Atkin om37 and a Martin d35. 

I've seen many articles about how old guitars had slotted bridges without slotted pins therefore making the break angle much steeper and actually improving the longevity of the bridge plate.

Has anyone converted to this setup or have guitars with a slotted bridge to shed some real world experience of it?

Cheers

Bo

BillDL

The holes in the bridge for the pins should be bored out with a tapered reamer at an angle to match the taper of the pins so they only have to be gently pushed down and can be pulled back out easily again.  The pins are only there to stop the ball end of the string from popping back into the bottom of the hole from where they should be wedged tightly up against the underside of the bridge plate / pad.  For a slotted pin to be absolutely perfect, the width of each slot of the 6 pins would have to exactly match the diameter of the string it's used for.  That would minimise the way the ball end eventually begins to dig into each side of the pin slot (on wooden pins) on the thinner strings and creep a little more towards the edges of the pin holes on the bridge plate.  A bridge with well slotted pin holes has the slots cut to different widths for each string, and the unslotted pin is more resilient to the ball end digging into it, but there can also be a tendency for the ball end to eventually start digging into the bridge plate at the slotted side of the keyhole shape.  I have seen this on older guitars that have the pin holes slotted.

As far as the break angle is concerned, because the hole for the bridge pins is conical, when a slot is cut down the side closest to the saddle, the actual takeoff point of the string from the bridge pin and the inside of the hole will be a little lower than the top of the bridge.  On a bridge with unslotted holes and slotted pins the takeoff point is from the top of the bridge at the edge of the hole, so if the saddle has to be filed down to compensate for changes to the shape of the soundboard under tension, you won't have much or any break angle, whereas you would still have some from a slotted hole.

A very common fix for the aforesaid problem on a guitar with slotted pins and smooth bore holes is to cut angled slots from the top of the bridge closer to the saddle back down into the pin holes, so the string takeoff point from the bridge pin inside the hole is further down inside the hole, a bit like a slotted pin hole but more exaggerated.

Yes, I've slotted unslotted bridge pin holes to use solid round pins in the belief it would make the guitars sound better.  They were not top end guitars, but were good sounding guitars nonetheless.  To be perfectly honest I didn't notice any difference at all.  If there was an improvement I couldn't hear it while playing or from recordings.  Given that the overall sound of an expensive hand made acoustic guitar is derived from multiple factors that, when combined make for an exceptional sound, it is possible that slotting the bridge on one of them might make an audible difference whereas it wouldn't be noticed on a cheaper guitar with a less complex sound.  It would probably be about the same subtle difference in sound between different hardnesses of bridge pins i.e. most people won't hear it.

lincolnblue

My Breedlove has a slotted bridge with no pins. I don't know if modern Breedloves are the same but I've been very pleased with it.