12-String Bass Bridges
There are primarily three different types of adjustable bridges that are found on 12-string basses: 4-saddle, 8-saddle and 12-saddle, plus a handful of 12's have recessed non-adjustable bridges. Recently non-adjustable rosewood bridges have appeared on inexpensive Chinese-made basses. Some of the bridges shown here are designed specifically to work on 12-string basses while others have been adapted for use on a 12.
4-Saddle Bridge on the
The very first 12-string bass (Tom Petersson's Hamer Quad) was equipped with a 4-saddle bridge. It did not take Hamer long to realize that the octave string pairs needed to be adjusted independently of the fundamental strings in order to achieve proper intonation. Hamer advanced to incorporating an 8-saddle bridge while still building the original 12-knob series of Quad 12's.
4-Saddle Bridge on Doug Pinnick's custom Yamaha 12-String Bass
The vast majority of 12-string basses in existence today incorporate an 8-saddle bridge. With an 8-saddle bridge the four fundamental strings have individual saddles and each pair of high octave strings share a saddle. As long as the two high octave strings are the same gauge this system works fine. This is because the distance between the saddle and the bridge is identical for each string so the strings will intonate properly. Many players will tune one high-octave string slightly flat and the other slightly sharp to give a chorus effect, so an 8-saddle bridge is perfectly acceptable. We think an 8-saddle bridge is the best option for achieving the optimum 12-string bass sound.
This Tune-o-matic style of bridge has been standard on many different brands of Korean 12's since it first appeared on the Musicvox Space Cadet in 2000. Aside from the redesigning of the mounting posts for a couple of those brands, the bridge itself has seen very little change. It has a broader span than that of the similar Hamer bridge, which increases string separation between courses. It also requires a wider neck than those on the 12's that preceded it.
Typical Korean 8-saddle bridge for the 12-string bass
These bridges incorporate a Nylock nut. The saddles are threaded and "float" along the screw as it's turned. As seen in this photo, the saddles can have enough space between them to allow the saddle to lean slightly to one side. When installed on 12's that allow it to sit close to the body, this bridge typically functions without problems. But if the design of the 12 requires it to sit at a significant height above the body, the added pressure of the strings can and will tend to force the middle of the bridge to sag. Some companies had their bridges redesigned in an attempt to correct this problem by increasing the thickness of the base of the bridge. This adjustment did help some, but C-channel material gets most of its strength from the sides and not the base. The proper adjustment to the design of this bridge should be to increase the side wall thickness.
Alembic 8-string bass bridges
These Alembic bridges could easily be modified for use on a 12-string bass simply by cutting additional string slots. The brass bridge may be an earlier version as it appears to be fabricated from parts that are screwed together. We think it's cool that when they needed a bridge for this application they figured out a way to simply make one out of brass instead of relying on other options that may have been available. The other bridge was obviously machined.
Hamer bridges are also made in the Tune-o-matic style but incorporate springs on each saddle. With this system, the saddle position is adjusted by turning a socket-head screw on the outside of the bridge. A spring located between the bridge wall and the saddle keeps the saddle tightly in position, and also allows the other end of the screw to freely rest in a hole in the bridge wall.
Hamer USA 12-string bass bridge
It is interesting to note that some Hamer bridges have the socket heads on the tailpiece side of the bridge (like the USA bridge above), while on others the socket heads are on the pickup side (as seen on the Korean bridge below). It is not known if this was done deliberately or if it is an idiosyncrasy of the company manufacturing the bridges. Having the socket heads on the pickup side allows more adjustment room.
Hamer Korean 12-string bass bridge
These bridges are designed to sit up off the body of the bass.
Kid's Dragon 8-saddlebridge
Waterstone Bass Bridges
The first production run of about 100 Waterstone basses (which included the TP-1 and TP-2 models) incorporated a bridge with a 2mm-thick base. The bridges on these basses were designed to sit well up off the body of the instrument. While these bridges work fine when positioned on or low to the body, positioning them high resulted in a more severe string angle to the tailpiece which quickly caused the bridges to bend in the center. Within one year the problem had been recognized so Waterstone ordered replacement bridges with a 4mm-thick base. The replacement bridges were provided free of charge to all bass owners who reported the bending problem.
While the bridges with the thicker bases have solved the bending problem, it should be noted that the side walls of the bridge actually provide more stability against bending than does the base. As shown in these photos, the side walls were not strengthened.
Korean 8-saddle bridge on new Waterstone and Tennessee 12-string basses
The 8-saddle bridge found on the Dean Rhapsody, new Tennessee and new Waterstone 12's sit directly on the body and are screwed down.
Schaller 471 8-string bass bridge with built-in tailpiece
The Schaller 8-saddle bridge / tailpiece is a good option for 8-string and 12-string basses as it is easily acquired and installed. Since it does not incorporate the use of a separate Tune-O-Matic style bridge it eliminates the sagging that has been known to happen with that style of bridge when the string angle coming off the bridge towards the tailpiece is substantial.
Schaller 471 8-string bass bridges are available in Chrome, Black and Gold finishes
The Schaller bridge unit also has more surface area that comes in contact with the body of the instrument which provides better vibration transfer from the strings to the body, thus increasing sustain and improving overall tonality. The design of the Schaller does determine the string spacing (as with all bridges) which in turn determines the neck width. The Schaller bridge width is wider than bridges that have dominated the 12's of recent years. A friend of ours discovered to his horror that he had miscalculated the neck width on a custom 12 he was building: Due to the wider bridge width combined with a thinner neck, the strings were positioned outside of the neck on the highest few frets.
Schaller 471 8-string bass bridge used on a 12-string bass
ABM 8-string bass bridge and tailpiece
We haven't yet seen any 12-string basses that use this ABM bridge. It appears the saddles are wide enough to accommodate two octave strings.
Players 8-string bass bridge
Not all 8-string bass bridges can be adapted to work on a 12-string bass. Due to the positioning of the height adjustment screws there is not enough room on this Players bridge to add additional string slots.
A small number of 12-string basses have been retrofitted with custom 12-saddle bridges. This Hamer Quad bass has had the original bridge replaced with a 12-saddle bridge and the string arrangement has been changed to Inverted. (Changing the string arrangement also required the nut to be changed.)
Custom 12-saddle 12-string bass bridge
After considerable thought we think a 12-saddle bridge might work contrary to the typical 12 sound. When using an 8-saddle bridge the pair of octave strings can be very slightly out of tune with each other due to minute variations in the angle of the saddle or the way the string slots are cut. A 12-saddle bridge would allow every string to be perfectly intonated, possibly making the tuning "too" precise. This could very well eliminate some of the natural chorusing effect inherent in the instrument, in effect "neutering" the 12-string bass sound to some degree.
In our opinion the only justifiable reason for having a 12-saddle bridge would be to use a 3-octave string set. While a 12-saddle bridge would solve the intonation problems inherent with such a set, it cannot make a 3-octave string set sound good enough to actually be useful.
It is also notable that, since the 12-string bass has been in existence for decades and no manufacturer has chosen to make a production model 12-saddle bridge, companies making 12's realize an 8-saddle bridge is completely acceptable for almost every application.
Warrior 12-string and 15-string basses are typically built with stationary recessed non-adjustable brass bridges. This type of bridge offers no possibility of properly tuning string harmonics. The bridge is installed at a slight angle; this virtually ensures that the string harmonics in each octave pair will be out of tune with each other since the distance between the bridge and nut will be slightly different for each string.
This Warrior 15-string bass was displayed at the 2008 NAMM show. Interestingly, it is strung E-A-D-G-C. It shows an unusual variation of the stationary non-adjustable bridge:
For the E strings, two short bridge sections have been used that are offset from each other. In our opinion, if anybody ever needed proof that an adjustable bridge is necessary, this is it. The offset placement of the two short bridge sections is confirmation that the fundamental string must be a different length than the octave strings for correct intonation. However, since these bridge sections are stationary they will only provide correct intonation for one specific set of string gauges. Change the string gauges and the bridge sections will not be in the correct place, therefore the harmonics will not intonate properly.
While the sales pitches for some inexpensive Chinese 12-string basses state that they have an "adjustable" bridge, the adjustment is limited to a height adjustment on each end of the bridge. The bridge is made of rosewood with slots cut for the strings rather than having metal string saddles. This kind of bridge is usually only found on the cheapest acoustic guitars and in our opinion is completely unacceptable for use on a 12-string bass. It offers no possibility of properly tuning the harmonics and the strings will quickly eat into the rosewood. We think the only way to make basses with these kinds of bridges playable is to immediately replace the bridge with a proper metal one.