Under saddle pickup issue

[Gerald Shaw]

I've got an Alvarez classical guitar that uses the Alvarez Natural Response pickup System. The volume on the Wound strings seems to be a good bit lower in volume than the unwound strings. It's a passive pickup I had work done on it years ago and the repairman replaced the Saddle, so it's not original. . When tapping the saddle I can tell the amplified tap is louder under the 3 treble strings than the wound strings. I haven't played the guitar through an amp in years so I can't really recall how well it worked with the original saddle. I'm not a player and don't really know much about these under saddle pickups. Any adivce on how I can get the bass strings to sound at the same volume as the unwound strings? Thanks in advance.

[FRANK]

ah i had this problem to a year ago a friend from school had me build a saddle out of bone it fit snug to snug so I had called frank ford he was gone for the week end an I talked to a RV student there who sees a lot of this he said pull it back out and break the edges all around sand the bottom of the saddle like a u shape almost instead of flat and tight to the fit that the fact that I had such a good fit made it great for nonamplified playing acoustical but plugged in only a few strings made any sound pretty much it fit so good the pick up could not pick up maby this has happened to yours ?
?

[Jeffrey L. Suits]

Do yourself a favor, and replace it with a K&K Pure Classical. I'm serious--you won't believe how good these sound, in a nylon string guitar.

[danove]

I agree with Jeffrey, but to fit the Alvarez UST, you may use
air-hardening modelling clay (brand name DAS)

Lay a string of fresh clay in the bottom, cover with thin plastic and
then press bone with full tension strings. Let dry at least over night,
before putting the UST back in place.

To add to alignment, and to prevent crosstalking, make a slit in
the saddle bone, from underneath, between each string support.

[FRANK]

hey can you send a photo of this saddle Danove

[danove]

Sorry. Have no photo,

[Mike Kolb]

With all due respect (and before changing pickup brands or using the clay) make certain the bottom of the saddle slot is dead flat.... and that's dead flat with the string tension approximated on the bridge. (measure the bridge bulge under string tension to pitch, remove the strings and jack the bridge from underneath until it rises to that height).

At this point, the job is to flatten the saddle slot. StewMac makes a nice routing jig for the job http://www.stewmac.com/shop/Tools/Dremel_rotary_tools,_attachments/... or you can make a do-it-yourself model out of lengths of steel rods to run the dremel along. But the flatness of that saddle slot is the starting point for any good undersaddle install.

[Mark Dobbins]

Paul i had the same problem on a esteve classical guitar, i removed the saddle and installed individual saddles for each string , it corrected the problem, and i thought the guitar sounded better ,so did my customer
Mark

[Russell Vance]

I'm with Mike Kolb on this subject. Plan A: The absolute first thing to do is to flatten the bottom of the saddle slot with the top pre stressed to approximate the string tension - otherwize we are just fiddling at the edges trying to stick bandaids on the problem. Plan B: Short of that use a plastic saddle with slots or feet cut in the bottom (don't use bone, it doesn't bend or conform to the undulations - if you want to use bone go to plan A) so it flexes some to make better contact with the transducer.

I have, in the early days, sanded and worried the bottom of the saddle and stuck bits and pieces of shielding tape to adjust the pressure on the transducers but I could not honestly say that this method would survive a change of string gauge or a variation in the local weather.....it was just too dodgy, especially with the old style piezo transducers which needed very even pressure to balance right. The solution was to bite the bullet and use a jig and small router (I don't use a Dremmel for this delicate operation as they move around too much with slack tolerances and poor load response) to flatten the bottom of the slot. Rusty.

[J R Emmett]

I've seen this issue in two guitars recently. 

 

One is also an Alvarez (of some vintage) that I replaced the "NB Ducer" elements with a Martin Thinline element a few years ago.  Because fo the geometry of the original transducers, I filled the bottom of the saddle slot with a tight fitting rosewood strip (glued in place) and re-cut the slot using a jig of my own design (similar to the Stewmac but more precise, IMHO).  The original saddle was trimmed to fit the new slot depth and edges lightly beveled.  It was a snug fit and had good string balance when it left my shop.  Unfortunately, the customer decided to sand the nut after reading some material online  on how to improve his guitar tone.  Needless to say - it came back but with the customer's financial state at the time, he needed an inexpensive, quick fix.  The complaint was that "sometimes the treble strings are loud... other times it's the bass strings. 

 

Fortunately, the bottom of the saddle and slot were still both flat.  The issue turned out to be uneven pressure on the saddle and was resolved merely by tuning the strings from a slack state from the center to the edge of the fretboard (order: D-G-A-B-Low E-High E) on each string change.  When the strings are at full tension, tuning order did not make any difference.  I would have rather fabricated and refit a new saddle but he couldn't afford it.  Ran into him a few weeks ago and confirms that the solution I provided him is still working.

 

Saw the same issue on a Martin DCPA5 (unaltered factory guitar, low mileage).  Same string tuning technique worked on it as well. 

 

The explanation of why this works is pretty simple.  If you bring one of the E-strings to pitch with the others slack, the saddle is pushed down on one end.  Intuitively, one might expect the bridge to move into an evenly balanced pressure state as the other strings are brought to pitch but this will not happen if the saddle is not properly fitted to the bridge. 

 

Please note that I am not offereing this tuning technique as a suggested repair method but it is a usefull diagnostic aid to guage saddle to bridge fit and zero in on the problem.