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Another undersaddle bridge (UST) problem
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=22084		 Page 1 of 1
Author:  Doctor Jeff [ Wed Apr 22, 2009 11:49 am ]
Post subject:  Another undersaddle bridge (UST) problem
I recently got an Alvarez AC60SC with the 600T piezo UST system. The middle 2 strings are much louder than the others when amplified. It is obvious the previous owner filed down the saddle to lower the action, so I removed the saddle and sanded it down flat with some improvement.

I tried the "clay fix" recommended by many people (http://acapella.harmony-central.com/arc ... 97621.html) to improve contact along the length of the pickup but found it drastically dampened and muddied the sound, so I removed it.

I am thinking of buying a new Tusq saddle and installing it, possibly shaping the bottom so it is slightly convex and will contact the outer edges better. LR Baggs website recommends placing relief cuts on the bottom surface to allow for variable pressure along the saddle. Another option would be to buy another piezo pickup and install it in place of the OEM one.

Any recommendations would be appreciated.
Author:  wbergman [ Wed Apr 22, 2009 12:08 pm ]
Post subject:  Re: Another undersaddle bridge (UST) problem
I am not familiar with your pickup, but I have the following observations.

As you noted, hollow slightly under the center so that the ends contact, which is superior than the opposite.

You can avoid gaps under any string by completely segmenting the saddle, so you really have six different saddles. You can test this by just sawing up the saddle that you have, or a scrap one if you want to save the existing one. I have seen this on 100 year old classicals--it's not a complex trick.

I do not know if these are compatible with your pickup.
Author:  Nick Oliver [ Wed Apr 22, 2009 5:50 pm ]
Post subject:  Re: Another undersaddle bridge (UST) problem
You say you sanded the bottom of the saddle flat "with some improvement" which, if you have done this with due care and the sound is still poor, would lead me to think of two other possibilities.
One: maybe the Transducer is faulty and not 'reading' and converting vibrations equally along it's length & fitting another UST should rectify this particular problem or,
Two: Maybe the bottom of the bridge slot is not flat or it's walls not perpendicular to the bottom (causing the saddle to tilt forwards under string tension and not make full & proper contact with the transducer's face), you say the previous owner has played with saddle/action height perhaps they have also messed with the slot? Another possibility is, having worked on supposedly 'top' brand named instruments that are mass produced, quality control and machining processes aren't always at their best wow7-eyes and little flaws can creep in on individual instruments. The problem could have been built in from birth, the bridge slot may have escaped the quality controllers eye! Not the norm thank god but it does occasionally happen.

Just another couple of possible area's to consider.
Author:  jordan aceto [ Wed Apr 22, 2009 6:48 pm ]
Post subject:  Re: Another undersaddle bridge (UST) problem
Like Nick said, often poor under saddle transducer balance is caused by the bottom of the saddle slot not being flat, either because of the pull of the strings deforming the whole bridge, or just because it aint flat. Chasing down string to string balance with an un-flat saddle slot is an exercise in frustration, and not worth the time in my opinion. If the root problem is indeed in the saddle slot, the fix is to re-route the slot.

Maybe thats not it though, but if you are spending way to much time trying to balance out the string outputs, suspect a wacky slot.
Author:  Doctor Jeff [ Thu Apr 23, 2009 7:53 am ]
Post subject:  Re: Another undersaddle bridge (UST) problem
Update: Thanks for all your help. Your comments on saddle slot not being flat is worth considering.

I removed saddle for umpteenth time and using a card scraper carved it out very slightly over the D and G strings so it was convex. To my delight when I replaced saddle the top 2 strings rang out like they were supposed to. Now the D string is perhaps very slightly dull to my ears, but not so much it's intolerable. Guess I can fine tune it later.

I would reroute slot but I don't think I can remove pickup without permanently damaging it, so I will leave it alone.

When I replace string set I will install a new saddle and see what happens.
Author:  Jeffrey L. Suits [ Thu Apr 23, 2009 8:30 am ]
Post subject:  Re: Another undersaddle bridge (UST) problem
Doctor Jeff wrote:
Update: Thanks for all your help. Your comments on saddle slot not being flat is worth considering.

I removed saddle for umpteenth time and using a card scraper carved it out very slightly over the D and G strings so it was convex. To my delight when I replaced saddle the top 2 strings rang out like they were supposed to. Now the D string is perhaps very slightly dull to my ears, but not so much it's intolerable. Guess I can fine tune it later.

I would reroute slot but I don't think I can remove pickup without permanently damaging it, so I will leave it alone.

When I replace string set I will install a new saddle and see what happens.


String balance problems and ugly sound, are why I stopped using USTs, and went with SBTs, nearly ten years ago.
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