# Help with a Fishman under-saddle piezo: high B and E strings give no output



## Guest (Aug 27, 2012)

Changed the battery thinking it might just be a weak cell but no dice. The high B is very low output, the high E is basically not there at all.

Is it the piezo? Is it the preamp?

Tapping on the bridge with a pick yields a strong signal from low E to G, but after that's it gets weak and then non-existant very quickly.

It's not a particularly expensive guitar. An old USA Guild thin-body acoustic thing. But I'm sort of running in to a fall acoustic gig schedule that's busy and need it functional. Reluctant to hand it over to a shop and then lose it for a month.

Any thoughts on what this kind of repair might run me if I can't do it myself? Are piezo's hard to replace? Can I drop any under-saddle piezo in there or does it need to be something specific for the preamp (one of those older Fishman Transducer jobs, the big rectangular ones)?


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## ronmac (Sep 22, 2006)

Piezos are pressure sensitive devices. What you describe is often caused by the strip not sensing pressure along the length of the strip, often caused by uneven saddle slot depth. A good repair shop will route the slot prior to assembly to make sure the bottom is smooth and even. It is also important to inspect the bottom of the saddle to see if it has a smooth and even surface.

A quick fix can sometimes save the day. Remove the saddle strip and spread a small amount of clay in the slot. Replace the PU and saddle and tune up. The clay should auto level the bottom of the slot.


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## Guest (Aug 27, 2012)

ronmac: thanks! This is definitely a straight-forward thing to try. Question about the clay: what kind? My wife has a bunch of Fimo here but that'd dry hard and I figure that's probably not what I want since it'd get brittle.


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## Swervin55 (Oct 30, 2009)

ronmac said:


> Piezos are pressure sensitive devices. What you describe is often caused by the strip not sensing pressure along the length of the strip, often caused by uneven saddle slot depth. A good repair shop will route the slot prior to assembly to make sure the bottom is smooth and even. It is also important to inspect the bottom of the saddle to see if it has a smooth and even surface.
> 
> A quick fix can sometimes save the day. Remove the saddle strip and spread a small amount of clay in the slot. Replace the PU and saddle and tune up. The clay should auto level the bottom of the slot.


+1. Also, if the saddle is too tight in the slot it may not bottom out effectively against the piezo strip. If this is the case you might try sanding a very slight taper on the sides of the saddle so that it goes to the bottom of the route but isn't sloppy at the top.


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## Greg Ellis (Oct 1, 2007)

My saddle falls out when I change strings, and if I'm not careful when putting it back, the pickup element slips out of position, usually giving me boomy bass, or weak response on the higher strings.

It could be as simple as that; have a look at how the strip is sitting, under the saddle. (Assuming you haven't already)


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## ronmac (Sep 22, 2006)

Sorry for the late reply. I am working a week long festival...

Try and find some "Marplex" clay at a craft store. Also good tips from Greg and Swervin55 to try.


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