Help Me Understand Piezo Pickups

[idsnowdog]

I have put Piezo pickups in three instruments recently. One is a dreadnought acoustic, one is a semi-hollow archtop and one is a solidbody electric mandolin. All three sound good in combination with a neck mounted magnetic pickup through a simple clean amp. When I use the piezo alone with an amp it's bright and thin which is not a surprise. However, it is plenty loud in comparison to the magnetic signal. I have a real cheap preamp with just a volume and tone control. The preamp doesn't do a lot for any of the three. The bass response is a bit fuller and levels are higher but that's about it. What I notice is the unwound strings ring a lot louder than the wound strings and I get distortion on the top two unwound strings. Through an amp you don't hear it much but through a USB interface it's really bad. When I look at the input/output levels on the amp simulator the levels aren't excessive. Is the distortion due to uneven surfaces or mechanical resonance of a loose bridge?

 

[ICTGoober]

We need more details than provided... What brand and model of pickups, your preamps, etc.

 

[idsnowdog]

Two of the three piezo pickups are rod piezo's. The third is a Tune O Matic piezo from Kaish. The TOM doesn't distort on the top two stings. The two rod piezo's are no name Asian OEM's as is the preamp. With the electric mandolin I routed a channel beneath the bridge for the pickup and put the metallic bridge on top of it. With the dreadnought I had to sand down the saddle to get the pickup to fit underneath in the bridge slot. Are all of the elements in a piezo rod the same or are they compensated to balance the string volume? Are they directional?

 

[DavidRavenMoon]

Are you using a preamp with the piezo? That’s important since they have a very high impedance. If you run then right into an amp they will be thin and scratchy sounding. You’ll also need to actively mix in the magnetic pickup.

If sone strings are louder than others it’s because the saddle is not supplying even pressure on the piezo. You must have a flat bottomed slot.

Sent from my iPhone using Tapatalk

 

[idsnowdog]

Are you using a preamp with the piezo? That’s important since they have a very high impedance. If you run then right into an amp they will be thin and scratchy sounding. You’ll also need to actively mix in the magnetic pickup.

If sone strings are louder than others it’s because the saddle is not supplying even pressure on the piezo. You must have a flat bottomed slot.

Sent from my iPhone using Tapatalk

Would the strings that are louder be under more or less pressure?