How to get the best string to string volume from your piezo pickup

Under saddle pickups work by detecting vibrations from the strings transmitted through the saddle. The piezo transducers in the pickup then transform the vibrations into electrical signals.

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The Common Problem with Under Saddle Pickups

String to string volume – the difference can be subtle or obvious, but once I notice even a slight unevenness, it just bugs me to no end. Like it’s always there, waiting to eat at my nerves every time I play the guitar. Once heard, it cannot be unheard, know what I mean? Luckily there’s an easy fix for most guitars.

Before we continue, let me state that uneven string volume can be attributed to many things, but an uneven saddle and a faulty or low quality piezo pickup are the most common causes.

This “mod” doesn’t just benefit guitars with under saddle piezo pickups either, although it’s effect is likely more noticeable on them because the pickup is in the direct path between saddle and bridge.

It’ll also work on guitars with piezo pickups attached to the guitar top as well as on non-electroacoustics. I’ll explain it in detail later but this “mod” improves the transmission of vibrations through the saddle onto the bridge and top by removing any vibration (and tone) robbing empty spaces caused by an uneven saddle.

What about guitars with magnetic soundhole pickups?

I’m not sure, given how those work, but done well, it can’t hurt.

Some Background

The Yamaha SLG200N is undoubtably a great guitar. I remember being blown away by the tones I was hearing at the music store when I was playing a demo unit.

I got the sales assistant to bring three new ones for me to choose from, and I picked the one with the most resonant body (strongest feeling vibrations) and luckily for me, it had perfect string to string volume when plugged in! Perfect guitar!

Except that it didn’t. And it wasn’t.

In my excitement to get it home, and because the store was really noisy at the time, I failed to notice that the high E string was just a tad lower in volume than the rest. When I got home and used my headphone monitors though, I started hearing a subtle difference in volume. Once I noticed it, it became super obvious and irritating!

The Fix

The concept is simple actually. The bottom of the saddle needs to have maximum contact with the pickup and bridge in order to transmit string vibrations faithfully.

This is true whether it’s a typical hollow guitar or a solid body guitar like my SLG200N. It doesn’t matter whether it’s a steel string or nylon string guitar either. If the guitar has a removable saddle, it will benefit from this exercise.

Guitar strings have 4 contact points on a typical acoustic guitar – at the tuning pegs, the nut, the saddle and the string anchor points on the bridge.

In very simplified terms, when a string is plucked, its energy vibrates the guitar top through the saddle and bridge, and we hear sound. Vibrations are also transmitted via the other 3 points, but their effect is relatively minor compared to the saddle and bridge. Just tap on the nut and the bridge on a typical acoustic guitar and you will hear a big difference in volume.

Unless yours is a very high end guitar, chances are that the saddle has not been perfectly flattened out at the bottom (the saddle probably doesn’t sit tightly in it’s slot either but that’s typical of most low and mid range guitars).

This is particularly common on plastic saddles like the one on my SLG200N. In fact, of the 9 acoustic guitars I’ve owned, only my Guild F4CE came with a perfectly flat and (very) tightly fitted bone saddle. It also happens to be the only high end guitar I have ever owned. It was a gift from my father, bought second hand, when I was in my teens. In the late Eighties I think, long, long time ago… okay moving on.

This is a great opportunity to upgrade your saddle too. If yours is plastic, I would recommend upgrading to bone or a quality synthetic bone material. Some guitarists recommend brass saddles too. I have no experience with those.

Stuff you will need:

  1. Your new saddle (optional)
  2. Medium grit sandpaper (400-600 grit) or a diamond lapping plate
  3. A whiteboard marker
  4. An extremely flat surface
  5. Some cloth for cleaning up

Step 1:

Set your guitar on a soft surface to prevent scratching, making sure to have enough space beneath the headstock to work the tuning pegs. I usually do this on a table and let the headstock extend over the edge.

Another solution is to place a cushion or thick towel under the neck to prop it up. There are commercial solutions you can buy as well.

Step 2:

Loosen or remove the strings and remove the saddle. This is a good opportunity to change to that fresh new pack of strings you bought but haven’t used. Mmm… fresh strings.

However, on some nylon string guitars, you can also loosen the strings just enough to slide the saddle out, like I did in the video. Be really gentle when you do this! Especially on solid top guitars!

If you prefer to avoid any chance of scratching or damaging the guitar top, just remove all the strings and proceed to step 3.

Step 3:

Prepare your sanding tools. Place your sandpaper on a perfectly flat surface. I prefer to wet the sandpaper first by running it under a tap. This helps minimise clogging and makes it harder for the sandpaper to move around when sanding down your saddle.

If, like me, you are using a diamond lapping plate, make sure it’s one of those thick and heavy types. Good quality ones like the DMT I’m using are perfectly flat. Quality Japanese ones are just as good.

Avoid those thin plates that are mounted on plastic. They could slightly be warped. I found this out the hard way.

Step 4:

Mark the bottom of the saddle with a whiteboard marker. Doing this helps to indicate when you can stop sanding. It’s important to stop when all of the marker ink has been sanded away.

Taking material off excessively may lower the action of the strings too much and cause buzzing. Normally only less than half millimetre needs to be removed.

Be careful in keeping the saddle perpendicular to the sanding surface and make smooth, even strokes. I like to spread my fingers as wide as possible across the saddle to help maintain equal downward force across. This avoids uneven sanding.

When you’re done, it helps to check that the bottom is still perpendicular to the sides. You can stand the saddle up on the table and eyeball it, or use a carpenter’s right angle tool. I usually just eyeball it.

Step 5:

Return the saddle to it’s slot on the bridge and string the guitar up. Check that the action is still okay, then plug the guitar in and listen for improvement.

I hope this guide has helped shed some light on the subject. Thank you for reading and here’s wishing you all the best in you guitar journey!

Video Production: Loud Kitchen
Background Music: ‘Stephish’ by Aaron Ang

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