Piezo help - one string is too loud

[reverendrally]

Hi all.

Got the fretless up and going, but I'm having an on going issue with the D string being MUCH louder than every other string on the bass.

Here are a few pics to recap on my setup. It' a 6 element acoustic guitar pickup with my own home brewed bridge...

The main issue seems to be that the D string has the highest tension, therefore it exerts the most pressure on the pickup. Similarly, the E has the lowest volume is a little quieter than the G and A. Not sure how to get round that and even out the volume of the strings. I'm using GHS precision flats in case the wondering.

Any ideas?

P.s. the slot appears to be flat as does the bottom of the bridge piece. Already checked that.

 

[countbassiedad]

I'm no help except to say that this seems to be a trait of piezo's. Maybe try different strings?

 

[ibateur]

You might need to research some of that equal tension stuff. Zachary Guitars (no plug) have a site dedicated to this.

 

[Jodaka]

does it have indiviual trim pots? if so, may want to look at that to help clear things up...

 

[reverendrally]

nope, one pickup with one output.

 

[T-Bird]

Hi.

First of all, IME piezos are a PITA to adjust.

Secondly, IME all piezos are a major PITA to adjust.

Thirdly... You get the point

The uneven volume is the most common problem and judging by the pics, I wouldn't hold my hopes too high up without some major redesigning.

The worst problem IME is the too narrow string spacing and the 6 individual notches on the element. The notches wouldn't be as much of a problem if the strip was long enough, but now even the slightest bend in the saddle will change things.

The second problem is the width/depth ratio being too big, the saddle will rock back and forth, causing uneven pressure, which in turn causes uneven volume, obviously.

As for the remedies, a full length element is a must. IME anyway.
As a band-aid remedy, You could try a support shim that's a hair thinner than the element on the E end of the groove.
The width of the strip is slightly narrower for the slot than I'd use, but there's a lot of opinions on that.

Deepening the slot and fabricating a higher saddle will reduce the rocking effect.

I have not had much luck with wooden saddles, they tend to bend, except for pockholz or ebenholz perhaps, but changing the existing one to a bone-saddle will improve the stability.

On one problematic acoustic guitar, the uneveness was helped slightly by dividing the saddle in two separate pieces, could be worth a try in Your case as well.

Good luck.

Regards
Sam

 

[Stealth]

Maybe shim the bridge at appropriate places with different woods to create a bit of damping? What I'm suggesting wouldn't be a shim so much as a small notch on the bridge itself which you would then fill with softer wood that'd soak some of the volume. Not saying it's perfect, but that's how it'd be in principle.

Edit: T-Bird was faster than me - but my approach is basically the inverse of his.

 

[bajerovaquero]

You might need to research some of that equal tension stuff. Zachary Guitars (no plug) have a site dedicated to this.

Thanks for point this site!
I totally agree with Zachary, why the **** they keep overtensioning the D string? Maybe this is the reason it sounds louder?
I started using daddarios (great for the bucks) and always feel like an idiot has chosen the gauges of the strings. Why the D string has +10 lbs of tension than B or E...
Just a sugestion, detune your D string and watch for a difference in volume, this can be the issue. If so it looks you can go in two directions:
Shim or file
Get a balanced set from Circle K or Zachary

 

[Musiclogic]

something that works on ocassion is to wrap a piece of tape(vinyl, packing or masking tape around the area of the louder string. I have used vinyl electrical tape with minor success, but never perfect

 

[tZer]

On my EUB build I created a sub-bridge that was raised off of the body so I could move my round piezo element around underneath the bridge to find the sweet spot.

I can't see your pics here (at work), so I am sure what I am talking about would involve a pretty significant re-design/build and is probably not the answer you are looking for. But I did run into the uneven sound thing early on in this build and redoing the bridge/sub-bridge system solved all my evenness issues.

My EUB has very even sound and I am considering a new fretless EB build using some of the same bridge principles.

 

[FBB Custom]

Thanks for point this site!
Why the D string has +10 lbs of tension than B or E...
Just a sugestion, detune your D string and watch for a difference in volume, this can be the issue.

This would be where I started if it were my instrument. See if it's due in full or part to tension. If not, then either shim (very, very slightly) the quiet strings or shave the saddle under the loud ones. Keep in mind that if you shim, you may create different pressure distributions and simply move the hot spot to another string.

As others have said, this is almost always a problem with undersaddle piezos. It is best to have them fit snugly but not tightly in the saddle slot so I would address that issue as well. If the element is round (i.e. Highlander or cable-type) it is best to have a round-bottomed slot.

Most manufacturers make different gauge strings, if you want a more balanced set, you can generally get them (with roundwounds, at least). For flats, I like the TI Jazz Flats by a mile over all others.

 

[reverendrally]

I'll try dropping the tension first and seeing if that helps. The GHS flats I have come in a smaller gauge set, so maybe I could just order a lower gauge D if it helps.

I've also ordered one of these...
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

So I can try that out too.

 

[reverendrally]

Had a fresh look at the bottom of the saddle and managed to shave off a tiny bump under the D string. Hooked it all back up and it is a little better. THe D and A strings are better matched. G is a little quieter and the E still more, but I guess that's part of the sound of it. I'm gonna try shimming the E later too. THanks all.

 

[Alex Xander]

Had a fresh look at the bottom of the saddle and managed to shave off a tiny bump under the D string. Hooked it all back up and it is a little better. THe D and A strings are better matched. G is a little quieter and the E still more, but I guess that's part of the sound of it. I'm gonna try shimming the E later too. THanks all.

I have an ABG that has a very similar bridge setup to the one you fabricated. The difference is the saddle is split into four pieces, so each on exerts pressure on the element, independent of the other strings. It could be that your bridge piece (or the element) is ever so slightly bumpy/off square, causing a stress concentration on the D, and the accompanying volume increase.

 

[reverendrally]

I'm guessing your ABG has 4 elements, one per string. I have 6 elements. I thought about cutting mine, but I think it would make it worse, not better... and then I'd have to make a new saddle. Yeah, I know, I'm just lazy. hehe

 

[ChrisHEB3]

Have been tweaking this lockdown build and I just read through this thread. I added a layer of masking tape to the underside of the saddle at the B and G: the balance across the strings is much improved and the tone not affected. Thanks !!