Double Bass String Noise/Piezo Amplification questions

[Jay Corwin]

I did some searching and didn't find anything specific about this topic.

I'm really getting serious about amplification with my upright. I've only practiced acoustically for the first couple of years - and just dabbled with my amp setup as needed (not enough steady gigs to even worry about it until now).

My current setup is:
Shen SB-80, Velvet Garbos, K&K bassmax, Genz Benz Shuttle 3.0-10T

Originally I was using a fishman pro plat, but things sound better without it straight into the amp.

What I'm curious about is string noise. With the piezo obviously every movement gets amplified. I'm hearing string noise that I never hear when playing acoustically - so I don't think it's just slop. It's just the typical stuff you would hear in a BG situation that gets buried in a mix and isn't a big deal anyway - squeeks/rubs/shifts.

However, I haven't used this current setup in a band situation yet. So for you guys that are experienced - is this nothing to worry about? Is it the kind of stuff that gets overpowered by the boom in a live setting with a band? Just curious because right now I'm EQ'ing and testing by myself, so I hear every little detail. Maybe I'm just being to critical, but the nice thing about the Genz is that it's crystal clear.

Let me know what you guys think. Thanks.

 

[Jason Sypher]

I would start here Invalid Link Removed

 

[Francois Blais]

Is the BassMax fit tight or loose?
Too loose it may pickup lots of unwanted noise.
Are the contact surfaces flat and parallel?

 

[Jay Corwin]

Is the BassMax fit tight or loose?
Too loose it may pickup lots of unwanted noise.
Are the contact surfaces flat and parallel?

On the bass side it fits perfectly. On the treble it's a little snug. Doesn't make a difference though in the amount of string noise - just the amount of output I get with respect to the g-string.

 

[agedhorse]

Here's a little something about this subject in general, what you are experiencing is common with piezo crystal pickups because of the way they work and how the pick up the signal.

When you play your acoustic bass (or any stringed acoustic instrument really), the string vibrates and transfers it's energy into the body of the instrument through the mechanical string to bridge interface, then the mechanical bridge to body interface, then the mechanical interafce of the body to the air. Each of these interfaces and materials has a frequency response unique to the material and mounting method. Ultimately, almost all of the sound you hear is from the body vibrating and then radiating to the air energy that you put into moving the string (plucking or bowing). Generally, each of these interfaces, but mostly the bridge to body and bosy to air interfaces act as low pass (high cut) filters to the energy that you ultimately hear. This is why material and design of the body (especially) has such a profound effect on the sound of an acoustic instrument.

Now, when you use a piezo cristal to detect the vibrations at the bridge to body interface, you have eliminated the natural low pass filtering of the body and the transition to the air, which will make the sound brighter and the mechanical noises much more pronounced. Additionally, the piezo crystal's own properties act as a first order high pass filter (relative to it's impedance) as well which makes the problem even more pronounced. Now add in the need for a relatively high impedance input (~500k-1M) and if the amp you are playing does not have this high of an impedance you add yet another low pass filter factor further compounding the issue. (The Shuttle's input is designed to work well with piezos, so that's not compounding things at least).

Now, is all of this going to be a practical issue for you? Maybe, maybe not. One thing about a brighter tone is that it MAY be more desireable for sitting in a mix, especially with guitars and percussion. It also will depend on your playing style, choice of strings, type of music, etc. Things that you can do to taylor this to your own needs is to roll off some high end using the high freq. eq on your amp, and depending on the bass, you might want to take out a bit of ~2kHz using the sweep mid.

Other ways to tame this when installing a (piezo) pick-up system is to change the interface materials between the pickup and bridge but on those systems where the pickup is sandwitched between the bridge foot and the body, this generally does not work because it also affects the acoustic tone too much. Sometimes, a contact type piezo that uses an elastomeric adhesive offers a better solution, the elatomeric material acts as a low pass filter that tempers some of the piezo effect.

There's a lot of science behind a good pick-up system and it's installation AND there's a lot of art to is as well. Hope this helps a bit.