Double Bass Playing direct thru PA, do i need DI box?

[brianrost]

I just dont really understand diff b/t when/why a DI is preferred over a preamp when going directly to an on-stage board/mixe, or vice-versa.

DI boxes are used to match impedance and level of magnetic instrument pickups to those of microphones. Most have too low an input impedance to work properly with piezo pickups. DIs typically have a ground lift switch to kill any hum caused by ground loops.

As far as what you should do:

Option #1: do nothing and expect the sound man will have a DI box that you can plug your Baggs preamp into.

Option #2: buy your own DI to plug the Baggs into just in case you might run into a sound man who has no DI of his own.

Option #3: switch to a different preamp that has an XLR output so no DI box is needed.

 

[Matthias Hacker]

Although everthing has been said already regarding the original question... I was traveling for years with only my bass, a piezo pickup and a radial pz di, and have been very happy with that. 10 MOhm inpu impedance, variable low cut, outstanding sonic quality, build like a tank and two outputs, a balanced DI out as well as a buffered jack out, that can be sent to the amp if needed. The cable between the bass and this unit lying on the ground can be quite short, wich will also result in a better sound.

 

[Ric Vice]

Isnt “impedance matching” what a DI does?.. apologies if misinformed

Agreed, DI’s were initially designed for guitar’s and electric basses. The Countryman 75 was one of the first ones I used that was set up for a piezo.

 

[damonsmith]

I would never recommend sending a dry signal from a piezo straight into the sound board. It usually ends up sounding like a fart trapped inside a metal garbage can.

Agreed. One day it might work, I still say we should only let unknown sound-people do anything other than mic'ing the bass or amp.

 

[Zbysek]

Thx 7yrsdown... sounds like i have the brunt of the issue covered w my pre, but should consider a DI downstream from it, optimally... correct? My basic Baggs pre does not have built-in DI

Correct...or you can upgrade to preamp with built-in DI out...

 

[Jefenator]

Apologies for a newb-ish question, but if i’ve got a transducer pickup & want to plug directly into PA, should i be using a DI box? Normally, i run thru a preamp (1/4” in/out) into my amp (& then into house if needed), but for small gigs, w no amp, whats the preferred setup? Bass > DI > PA?.. Bass > preamp > PA?.. Bass > PA? Again, i’ve only enough working knowledge re PA systems & electronics to be dangerous here... Thx for “feedback”

I used to use the PA the majority of the time with just a 1/4" preamp. It always worked fine to my ears. (Impedance matching may not be optimal in theory but in practice I never had an issue - and I can be picky.)
I like to have my preamp physically attached to my bass for practical reasons (no extra thing to unpack & plug in) and sonic reasons (response seems noticeably compromised with a long-ish cable inserted before the buffer).
Almost every mixer *should* have a workable 1/4" input but one does need to at least be prepared for an XLR-only contingency. (Cable, adapter and/or DI, good things to have & not need rather than vice versa.)

 

[Matthias Hacker]

I used to use the PA the majority of the time with just a 1/4" preamp. It always worked fine to my ears. (Impedance matching may not be optimal in theory but in practice I never had an issue - and I can be picky.)
I like to have my preamp physically attached to my bass for practical reasons (no extra thing to unpack & plug in) and sonic reasons (response seems noticeably compromised with a long-ish cable inserted before the buffer).
Almost every mixer *should* have a workable 1/4" input but one does need to at least be prepared for an XLR-only contingency. (Cable, adapter and/or DI, good things to have & not need rather than vice versa.)

This is also my experience, the cable between piezo and buffer/preamp should be as short as possible. The weak piezo signal seems to suffer a lot from long cable runs. Then it doesn´t matter that much whats happening behind the buffer. What kind of preamp did you use mounted on your bass? I do have a John East mpm mixer (2x 5Mohm input) inside a little box, that fits behind the tailpiece together with a long lasting 9v battery. Couldn´t be better for me!

 

[Don Hergert]

I've done a number of gigs, including a pretty fancy wedding using my own FOH system, and have studio-recorded a soon-to-be released 2-CD album with my bass, using the signal directly from the piezo without a pre-amp or a DI. It required some EQ'ing at the board level, but the sound was great.

I do think that we were lucky these all worked out so well, it just depends on the FOH board or the studio system you're plugging into.

I do have a pre-amp on the bass now and I do have much more headroom because of that, so I'd guess that the likelihood of success is much greater with the pre-amp.

 

[Jefenator]

In the past I've used a Biesele magnetic pickup which incorporates a piezo input and a blend knob - loved that. At the moment I'm using an fDeck HPF-Pre. It's a bit of a pain in the butt to strap securely on the tailpiece but once it's on there, it works very well. (Phase switch & hi-pass seem like essential controls to me - volume knob also very helpful.)
I'd love to just stay passive and plug straight in (like I often do with the electric basses) but I've never had much luck with that approach with the piezo pickups. Whenever I get a new pickup or amp I try it all sorts of ways and the buffer has always remained thus far.
I notice many boards now include some higher impedance inputs that might supposedly be good for piezo signals. Alas, practical experience has left me distrustful. (The one on my Allen & Heath board has headroom issues & just doesn't "feel" very good, even with my electric bass.)

 

[DoubleMIDI]

Since cables to mixer boards are often rather long, a bit lower impedance at the inputs make sense for the long cable and adding a high impedance buffer/preamp close to the piezo keeps cable losses on the short cable and sensitivity to electric noise on long cable low. A simple impedance buffer like the mint box or Quick 'n' dirty with a good JFET and selected resistors for it would do the job well.