Loudness, feedback, and a balanced sound.

I recently started playing in a punk/psychobilly band.  Playing punk on an upright is hard, and I haven’t quite nailed down the slap technique.  But the hardest and most expensive part was dealing with feedback.  When I joined the band I had to use my Ergo electric upright that I bought for night practicing just to be amplified enough to be heard over the drummer.  Unfortunately, I am a bit of a purist and really don’t like the sound of an EUB–besides it lacks the stage presence that a big bass has.

So I began on a journey to eliminate feedback.  This is a frequent topic on many upright bass related discussion boards.  Many rockabilly and psychobilly bassists simply tape the F-holes on their bass with duct tape to reduce ambient resonance.  I think it looks really dumb, and shows an unwillingness to understand the dynamics of the instrument they choose.  Really, if you don’t care why not just play an electric?

There are several things that can be done to prevent feedback at ear-splitting volume levels:

• Use a laminate or hybrid bass, fully carved basses are much more susceptible to feedback.  The carved surface vibrates more freely.  At one point during a band practice I got that familiar low frequency feedback loop that upright players dread and looked down to see the top plate on my fully carved Calin Wultur moving almost a full inch!  Not good for creating cracks and really not good for sound post placement.
• Get a good pre-amp with phase inversion abilities.  If you can get the signal coming from you bass out of phase with your amp it will not feedback as much.  One downside is that the bass loses a bit of the warmth through the amp, but it works in a pinch.  Better to sound thuddy than not be able to play at all.
• Turn down the volume.  Duh.  Not an option when playing with a punk drummer though.
• Feedback eliminators.  These are digital signal processors that detect feedback and eliminate it.  I tried a Behringer model, and it was rather inexpensive.  It works really well.  There are several ways to use it.  One way is to set it to automatically eliminate feedback.  I don’t recommend using this method because it will start to cut frequencies that you need to sound good, and if you play arco forget it–it will think it is hearing feedback not music.  The second way is to “train” it.  You set up, crank the volume and tell it to locate feedback.  Once you start playing and get feedback it will lock that frequency out.  Doing it this way only required five or so frequencies before it was totally eliminated.  Remember though, this is a band-aid and is really not the best option–besides these devices were designed for vocal use, not bass.  And another thing to consider is that because it is a DSP you are going from analog to digital and back to analog.  It will slightly degrade the sound and add a small (barely noticeable) amount of delay to the signal.
• Get a magnetic pickup.  I picked up a KRIVO on eBay, based upon reviews from the talkbass forums.  It sounds well.  But there are a few gotchas.  It requires a steel-core string to pickup the signal, so strings like Obligatos won’t work.  Also it requires a metallic outer casing on the string for grounding–so you can’t use something like a Eurosonic string either.  I can’t even begin to explain how much money I spent on strings during this experiment.  The two major problems I have with the humbucking style magnetic pickup is that it doesn’t work well playing arco, and there is an ambient hum noise–the whole setup is very sensitive to proper, clean power.  Not always available at bars and practice areas.

So what was my final solution?  I ended up getting a 1960’s Knilling Hybrid 3/4 Bass (yes, that is my third double-bass and yes I know I have a problem,) and blending the Krivo pickup with a Realist transducer via a K&K pre-amp.  This allows incredible volume levels without feedback.  I am running through a Gallien Kruger 800RB head into a Trace Elliot 4×10 cabinet.  At almost full volume there is no feedback, and the blending allows me to play arco.  One really interesting side effect is that at really high volumes the strings will vibrate as if they are being bowed just through conducting the sound from the amplifier–it provides an uncanny amount of sustain for a double bass.