[Dixielandjazz] Electric Bass amp position

[GWW174@aol.com]

Positioning of the BASS amp is important.  Suprisingly a large venue usually 
works best with a small bass amp kept at a low level and rely on the house 
sound system to provide the proper level of bass in the house mix.  

Mike Marios suggested placing the amp on a chair tilted slightly upwards.  
This works good.  A microphone on a baby-boom positioned close to the speaker 
(slightly off-axis) provides the best pickup.   Be sure the microphone 
doesn't TOUCH the bass amplifier.  A good sound person will mix the bass into 
the monitor and house systems.  The bass player should keep the level of the 
amplifier at the point where they can adequately hear their playing.  The 
bass player should not worry about being heard in the audience - let the 
sound person take that responsibility.

What happens when you have the bass amp too loud.  Bass is a low frequency 
signal.  This means the bass sound has longer wavelengths.  (The Laws of 
Physics)  If the wavelength is longer than the distance between the ears (and 
it is), the listener can't tell where the signal is coming from. In other 
words listeners (and microphones) can't localize on the source of the sound - 
i.e.  the location or direction of the bass signal.   This is why we can get 
away with single sub-woofer in your home stereo (or any other sound system).  
Try it one day when you are listening to music.  Can you tell if the BASS is 
on the Left or Right.  You can't.

If the bass signal (longer wavelength) is loud enough, it is picked up by ALL 
of the stage microphones.  The microphone in front of the bass can be 
non-existant or turned completely off, the other microphones are picking up 
those low notes.  The only way around that is to keep the levels of all stage 
microphones low and physically removed from the bass amp.  Hopefully the 
other musicians will play to their respective microphones.    

If the sound tech is forced to "pull a musician out of the background" by 
turning up their microphone (because the musician is not playing to the 
microphone), don't be surprised if you get a lot of BASS in the sound.  

Another problem which causes that "muddy" or "flat" bass sound occurs when 
multiple microphones picks up sound from the same source - i.e.  the BASS.  
That is a topic for another discussion one day.

Re:  Direct boxes.  Essentially a direct box uses a pick-up on the bass as a 
microphone.  The feedback which Pat (I think it was Pat) referred to occurs 
when the bass amp is facing the bass body or pickup.  Same effect as placing 
a microphone in front of a speaker.  The bass pickup is usually very 
sensitive and if the bass amp is facing the pickup or bass body, it doesn't 
take much volume before getting feedback.  

Personally I prefer a small good quality bass amp with a microphone close and 
slightly off axis from the bass amp speaker.  

BASS NO-NO's

KEEP THE BASS AMPLIFIER AWAY FROM THE PIANO SOUNDING BOARD.  Again, longer 
wavelength sounds are picked up by the large piano sounding board... and sent 
to the piano microphone for processing.  Usually sounds like h...l...  If you 
are at a gig and see the bass amplifier under the piano, be prepared for 
problems and lousy sound.

Lastly, remember to keep you level low enough to prevent pickup by every 
microphone on the stage - but loud enough so you can make that marvellous 
music.

Gordon