|AMPLIFYING A HARMONICA QUARTET by Jouko Kyhälä
Throughout the carrier of Sväng we have developed the on-stage
sound system needed to make Sväng sound as we want it to sound.
The instruments we use, especially the bass harmonica and Harmonetta
need special attention with their amplifying.
The acoustic sound of Bass harmonica is really quiet. It is hardly
audible in a distance of five meters. Especially the the very
low frequencies of the sound have just a little of energy. That
is because there is not any resonating chamber to make the acoustic
sound louder. Only a quite small reed is making the air vibrate
and that can not cause very strong movement of the air (audible
sound). Also the notes are located on two separate combs and thus
a normal microphone set in a mic stand can not pick up all notes
Sväng is using a special bass harmonica microphone manufactured
by Japanese company Suzuki. This mic is attached directly to the
body of bass harmonica, so it gets really close to the source
of the sound. The mic size is of the whole length of the instrument,
and there are several electric condenser mic capsules in it. The
capsules have a different frequency response depending on their
location on the scale of bass harmonica. The mic has an in-built
pre amp operating on battery power. Cause the capsules are omni
directional condenser capsules the mic is very prone to feedback
on stage. It feeds back really easily in the monitors and some
times also on the main PA. To solve this problem Sväng uses
in ear monitoring and very careful equalizing on bass harp. More
of these aspects in their own parts.
The sound of Harmonetta is reasonably strong acoustically, but
there is another problem when amplifying it. Half of the sound
is produced by reeds on top of the instrument and the other half
of the reeds are located on the bottom of the instrument. Micing
Harmonetta with only one mic on a stand gives really uneven sound.
Sväng amplifies Harmonetta with two Sennheiser e608 mini
microphones. These mics were originally designed for toms in a
drum set. Gooseneck equipped e608 is dynamic and has a polar pattern
of supercardioid. In my experience using condenser mini mics for
Harmonetta produces too crispy and sizzling sound to my taste.
The sound of e608s´ is smooth and full. The e608 is quite
un sensitive, so it needs a lot of gain, but it is still almost
impossible two make it feedback. One e608 is located above the
top reeds and another below the bottom reeds. Placing the mics
so close to each other produces some phase cancellation, but this
is easily corrected by changing the phase on one of the Harmonetta
For diatonic and chromatic harmonicas Sväng uses handheld
Technica ATM350's. The mic is held between player´s
left hand fingers, but there is seldom problems with any extra
handling noises. Microvox has it´s own belt clip pre amp
with volume control knob. Because the mic is very close to the
sound source it produces a nice strong signal and it does not
feedback easily. We switched over to Audio Technica recently due
to it's far better sound and uniform characteristics.
PREAMPS AND AUDIO INTERFACE
Sväng´s stage setup includes two racks size of 2 rack
units each. In the first rack there is a 8 channel mic pre amp
and audio interface, in the second rack is a headphone amplifier
and another 8 channel mic pre amp. The primary mic pre amp for
the instrument mics is Swedish made Line Audio 8MP. 8MP is a nice
clean and quiet pre amp that is capable of producing lots of gain
without unwanted noise or hissing.
From 8MP the mic signals are routed to Mac Powerbook laptop via
RME Multiface II sound card. Multiface has 8 analog ins and outs
plus 8 digital ins/outs via ADAT lightpipe optical cable. Multiface
is connected to computer with PCI express card. This connection
enables really low latencies needed for live use. After equalizing
and processing the mic signals on the computer they are returned
to analog outputs of the Multiface. From them they are connected
to the venue PA.
I have built for the pre amp/audio interface rack a back panel
and internal cabling. The eight mic inputs of 8MP are right there
at the panel as are the eight analog outputs of the Multiface.
Because the outputs of the Multiface are line level, and mic level
is usually preferred on stage, the signal levels are lowered -20dB
in the computer. I have also added separate transformers with
ground lift switches to the output lines of Multiface, because
a computer on stage setup is a very common source of unwanted
ground hums and noise. So far the rack system has been totally
silent and reliable on any stage. Ground switches have been used
only two times.
THE COMPUTER, EQ AND EFFECTS
The computer has a role of a digital mixer in Sväng´s
stage setup. We are using Apple MainStage software, an application
based on Apple Logic Studio sequencing software. MainStage is
basically Logic Studio software without recording possibilities.
It has the same mixer functionality with plugin effects as Logic,
plus some very handy functions designed specially for live use.
The mic signals are routed to separate mixer channels in MainStage.
Signals are equalized, compressed and effects added. In MainStage
user creates for every song a patch, that holds all volume, routing
and plug in parameters. By changing a patch all parameters are
changed immediately. This way we have perfect outgoing balance
on every piece of music even we are changing the instrumentation
or soloist for different songs.
Some heavy equalizing is used on bass harmonica, because it has
the tendency to feedback easily. Also a gate is added for bass
harmonica channel to block bassy resonance that are sustaining
inside the bass harmonica.
Other channels need only slight eq:ing. After eq the soloist channels
are slightly compressed. Because the Microvox is held really close
to the instrument, there appears serious dynamic peaks while playing
if not using compression. Like mentioned before, the phase on
one of the Harmonetta channels has to be flipped. This is also
done in MainStage.
On some of the tunes we use reverb. For basic natural sounding
reverb we use the convolution plugin of Logic/MainStage. For more
effective reverb a plate reverb plugin is used. On one tune we
use heavy overdrive sound on two harmonicas. That is also produced
with MainStage plugins.
After eq´s, compression and effects the mic signals are
sent back to RME Multiface in the stage rack. From the back of
the rack separate, processed instrument lines are connected to
CONTROLLING THE COMPUTER ON STAGE
During the gig we don´t want to mess around with the computer.
The role of the computer should be as transparent as possible.
Still we need some control of MainStage. We must change patches
for the songs and mute the channels when plugging in our mics.
These operations are handled with Frontier Tranzport wireless
midi controller. Tranzport is assembled to a mic stand and a simple
foot pedal is connected to it. The pedal is used to change patches.
On some songs the patches are changed even in the middle of a
song to have different effects in different parts of the song.
The mute button of Tranzport is programmed to act as the master
mute of the MainStage software mixer.
IN EAR MONITORING
As mentioned before, the bass harmonica mic is very prone to feedback.
After experiencing serious problems on hundred gigs we finally
moved to in ear monitoring. We wanted to get the bass harmonica
really audible on stage. Sväng uses wired in ear system.
As ear plugs we use Shure CL3s. Every musician has a Fisher Amp
body pack volume controller hanging on his belt. This is a handy
small level control always near you on stage. The body pack is
connected to stage rack, where a PreSonus HP60 headphone amplifier
feeds the monitor signals. HP60 has six separate headphone outputs
with dedicated volume and mix balance controls.
The monitor mix is made in MainStage. Cause every song has it´s
dedicated patch, it is possible to have a different monitor balance
for every song. From Main Stage we send two separate monitor mixes:
mix of the melody players´ channels and the bass and Harmonetta
channels mix. The HP60 has two stereo inputs that can be mixed
freely on every output. Basically every player adjusts the volume
and balance between melody and accompaniment instruments on the
front panel of HP60. The fine adjustment of the balance and stereo
panning is done in MainStage.
The in ear plugs isolate the player effectively from outside
noises and surrounding acoustics. That can be quite unpleasant
for the feel of the gig. It is a bit weird to see the audience
clap their hands and open their mouths but to hear nothing:-)
To get some live ambience in our monitors we have placed two miniature
mics on the sides of the stage rack. The mics are Soundman OMK´s.
The other mic pre amp on the second stage rack is PreSonus Digimax
AFS. This pre amp is connected to RME Multiface by ADAT optical
cable. The ambience mics are connected to two channels of Digimax
and then sent via optical cable to RME. The ambience signal is
mixed to monitoring with RME´s Totalmix software, which
controls the latency free input/output matrix of Multiface.
Digimax is also used to route the monitor mixes from Multiface
to headphone amplifier. Via optical cable the two monitor mixes
are sent to Digimax and further as analog signals to headphone
Finally there is two speak mics in Sväng stage setup. These
are provided by the venue. To hear our speaks with our in ear
monitors we need to get one monitor line from the front of the
house mixer. This line is connected to Digimax input and mixed
to monitor with RME Totalmix again. Only the speak mics are fed
to this monitor line.
Here is the simplified block diagram which desribes it all.