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Sväng technology 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.


MICROPHONES
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 equally.

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 channels.

For diatonic and chromatic harmonicas Sväng uses handheld Audio 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 house PA.

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 amp.

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.

  Text and pictures © Jouko Kyhälä, Eero Grundström, Pasi Leino
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