The RCA jacks are Ideal for using a cassette deck to record a mix with using the TAPE SEND jacks and playing it back through the TAPE RETURN jacks with out using up any channels for play back or having to use adapters to hook up the cassette deck.
10. PROTECT LED
The PROTECT LED indicates the internal relays have disengaged the amplifiers from the speaker output jacks on the rear panel. The LED is not used in the non- powered versions.
There are three instances that will engage the protection circuitry.
The first is in the case of a short on the speaker outputs. The second is if the total speaker impedance is lower than the minimum impedance rating. And the third is if the maximum operating temperature of the power amplifier is exceeded due to poor air circulation and/or over-loading.
11. POWER LED
The Power LED indicates when the mixer is powered up.
12. PHANTOM POWER SWITCH AND LED
The PHANTOM power switch turns on the microphone phantom power in the channel XLR jacks. This power is used for supplying a bias voltage to condenser microphones. The LED indicates the phantom power is turned on. The phantom power will not damage dynamic microphones.
13. THE GRAPHIC EQUALIZER
Each mixer has two nine band graphic EQ’s (equalizer). The graphic EQ’s are dedicated to the left and right outputs following (or post) the amp patch jacks of the mixer. The 9 band Graphic EQ’s provide a wide degree of tonal flexibility.
The Frequencies:
Here are some tonal reference ranges for the individual sliders to help relate the frequencies in hertz to perceived tonal changes.
In order from left to right:
-the 63 Hz slider effects deep sub bass levels. -the 125 Hz is typical bass adjustments.
-the 250, 500 and 1K Hz are for low mid and high mid adjustments. -the 2K and 4K Hz are for lower treble adjustments.
-the 8K and 16K Hz are for the very high treble adjustments.
Adjusting:
When the sliders are in their center detent position they do not affect the audio signal. When a slider is raised or lowered from the center position, it boost and cuts respectively the level of a narrow frequency band assigned to that particular slider. It is recommended that all sliders are set in their center position before equalizing your tone. Typically low frequency feedback is in the 125 and 250 Hz range while high feedback is in the 2k and 4k Hz range. Occasionally one fre- quency (slider) of the equalizer will have to be pulled down to -12dB to stop feed- back. If many of the sliders have to be pulled down to stop feedback, the place- ment of the speakers with respect to the microphones may need to be reconsid- ered. As much as possible, try to have the main speaker facing away from and in front of the microphones not on stage behind them. The graphic EQ is mainly used to “equalize” the response of the main room and reduce feedback from microphones. Don’t be afraid to use the Graphic EQ, but take care not to over-
lem has been corrected start again with turning up the low level signal and use this low level signal to check if all the speakers are working. Now the main sys- tem is ready for the sound check.
7. TESTING THE MONITOR AMPLIFIER AND SPEAKERS
Each input channel of the mixer has a knob labeled MON. This knob is used to adjust the volume of each channel’s send to the monitor buss.
The channel monitor signal is pre the channel tone controls and the channel level control. What this means is any adjustments to the channel tone controls or the channel level control will not effect the monitor mix. The advantage of this is, if more high frequencies are wanted in the main mix speakers from one chan- nel, turning up the HI tone control will not result in feedback in the monitors.
With the mixer set as suggested in section 6, the MONITOR master level can be brought up to 5 or 6 on the dial and a channel, with signal, can have its monitor level turned up until it is heard in the monitors. If nothing is heard in the monitors first make sure the channel does have signal. One way to test the signal is to turn it up in the main speakers. If the signal is present in the mains, but not in the monitors then turn them both down again and start checking the monitor sys- tem connections from the mixer output to the amplifiers and speakers. When the problem has been corrected start again with turning up the level and use the sig- nal to check that all the monitor speakers are working. Now the monitor system is ready for the sound check.
8. THE SOUND CHECK
The sound check takes some skill, but mostly patience from the performers and especially you the system operator. If you get frustrated during the sound check the performers can lose confidence and the sound may suffer due to things missed in the sound check. The basic sound check follows this format: First test all microphones and other input devices(direct boxes, etc.) before the performers are included in the sound check. A good thing to also check here is feedback in the monitors from the microphones. Good positioning of the monitors and the use of a graphic equalizer before the monitor power amp solves most major monitor feedback problems. Now for a sound check with the performers. First set the level of each performers individually and in cases where a performer has multiple microphones, such as with a drummer, set each drum mic individually then the drum set as a whole. This is also a good time to make some channel tone control adjustments to tailor the sound of the individual performers and instruments. Next after setting each individual have the performers run through a song or a portion of the show. Don’t hesitate to stop the performers if some- thing needs to be adjusted or if an individual performer or microphone needs to be heard solo again. Remember the sound check is not a rehearsal, but a sys- tem check, a time to work the bugs out of the system so the show can go smoothly. It is always a good idea for the mixer operator to have a microphone to inform the performers of what is needed during the sound check. If a monitor system is being used, the mixer operator’s microphone should only be heard through the monitors when addressing the on stage performers, especially if something needs to be checked during the show. If the sound check is allowed to run through its full course, the system should run smoothly at show time.
