OWNERS MANUAL 600 STEREO 600S Mixer INPUT CIRCUITRY - It is absolutely neces- sary for a mixer to be compatable in most ap- plications and to have the capability of being able to control the sensitivity of the input circuitry of each channel. This requires an input attenuator, (1) sometimes referred to as an input pad. Some mics and signal sources can be at such a level as to overdrive or clip the input circuitry of a mixer, An input attenuator allows the operator to reduce the input gain when input clipping occurs. Some manufacturers put attenuators in their snake or stage box to be able to control the sensitivity of the mic or signal source. This is not the best ap- proach if you are sending your signals through ca- ble runs of any length. Many times it would be impossible to make an adjustment on one of the attenuators if necessary during the per- formance. You shouldnt have to run up to the stage and pick up the drummer's leg so you can ad- just a mic input! In use, the operator must adjust the input attenuator in such a manner that input clipping is avoided. This can easily be done by setting up the channel with the highest expected input signal level and adjusting the input attenuator so that no clipping or distortion is heard from the speaker system. After the mixer has been used several times, the operator will have a very good idea of the signal levels encountered and will be able to set Up the attenuators accordingly. The different types of microphones will have different output levels and different performers will get widely varying levels from mics depending on the strength of their voices and/or their basic “mic techniques”, The input attenuator should be operated in the position yeilding the least attenuation required to avoid clipping. Operation in this mode allows maximum gain to be utilized in the input preamp where it is most efficiently obtained. Excessive input padding sometimes makes necessary higher settings of the channel gain controls and/or master control thus yeilding a less than optimum signal-to- noise ratio for any given situation. It is important to realize that not all “break- up” is caused by the mic signal overloading the in- put stage of the mixer. If the performers mic technique includes very close and/or very loud situations, the internal elements of the mic can “bottom out” or distort just as a loudspeaker can when it is overdriven. Quite a few of the mics now used by performers lack the dynamic range re- quired to adequately handle the tremendous sound pressure levels encountered in a very loud rock and roll concert situation, It is vital for the profes- sional soundman and the musicians to be aware of the limitations of the various links in the audio sys- tem in order to correctly diagnose and solve the various problems encountered in a sound rein- forcement situation. Overall, the input attenuator 15 the first control in the circuit and must be set up properly in order for the remaining circuits to function pro- perly. “Common sense” and experience operating the 600 Stereo Mixer on several jobs will allow the operator to achieve superb results in virtually any mixing situation. Our variable input attenuator allows for much more fiexibility than some other manufacturer's mixers that only have switchable fixed attenuation of maybe 10 to 20 dB, where sometimes 10 dB may not be enough and 20 dB may be too much attenuation. The 600 Stereo Mixers input attenuator is continuously variable from 0 dB to —40 dB. The MONITOR SEND CONTROL (2) is the channel mixing element for determining the all im- partant monitor mix. The signal for the monitor send is obtained right after the input preamp and before the channel EQ. This is referred to as a Monitor Pre-send Control, i.e., it is before or pre to the channel equalization and slider level control. This makes it independent of these controls, mean- ing that any changes made to the EC or channel le- vel will not affect the monitor system, Having the monitor send with the pre capability is absolutely vital to avoid feedback of the monitor system when EQ and normal incremental output varia- tions are made in the channel fader during the course of the performance, a Г, ово LAE | Tea = EQUALIZATION The equalization cir- cuitry of the 600 Stereo Mixer is the latest active type, utilizing negative feedback technology. We selected circuitry that produces a “shelving” type of action because the conventional type circuitry used by some manufacturers tends to create erratic or sometimes harsh sounding results when in the near-maximum boost positions. These two equalization controls will produce extremely smooth action as well as giving effective tone control. Experience will show their utility in achieving professional channel equalization on the job. It should be remembered that these active equalization circuits are a form of “electronic crossover” in which the equalization controls are similar to level controls for their respective fre- guency bands. Generally, it is poor operating practice to use both equalizer controls in the deep cut (counter-clockwise) positions since this results in substantially lower gain from the channel. |1 should be remembered that the balance of highs and lows is a relative situation, and cutting over- all channel gain should properly be done by the output slide attenuator or input attenuator. The LOW FREQUENCY EQUALIZER (4) is capable of better than 15 dB boost or cut @ 100 Hz with a sloping characteristic exhibited up to the crossover point. The shelving action of this control has proven to yeild a much more satisfying and effective equalization characteristic than same of the “wide open” equalization circuits claiming 20 - 25 dB boost and cut. The action of this equalization control is conventional and should present no problem in operation. Boost is obtained in the righthand (clockwise) position while cut is obtained in the lefthand (counter- clockwise) position. The vertical (12 o'clock) position veilds a flat (no boost or cut) response and is the position from which all tonal balancing should be started. The HIGH FREQUENCY EQUALIZER (3) is capable of 15 dB boost or cut O 5 kHz with a shelving characteristic sloping down ta the cross- over point, The boost or cut action of this control is very similar to that of the low equalizer with the exception of its high frequency effect. Boost is ob- tained to the right of center position while cut is obtained to the left of the center position. Flat response is obtained in the center (12 o'clock) po- sition. Caution should be exercised in using ex- treme low-frequency boost to avoid emphasing objectionable wind noises or rumble from the mi- crophone as well as any hum that might enter the mixer from external sources. Excessive treble boost should be avoided to keep residual noise from the amplification circuitry to reasonable |e- vel as well as to avoid a strident or screeching tonality in the output program material. The EFFECTS SEND CONTROL (5) is the channel level for determining the amount of signal from each respective channel to be sent to the ef- fects output or to be mixed into the reverb sum- ming buss. The effects send circuit has been de- signed to provide multiple functions which will be explained further in the master control section. The STEREO PAN (6) is the control used to achieve the desired balance from each individual channel into the A and B main output mixing buss- es. The Pan control may be thought of as a kind of balance control determining the signal sent to either of the stereo outputs of the 600 Stereo. This Pan control is present on all professional multi-channel mixers, and is useful in achieving many special effects in sound reinforcement as well as being absolutely necessary in stereo tape recording. Again, experimentation and “hands on” experience with the 600 Stereo Mixer are key factors in the use of the Pan control. The Pan is capable of assigning the channel output to either A or B main channels or any combination in between. [tis important to remember that the Pan control follows (post) the channel output fader. The CHANNEL ATTENUATOR SLIDER (7) 15 the ouput level control that determines the mix into the main summing buss. lts calibration is in decibels of attenuation and this is why the num- bering sequence goes from off (infinity = <2 ),or maximum attenuation to zero (0), or no attenua- tion. Remember that attenuation is the cutting or reduction of the signal level i.e., the more attenua- tion, the more you have cut down the signal level. The output fader is calibrated in accordance with standard practice for professional audio equip- ment. Proper setting of the input attenuator (pad) should produce adequate gain within the input pre- amp to allow slider settings approximately in the center (approximately —40 to —20 dB). You should remember that the input attenuator is a kind of pre gain control and its settings will most definitely influence the settings for the output slider with any given input signal. The input atten- uator should be adjusted for the maximum gain that will allow distortion free performance, then the output slider level should be adjusted for proper mix. It is very poor operating practice to use the input pads in the extreme cut positions and then have to set the output sliders in their close to max- imum positions to obtain adequate channel output. This type of operation results in less than optimum signal-to-noise ratios as well as contributing to headroom problems. As with any system, “com- mon sense” must be combined with operating knowledge to produce satisfactory results. Qver- all, the channel controls should be set to provide a reasonable amount of “adjustment” i.e., none of the gain controlling elements (input attenua- tor/output slider) should be operated near their ex- treme up or down positions. After several hours usage, the operator will have acquired a good “feel” for the characteristics of the controls and should be able to suitably handle any mixdown situation encountered in the field with satisfactory results. MASTER AREA - The master area of the 600 Stereo Mixer contains all the master or final output controls for the mixing busses. The main mixing buss equalization features shelving type high and low EQ. The Effects level (17) is the master control for the effects mixing buss. The master level controls (8) (9) (10) of the 600 Stereo Mixer should be set in such a manner that they are close to the center of their travel to take advantage of maximum control action. It is poor practice to run the channel faders up near maximum and then run the main faders near the low end to achieve the desired output levels. Operation in this manner will cause the operator to loose his “range” in control action with all the gain located in one element while the other is near its stop position, Best practice calls for most controls to be operated in their middle or slightly higher positions to allow maximum mixing control margins (travel). Remember, when mixing, you MUST allow yourself adequate margins within which to operate and by using any of the faders in their extreme (close to the stop) positions, you ance, should be practiced on and learned. To properly have effectively reduced your range of control. This manner of operation also tends to create “headroom” problems. These master controls allow the operator complete flexibility for functions and should allow almost any mixing situation to be handled by the 600 Stereo. As with any reasonably complex system, experience and operator knowledge of the equipment are essential for satisfactory perform- The mixer, like the musician's instrument, operate a mixer during a performance requires thorough knowledge and trained reflexes to allow proper responses under the stress of demanding and sometimes sudden situations. The musician should know his mixer almost as well as he knows his instrument, so that his reactions will be both smooth and proper to correct whatever problem or requirement that should arise during a perform- ance. . . a professional must work at it! | The MASTER OUTPUT FADERS (8) (9) are the controls that determine the main output level for the output connectors located on the rear pa- nel. The main summing amps, as well as the other summing busses, are of the very latest “zero null” type using negative feedback to achieve maximum dynamic range, lowest noise, and crosstalk. The master faders should be operated in accord with the proper operating practices as outlined above. Experimentation and experience on several jobs will allow the operator to achieve a "feel” for the right settings for his requirements. The MASTER LOW FREQUENCY EQUAL- IZERS (11) (12) are capable of 15 dB boost or cut @ 50 Hz. These equalizers are similar to those used in the individual channels and are designed to exhibit a “shelving” characteristic which has proven to yeild the best results in this type ap- plication. The controls are “flat” with no boost or cut in the straight up (12 o'clock) position with boost being obtained in the righthand (clockwise) position. Care should be taken NOT to over-boost with the master EQ controls. Since each channel is equipped with equalization, it is poor practice to use too much additional boost in this master section. Over-boosting on low frequencies will im- part a boomy and muffled tonality to the program material and will substantially decrease the intelli- gibility of voices being mixed through the console. The MASTER HIGH FREQUENCY EQUAL- IZERS (13) (14) are capable of 15 dB boost or cut @ 10 kHz and are designed to exhibit a “shelving” characteristic. The operation of these EQ controls is similar to the low EQ with the exception of the fact that they control the high frequency portion of the audio spectrum on their respective channels. Care should be taken not to over-boost the high frequencies to avoid undue amplification of resi- dual system noise (hiss) as well as creating a “strident’’ or screechy sounding system. High fre- quency over-boost also tends to create undue acoustic feedback. When balancing ANY of the equalizers for proper tonality, you always start with ALL equalizers in their flat (12 o'clock) po- sitions and work from there. After you have spent several hours working with any particular setup of mics, performers, etc., you will acquire a good working equalization setup and be able to achieve the desired tonality. The important thing to keep in mind about the equalization on the 600 Stereo Mixer is that each channel is provided with its own set of EQ controls to correct problems in that particular channel, while Master EQ is provided to allow for overall tonal balance and feedback control. We have not included this equalization system to allow tremendous boost or cut but rather to allow in- cremental EQ where it is needed. You must use common sense in the use of these controls in arder to achieve satisfactory tonal balance and intelli- gibility. In sound reinforcement, there is nothing holy about an entirely flat equalization setting. If it is necessary to use moderate amounts of equal- ization, then you should be willing to do so, con- sidering that the “ideal” flat settings are almost never used, even in the recording studio, and even less often in most sound reinforcement applica- tions. The EFFECTS RETURN (15) is the gain con- trol for the effects return jack located on the rear panel. This effects return input enables the signal from an external source to be mixed back into the main (A and B) mixing busses. This Effects return is similar to an auxiliary input and actually may be used as such. This feature is intended to be used with effects or other devices that are used in con- junction with the effects output, and the signal return from the external unit should be brought into the effects return whose level is controlled by the Effects Return Control. The EFFECTS PAN (16) is the control that enables the operator to place the signal from the effects level return contral on either, bath, ar any combination in between the A and B main chan- nels. This panning capability MUST be present to retain true stereo capability for the 600 Stereo. The action of this pan control is similar to those on the individual channels and should present no pro- blem in operation. The EFFECTS LEVEL (17) is the control that determines the overall signal output level for the effects send buss. This effects buss has two output connectors associated with it, one is a high level output that can be used to drive a power amp- lifier for an additional monitor system and the other is a low level output designed to drive the in- put of an effects device such as an echo unit, phasor, digital delay line, etc. In addition to driving the high and low level effects outputs, the effects level control also determines the drive to the internal reverb delay lines. This effects level control must be adjusted so that the output level from the jack on the rear panel does not overload the input circuitry of the effects unit you are driving, thus causing clipping or other forms of distortion. This is especially critical on some of the special effects units that are designed to work with guitars or other instruments with relatively low output levels. The REVERB CONTOUR (18) is the соп- trol used to vary the tonality of the reverb signal and is a low cut type equalizer. This contour con- trol is very useful in tailoring the reverb sound and in controlling reverb induced feedback. Balancing these reverb controls will yeild many combinations of reverb delay, tonality, and sustain. The MONITOR MASTER FADER (10) is the output level control for the main monitor sys- tem. The same operating practices should be ob- served when using this control as when using the main channel controls. The individual channel monitor send controls should be set in such a man- ner that will allow the monitor master slider (fa- der) to be operated somewhere in the middle of its travel to allow yourself adequate control margins, up or down, as might be required on the job. The monitor output signal is flat, that is, we did not include equalization for the monitor in the 600 Stereo Mixer since this equalization is usually ex- ternal to the mixer and is best performed on the stage itself, which is generally at some considerable distance from the mixer. It is because the mixer is usually located remotely from the performing area that it is sometimes difficult for the monitor equalization to be performed at the mixer. The METER SET CONTROLS (19) (21) enables the VU meters (20) (22) to be adjusted for proper indication with any power amplifier, tape recorder, or other equipment driven by the mixer. If your power amp, tape recorder, etc... has VU meters, the level set control can be adjusted to track the 600's VU meters with a constant input signal, i.e., set the 600's meters to read “0 VU at the same level as the external equipments VU does. With equipment that has LED overload in- dicators, the 600's meters should be set to zero VU at the point where the LED peak indicator initially lights up. If the equipment being fed by the 600 has no maximum level indicator, you should refer any adjustment of VU meters to a properly equipped sound technician to avoid problems in matching VU readings with maximum output and/or modu- lation. You should be aware that we have designed the 600 Stereo Mixer to be able to drive power amplifiers with very low input sensitivities of 2 volts or higher. Because of the high output capa- bility of the 600 Stereo, it may appear that the 600 is excessively noisy when plugged into power amplifiers with high input sensitivity such as the Peavey 260 or 800 Boosters which require only 2 volt for FULL output. The extra gain designed into the 600 to allow use with the less sensitive power amps should NOT be interpreted as poor design but as additional gain capability. It is pos- sible to use “high gain” power amps with very good results by generally using less channel and master gain, or by decreasing the power amps sensi- tivity by turning down the power amps level con- trol. The 600 Stereo Mixer rear panel features a complete patching panel for various output and in- out functions, as well as the microphone input con- nectors for each channel. Each channel's input connectors are labeled with its identification number, as well as an indica- tion of whether the input is for high (23) or low (24) impedance. The high impedance connectors are standard phone jacks. The low impedance con- nectors are of the cannon type, three conductor connector to be used for low impedance micro- phones only, and will accept 150 to 600 ohm mies. CAUTION SHOULD BE USED NEVER TO USE THE LOW IMPEDANCE INPUT AND THE HIGH IMPEDANCE INPUTS OF ANY ONE CHANNEL SIMULTANEOUSLY. The STEREO TAPE OUTPUT JACK (25) is to allow simultaneous tape recording during a performance when the 600 Stereo is used as a sound reinforcement mixer, The MAIN AUXILIARY INPUTS A and B (26) are inputs to the main A and B mixing busses of the 600 Stereo Mixer. These inputs are used when patching another mixer to the 600 Stereo or any time a signal source is to be placed either on the main A or B mixing buss. The MONITOR AUXILIARY INPUT (29) is an input to the monitor mixing buss and is to be used when patching another mixer to the 600 Stereo or anytime a signal is to be placed on the monitor mixing buss. The EFFECTS AUXILIARY INPUT (27) is the input to the effects mixing buss of the 600. This input mixes a signal with the effects buss at the same point as the individual channels and is to be used when patching two mixers together or any time access is needed to the effects mixing buss. The EFFECTS RETURN JACK (39) is where the signal returning from an effects device patches into the 600 Stereo Mixer. The MONITOR OUTPUT (32) is unbalanced and is capable of 5 volts RMS into 10K ohms load impedance. The A € B MAIN OUTPUTS (30) (31) are located on the rear panel and are standard 4 phone jacks. The outputs are unbalanced and are capable of 5 volts RMS into 10 K ohms load impedance. These levels are capable of driving most commer- cial power amplifiers or other auxiliary equipment to full performance by a wide margin and should allow a more than adeguate amount of headroom in nearly any application. The EFFECTS HIGH OUTPUT (33) is capa- ble of 2 volts RMS into 10K ohms load and can be used to drive an additional power amplifier and speaker system from the effects buss to obtain an additional monitor. The EFFECTS LOW OUTPUT (34) is a lower level signal than the effects high and 1$ intended to drive the input of an effects device such as an echo unit, phasor, etc. lt is capable of 0.4 volts RMS into TOK ohms. Both the effects high and effects low out- puts are controlled by the effects level control and both jacks can be used simultaneously. The REVERB FOOTSWITCH JACK (35) is used with an auxiliary footswitch to enable the operator to defeat the reverb function of the mixer remotely. The POWER SWITCH (36) is the type that enables the operator to easily reverse the polarity of the line (mains) cable, thus veilding the abili- ty to minimize hum by proper polarization of the power supply (mains) connection. SPECIAL NOTE... Some export versions of the 600 Stereo Mixer do not have the two-way switch, and this information should be disregarded for those models. A HEAVY-DUTY POWER (MAINS) CABLE (37) is provided for durability under road condi- tions. This is a three wire approved cord, and it is MOT advisable to remove the ground pin under ANY circumstances. IT vou should find it neces sary to operate the system where the proper three wire receptacles are NOT available, you should use a three-to-two wire adapter. ps oo © "© 36 : 33 |29 27 | 24 ox à [© 617: ÓLEO e 37 3 35 = SPECS Frequency Response: 20 Hz - 20 kHz + 2 dB @ 2v rms output (+8 dBm) Total Harmonic Distortion: 0.1% THD 20 Hz - 10 kHz @ 2v rms output (+8 dBm) Equivalent Input Noise: Low Z input, -123 dBv 6 150 ohms (0.7 wuV) High Z input, -80 dB below 2v rms @ 20 dB gain Crosstalk: —50 dB e 1 kHz (between A and B mains) -70 dB 6 1 kHz (between mains and monitor or effects) Inputs: Low impedance unbalanced microphone 600 ohm (cannon plug) High impedance unbalanced line 50 K ohm (phono plug) Input Attenuator: Continuously variable from 0 dB to —40 dB operational on mic or line inputs Total gain of mixer @ 0 dB attenuation =60 dB Outputs: À and B main and monitor Unbalanced 5v rms into 10 K ohms, 2v rms inte 600 ohms (+8 dBm) Effects High: Unbalanced, 2v rms into 10 K ohms Effects Low: Unbalanced, 0.4v rms into 10 K ohms Equalization: Infinitely variable boost and cut, +15 dB @ 100 Hz and 5 kHz ea channel +15 dB @ 50 Hz and 10 kHz Master Effects: Built-in reverb unit with contour control, effects out and return capability for external effects units Cue System: Stereo tape output - 2v rms into 10 K ohms PEAVEY ELECTRONICS CORP.
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