Transcript
SAFETY PRECAUTIONS! WARNING - TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE. Do not allow water or liquids to be spilled into this unit, if the unit has been exposed to rain or liquids, please unplug the power cord immediately from the outlet (with DRY HANDS) and get a qualified service technician to check. Keep this unit away from heat sources such as radiators, heat registers, stoves etc. that produce heat.
The unit contains no serviceable parts. Refer all servicing to a qualified Service engineer, through the appropriate Phonic dealer.
CAUTION RISK OF ELECTRIC SHOCK
DO NOT OPEN
This triangle, which appears on your component, alerts you to the presence of uninsulated dangerous voltage inside the enclosure that may be sufficient to constitute a risk of shock.
This triangle, which appears on your component, alerts you to important operating and maintenance instructions in this accompanying literature.
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER (OR BACK). NO USERSERVICEABLE PARTS INSIDE. REFER ALL SERVICING TO QUALIFIED SERVICE PERSONNEL.
Keep this unit away from dust and dirty environment; cover the unit when not in use. Using a soft dry brush and occasional wipe with a damp cloth, do not use any other solvents, which may cause damage to paint or plastic parts. Regular care and inspection will be rewarded by a long life and maximum reliability.
CONTENTS
FRONT-PANEL DESCRIPTION ..................................................................... 3 CHANNEL STRIP ....................................................................................................... 3 MASTER SECTION .................................................................................................... 5
JACK-PANEL DESCRIPTION........................................................................ 6 BACK-PANEL DESCRIPTION ....................................................................... 8 GAIN STRUCTURE AND NATURE OF NOISE ............................................. 9 MODIFICATION ............................................................................................ 10 HOOK-UPS INTRO ....................................................................................... 11 HOOK-UPS ................................................................................................... 13 HOOK-UP #1:FOUR-TRACK RECORDING ............................................................ 13 HOOK-UP #2: STEREO PA AND MONITORS ........................................................ 14 HOOK-UP #3: SUBMIXER ....................................................................................... 15 HOOK-UP #4: FOUR-TRACK ALTERNATIVE ......................................................... 16
SYSTEM BLOCK DIAGRAM........................................................................ 17 SPECIFICATIONS ........................................................................................ 18
FRONT-PANEL DESCRIPTION
CHANNEL STRIP 7-8, and can use the MM122's input gain controls.
1. Input gain control This control brings the incoming signal to the optimal level for the mixer to work with. It works in conjunction with the LED ladder (9). Boosting a signal too much will overload the circuitry and cause the sound to distort. A signal that is not boosted enough results in a lower overall sound to noise ratio. By adjusting this control properly, the signal (your music) will be at its strongest compared to the background noise. Channels 9-10 and 11-12 have no input gain control. However, most stereo devices have an output gain control that can be used instead to set the level coming in to the mixer. Generally, just set it to maximum because the MM122 has enough headroom to handle high input levels without clipping. in most cases you will be able to arrange your gear so that any stereo devices without output gain are put on channels 5-6 and
2. Hi EQ High EQ, or equalization, affects the high frequency content of the sound. Technically this is up to a 15dB cut/boost shelving at 12kHz. Even a sweet sounding EQ like the MM122's is best if used sparingly - and remember to cut as well as boost. It is good practice to try and achieve the desired sound by adjusting the instrument, mic position, etc. rather than resorting to an electronic 'fix'. The 'zero' or 'flat' position for all the EQ controls is at 12 O'clock.
3. Low EQ This affects the low frequencies in the same way the Hi EQ affects the highs. A 15dB boost/cut shelving at 80Hz. Increases can bring up kickdrums and bass, and cuts are
!
useful to reduce mic rumble. A channel that has been well set up by adjusting the input gain can be overloaded by EQ boosts. Be careful. If you hear distortion, reduce the gain or EQ a little.
mono channels can be used for each additional stereo device. For the best stereo effect, the PAN controls on each channel should be panned hard left and right respectively, and the same EQ and fader settings applied to both channels.
4. AUX send 1 AUX sends are for making a separate mix to the main outputs. AUX send 1 is pre-fader, which means that the signal is tapped at a point before the channel fader (see block diagram). Adjustments to the channel fader do not change the AUX1 levels - this is suitable for a monitor system feed. The musicians can then hear a raw mix of all the instruments and can hear cues and intros from instruments that are faded down in the main mix.
7. Channel fader The level control for each channel is a high quality slider, compared to the rotary faders which feature on most small mixers. This gives you much more freedom to actually mix rather than just setting levels and leaving the mixer alone. The markings on the main faders are designed for easier use too. Gain scales (in dB) have become popular over recent years because they help maximize the S/N, or sound to noise ratio, by keeping a quantitative track on gain. The disadvantage really becomes apparent when you want to accurately note settings. Interpolating, or estimating a value that falls between two numbered divisions, is difficult because the numbers aren't evenly spaced. Try to quickly note a few fader positions on a gain scale and then reproduce them quickly and accurately. Even a rocket scientist's mind is more at home with a linear 0-10. It may indicate arbitrary values, but for a position reference, it's still the best. To keep everyone happy, we've marked each slider fader with a gain scale on the right and a 0-10 on the left. The rotaries have the important gain values marked but have divisions marked which you can think of as a 0-10 or even points on the clock.
5. AUX send 2 AUX send 2 is a post-fader mix which is perfect as an effect send. A mix of various channels can be sent to a reverb unit, for example, processed, and returned to the master through an AUX return or 2 input channels. Being post fader means that adjustments in the channel faders will affect the AUX 2 mix. When you fade down the guitar, the reverb on that instrument is reduced in the main mix too.
6. PAN/BAL The PAN control places the channel's output within the stereo output mix. The signal can be positioned anywhere between hard left, and hard right. On the stereo channels, this is effectively a balance control, which adjusts the relative levels of the left and right signals to effect stereo placement. When inputting stereo signals on the stereo channels, putting BAL in the central position will allow the external device's own BAL control to set stereo positioning. If you are using the MM122 for mixing more than four stereo devices, two
8. Scribble strip The white patch that contains the channel numbers is to help identify what is on each channel. Clear tape (the kind that doesn't leave a residue) can be laid along the strip and any notes needed to remind you what's on each channel can be entered on this and discarded afterwards.
"
around 0. This channel is now set-up. Remember that if you change the input device or modify its output settings, you will need to readjust the trim. For the two stereo channels without trim controls, adjust the output gain of the input device to its highest setting. If you have some old gear with a low output, remember that channel 5-6 and 7-8 have trim. It may be possible to switch things around to get the best results. The extra gain on the fader is available if the input is still too quiet.
MASTER SECTION
11. Power/Phantom Power LEDs These are a front panel indication of whether the power and phantom power supplies are on. The switches are located on the back of the unit (see 27 and 28).
12. Headphone level This knob controls the level of the headphone output.
13. Phones Jack This is the place to plug in your headphones. The headphone output plays the same material as the L R main outputs. The output may also be connected to an amp and speakers for control room mixing.
9. LED ladder meter A visual representation of mixer levels is essential. Not only does it help you set up the input levels, but it helps avoid overloading the main outputs and causing distortion of your sound. The standard display is the levels of the left and right main outputs.
14. AUX return 1 Think of this as an extra stereo input channel without all the extras. AUX returns can be used for instruments if necessary, but are typically for returning the AUX send mixes to the L-R main mix.
10. Meter selector switch To set the input gain levels, first activate the channel metering with the meter selector switch (10). Reduce all the channel faders to minus infinity. The scales then show the mic levels on the left (XLR inputs) and the line levels on the right. Plug in the device (instrument, mic, etc.) and set the main fader to the unity position. Play the input device at the sort of level it will be used, then simply adjust the trim control until the level on the appropriate side of the scale peaks
15. AUX return 2 This is the same as the first AUX return, but has one extra feature (see 16 & 24).
16. Tape in switch When this switch is pushed, the input to the AUX return 2 1/4" jacks is replaced by the input of the tape-in jacks (see 24).
#
17. Main output faders These control the main L-R output levels and the tape output levels (see 24 & 25).
JACK-PANEL DESCRIPTION
circuitry.
18. Mic input A high quality balanced XLR input for connection of microphones and other equipment. +48V of phantom power is available if necessary to power condenser mics.
20. Channel inserts
IMPORTANT: BEFORE PLUGGING ANYTHING INTO THE XLRs, ENSURE THAT THE PHANTOM POWER IS NOT ON BY CHECKING THE FRONT PANEL LED AND, IF POSSIBLE, THE BACK PANEL SWITCH. ONLY ENGAGE THE PHANTOM POWER ONCE YOU HAVE VERIFIED THAT EVERYTHING CONNECTED TO THE XLR JACKS IS SUITABLE FOR USE WITH +48V PHANTOM POWER.
These features on the four mono channels and serve a variety of uses, depending on what you plug in, and how far you push the plug in. They allow the connection of processors to the signal path using insert Y-cords, or can be used as direct outs for multitrack recording. The insert point (see block diagram) is fixed prefader on channels 3 & 4, but may be switched to post-fader on the first two channels (see 29). (See page 11. for diagrams of the various plugs, connections and wiring schemes relating to channel inserts.)
19. Mono line inputs
21. Stereo line inputs
These line inputs use female 1/4" jacks and are suitable for almost any musical instruments, effects and tape recorders. There is a wide gain range-both balanced and unbalanced inputs can be incorporated, allowing you to use professional gear at +4dB or semi-professional gear at-10dB, No manual switching is necessary. The circuitry will detect a TRS (tip positive, ring negative, sleeve shield) plug and engage the balanced
These are the inputs for the four stereo channels. They are 1/4" mono jacks, one for the left input, one for the right input. If the channel is needed for a mono input, then one input plugged into just the left jack will automatically be treated as mono. Just one plug in the right jack will mean a signal that is only on the right side. If for some reason you desire to only put an input in the left
$
side, putting a dummy plug into the right input will fool the mixer into not mono-ing the signal.
24. Tape-in jacks These are a pair of RCA type mono jacks, similar to those used on most tape decks and home audio systems. The tape-in jacks of the MM122 are electrically identical to the 1/4" jacks of AUX return 2. When the tape-in switch (16) is down, the RCA jacks take over from the AUX return 2 jacks, and the AUX RTN 2 control in the main section sets the level of the incoming signal.
22. AUX send jacks These are the two mono AUX outputs (see 4 & 5) or 'sends'. These send mono mixes according to the position of the various AUX level pots on the front panel.
23. AUX return jacks Effects sends are typically returned through the AUX returns, which are really just extra input channels without the normal channel features such as EQ. There are no laws that say you have to use AUX return 2 to bring back the signal from AUX send 2. An AUX return can also be used as an extra stereo input channel if required. There is also no reason why you shouldn't return effects through the input channels if you need the EQ for example.
25. Main outputs The main outputs supply the final stereo mix to a power amp, tape recorder, etc.
26. Tape-out jacks These are alternative main outputs fitted with RCA jacks for more widespread connection to cassette decks and home stereo equipment. They output exactly the same signal as the main outputs but are unbalanced.
%
BACK-PANEL DESCRIPTION
27. Power switch
position, the signal is tapped just before the EQ, which is the traditional place for certain processors like compressor/limiter and external equalizers. Sometimes processing such as limiting may be wanted post fader, or a reverb on just one channel may be required. In these cases, the inserts can be used postfader, The inserts on channels 3 and 4 are fixed pre-fader. These inserts can also serve as direct outputs for four-track recording. A mono (TS) plug inserted all the way into the second click will interrupt the signal and route it out through the jack. This can be sent to the recording device and returned for monitoring using the four stereo channels (use only left input per stereo channel for this). For more details see Hook-ups: Channel Inserts, beginning page 11.
This switches the mixer on and off.
28. Phantom power switch This applies +48V of phantom power to the XLR mic inputs. it's been mentioned before, but MAKE SURE THERE IS NO EQUIPMENT PLUGGED INTO THE XLR INPUTS THAT WILL BE DAMAGED BY THE APPLICATION OF +48V OF PHANTOM POWER. ONLY CERTAIN TYPES OF CONDENSER MIC REQUIRE SUCH EXTERNAL POWER. AS A PRECAUTION, WAIT UP TO A MINUTE AFTER SWITCHING OFF THE PHANTOM POWER BEFORE CONNECTING ANY NEW DEVICES, BECAUSE THE ACTUAL LEVEL CAN TAKE A WHILE TO DROP TO ZERO. Notice that the phantom power switch is small and different to the main switch. This ensures that it is not flicked accidentally, or mistaken for the main power switch when you want to switch off.
30. Power cable This cable carries mains voltage to the mixer's internal power supply. It is more durable than flimsy cables with external supplies, but some precautions are necessary. Ensure that the cable isn't pulled, or that nothing heavy that might damage the cable is resting on it.
29. Ch1 & 2 Insert switches The inserts on the first two channels may be switched pre or post fader. When in the pre
&
Mixers generally have some aid to setting up a channel, such as a peak light or metering like the MM122. This allows you to observe the peaks and adjust the gain to avoid clipping. When all the channels have been set in this way, the other big bonus is that they are all conveniently at roughly the same level to start mixing with. A mixer has several levels of gain: input trim, EQ, channel fader and main fader, not to mention any gain due to insert processors and the AUX sends, returns and effects. The key is to keep them below clipping, but high enough to maximize the S/ N. It is also beneficial in the real world to have enough space to crank it up should you need to.
GAIN STRUCTURE
8
The most fundamental basic of mixing is to obtain a good 'gain structure'. Gain is the amount of amplification applied to an input signal, and is expressed in dB, a logarithmic ratio. Therefore zero gain (also called 'unity') means no increase or decrease in the level of a signal as it passes through an amplifier or 'gain stage'. Anything above zero makes the signar 'louder' and anything below reduces the level (also called 'attenuation'). Attenuation of minus infinity (- ) means a total reduction in signal level, ie, no signal comes out the other end. Most professional mixers have an input gain or trim control, which is the first circuitry the signal passes through. The aim of this is to bring the signal up to the optimum level for the mixer to work with. This is the most crucial part of the signal chain; it typically has more gain available than the other stages and any mistakes here will taint the signal through the whole mixer. All amplifiers add some noise to the signal as it passes through, but by keeping the gain high, the sound to noise ratio (S/N) is generally increased. However, at the other end of the scale there is the problem of overload or 'clipping'. An amplifier only has limited power. If you push it too far and try to amplify a signal too much, the peaks of the signal will be clipped off when they pass the amp's limit. This results in distortion and is audiable as a harsh, unpleasant 'breaking-up' sound.
NATURE OF NOISE Noise is typified by a hiss and is present to some degree in all amplified music. It is caused by random thermal movement of atoms in the electrical components. To eradicate it requires temperatures approaching absolute zero (-273 degrees Celsius), but careful circuit design and gain staging can minimize it at room temperature. The shorter the path of a signal, and the fewer the gain stages, the less noise the signal will be picked up. Another type of audio problem is RF (radio frequency) interference. This is caused by the circuitry and wiring of electronic devices picking up radio signals which are amplified through the gain stages. One way to minimize this is by keeping signal levels high so that any interference picked up is much quieter than the signal. Shielding the wires with a foil layer also helps, and steel casings like the MM122's are very effective at preventing RF from entering the mixer. RF is a big problem with longer cable runs, and so balanced lines, which electrically reject interference, are commonly used for these.
'
This simple mod requires removing the back of the MM122 and shifting plastic jumper blocks on all eight channels. It is very simple and requires no soldering or cutting of circuit board tracks. Also, it is repeatable and can be reversed without any damage to the mixer, providing it is done properly. However, since it involves opening your MM122 to gain access, care must be taken, and in some countries it may affect your warranty. Repeated changing of the configuration is not recommended. Check first with the distributor or wait for the warranty to expire.
MODIFICATION The MM122 is a flexible mixer, and should accomplish most tasks in its factory-shipped configuration. The inserts on channels 1 & 2 can be switched pre or post-fader by back panel buttons, negating the need for any tools or a penchant for living dangerously. In the factory-shipped configuration, there is one pre-fader AUX send (AUX1) and one post-fader (AUX2). However, some users may prefer two post-fader AUX sends if they want more effects, for example.
AUX1 to post-fader mod First, unplug the mixer from the mains and remove any devices connected to it. Turn it over and lay it face down on a soft slip proof surface. Remove the small screws in the sides, which hold the bottom plate in place. Once all the required screws have been removed, gently ease the bottom panel off of the mixer. Inside you should be able to see eight black plastic blocks in a rough line across the circuit board of the mixer, from left to right. Each block contains a black jumper sitting on a group of four copper pins. In the factory preset position, the jumper links the top two pins (the two pins closest to the jack panel).
Carefully remove the plastic jumper from the top two pins and place it on the lower two pins. Repeat for all eight channels. Replace bottom panel and screws.
plugs wired together to send an output signal to two inputs.
HOOK-UPS INTRO The MM122 has a number of different types of jacks, and a variety of hook-up methods for some of the jacks. First, a brief outline of the wiring scheme for 1/4" mono and stereo plugs.
Cnannel Inserts The channel inserts can be used in the following ways:
This will tap the signal at the insert point without interrupting the signal flow. This is sometimes used for monitoring an input signal on one channel without affecting the mix (pre-fader insert) or for recording certain channels direct to four-track tape during a live show.
When it comes to connecting external processors to the channel inserts, you will need a special Y-cord arrangement. This uses a stereo plug at the mixer end and twin mono plugs at the device end. Note that this insert Y-cord isn't the same as a widespread "splitter". That is simply 3 mono
Above left: signal path with no plug in the insert. Above right: signal path with a mono plug inserted in to the first latch.
The second method is a mono plug inserted all the way to the second latch. This not only taps the signal at this point, but prevents it from feeding to the main mix. This is particularly useful for 4track recording (inserts all-fader). The first four channels can output to tape, and the returns can be entered through the stereo channels (through left jack only = mono mode). The first four channels are disconnected from the main mix by the channel insert mechanism, so only the returns are heard on the phones and main outputs. This allows you to listen to the tape as you record it, so you can check for distortion and set EQ and effects whilst knowing exactly how it sounds on the tape itself (see Hook-up #1). Set the level going to tape with the gain pots.
The tip of the plug is connected to one wire which carries the signal to the processor. The processor's output flows down another wire and back into the mixer through the stereo plug's ring. By this method, the signal can be processed after the initial gain stage (where it was boosted to a suitable level) and sent on to the EQ, AUXes and fader. Most processing is best done with the inserts pre-fader, but the post-fader switch allows a volume dependent option for reverb or effects on just one channel.
Hook-up Examples The following pages feature some sample "Hook-ups", ways to connect the MM122 for a variety of tasks. These are only guides, and experimentation and an understanding of the features and signal path will help devise the best set-up for your situation. In the end, much comes down to personal choice of where you prefer things to be for convenience, nicest sound and flexibility. Here are a few thoughts to fill the unsightly gap at the end of the page:
z if you need to use the AUX returns as
Above: signal path with mono plug inserted in to second latch.
input channels in mixdown, use them for the stereo instruments which need least or no EQ and effects.
The third example uses a stereo plug as an insert send and return cable. When used as inserts, the jacks can output and bring back a signal through the same hole.
zif you need the mono channels for stereo instruments, try and use the instruments which require least changes to EQ and AUX settings during the program - if not you'll spend twice as long making changes to both channels to preserve stereo.
zif two or more insert devices are needed, simply connect them in series and experiment with the order to get the desired effect.
Above: signal path with stereo plug inserted in to second latch.
HOOK-UPS
Hook-up #1:Four-track Recording
Notes 1. Most people record tracks "dry" (without reverb and effects) because this leaves the option of adding them later at mixdown. The effect on AUX 2 won't come out on the tape tracks - it is just for those who like a little reverb while they're mixing to make things a bit more pleasant sounding. 2. Unless you have a triple glazed soundproof booth, it is essential to monitor on heaphones when recording with mics, otherwise you will record your monitor output to tape. 3. The stereo cassette deck can be used to record rough mixes during tracking, and these can be quickly reviewed by pressing the tape-in button to patch the tape deck into AUX 2. 4. For mixdown, connect the 4-tk outputs to the mono channel inputs. Channels 5-12 and the AUX returns are available for additional dubbing or effects returns. The cassette deck is already patched in and ready to record. 5. Control the level going to tape with the gain pots on channels 1-4.
!
Hook-up #2: Stereo PA and Monitors
Notes 1. Many guitar effects have a pre-amp stage built in. It is fine to serial effects between this and the mixer's inputs. If the guitar rig outputs in stereo, treat the whole rig as you would a keyboard or synth input. 2. Narrow band graphic EQs can be inserted between the power amps and the mixer to reduce feedback. By sliding down the frequencies with most tendency to feedback, the output level before feedback of the whole system is increased. Graphic EQs are also useful for shaping the sound to the acoustics of a room, or for purely aesthetic changes. 3. Inserts are typically used pre-fader for processing such as in this example.
"
Hook-up #3: Submixer
Notes 1. This basic set-up could be used for many submixing applications including keyboards. The mics can be replaced by two stereo keyboards using the line jacks of the first four channels. 2. Monitoring can be accomplished a number of ways. The MM122's main outputs feed a stereo signal to the main console which can take a pre-fade mix of these and the other instruments to send to the monitors. Where a console with individual monitor sends is used, the drummers feed can be without drums, and passed back to the MM122, as in the diagram above. The monitor EQ and drum-instrument mix is then controllable from the MM122.
#
Hook-up #4: Four-track Alternative
Notes 1. The 4-tk sends come from the insert and are returned through the same insert. A send and return Y-cable should be used with the jacks inserted all the way in. The tape returns will then be sent to the master. The trim pots set the level going to tape, the main fader sets the monitoring level. 2. Track 4 contains a MIDI sync code, and so is not recorded on or played through the mixer. With the key boards and drum machine synchronised to the 4-tk, vocals and acoustic instruments can be recorded. The studio monitors play the tape returns plus the keyboards and drum machine. 3. The performers can hear themselves and the backing music through the AUX 1 send to the headphone amp. 4. For mixdown, the tape can be rolled through the channel inputs, and the keyboards and drum machine again synchronised.
$
System Block Diagram
%
SPECIFICATIONS THD Frequency response Max voltage gain
Hum & noise (Rs = short, input sensitivity = -60dB, fader @ nominal, IHF-A) Input channel eq.
Clip indicators Gain range Pan attenuation Crosstalk Phantom power LED display Input impedance Output impedance Max. output level Power requirements Dimensions Net weight
Less than 0.1% 20Hz-20kHz 20Hz-30kHz 2dB(ch 5-12 line in to main out) 20Hz-30kHz 3dB(mic in to main out) 84dB mic. channel in to stereo L & R out(balanced) 80dB mic. channel in to AUX send 2 (post-fader) 60dB channel mic in to AUX send 1 (pre-fader) 76dB channel 1-4 line in to stereo L & R out (balanced) 74dB channel 1-4 line in to AUX send 2 58dB channel 5-8 line in to stereo L & R out (balanced) 32dB AUX rtn, tape in to stereo L & R out (balanced) 38dB ch 9-12 in to stereo L & R out (balanced) 44dB channel mic in to channel insert 66dB mic. channel in to tape out -128dB equivalent input noise -90dB residual output noise -72dB stereo out (master fader @ nominal, all channel faders @ minimum) 15dB max cut/boost in 2 bands HIGH: 12kHz shelving LOW: 80Hz shelving red LED lights when post-EQ signal is 3dB below clipping level (channel/master faders at normal) channels 1-4, -60dB to -20dB channels 5-12, -16dB to +4dB -65dB @ 1kHz -85dB(1kHz, IHF-A adjacent input channels @ insert out) +48VDC applied to balanced inputs for condenser mics OdB = 0.775V 150 ohms to 47k ohms 600 ohms to 10k ohms +28dBu balanced, +22dBu unbalanced 120V / 60Hz (USA & Can.), 230V / 50Hz (Europe) 303(w) x 296(d) x 83(h) mm 3.3 kg
&
