Rear Panel

Output

Connection / Setting

Connect to input of console, tape recorder, etc. Connect line-level source here. Connect microphone here. Depress if mic requires phantom powering.
Line Input Mic Input Phantom Power
528E Voice Processor Settings
Set the controls and switches on the front of the 528E as per the table below.

De-Esser Settings

The De-Esser is used to reduce the level of objectionable sibilant sounds (S and T sounds). Engage the De-Esser by pressing the DE-ESS IN / OUT button IN. Set the THRESHOLD control so that the de-esser gain reduction LED display shows about 12 dB of reduction. Now, tune the FREQUENCY control for the maximum sibilance reduction. Finally, reduce the setting of the THRESHOLD control until you reduce the sibilance to a tolerable level without harming the quality of the audio signal.

Front Panel Control

MIC / LINE -15 PAD MIC GAIN DE-ESS FREQUENCY DE-ESS THRESHOLD DE-ESS IN / OUT DOWNWARD EXPANDER EXP THRES COMPRESSOR COMP THRES COMPRESSOR COMP RATIO EXP/COMP IN / OUT VOICE SYMMETRY IN / OUT LOW EQ FREQUENCY LOW EQ BANDWIDTH LOW EQ CUT/BOOST MID EQ FREQUENCY MID EQ BANDWIDTH MID EQ CUT/BOOST HIGH EQ FREQUENCY HIGH EQ BANDWIDTH HIGH EQ CUT/BOOST EQ IN / OUT GAIN

Setting

As required Out 12 oclock 3K (12 oclock) 0 (Full CW) Out BYPASS (Full CCW)
Downward Expander Settings
Use the Expander to reduce room noise or other low level or background noise. Set the THRESHOLD control to allow low level speech sounds to pass while still blocking out room sound or noise.

Compressor Settings

Use the COMP THRES control to determine the level at which the compressor starts to work. As the sound level increases above the set threshold, you will see the gain reduction LED display start to work indicating the amount of gain reduction taking place. Generally 3 to 6 dB is sufficient, unless you are using a low compression ratio (below 2:1), or you want a special effect. Pick a ratio suited to the task at hand: low ratios and low thresholds for unobtrusive level control, medium ratios for overall level control and consistency, high ratios (greater than 8:1) for limiting or in-your-face sorts of sounds.
+20 (Full CW) 2 (12 oclock) Out Out 160 Hz (12 oclock) 1.5 octaves (12 oclock) 0 (12 oclock) 2.5K (12 oclock) 1.5 octaves (12 oclock) 0 (12 oclock) 6.8K (12 oclock) 1.5 octaves (12 oclock) 0 (12 oclock) Out 0 (12 oclock)

Equalizer Settings

Equalization is entirely dependent upon many factors and should generally be used to correct or enhance the frequency content of the signal. For example, the default settings should be close for the male voice. For female voices, the LOW EQ range shifts up to 200 or 300 Hz and the MID EQ range shifts up to 3-5 kHz. If you are using a microphone that exhibits proximity effect, then youll probably need to reduce (cut) the bass (LOW EQ) response somewhat. 3-6 dB should be fine, but youll have to compromise between a big full sound and the overbearing low frequency content. A bit of MID EQ will help make voices cut through and seem louder. The HIGH EQ can add brightness and intimacy. It will take some tuning and experimentation based on the signal source, microphone used and personal taste.

Output Settings

For many applications, setting the output GAIN control to 0 dB works fine. If you are adding a lot of EQ, this will tend to cause an overall level increase. Thus, you may need to lower the output GAIN appropriately. Likewise, if you are using a fair amount of compression, you may need to add some gain to compensate for the gain reduction in the compressor section. You should adjust the output GAIN control so that it provides enough signal level to your connections downstream, yet still prevents the CLIP LED from illuminating. The output CLIP LED monitors both the equalizer and the output stage. Large amounts of EQ boost and/or high signal levels can cause CLIP indications. If this occurs, lower the signal level via the GAIN control. It is also possible for the output stage to clip if a processor, inserted via the OUTPUT STAGE INPUT jack, is contributing gain to the overall signal path. In this case, either lower the gain of the inserted processor or reduce the setting of the output GAIN control.
You can now power on the 528E and it should pass signal. The POWER LED should be illuminated and the OUTPUT LEVEL LED display should show some activity.We can now move on to fine tuning your settings.

Mic Preamp Gain

Set the MIC GAIN control so that the OUTPUT LEVEL LED display indicates a signal between -10 and 0 VU. The CLIP LED should almost never light. If it does, decrease the MIC GAIN control until it does not. Any loss in gain can be made up for later in the signal chain.
Front and Rear Panel Overview

Mic Preamp

MIC/LINE Selects between the Mic input (switch in) and Line input (switch out). -15 PAD Inserts 15 dB pad for strong mic signals. M IC GAIN(dB)Sets the gain of the mic preamp for best compromise between signal-tonoise ratio and headroom. CLIP Monitors inputs (mic and line) for clipping. Illuminates 3 dB below the actual clip point. PHANTOM Illuminates when 48V phantom power is present at the microphone input connector. The phantom power switch is located on the rear panel.

De-Esser

F REQUENCY Sets the rolloff (cutoff) frequency of the de-esser. T HRESHOLD Sets the threshold level for the de-esser. Signals above this level cause de-esser action, signals below do not. DE-ESS Hard-wire bypasses the de-esser. The de-esser is active when this switch is in. IN/OUT ED Display Indicates the amount of de-esser activity at any instant in time. L
Downward Expander / Compressor
EXP THRES Sets the threshold level for the downward expander. Signals below this threshold are downward expanded (reduced in level). EXPANDER Indicates the amount of de-esser activity at any instant in time. LED Display C OMP THRESSets the threshold level for the compressor. Signals above this threshold cause gain reduction in the compressor. C OMP RATIO Sets the compression ratio of the compressor. EXP/COMP Defeats the downward expander /compressor. This is not a hard-wire bypass. IN/ OUT C OMPRESSOR Indicates the amount of compressor activity (gain reduction) at any given instant in time. LED Display

Lisping Quality

The 3 kHz range delivers a generous stimulus to the ear. At very loud levels the region of greatest ear sensitivity shifts downward from 5 kHz; this is why many PA speakers have broad peaks in this region. A characteristic of low-level signals peaked at 3 kHz is a lisping quality, and the total inability to distinguish labial sounds such as m, b, and v. In wide-range lower level systems, a peak in the 3 kHz region has a masking effect on important recognition sounds, and on others which lie above 4 kHz. Brilliance and clarity are lost and without attenuation of this region, an unconscious strain with increasing fatigue is felt according to the amount of 3 kHz boost.

Conclusions

When the article containing the above excerpts was written (probably around 1963), stereo was just becoming a commercial reality (you could still purchase mono and stereo versions of an LP and there were still more FM stations broadcasting in mono than stereo), and as many mixers contained rotary mix pots as those that used slide pots. The value of individual channel equalization was known, but it was both technologically and financially prohibitive. The article concludes thusly: With the advent of stereo and three-channel recording, nearly three times the equipment, with more elaboration, seems indicated, and expansion of console area in the horizontal plane offers the only direction in which to proceed. But a single engineer has arms only so long. How times have changed!

Presence Range

The usual band affecting clarity in male speech is 3000 to 6000 Hz. In a womans voice, the fundamentals are roughly an octave higher than a mans, and a womans range of consonant clarity lies between 5000 and 8000 Hz (the high-end of this range approaches a region of hearing insensitivity in humans). Furthermore, the total range of a womans voice is about half that of a mans, stimulating fewer hearing nerves, and for this reason, is consequently still weaker upon reception. Wide range sounds, especially those of singing voices, have fundamentals with harmonics in the 5 kHz region of good ear sensitivity. Voices that are powerful or rich with harmonics at 5 kHz sound especially pleasing, clear and full. Male opera singers are particularly favored with 5 kHz sounds, women less so. In popular music, this range shifts downward somewhat. It follows that voices deficient in the 5 kHz range can be enhanced in listening value by a generous boost on the order of 5 to 8 dB at 5 kHz. A secondary benefit of this boost is an apparent increase in level; a 6 dB rise at 5 kHz frequently gives an apparent increase of 3 dB to the overall signal.
Using the Parametric Equalizer
Great care must be exercised when using equalization. The following paragraphs give some general hints and precautions for using the 528Es parametric equalizer (or any other equalizer, for that matter).

Beware of Distortion and Noise
When a frequency or group of frequencies are boosted, the overall operating level is boosted as well. For example, 12 dB of boost (no matter what the frequency) increases the 528Es output level 12 dB (at that frequency). This kind of boost reduces headroom by 12 dB in every circuit from the 528Es own line driver to the last device in the signal chain (transmitter, tape machine, or what have you). Unless signal levels are very low to begin with, the 528Es output gain will have to be reduced to compensate for increased levels whenever the equalizer is used for boost. The Clip LED in the Output LED meter monitors levels in the equalizer as well as at the output of the 528E. If the Clip LED glows, try switching the equalizer to Bypass. If the LED still glows, reduce the setting of the Output Gain control. If switching the equalizer to Bypass eliminates the clip indication, then the input level must be reduced via the Mic Gain control or by lowering the level of the line input. On the other hand, if the levels within the 528E are too low to start with, using the equalizer for boost may increase noise to unacceptable levels. If levels are too low, increase the preamp gain (or the output level of the device feeding the line input).
to +15 dB (be very careful of feedback if you are monitoring on a loudspeaker!). Set the bandwidth for about.3 octave (max CCW). Tune the frequency control until you distinctly hear the part of the sound you wish to control. Then, adjust the cut/boost control for the appropriate amount of change, and readjust the bandwidth control if necessary.

Equalizing for Speech

In broadcast, equalizers are often used to create a sonic personality for the stations on-air talent. In production applications, it is practical to write down each persons settings. In broadcast applications (on-air), most stations try to find a single composite setting that works for all of their on-air talent. If your stations on-air talent is comprised of both men and women then finding a single, compromise setting becomes more difficult. A possibly more workable solution might be to use a single-D3 microphone (so it has proximity effect) and to vary the working distance to alter the low-frequency response somewhat.
Some general thoughts on speech equalization: !Try to use wider bandwidths. Narrower bandwidths
(1/2 octave and less) are less audible (harder to hear) and are generally only useful for remedial work. Broader bandwidths are less obnoxious, more pleasing sounding, and easier to work with (especially if youre boosting a range of frequencies).

Know What You Are Listening To
Low frequency boost may increase the level of some frequencies that cannot be heard, for one reason or another. Many high quality microphones are capable of generating substantial output at very low frequencies (below 50 Hz) which cannot be adequately reproduced by most monitor speakers or headphones. Be aware that the true effects of low frequency boost may not be audible, and may actually result in a muddy or distorted sound.
@Try to avoid massive amounts of boost or cut. If youre
only trying to impart a flavor (like sprinkling salt and pepper on a meal), then 6-8 dB of boost or cut should be all that you need.
#A wide bandwidth cut is equivalent to a boost at the
frequencies surrounding the cut.
$A quick way to figure out whats going on is to set the
level of one band of the equalizer to full boost (+15 dB), then switch to the frequency control and vary the frequency of that band of the equalizer while listening to program material fed through the unit. This usually makes quick work out of finding the region that you want to work on. Now reduce the level setting to something tasteful. A common problem when trying to set an equalizer for someones voice is converting the descriptive adjectives that people use in describing the character of a voice into the numbers that make equalizers happy. The following table list some commonly used adjectives and their corresponding frequency ranges. You can use the table on the following page as a guide.
Use Wide Peaks, Narrow Dips
In general, the human ear prefers wide bandwidth peaks and narrow bandwidth dips. Boosting a narrow bandwidth produces a sound usually perceived as offensive, while boosting wider bandwidths (.7 octave or greater) usually results in a sound deemed musical. It has also been observed that very few people will notice anythings missing when a narrow bandwidth (.3 octave or less) is cut, even when its cut as much as 30 dB. But, cut a wide bandwidth and the resulting sound quality is often called empty.
Tuning the EQ/Notch Filter
To tune the equalizer, use full boost. For both boost and cut, the 528Es parametric equalizer is intended to be put to work on specific frequencies. To find a particular frequency by ear (the method used by everyone who doesnt have a real-time analyzer), turn the cut/boost control all the way up
528E Voice Processor Range
100-250 Hz 250-400 Hz 400-600 Hz 600 Hz-1 kHz 2 kHz-4 kHz 3 kHz - 5 kHz 5 kHz-8 kHz 10 kHz up

Description (women)

Fullness Bassiness, bigness Warmth Volume Clarity Nasal, yell, presence Enunciation, intimacy Air, mouth noises

Stand-alone Operation

A vast majority of users use the 528E as a stand-alone device. Here the 528E replaces their usual microphone preamp and either feeds their tape machine or workstation directly, in essence becoming a one-input, one-output console. For best results, the 528E should replace the mic preamp in your console or recording chain. If you have to plug the 528E into a microphone input (-40 dBu nominal level), then youll need to pad (attenuate) the output of the 528E down to microphone level. An internal jumper connection reduces the 528Es output to this level. Although a far preferable connection would be to bypass your consoles mic preamp, this will work. When configured for mic-level output, the 528Es circuitry doesnt care if phantom powering is or isnt present at the consoles mic input. Appendix A contains instructions for altering the output level of the 528E. Note: Padding (attenuating) the output of the 528E back to microphone level is a workable solution towards interfacing the 528E into a console or system having only microphone level inputs. However workable, the ultimate performance of the 528E will be limited by the perormance of your systems f existing microphone preamps. If you can find a way to bypass the existing microphone preamps in your system, do so. Itll be worth the trouble.

Operational Details

This section describes the details of operating the 528E. Usage information can be found later in this section.

OUTPUT STAGE

UNBALANCED OUTPUT

EQUALIZER

EXPANDER/COMPRESSOR

DE-ESS

PRE-AMP STAGE

PHANTOM POWER

SIDECHAIN

BALANCED OUTPUT

TIP = RETURN RING = SEND

LINE INPUT

MIC INPUT

+48V BYPASS

FRONTPANEL INPUT SELECT SWITCH IN 'MIC' POSITION USB AUDIO INTERFACE
528E Voice Processor Using the 528E as a Channel Insert Device
The 528E can also be used as a channel-insert device with your console. Use the 528Es line input and line output as shown below.
FRONTPANEL INPUT SELECT SWITCH IN `LINE' (OUT) POSITION
TO CHANNEL PATCH RETURN INPUT
FROM CHANNEL PATCH SEND OUTPUT
Using the 528E in an Effects Loop
Signal processors used in a consoles effects (send-receive) loop should not be insert or series processors. A series processor means that you have to break the signal path to insert the processor. Since using the effects loop does not break the signal path, we dont recommend that you connect the 528E here. Use the channel-insert jacks as described under the previous heading or insert the 528E between your console and your tape machine.

528E Voice Processor Equalization
The 528Es parametric equalizer has three overlapping bands. Each band can operate as a peaking or dipping equalizer. The boost and cut range for each band is 15 dB. The bandwidth may be varied from 0.3 to 4-octaves wide. Since the bands overlap, it is possible to apply equalization at the same frequency in two places. Doing so could conceivably increase the signal level by 30 dB at one frequency. You may need to reduce the Input or Output Gain to avoid distortion. Likewise, large amounts of boost in any one band may require reducing the setting of the Output Gain control to prevent overload. Let the Output Clip LED be your guide. Electronic considerations aside, one of the contributing factors to an equalizers sound is its bandwidth. The table above lists the bandwidths (octaves) for several (possibly) familiar equalizers, as found on their respective mixing consoles. While we make no promise that the 528E will sound the same, these settings may be a good starting point if one of these equalizers is within your frame of reference. A parametric equalizer offers perhaps the greatest flexibility of any type of equalizer, however it can be more difficult to arrive at a setting than with other equalizers. A good strategy for setting any equalizer is to set the level control for maximum boost, then vary the Frequency and Bandwidth until you locate the portion of the spectrum that you wish to modify. Then refine the setting of the Level control for that band. Next refine the setting of the Bandwidth control. You may have to go back and forth between Level and Bandwidth to find the magic setting. Toggling the EQ Bypass switch between in and out can help too. As a rule, it is much easier to hear changes in amplitude (level) than it is to hear bandwidth changes. It is also easier to hear the abundance of something rather than the absence of the same thing. Even if you intend to apply cut (negative level) to a particular frequency, it is still easier to find that frequency by boosting first, tuning second, and resetting the boost/cut last according to taste or need. Finally, you may find that more natural sounds result when you use wider bandwidths for boosting, narrower bandwidths for cutting. Regardless, there are no hard and fast rules and in the end, whatever works for you is best. Its generally easier to apply boost to a sound for shaping (and thats how many engineers start). Many times, however, you may want to experiment with removing an offending sound (as opposed to drowning it out with something else). In a complex mix, this may work better because it may require less overall EQ to remove the offending sound; the end result will sound more natural.

Using the Sidechain

The sidechain is a patch point in the control circuit of a dynamic range processor, which provides access to the part of the circuitry that tells the VCA what to do. The 528Es sidechain routes through a rear panel TRS jack that allows the control signal to be processed outside the unit. Refer to the block diagram at the beginning of this section. Notice the sidechain connections that come from the compressor/downward expander section. These connections allow access to the audio signal at the input to the control circuit that drives the dynamics processor. This control signal is derived from, but kept totally separate from, the audio signal path, which means that the control signal can be processed outside the 528E without actually processing the signal thats going through the VCA (the audio signal itself). This presents some very interesting possibilities for changing or improving the operation of the dynamic range processor. The best use of the sidechain is to make the action of the 528Es compressor/downward expander frequency dependent, that is, to make it respond more (or less) to certain frequencies. Because the audio signal and the control signal remain completely separate (even while the control circuit tells the VCA whether to turn the gain up or down), you can equalize the sidechain without changing the EQ in the main audio path. Removing unwanted frequencies from the control signal before it actually reaches the VCA prevents those frequencies from being used to create gain changes. Applications utilizing the sidechain may be found in the next section of this manual.
Users Guide The Voice Symmetry Switch
Human speech, especially male human speech, contains a great deal of asymmetry. In broadcast (especially AM broadcast), this wastes transmitter power because the asymmetrical waveforms do not utilize the full power of the modulator. The bottom line is that you risk negative overmodulation if you dont correct speech asymmetry before the modulator. The Voice Symmetry switch corrects asymmetric speech waveforms before they get to your board; an added bonus is that you can apply the correction only to the announce mics without affecting the music. In recording applications, this switch may help give slightly higher overall levels by improving the symmetry of speech signals which may allow lightening up on the compression. Non-speech signals may be adversely affected by the Voice Symmetry switch. Let your ears be your guide.

Polarity Convention

The 528E uses the international standard polarity convention of pin 2 hot. Therefore:

Tip-Ring-Sleeve

Sleeve Tip Ring

Signal

Ground High Low
If your system uses balanced inputs and outputs, and uses the 528E this way, then the polarity convention is unimportant. If your system is both balanced and unbalanced, then you must pay attention to this, especially when going in and coming out through different connector types (like input on an XLR, output on a phone jack).
Input and Output Connections
The illustration on the following page shows how to connect the 528E to balanced and unbalanced sources and loads. To operate the 528E from line level unbalanced sources, run a 2-conductor shielded cable (thats two conductors plus the shield) from the source to the 528Es line input. At the source, connect the low/minus side to the shield, these connect to the sources ground; connect the high/plus side to the sources signal connection. At the 528E, the high/ plus wire connects to pin 2, the low/minus wire connects to pin 3, and the shield (always) connects to pin 1. This is the preferred method as it makes best use of the 528Es balanced input (even though the source is unbalanced). The other alternative shown converts the 528Es balanced input into an unbalanced input at the input connector. This works, but is more susceptible to hum and buzz than the preferred method. There is no level difference between either method. The 528E has two output connectors: XLR-male and TRS female. The XLR connector may be configured for either microphone-level or line-level output. The TRS connector is always line level. Refer to Appendix A for conversion instructions. You can drive unbalanced loads with the 528Es outputs by using the XLR connector with pin 3 left open. In an emergency (the show must go on), you can ground pin 3, but if you have the choice.leave it open. If you must ground pin 3, it must be grounded at the 528E, rather than at the other end of the cable. The price, regardless of whether or not pin 3 is grounded is 6 dB less output level. This can be easily made up via the output gain controls. If your system is wired with pin 3 hot, pin 2 must float if you are driving an unbalanced load.

I/O Impedances

The 528E is designed to interface into almost any recording studio or sound reinforcement application. This includes: Ohm systems where input and output impedances are matched. 7 Unbalanced semi-professional equipment applications. 7 Modern bridging systems where inputs bridge and outputs are low source impedances (voltage transmission systems). The 528Es microphone input is intended to bridge a 150-Ohm balanced source. The actual input impedance is approximately 8-kilOhms. 48V phantom powering for condenser microphones is present if the Phantom Power switch has been depressed. Refer to the discussion of phantom powering on the next page for additional information. The 528Es line input impedance is 10-kilOhms balanced, and 10-kilOhms unbalanced. The inputs may be driven from any source (balanced or unbalanced) capable of delivering at least -10 dBu into the aforementioned impedances. The 528Es output impedance is 200 Ohms balanced, 100 Ohms unbalanced. The output line driver delivers +18 dBm into a 600-Ohm balanced load or +18 dBm into 600-Ohm unbalanced loads.

The 1/4-inch unbalanced output uses a TRS female jack with the ring contact wired to circuit ground. This jack is unaffected by the internal output level switch. Unlike the XLR connector, using this jack corrects the gain so that it is unity. The interstage patching jacks are half-normalled (only the input jack breaks normal) TRS jacks wired for unbalanced operation. This means that the tip is the signal connection, ring and sleeve are ground. This method of connection allows either TRS or TS plugs to be used, with either balanced or unbalanced inputs or output on the remote equipment. Aside from that, the TRS jack grabs the plug better. Ensure that your plug is fully inserted into the jack. The sidechain access jack for the dynamics processor uses a TRS jack wired as an insert jack. This means that the ring connection is the send to and the tip connection is the return from the remote processor. The figure below shows the wiring for the plug as well as the connections to/from the external processor.
Phantom Powering Condenser Microphones
Most modern condenser microphones have provisions for being remotely powered via the microphone cable. The dominant system in use today is the phantom power system which is compatible with both condenser and noncondenser microphones (dynamics, ribbons, etc.). If your microphones data sheet says that it is phantom powered, the 528E can power it. Another remote powering system exists called A-B powering, modulation lead powering, or T system. A-B powering is incompatible with phantom powering as well as other non-powered microphones. The technical requirements for operation and/or compatibility are: 7 The microphone must have a balanced, low-impedance output. 7 The balanced output must be floating with respect to ground. If there is a center tap, it must also float with respect to ground. (In the past, it was common to ground the center tap of the microphones output transformer. This was especially true of ribbon microphones.)

Further Information

More information including an online tutorial, customer submitted settings, frequently asked questions and trouble shooting information can be found on the Symetrix web site at http://www.SymetrixAudio.com.
528E Voice Processor Balanced Connections
Any of these connectors can appear on either side of a balanced connection.

Wiring Reference

NOTE: In the case of an XLR connector, the Female attaches to an output, while the Male attaches to an input.

Euroblock [balanced]

Terminal Strip [balanced]
NOTE: Detachable Euroblock and Terminal Strip connectors are designed for use with bare wire. Do not tin stranded wires before inserting them into the connectors.
TRS 1/4" Plug [balanced]
Tip = (+) Plus Ring = () Minus Sleeve = Ground
XLR Female Plug [balanced]
Pin 2 Pin 3 Pin 1 Pin 2 = (+) Plus Pin 3 = () Minus Pin 1 = Ground

XLR Male Plug [balanced]

Pin 2 Pin 2 = (+) Plus Pin 3 Pin 3 = () Minus Pin 1 Pin 1 = Ground Special Case: Female XLR connectors will ALWAYS be used coming from the OUTPUT of a device. Male connecters plug into the INPUT of a device.

Unbalanced Connections

The RCA connector and the 1/4 TS connector are unbalanced connectors, wired with a single strand shielded wire and can be placed on either end of an unbalanced connection
TS 1/4" Plug [unbalanced]
Tip = (+) Plus Sleeve = (-) minus and Ground

! ! 1 IMPORTANT NOTICE 1

The wiring diagrams on these pages are included for information purposes only. Symetrix can not anticipate every connector type on non-Symetrix products. It is the users responsibility to determine what connection is needed.

RCA Plug [unbalanced]

In addition, Symetrix accepts no responsibility for injury or damage caused by user created wiring.
Sleeve = (-) minus and Ground Tip = (+) Plus

Unbalanced Connections:

Unbalanced out to balanced in
The RCA connector and the 1/4 TS connector are unbalanced connectors. However, the wiring differs depending on if they are sending to, or receiving from a balanced connector.
In this example, the unbalanced connector is sending signal to a balanced connector. When wiring this connection, use a shielded twisted pair cable. The balanced side wires the same as a standard, balanced connection. On the unbalanced side, you wire the white (minus) wire together with the ground. This provides some common mode rejection at the balanced input.
TS 1/4" Plug [unbalanced out to balanced in]
Euroblock [balanced] RCA Plug [unbalanced out to balanced in]
Balanced out to unbalanced in
When your output requires a balanced connector, but you
are sending signal to an unbalanced input, the rules change. Use a single strand shielded wire. Wire only to the plus and ground terminals of what would the typically be the balanced connector.
XLR Female Plug [unbalanced]
Pin 2 Pin 3 Pin 1 Pin 2 = (+) Plus Pin 3 = Unused Pin 1 = Ground
TS 1/4" Plug [balanced out to unbalanced in]
Tip = (+) Plus Sleeve = Ground
Euroblock [unbalanced] Terminal Strip [unbalanced]
RCA Plug [balanced out to unbalanced in]
Tip = (+) Plus Ring = unused Sleeve = Ground
Sleeve = Ground Tip = (+) Plus
528E Voice Processor Troubleshooting Chart

Symptom Probable Cause

Troubleshooting

No output

Hum or buzz in output Distortion

Architects and Engineers Specs
There shall also be a single LED clip indicator to indicate clipping within either of the input preamplifiers or buffers. The microphone input shall be an active balanced bridging design terminated with 3-pin XLR-female connector (AES/ IEC standard wiring). The microphone preamp shall be capable of an equivalent input noise specification of at least -126 dBu (150-Ohm source, 60 dB gain, 20 Hz to 20 kHz). The line input shall be a balanced, transformerless design using a 3-pin XLR-female connector (AES/IEC standard wiring). All input circuitry shall incorporate RFI filters of the LC low-pass type. The output shall be an active balanced design terminated with a 3-pin XLR-male connector (AES/IEC standard wiring). The output signal level shall be switchable to accommodate subsequent line or microphone inputs. The output section shall provide a switchable phase rotator for the purpose of improving the asymmetry of speech waveforms. Access to the dynamics processing sidechain shall be provided via a " TRS jack. Access to the interstage connections between all processing sections (mic/line preamp, de-esser, compressor/limiter/downward expander, equalizer, output stage) shall be provided via half-normalled tip-ring-sleeve (TRS) jacks. The voice processor shall be capable of operating by means of its own built-in power supply connected to 115 VAC nominal (105 to 130 VAC), 50/60 Hz or 230 VAC nominal (207 to 253 VAC ), 50 Hz. The unit shall be a Symetrix Incorporated model 528E Voice Processor.
Declaration of conformity
We, Symetrix Incorporated, 6408 216th St. SW, Mountlake Terrace, Washington, USA, declare under our sole responsibility that the product: 528E Voice Processor to which this declaration relates, is in conformity with the following standards: EN 60065
Safety requirements for mains operated electronic and related apparatus for household and similar general use. EN 55103-2 Electromagnetic compatibility - Generic immunity standard Part 1: Residential, commercial, and light industry. The technical construction file is maintained at: Symetrix, Inc. 6408 216th St. SW Mountlake Terrace, WA, 98043 USA The authorized representative located within the European Community is: World Marketing Associates P.O. Box 100 St. Austell, Cornwall, PL26 6YU, U.K. Date of issue: March 15, 1999 Place of issue: Lynnwood, Washington, USA Authorized signature:
Dane Butcher, President, Symetrix Incorporated.
WARNING: Lethal voltages are present inside the chassis. Perform all service work with the unit disconnected from all AC power. CAUTION: These servicing instructions are for use by qualified personnel only. To avoid electric shock, do not perform any servicing other than that contained in the operating instructions portion of this manual unless you are qualified to do so. Refer all servicing to qualified service personnel.
Appendix A: Level Output Switch
Changing The XLR Output Level

DATA SHEET: 528E Voice Processor
The 528E Voice Processor from Symetrix.
This complete analog channel strip performs six separate functions: microphone preamplification, de-essing (sibilance removal), compression/ limiting, downward expansion, parametric EQ, and voice symmetry alignment. All six processes may be used simultaneously. Although we call the 528E a Voice Processor, it is perfectly suitable for any mic- or line-level source. Revered as the choice for broadcast voices and known as the classic one channel console by recording studios, the 528E delivers all the control you need, without the cost or complication of separate units. Each function has a full complement of controls in an easy-touse layout. The 528E works with any professional microphone. Mic preamp gain is variable up to 60 dB, and 48 volt phantom power is provided for condenser mics. A switchable 15 dB pad reduces gain in front of the mic preamp to prevent distortion in super-close micing situations. A front panel switch selects between microphone or line input. Both inputs are transformerless and are equipped with filters to prevent radio frequency interference (RFI). The de-esser senses and regulates selectable high frequencies to reduce or eliminate annoying sibilance and lip smacking. Symetrix program-controlled Integrated Dynamics Processing (IDP) techniques combine the best attributes of compressor/limiters and downward expanders. The compressor/ limiter maintains uniform levels while the downward expander eliminates pumping, breathing, and noise build up. Because its program controlled, the 528Es dynamic range processor responds quickly to transients, and gently to smaller level changes. Separate LED meters display mic/input gain and gain reduction, for quick and accurate adjustment of dynamics functions. The three band parametric EQ performs both creative enhancement and corrective (eliminating resonances and interference) operations, with bandwidth variable from 0.3 octave to 4 octaves, 15 dB boost/cut, and overlapping frequency ranges. A unique leap frog topology minimizes the number of amplifiers in the signal path while ensuring that each frequency band interacts with its neighbor in a desirable and musical fashion. The Voice Symmetry switch corrects for excessive positive or negative signal peaks of the human voice. Get the same processing power found in an entire recording studio signal chain with the 528E Voice Processor from Symetrix, the engineering-driven company of signal processing specialists.

Features

Single rack space classic analog channel strip. Applications: Broadcast, Studio, Podcasting, Installed Sound. Add warmth and color to your digital broadcasts & recordings. World renowned Symetrix sound quality, reliability and performance. Six (6) processes in one box: Mic Preamp, De-esser, Downward Expander, Compressor, 3-band EQ, and Voice Symmetry. Rear panel patch points allow re-ordering of processes or external effects inserts.
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528E Architects and Engineers Specifications
The voice processor shall be capable of all signal processing functions commonly found on a mixing console input channel, including microphone signal preamplification, line input buffering, simultaneous de-essing, downward expansion, compression/limiting, and parametric equalization. The unit shall have a low-noise, low distortion microphone preamplifier with variable gain (22 dB to 60 dB) and switchable (on/off) +48V phantom power. A 15 dB pad shall be provided to accommodate high output microphone signals. A balancedbridging line input suitable for +4 dBu input signals shall also be provided along with a switch to select either the microphone or line inputs. The voice processor shall have an integral de-esser which shall offer up to 20 db of attenuation within a manually sweepable frequency range of 800 Hz to 8 kHz. There shall be front panel controls for range, frequency, and a bypass switch. The dynamics processing section shall contain an interactive compressor/limiter and downward expander. There shall be front panel controls for compression ratio (1:1 to 10:1), compressor threshold (-50 dBm to +20 dBm), expander threshold (-30 dBm to 0 dBm), and a bypass switch. There shall be a three-band parametric equalizer. Each band shall have 15 dB maximum boost/cut, and continuously variable bandwidth (0.3 octaves to 4 octaves). The equalizer bands shall have substantially overlapping frequency ranges, with a combined range of 16 Hz to 22 kHz. There shall be a front panel bypass switch. The voice processor shall be equipped with the following LED displays: An eightsegment LED display shall be provided for monitoring the overall output level, sixsegment displays for monitoring the de-esser, compressor/limiter, and downward expander. All displays shall be independent. There shall also be a single LED clip indicator to indicate clipping within either of the input preamplifiers or buffers. The microphone input shall be an active balanced bridging design terminated with 3-pin XLR-female connector (AES/IEC standard wiring). The microphone preamp shall be capable of an equivalent input noise specification of at least -126 dBu (150-Ohm source, 60 dB gain, 20 Hz to 20 kHz). The line input shall be a balanced, transformerless design using a 3-pin XLR-female connector (AES/IEC standard wiring). All input circuitry shall incorporate RFI filters of the LC low-pass type. The output shall be an active balanced design terminated with a 3-pin XLR-male connector (AES/IEC standard wiring). The output signal level shall be switchable to accommodate subsequent line or microphone inputs. The output section shall provide a switchable phase rotator for the purpose of improving the asymmetry of speech waveforms. Access to the dynamics processing sidechain shall be provided via a TRS jack. Access to the interstage connections between all processing sections (mic/line preamp, de-esser, compressor/limiter/downward expander, equalizer, output stage) shall be provided via half-normalled tip-ring-sleeve (TRS) jacks. The voice processor shall be capable of operating by means of its own built-in power supply connected to 115 VAC nominal (105 to 130 VAC), 50/60 Hz or 230 VAC nominal (207 to 253 VAC ), 50 Hz. The unit shall be a Symetrix Incorporated model 528E Voice Processor.

Specifications

Input/Output
Controls and Switches: Mic Gain, Phantom Power, Mic/Line Mic and Line Input Connectors: XLR-female (2) Clip LED: Lights at +17 dBu output level from mic preamp or line input amplifier Microphone Input Type: Balanced Transformerless, Low Impedance Phantom Power (DIN 45 596): +48V, nominal Microphone Preamp Gain: 22 to 60 dB (pad out), 7 to 45 dB (pad in) Microphone Input Maximum Input Level: -3 dBu (pad out) Equivalent Input Noise (EIN): -126 dBV (150-0 Ohm source, 20 Hz to 20 kHz) THD + Noise (Preamp only): 0.05% (2 kHz, 50 dB gain, +17 dBu output) Mic Preamp CMRR: > 50 dB (40 dB gain, 20 Hz to 20 kHz) Line Input Type and Impedance: 10k Ohm Transformerless Balanced Bridging Line Input Maximum Input Level: +24 dBu Line Input Nominal Input Level: +4 dBu Line Input CMRR: > 50 dB (0 dBu, 20 Hz to 20 kHz)

Dynamic Range Processor

Type: Interactive Comp/Limiter-Downward Expander Comp/Limiter Ratio: 1:1 to 10:1 Downward Expansion Ratio (max): 1:1.8 De-esser Type: Program controlled high-cut filter 12 dB/octave Frequency Range: 800 Hz to 8000 Hz Threshold: -30 to 0 dBu Output Section Type: Balanced, Transformerless Maximum Output Level: +24 dBm Balanced, +18 dBm Unbalanced Connector: XLR-male Output Clip LED: Lights 3 dB below clipping Output Source Impedance: 200 Ohms, Balanced Minimum Load Impedance: 600 Ohms Balanced or Unbalanced Voice Symmetry Switch: Improves modulation symmetry of speech signals Output Gain: +/- 15 dB

Physical

Size (hwd): 1.72 x 19 x 7.25, 4.37 x 48.26 x 18.42 cm) Weight: 7.6 lbs (3.5 kg) net, 10 lbs (4.6 kg) shipping

Parametric Equalizer

Type: Three-band Parametric Equalizer Bands: Low: 16 to 500 Hz, Mid: 160 to 6300 Hz, High: 680 Hz to 22 kHz Peak/Dip Bandwidth: 0.3 to 4 octaves, measured at maximum boost Maximum Boost/Cut: +/- 15 dB

Electrical

Power Requirements: 115 VAC nominal, 95 to 130 VAC, 50 to 60 Hz, 15 watts maximum 230V nominal, 207 to 253 VAC, 50 Hz 15 watts maximum Note: The maximum operating ambient temperature is 30 C.

Metering

Type: Multi-segment LED bar graph Output Level: -20 to +3 VU (0 VU = +4 dBu), VU calibrated, peak responding Gain Reduction: Separate displays for: de-esser, downward expander, and compressor 0 to 20 dB per display
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Overall Performance Data

Frequency Response: 20 Hz to 20 kHz (+0, -0.5 dB), EQ out, compressor out, downward expander out, de-esser out THD + Noise: 0.05%, 20 Hz to 20 kHz, +4 dBm output Noise Floor: Better than -89 dBu, 20 Hz to 20 kHz