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How can I change the XLR line output on my 528E Voice Processor to microphone level?

Tools Required:

#2 Phillips-head screwdriver

Top Cover Removal:

Ensure that the 528E is disconnected from the AC power source.

Remove two 6-32 x 1/2 inch screws from the top panel and two 6-32 x 1/2 inch screws from each side of the chassis.

Lift the top cover free of the chassis.

Changing The XLR Output Level:
The 528E ships from Symetrix with the XLR output configured for a line level output. If you must have a microphone level output, the following steps lead you through the process of switching the XLR line level output to microphone level (or back to line level).

Remove the top cover according to the steps outlined above.
As you look at the unit with the front panel facing you, locate the OUTPUT LEVEL switch (SW7) in the upper right side of the unit just below the XLR output connector. SW7 is in red in the diagram below.
Push the switch in to select MIC level output or out to select LINE level output.
Replace the top cover.
Reinstall the 528E into your setup.

528E Mic/Line switch

How can I use both the mic and line inputs simultaneously on the 528E Voice Processor?

Remove the 528E’s LED board
Cut Pin #2 between the two switches.
Add two 1K resistors as shown below.

528E Mic/Line Switch Mod

Where can I find a Data Sheet for the 528E Voice Processor?

Where can I find a schematic for the 528E Voice Processor?

In order to choose the correct schematic for your particular 528E unit, you will need to derive both the unit revision and the manufactured date from the serial number of the unit. This number always begins with the number “80”, and will be on a sticker on the bottom of the 528E.

Depending on the age of the unit, this number could appear in a couple of possible formats. This is a key detail, as schematics are not available for current serial numbers.

Current Serial Numbers:
Current units have serial numbers in the following format:

120V version: 80-4528EANA0912176
230V version:  80-4528EAEU0912176

The presence of a hyphen and either “NA” or “EU” in the serial number are both indicators that this is a current serial number.

If you need repairs for current serial numbers, please contact Symetrix Support at support@symetrix.co.

Old Serial Numbers:
Older units have serial numbers that appear without a hyphen, and will have the manufacture date printed on the sticker.

Example: 800528E0B0854

The unit revision is shown by the two characters following the model number (800528E). In the example above, the “0B” points to a Revision B unit.

The manufacture date for older units can appear in a couple of different date formats. One may see a more typical date format (e.g. 09/19/05), or perhaps a format as shown in the picture below. In this example, the year is first – so the manufacture date is May 7, 2008.

image004

Once the unit revision and manufacture date have been established, download the relevant schematic from among the links below.

528E_A00 (1995) Schematic
528E_D1 (1996) Schematic
528E_D02 (1996) Schematic
528E_D03 (1996) Schematic
528E_B00 (1997) Schematic
528E_B01 (1998) Schematic
528E_1C00 (1999) Schematic
528E_1D01 (2002) Schematic
528E_1D02 (2007) Schematic

What can I do about RF interference in my 528E Voice Processor?

For AM interference, replace the ferrite beads, FB1 and FB2, with 470 mH chokes.
Replace the ferrite beads with an EMI filter, Symetrix part number 150005.

I need to replace a pot or switch on my 528E.

Spare or replacement pots and switches for the Symetrix 528E are available factory direct, (US only, international inquiries please contact the Symetrix distributor in your country).

Note the unit serial number contact Sales@symetrix.co.

How should I set the mic gain on the 528E Voice Processor?

Set all processing sections to the BYPASS mode.
Set the OUTPUT LEVEL control to “0” dB.
Adjust the MIC GAIN to provide peaks of “0” dB on the OUTPUT LEVEL meter. The CLIP LED should not flash during normal use.

Where can I find a Flow Chart for the 528E Voice Processor?

528E Voice Processor settings tutorial.

Get the Perfect Settings for Your 528E Voice Processor
The 528E is one of the most complete and versatile Voice Processors on the market today. The ability to tune the timbre and quality of your voice is essential in creating the kind of quality production and/or on-air product that your listeners demand and deserve. Getting the perfect settings to work for your specific application will take a little practice and experimentation. So, to get you up and running as quickly as possible here’s a brief tutorial to get the most out of your 528E Voice Processor.

We strongly encourage you to read the 528E Voice Processor User’s Guide because it’s filled with a lot of useful information about getting the most out of your microphone and your voice. If you can’t find yours anywhere around the station, feel free to download a copy.

Initial Settings

With all hardware connections made, and the 528E powered on (LED displays activity), set the controls and switches on the front panel as shown.

528E starting settings

Red marked X indicates that button is pushed IN.

Mic Preamp Gain

Push out the DE-ESS, EXP/COMP, and the EQ buttons into bypass mode.

Set the MIC GAIN control so that the CLIP LED should almost never illuminate.

De-esser Settings

To reduce the level of sibilant sounds (S and T sounds)

Set the THRESHOLD control to show about 12 dB of gain reduction.

Adjust the FREQUENCY control for maximum sibilance reduction.

Decrease the THRESHOLD setting until you reduce the sibilance to a tolerable level.

Downward Expander Settings

To reduce room noise and/or mouth noises

Set the THRESHOLD control to allow low-level speech sounds to pass while still blocking the room sound.

Compressor Settings

To vary the amount of gain reduction

3 to 6 dB is sufficient unless you are using a low compression ratio (below 2:1), or you want a special effect. Choose a ratio suited to the task at hand:

Low level ratios and low thresholds for unobtrusive level control.

Medium ratios for overall level control and consistency.

High ratios (>8:1) for limiting or ‘in-your-face’ sorts of sounds.

Equalizer Settings

The initial settings work well with male voices.

For women

Increase low-EQ range to 200 or 300 Hz.

Increase mid-EQ range to 3 to 5 kHz.

If you are using a mic that exhibits proximity effect when close-micing

Decrease (cut) the bass (low) response somewhat. 3 to 6 dB should be fine (don’t do this if you want a big, ballsy sound).

Some mid-EQ helps make voices cut and seem loud.

High-EQ adds brightness and intimacy.

If you are using a mic that has no proximity effect when close-micing

Increase (boost) the bass response somewhat. 3 to 6 dB should do the job.

Some mid-EQ helps make voices cut and seem loud.

High-EQ adds brightness and intimacy.

Output Settings

For many applications, the output GAIN control at 0 dB works fine.

Push in the buttons for DE-ESSER, EXP/COMP, and EQ.

If you increased the EQ, then you may need to increase GAIN.

If you increased compression, you may need to increase GAIN.

Choose a setting that gives you enough signal downstream, yet keeps the CLIP LED from illuminating.

The output CLIP LED monitors both the EQ and the output stage. Large amounts of boost and /or high level signals can cause CLIP indications. If this occurs, lower the signal level by adjusting the GAIN control.

It is also possible for the output stage to clip if a processor, inserted using the output stage access jacks, is contributing gain to the overall signal path. In this case, either lower the gain of the insert processor or decrease the setting of the GAIN control.

The output level of my early version 528E Voice Processor suddenly became very noisy. What can I do?

This pertains to the late revision 528 and early revision 528E manufactured between approximately 1993 and 1996.  The board will be a ‘through-hole’ assembly.

Turn the power off. Cut Jfets Q2 and Q3 out of the circuit.

I have an older 528E without the internal mic/line switch. How can I change the XLR line output to microphone level?

Tools Required:

#2 Phillips-head screwdriver

Top Cover Removal:

Ensure that the 528E is disconnected from the AC power source.

Remove two 6-32 x 1/2 inch screws from the top panel and two 6-32 x 1/2 inch screws from each side of the chassis.

Lift the top cover free of the chassis.

Changing The XLR Output Level:

The 528E ships from Symetrix with the XLR output configured for a line level output. If you must have a microphone level output, the following steps lead you through the process of switching the XLR line level output to microphone level (or back to line level).

Remove the top cover according to the steps outlined above.

Locate the XLR output connector.

Find the “Output Level” solder pads J17 and J18 directly behind the XLR connector.

Fill the space between the J17 pads with solder.

Fill the space between the J18 pads with solder.

Locate the two circuit board traces next to J18 marked by the word “Cut”.

Cut these two traces with a small, sharp knife.

Replace the top cover.

Reinstall the 528E into your setup.

How should I set up my 528E Voice Processor to get going?

Push the MIC/LINE switch IN.
Put the -15 PAD switch in the NORM position (OUT).
Set the OUTPUT LEVEL control at “0”, the 12 o’clock position.
Set the MIC GAIN control to achieve peaks of “0” dB on the output meter when speaking into the microphone.
Set the De-ess FREQUENCY control to 3 o’clock.
Set the De-ess THRESHOLD control to “0”.
Push the DE-ESS switch IN.
Set the EXP THRES control to “-25” (12 o’clock).
Set the COMP THRES control to “-10” (12 o’clock).
Set the COMP RATIO control to “2” (12 o’clock).
Push the EXP/COMP switch IN.
Set the Low EQ FREQUENCY control to 11 o’clock.
Set the Low EQ BANDWIDTH control to 11 o’clock.
Set the Low EQ CUT/BOOST control to 2 o’clock.
Set the Mid EQ FREQUENCY control to 8 o’clock.
Set the Mid EQ BANDWIDTH control to 11 o’clock.
Set the Mid EQ CUT/BOOST control to 11 o’clock.
Set the High EQ FREQUENCY control to 10 o’clock.
Set the High EQ BANDWIDTH control to 2 o’clock).
Set the High EQ CUT/BOOST control to 2 o’clock.
Push the EQ IN/OUT switch IN.
Set the Output Level GAIN (dB) control to “0” (12 o’clock).
Push the VOICE SYMMETRY switch IN.

What is the voltage of the 528E Voice Processor's phantom power supply?

With the phantom power switched on and no microphone connected, the 528E will provide phantom voltage of about 48 volts measured between either pins #2 or #3 and ground (pin #1, of the input connector is ground).
With the phantom power switched on and an active microphone connected, the voltage of the 528E’s phantom power supply will typically be between 34 and 38 volts.