Universal Audio LA-3A Manual
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Universal Audio LA-3A Manual

Audio leveler
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Model LA-3A
AUDIO LEVELER
Universal Audio Manual Number 65-1301
Revision 1.53

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Summary of Contents for Universal Audio LA-3A

  • Page 1 Model LA-3A AUDIO LEVELER Universal Audio Manual Number 65-1301 Revision 1.53...
  • Page 2 Inc. makes no warranties of any kind with regard to this manual, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Universal Audio, Inc. shall not be liable for errors contained herein or direct, indirect, special, incidental, or consequential damages in connection with the furnishing, performance, or use of this material.
  • Page 3 THE LA-3A AUDIO LEVELER Thank you for purchasing the LA-3A Audio Leveler. The LA-3A is a solid-state version of Universal Audio’s vacuum tube based Teletronrix LA-2A, and was designed by Brad Plunkett. In it’s day, the LA-3A was consid- ered an improvement over the LA-2A because it eliminated “noisy tubes” and maintenance issues. Today, both products are revered for their smooth and musical control of audio levels.

  • Page 4: Table Of Contents

    TABLE OF CONTENTS LA-3A SPECIFICATIONS LA-3A FRONT PANEL Peak Reduction....... 4 Gain.
  • Page 5 COMPRESSOR THEORY OF OPERATION Compressor Basics......12 The T4 Cell........14 Side-Chain Circuit.

  • Page 6: La-3A Specifications

    LA-3A SPECIFICATIONS Balanced Line Input Impedance..600Ω floating Max. Input Level....-0dBm @ 50dBm gain setting Internal Output Impedance.

  • Page 7: La-3A Front Panel

    �� � �� �� �� �� ��� OUTPUT POWER UNIVERSAL AUDIO, INC. SANTA CRUZ, CALIFORNIA Peak Reduction The PEAK REDUCTION control determines when the compressor receives a signal “loud” enough to trigger gain reduction as well as total output level. Higher settings will increase the relative amount of compression. The GR / OUTPUT switch below the GAIN knob should be set to GR to view the amount of gain reduction the LA-3A is doing.

  • Page 8: Meter Calibration

    function is determined using the two-position switch below the GAIN knob to the left of the meter. When OUT- PUT is selected, a meter reading of 0 corresponds to an output level of +4 dBm at the LA-3A output. In the GR mode the meter will move from 0 to negative numbers on the left side.

  • Page 9: 50/30 Db Gain Switch

    50/30 dB Gain Switch The 50/30 dB GAIN switch is an input pad to prevent high output devices from overdriving the input transform- er of the LA-3A. Setting the switch to the 30dB position will attenuate the incoming signal by 20dB. For studio use, the normal setting is down (30dB) when not using the MOD function.

  • Page 10: Unbalanced Connections

    • When changing operating voltage, the fuse value must be changed as well. • Make sure the LA-3A is properly set for the voltage in your area before applying AC power to unit! Input/Output Terminal Strip The terminal strip provides screw connections for INPUT, OUTPUT, STEREO balance and CHASSIS GROUND. The strip can be used instead of the XLR connections.

  • Page 11: Stereo Setup / Calibration

    Stereo Setup / Calibration 1. Set the STEREO ADJ control to full Clockwise. 2. Set the PEAK REDUCTION knob to 0. 3. Set the GR / OUTPUT switch to OUTPUT. 4. Connect a signal generator to the inputs of both LA-3A units. 400 to 1000 Hz recommended. Set the signal generator output level to produce a typical level for your application.

  • Page 12: What Compressors Do

    Due to the automatic and extremely musical way the LA-3 rides level, it’s quick and easy to get good results. The down side: sometimes you need a quicker release time or you want to manipulate the attack time as mentioned previously. In this case the Universal Audio 1176, 2-1176 or 6176 may be the perfect tool.

  • Page 13: Compressing Vocals

    Compressing Vocals The LA-3A is very popular for vocals. First of all, like many pieces of “vintage” gear the LA-3A has a unique “sonic signature” produced by the audio path transformers and discrete amplifier components. This, coupled with the attack and release character, produces great results that bring vocals forward. Bass Guitar The LA-3A is also very popular for Bass.

  • Page 14: Dual Unit

    Dual Unit The LA-3A shipping carton contains all the necessary brackets and hardware required for standard 19” rack mount. Bracket and hardware locations are shown below Instructions 1. Set the two LA-3As next to each other as pictured. Remove the 4 screws on the top cover on the left unit (as shown in the FRONT VIEW drawing below).

  • Page 15: Compressor Theory Of Operation

    COMPRESSOR THEORY OF OPERATION Compressor Basics Before we dig in to a description of the compressor circuit, it is useful to examine the general characteristics of compressors and review some terminology. The chart below depicts the input/output characteristics of a com- pressor, an expander and a perfect amplifier.
  • Page 16 In contrast to an amplifier, whose job is to present a constant gain, a compressor varies its gain in response to the level of the input signal. Large input signals result in less gain, thus reducing or “compressing” the dy- namic range of the signal.

  • Page 17: The T4 Cell

    The T4 Cell D I A G R A M OF THE T4 ELEC TR O- O PTICAL C ELL The cell T4 is comprised of an electro-luminescent (EL) panel and a photoelectric cell housed in a light proof box or can. The EL panel is essentially a night-light. As you would expect, the larger the signal that is applied to it, the brighter the light that is generated.

  • Page 18: Side-Chain Circuit

    milliseconds) to approximately half of its off resistance. The remainder of its release can take place over as much as several seconds. The next aspect is the “memory” of the cell. This results in two important aspects of the character of the LA- 3A.

  • Page 19: Historical Notes

    In 1999 Bill Jr. and James Putnam re-launched Universal Audio and merged with Kind of Loud technologies - a leading audio software company - with two goals: Reproduce classic analog recording equipment designed by their father and his colleagues, research and design new recording tools in the spirit of vintage analog technol- ogy.

  • Page 20: The 610 Preamp

    The 1176LN The original Universal Audio 1176LN was a major breakthrough in limiter technology - the first true peak limiter with all transistor circuitry offering superior performance and a signature sound. Evolved from the popular...

  • Page 21: The La-2A

    Universal Audio 175 and 176 vacuum tube limiters, the 1176LN retained the proven qualities of these industry leaders, and set the standard for all limiters to follow. It was Bill Putnam himself who, in 1966, was respon- sible for the initial design of the 1176. Its circuit was rooted in the 1108 preamplifier, which was also designed by Putnam.

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