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Related Manuals for Symetrix 420
Summary of Contents for Symetrix 420
- Page 1 420 Stereo Power Amplifier...
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Page 2: Table Of Contents
Symetrix part number 53420-0A00 Subject to change without notice. ©1999, Symetrix, Inc. All right reserved. Symetrix is a registered trademark of Symetrix, Inc. Mention of third-party products is for informational purposes only and constitutes neither an endorsement nor a recommendation. Symetrix assumes no responsibility with regard to the performance or use of these products. -
Page 3: Introduction
The Symetrix 420 is a two-channel power amplifier intended for use in professional and commercial audio systems. The 420 may be operated as a two channel amplifier with 20-watts per channel, or as a single channel amplifier capable of 40-watts output (mono-bridged mode). The amplifier is intended for use with near-field monitors, small speakers used for “radio reference”... -
Page 4: Chapter 2 Operator Safety Summary
Please read and keep these instructions. Heed User-serviceable parts There are no user and follow all warnings and instructions. serviceable parts inside the 420. In case of failure, Install in accordance with the manufacturer’s refer all servicing to the factory. Servicing is instructions. -
Page 5: Chapter 3 Fast Setup
420’s output to the loudspeakers (or other load) using the barrier strip connector located at the rear of the unit. If the 420 is driving a headphone distribution system, you’ll get better results (read louder) if you use the screw terminals on the rear of the unit. The front-panel headphone jack is really only intended to drive one pair of ‘phones. - Page 6 With the signal level of the source at a reasonable level, increase the gain of the 420 until either the indicators illuminate or the acoustical output of the loudspeakers is sufficient.
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Page 7: Chapter 4 Front & Rear Panel Overview
Channel 2 Indicates the onset of clipping at the output of the 420. Controls the gain, or input sensitivity, of channel 2 of the 420. A volume control by any other name. This control is active only in I NDEPENDENT mode. - Page 8 1Ampere Slow-blow fuse. Replace only with same type of fuse 117V ac: 1A, 250V AC, slow blowing (Bussman type MDL-1) 230V AC: 0.5A, 250V ac, slow blowing (Bussman type GDC-500ma). #6 screw terminals. This is the output of the 420. These terminals may be UTPUTS turned on/off via the front-panel S switch.
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Page 9: 420 Basics
Chapter 5 420 Basics Although power amplifiers are one of the basic building blocks of any audio system, they still remain one of the least understood. Why is minimum load impedance important? What really happens when you mono-bridge an amplifier? Do you really need a BIG amplifier to run head- phones in your studio? We’ll try to answer these questions, and more, in this chapter. - Page 10 (if the amplifier is well protected and/or extremely underrated) to triggering smoke alarms. A good rule-of-thumb is DON’T operate any amplifier below its rated minimum load impedance. The minimum load impedance of the 420 is 4 ohms in stereo or dual-mono mode and 8 ohms in mono-bridged mode.
- Page 11 gauge zip cord works just fine. If you can, 14-gauge wire is even better. Use godzilla-cable if you want. The biggest single thing you can do for your loudspeakers when you pick a cable for them is to minimize the wire resistance. Aside from using silver (which has higher conductivity than copper), sheer physical size is the way to fly.
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Page 12: Chapter 6 Using The 420
This section is intended for more advanced users. If you are a first-time user, we recommend that you start out by using the procedure found in “Fast Setup.” Block Diagram On the following page you can find the block diagram for the 420. Please take a moment and take note of the following: •... - Page 14 If you connect a pair of headphones to the front panel S jack, they TEREO EADPHONES will receive out-of-phase signals (not harmful to anything except phase or polarity fanatics). In mono-bridge mode, the 420 delivers 40 watts into an 8 ohm load. The minimum load impedance is 8 ohms.
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Page 15: Chapter 7 Applications
Here are a few applications that the 420 lends itself to. Recording Studios This is probably the primary use for the 420. Use it to drive the Auratones or the small home-stereo reference speakers. The 420 probably isn’t powerful enough to drive most near-field monitors except in very small studios. - Page 16 Headphone Distribution Systems The 420 is ideally suited to headphone distribution systems. There are two basic strategies involved in making a loud headphone system: If you have low impedance phones, then you need high current capability to make them loud.
- Page 17 TRS plugs or stereo phone plugs short their tip and ring connections momentarily as they are mated or unmated. This can be harmful to the 420 (most other amplifiers, too). Figure 7-3 shows the connections needed at the amplifier end. Notice that all connectors are simply wired in parallel.
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Page 18: Chapter 8 Technical Tutorial
Technical Tutorial Chapter 8 This section discusses a multitude of things, all related to getting signals in and out of the 420. Matching Levels vs Matching Impedances In any audio equipment application, the question of “matching” inevitably comes up. Without digging a hole any deeper than absolutely necessary, we offer the following discussion to (hope- fully) clarify your understanding of the subject. - Page 19 The 420 is designed around studio/professional line levels: +4 dBu or 1.23 volts. The input sensi- tivity is high enough that the 420 can be driven to full output with the input gain controls set to less than wide open. The unit is quiet enough to operate at lower signal levels such as those found in semipro or musical-instrument (MI) equipment (-10 dBu or 300 millivolts).
- Page 20 420’s balanced input (even though the source is unbalanced). The other alternative shown in Figure 8-1 converts the 420’s 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.
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Page 21: Chapter 9 Troubleshooting
Chapter 9 Troubleshooting Troubleshooting Chart SYMPTOM PROBABLE CAUSE No output Check cables and connections. Are inputs driven by outputs, and outputs driving speakers or headphones? Are all of the cables good? Is there signal coming out of the source? Are the loudspeakers or headphones OK? Is the front-panel S switch out? PEAKER... -
Page 22: Chapter 10 Specifications
Independent clipping indicators shall be provided for each output channel. The amplifier shall be capable of operating by means of its own built-in power supply connected to 120V nominal AC (108 to 132V) 60 Hz. The unit shall be a Symetrix Incorporated model 420 Stereo Amplifier. -
Page 23: Chapter 11 Warranty & Service
In no event will Symetrix be liable for any incidental or consequential damages including but not limited to damage for loss of... - Page 24 Servicing the 420 If you have determined that your 420 requires repair services and you live outside of the United States please contact your local Symetrix dealer or distributor for instructions on how to obtain service. If you reside in the U.S. then proceed as follows: At the Symetrix factory, Symetrix will perform in-warranty or out-of-warranty service on any product it has manufactured for a period of five years from date of manufacture.
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Page 25: Appendix A Disassembly Instructions & Bridged-Mono Mode Switch
Bridged-Mono Mode Switch To prevent inadvertent setting, the bridged-mono mode switch is located inside of the 420. To set or reset the switch, use the following procedure. Disconnect the 420 from the AC power source. - Page 26 Symetrix, Inc. 6408 216th St. SW Mountlake Terrace, WA, 98043 Tel: (425) 778-7728 Fax: (425) 778-7727 Website: http://www.symetrixaudio.com Email: symetrix@symetrixaudio.com...
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