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****** Page 1 ****** Owner’s Manual Model LS22 LINE STAGE AMPLIFIER audio research HIGH DEFINITIONØ 5740 Green Circle Drive / Minnetonka, Minnesota 55343-4424 / Phone; 612-939-0600 FAX: 612-939-0604

****** Page 2 ****** Contents Model LS22 Section Preface Warnings Packaging Description of Controls Connections Installation Instructions Operating Procedure Tape Recording Procedure Muting Provisions Shut Down Servicing Cleaning Warranty Terms and Conditions Warranty Outside the USA Specifications Page No.

****** Page 3 ****** Model LS22 Preface Please take the time to carefully read this instruction manual prior to installation or use of your LS22 Line Stage Amplifier. Because it is a highly advanced electronic instrument, there are several facts and procedures you should know before you place it in operation. Just as you would not purchase and attempt to oper- ate an expensive camera, computer system or high- performance automobile without first learning some- thing about performance parameters and correct operating procedures, so too your line stage amplifi- er requires some familiarization before you make it part of your music reproduction system. Your reward, in terms of maximum performance and a long service life, will be well worth the effort. Warnings 1. To prevent fire, or shock hazard, do not expose your LS22 to rain or moisture. 2. This unit contains voltages which can cause seri- ous injury or death. Do not operate with cover removed. Refer servicing to your authorized Audio Research dealer or other qualified personneL 3. The power cord on your LS22 is equipped with a heavy gauge, 3-conductor cable and a standard three-prong grounding plug. For absolute protec- tion, do not defeat the ground power plug. This provides powerline grounding of the LS22 chassis to provide absolute protection from electrical shock. 4. For continued protection against fire hazard, replace the fuse only with the same type and rating as specified at the fuse holder. Packaging Save all packaging in a dry place away from fire hazard. Your LS22 line stage amplifier is a precision electronic instrument and should be properly car- toned any time shipment is made. You may not have occasion to return your unit to the factory for service, but if that should prove necessary, or other occasion requiring shipment occurs, the original packaging will protect your LS22 from unnecessary damage or delay. Note that your LS22 has been shipped with the vac- uum tubes installed in a protective foam block under the top cover. Using a phillips-head screwdriver to loosen the fastening screws, remove the top cover and set aside. Install the numbered tubes in their respective sockets, refasten the top cover and store the foam block with your carton. DO NOT ATTEMPT TO OPERATE THIS PREAMPLIFIER BEFORE INSTALLING THE VACUUM TUBES IN THEIR PROPER SOCKETS. REAR TUBE LOCATIONS TOP VIEW VI FRONT 1

****** Page 4 ****** Model LS22 Description of Controls GAIN CONTROL: Use it to control volume. Rotation to the left attenuates gain, rotation to the right increases gain. INPUT SELECTOR; Detents indicate selection of var- ious source material options: “Tuner” for AM/FM radio tuners; “Video” for audio input from HiFi videotapes, discs or broadcasts; “Phono” for phono preamplifiers; “CD” for compact disc players or digi- tal-to-analog processors; “Auxi’ for any additional high level source tape, tuner, CD, video, etc. The signal source chosen by the input selector is fed to the Tape outputs. NOTE: See “Monitor/Source’i for primary tape recorder selection. POWER SWITCH: Supplies power from AC wall out- let to LS22 when in “Power” position. Although not strictly necessary, it is nonetheless good practice to put the LS22 in “Mute” before turning on power for maximum protection of your power amplifier(s) and speakers. UNBALANCED/BALANCED INPUT SELECTOR SWITCH: Each of the 5 sets of inputs on the rear panel (chosen via the front panel rotary input selec- tor switch) as well as a set of tape inputs will accept either an unbalanced or balanced pair of connectors. Note: Although you may connect as many as 6 input sources at once to the LS22, only one pair of input cables—either unbalanced or balanced—should be connected to any one of the LS22 inputs at a time. Hooking up both unbalanced and balanced sources simultaneously to the same Input may seriously degrade the sound Once you have made all your input connections to the LS22, choosing either unbalanced or balanced hookup, simply set the Unbalanced/Balanced input toggle in the position corresponding to the unbal- anced or balanced output of the source component you’ve chosen to listen to. MONITOR/SOURCE: In “Monitor” position this control selects the audio output of the primary tape recorder. “Source” accesses the input selector’s five high-level sources. MUTE/OPERATE SWITCH: In “Mute” position, shorts the main outputs of the line stage amplifier to allow listening interruptions for telephone answer- ing or other reasons. This switch should always be activated between listening uses or switching of inputs, in addition to turning the Gain (volume) control counter-dockwise. These two simple precau- tions will prevent inadvertent misuse of your LS22 and help protect your power amplifier(s) and speakers from unexpected transient signal pulses. In “Operate” position, this switch allows the signal to pass normally to the outputs. CAUTION: Do not turn up the gain control beyond normal listening positions when the LS22 is in the mute mode. Always turn the gain control down when changing program sources, even when it is muted. POWER/MUTING CIRCUIT LED; Glows green to indicate unit is on and receiving power from the power supply. Note that for approximately 45 seconds after start-up or in “Mute” mode, this LED will glow more dimly, indicating proper operation of the muting circuit. In the “Operate” mode (after warm-up) the LED brightens and your LS22 is ready for normal operation. audio rcsca’rctl’. MON rx-on PH0N0 VIDEO co TUHUA HIGH MODEL LB22 BAL 2

****** Page 5 ****** Model LS22 Connections INPUT CONNECTORS: All are clearly marked to indicate use. The inputs are 200K ohms impedance balanced, and 100K ohms unbalanced. MAIN OUTPUT CONNECTORS: For maximum flex- ibility, there are two sets of unbalanced and 2 sets of balanced output connectors. Any or all 4 sets may be connected simultaneously to your crossover or amplifiers(s) as necessary. NOTE: The XLR connector pin leads are as follows: I-shield; 2-positive; 3-negative. If used with a power amplifier which utilizes different pin leads for posi- tive, negative and/or shield, the signal being fed to the loudspeakers will be incorrect. Please consult your Audio Research dealer. At the performance level of the LS22, high-quality audio signal interconnect cables are critical to pre- serving maximum fidelity. Audio Research intercon- nect cables are highly recommended for connection to your power amplifier(s) and to other ancillary equipment. See your authorized Audio Research dealer for recommended lengths. TAPE OUTPUT CONNECTORS: The LS22’s Tape outputs should be connected to your tape deck’s “REC” or “LINE” inputs. These outputs supply what- ever is selected by the Input selector control to the tape deck for recording. Level is non-variable and approximately the same as the selected input source. Installation Instructions While the LS22 does not dissipate an unusual amount of heat, it is important that it be provided with reasonable airflow to assure long, trouble-free operation. In addition, the following installation guidelines will help insure maximum sonic perfor- mance as well as reliable service. 1. Upright and horizontal mounting is suggested if extended operation (longer than one hour) is con- templated. 2. Do not “stack” the LS22 on top of a power amplifi- er: not only could this cause overheating, but “hum” may be introduced into the LS22 from the proximity of the amplifier’s power transformer. 3. Do not place or operate your LS22 on a soft or irregular surface such as a rug. This will prevent proper ventilation. 4. Do not operate your LS22 without the top and bottom covers installed. These are required both for safety as well as shielding from interference (except in service operations). 5. If rack mounting is employed, use Audio Research Rack Mount Ventilators (RMV-3) below and above your LS22. 6. If side-by-side mounting with other equipment is employed, place the LS22 to the left of the other chassis, so as to provide maximum spacing between the transformer of the LS22 and the other component. 7. In a cabinet or rack-mount installation which has an endosed back, an exhaust fan is desirable so as not to operate the LS22 in overheated ambient air. Operation of vacuum tube equipment for long periods of time in hot ambient air will shorten tube life and increase chance of failure of other component parts. TVNER TUNER VIDEO VIDEO PHONO INPUTS Aux TAPE TAPE TAPE OUT TAPE OUT out t OUT 2 CAUTION WAflNlNG MODEL usee audio rescarcll WNNESOTA UAOE u.3A cm.JT10N XOAFUSE wwArrs OLO.ØLO MAXIMUM X 6060HZ LAIN OUT UALNOUT2 3

****** Page 6 ****** Model LS22 Operating Procedure Start-Up: 1. Make sure Power switch is set to “Off’ position; Mute switch should be in “Mute” position; and “Gain” control should be at minimum (full counter-dockwise rotation). 2. Secure all rear-panel connections between LS22, power amplifier(s) and input sources. Note: Given the advanced performance capabilities of the LS22, it is extremely important that high-quality interconnects be used for connection to ancillary electronics. Audio Research brand interconnects are strongly recommended. Your authorized Audio Research dealer can assist you in determin- ing optimal lengths for your system. 3. Plug 3-prong powerline cord from rear of LS22 in- to grounded AC wall receptade. 4. Turn Power switch to “Power.” Green LED will glow dimly for approximately 45 seconds while power supply stabilizes, indicating operation of automatic muting circuit. After this warm-up muting period, the LED will brighten when ‘Operate” is selected, indicating that your LS22 is ready for operation. Note: For superior sonic performance, a warm-up pe- riod of at least one hour is recommended. In addi- tion, your LS22 may be safely left “on” continu- ously for maximum performance at all times, but at the expense of higher maintenance costs (more frequent tube replacement). 5. Rotate input selector to source desired; set switch options to positions desired. 6. Activate input source, then deactivate Mute switch and adjust Gain control as necessary. Tape Recording Procedure When using the LS22 as a control center for record- ing, the program source to be recorded must be con- nected to one of the five inputs controlled by the Input selector. This routes the selected program to the Tape outputs. It is also possible to dub from one tape deck to another. Simply connect the output from a secondary tape deck to an unused set of inputs controlled by the Input selector (Aux, Video, etc.) on the LS22. This signal will then be routed to the 4 primary tape deck when the appropriate input is selected on the Input selector. Muting Provisions The LS22 has several provisions to help protect against misuse of the exceptional dynamic range and wide bandwidth that it offers. It is not subject to damage itself, but some power amplifiers and speak- ers are more limited in their ability to withstand signal extremes. These provisions, both manual and automatic, are designed not to interfere with the listening experience, while giving reasonable protection against warm-up surges and power line interruptions. However, for absolute protection of associated equipment some operator understanding and responsibility are required. Initial “settling” time of all circuit parameters within the LS22 requires approximately 5 to 10 minutes. The automatic muting circuitry timer is adjusted for about 45 seconds. (This is because recurrent inter- ruption “settling” time is much less. You would not want to wait for 5 to 10 minutes each time such an interruption occurred.) The Mute/Operate switch allows manual disabling of the LS22 outputs during the switching of equipment. Use of this switch will minimize stress on your amplifier even if it is “off”. It is also highly recom- mended that manual muting be employed during the initial 45-second warm-up period as well as during turn-off for maximum protection. While it is true that the automatic muting will pro- vide reasonably adequate protection against speaker burnout during these periods, it has limitations. At the 45-second point the automatic timer “releases” the output. Although this is normally adequate pro- tection, utilization of the manual mute provision will completely avoid stress to your speakers, Some solid-state power amplifiers have a DC offset present at their input connections. (This, of course, should not be.) Operation of the manual muting switch with such an amplifier connected will result in a “click” or “pop” in your loudspeaker (commensu- rate in level with the amount of the offset) each time the switch is activated. Repair or replacement of such amplifiers is suggested.

****** Page 7 ****** Model LS22 The automatic muting operates a follows: 1. The manual mute switch always disables all “main” outputs and overrides any automatic provi- sions, even when the LS22 is turned off. (The “Operate” position of the manual mute switch is functional only when the unit is not in the automatic mute mode.) 2. The 45-second warm-up timer will restart auto- matically and the LED will dim if the power is temporarily interrupted for 0.1 second or more. Note: Power supply regulation of the LS22 is effec- tive down to 105VAC without serious sonic degradation. 3. The automatic muting of the LS22 is designed to be effective only against power line interruptions and power line failures. It will not mute against subsonic signal transmissions from your input source. Proper fusing of speakers Is essential to protect against excessive audio level or power amplifier fa ults. Shut-Down: 1. Set ‘Mute” switch to “Mute” position. 2. Rotate “Gain” control counter-dockwise to minimum setting. 3. Turn off power amplifier(s). 4. Turn off all input sources. 5. Set LS22 Power Switch to J’Off” position. Servicing Because of its careful design and exacting standards of manufacture, your LS22 should normally require only minimal routine service to maintain its high level of performance. CAUTION: Your LS22 contains sufficient levels of voltage and current to be lethal. Do not tamper with a component or part inside the unit. Refer any need- ed service to your authorized Audio Research dealer or other qualified technician. The vacuum tubes inside your LS22 are quality 6922/E88cc twin triodes, and with normal use should not need to be changed for approximately 4,000 hours of use. Replacement tubes should be of equivalent quality and are available from Audio Research. Should service be necessary, please contact your Audio Research dealer, or Audio Research Customer Service at (612) 939-0600. Cleaning To maintain the visual appearance of your LS22 line stage amplifier, occasionally wipe the front panel and top cover surfaces with a soft damp (not wet) cloth to remove dust. A mild, non-alkaline soap solu- tion may be used to remove fingerprints or similar smudges. Cleaners containing abrasives should not be used as they will damage the “brushed” grain of the front panel finish. A dry 2-inch pure bristle paint brush works well to remove dust from bevels, reliefs and switches. 5

****** Page 8 ****** Limited Warranty Terms and Conditions 1. LIMITED WARRANTY Audio Research warrants the product designated herein to be free of manufacturing defects in material and workmanship, subject to the conditions hereinafter set forth, for a period of three (3) years from the date of purchase by the original purchas- er or no later than five (5) years from the date of shipment to the authorized Audio Research dealer, whichever comes first, excepting vacuum tubes which are warranted for 90 days only (See 6), and CD players or transports, which are warranted for two (2) years from date of purchase (four (4) years from date of shipment). 2. CONDITIONS This Warranty is subject to the following conditions and limita- tions. The Warranty is void and inapplicable if the product has been used or handled other than in accordance with the instruc- tions in the owner’s manual, abused, or misused, damaged by accident or neglect or in being transported, or the defect is due to the product being repaired or tampered with by anyone other than Audio Research or an authorized Audio Research repair center. The product must be packed and returned to Audio Research or an authorized Audio Research repair center by the customer at his or her sole expense. Audio Research will pay return freight of its choice. A RETURNED PRODUCT MUST BE ACCOMPANIED BY A WRITTEN DESCRIPTION OF THE DEFECT AND A PHOTOCOPY OF THE ORIGINAL PURCHASE RECEIPT. This receipt must dearly list model and serial number, the date of purchase, the name and address of the purchaser and authorized dealer and the price paid by the purchaser. Audio Research reserves the right to modify the design of any product without obligation to purchasers of previously manufactured products and to change the prices or specifications of any prcxl- uct without notice or obligation to any person. 3. REMEDY In the event the above product fails to meet the above Warranty and the above conditions have been met, the purchaser’s sole remedy under this Limited Warranty shall be to return the prod- uct to Audio Research or an authorized Audio Research repair center where the defect will be rectified without charge for parts or labor, except vacuum tubes (See 6). 4. LIMITED TO ORIGINAL PURCHASER This Warranty is for the sole benefit of the original purchaser of the covered product and shall not be transferred to a subsequent purchaser of the product. 5. DURATION OF WARRANTY This Warranty expires on the third anniversary (second for CD players and transports) of the date of purchase or no later than the fifth anniversary (fourth for CD players and transports) of the date of shipment to the authorized Audio Research dealer, whichever comes first. Warranty Outside the U.S.A. Audio Research has authorized distribution in many countries of the world. In each country, the authorized importing retailer or distributor has accepted the responsibility for warranty of products sold by that retailer or distributor. Warranty service should normally be obtained from the importing retailer or distributor from whom you purchased your product. 6 6. VACUUM TUBES Vacuum tubes are warranted for the original 90-day period only. 7. DEMONSTRATION EQUIPMENT Equipment used by an authorized dealer for demonstration pur- poses is warranted to be free of manufacturing defects in materi- als and workmanship for a period of three (3) years from the date of shipment to the dealer,or two (2) years in the case of CD players and transports. Vacuum tubes are warranted for days. After the first year, demo equipment needing warranty service must be packed and returned to Audio Research by the dealer at his sole expense. Audio Research will pay return freight of its choice. A returned prcxluct must be accompanied by a written description of the defect on an AUDIO RESEARCH RETURNED GOODS AUTHORIZATION form. demonstration equipment sold at retail within three (3) years of date of ship- ment to the dealer is warranted to the first retail customer to be free of manufacturing defects in materials and workmanship for the duration of the 3-Year Limited Warranty remaining (as mea- sured from the date of shiprnent of the equipment to the dealer); this period of warranty is two (2) years in the case of CD players and transports. Vacuum tubes are not warranted for any period under these conditions of sale. In the event warranty service is needed under these conditions, the owner of the equipment must provide a copy of his purchase receipt, fulfilling the requirements described under “2. Conditions” above. The prod- uct must be packed and returned to Audio Research or an autho- rized Audio Research repair center by the customer at his or her sole expense. Audio Research will pay return freight of its choice. 8. MISCELLANEOUS ANY IMPLIED WARRANTIES RELATING TO THE ABOVE PRODUCT SHALL BE LIMITED To THE DURATION OF THIS WARRANTY. THE WARRANTY DOES NOT EXTEND TO ANY INCIDENTAL OR CONSEQUENTIAL COSTS OR DAMAGES TO THE PURCHASER. Some states do not allow limitations on how long an implied warranty lasts or an exclusion or limitation of incidental or consequential damages, so the above limitations or exclusions may not apply to you. This Warranty gives you spe- cific legal rights, and you may also have other rights which vary from state to state. 9. WARRANTOR Inquiries regarding the above Limited Warranty may be sent to the following address: Audio Research 5740 Green Circle Drive, Minnetonka, Minnesota 553434424 ATTN: Customer Services. In the unlikely event of service required beyond the capability of the importer, Audio Research will fulfill the conditions of the warranty. Such product must be returned at the owner’s expense to the Audio Research factory, together with a photocopy of the bill of sale for that product, a detailed description of the prob- lem, and any information necessary for return shipment.

****** Page 9 ****** Specifications Model LS22 FREQUENCY RESPONSE: ±.5dB, 1.5Hz to 100kHz -3dB points below 0.1 Hz and above 400kHz. DISTORTION: Less than .010% at 2V RMS output. GAIN: Main output: 18.3dB Bal., 12.7dB Unbal. Tape output: OdB. INPUT IMPEDANCE: 200K ohms Balanced, 100K ohms Unbalanced, Inputs (6): tuner, video, phono, CD, aux, tape (XLR and RCA connectors). OUTPUT IMPEDANCE: 400 ohms Balanced, 200 ohms Unbalanced main (2), 20K ohms minimum load and 2000pF maximum capacitance. Outputs (3): 2 main, 1 tape (XLR and RCA connectors). MAXIMUM INPUT: 20V maximum. RATED OUTPUTS: 2V RMS IHz to IOOkHz into 100K ohm balanced load (maximum balanced output capability is 35V RMS at less than 0.5% THD at 1 kHz) CONTROLS: Gain, Input selector. Toggle switches: Power/Off, Unbalanced/ Balanced input, Monitor/ Source, Mute/Operate. POWER SUPPLIES: Electronically-regulated low and high voltage supplies. Automatic 45 sec. warm- up/brown-out mute. Line regulation better than .010/0. NOISE: 12uv RMS residual II-IF weighted balanced noise output with gain control minimum, (104dB below 2V RMS output). TUBE COMPLEMENT: 8-6922/E88cc dual triode. (Vacuum tube audio circuit, solid-state power supply) POWER REQUIREMENTS: 100-135VAC 60Hz (200- 270VAC 50/60Hz) 90 watts maximum DIMENSIONS: 19″ (48 cm) W x 51/4″ (13.4 cm) H (standard rack panel) x 113/4″ (29.8 cm) D. Handles extend 1/2″ (3.8 cm) forward of the front panel. Rear chassis fittings extend 7/8″ (2.3 cm). WEIGHT: 17 lbs. (7.7 kg) Net; 27 lbs. (12.3 kg) Shipping. Specifications subject to change without notice. 01995 Audio Research Corporation. 7








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