DUAL MP

Two Channel Tube Microphone Preamplifier

USERS GUIDE

Introduction
Thank you for purchasing the Dual MP - and congratulations: You now own one of the most sophisticated pieces of audio signal processing available. Offering a superb level of sound quality, the Dual MPs special tube and integrated circuit design combined with a straightforward user interface quickly and easily gives you access to all of its features.

Features

The A R T SOUND! - (not available elsewhere) Two independent channels of operation XLR balanced inputs and outputs 1/4 TS unbalanced inputs and outputs Hybrid- 12AX7/ quad transistor gain stages +48V Phantom power Phase Reversal 20dB gain switch Independent input and output level controls Four stage sonic character LED Array >60dB of gain >100dB dynamic range Internal power supply Front panel instrument/ line input jacks All steel construction Designed and manufactured in the USA Fill in the following for your future reference: Date of purchase: ___________________ Purchased From: ____________________ Serial Number: 254-________ This a great time to fill out the User Registration card included with you Dual MP to become a completely informed A R T Artist. Return-ing the card to us ensures you of becoming the first to know about new A R T products as well as any further developments from A R T.

Were Online!

For Product information, questions, applications, tips, answers and general discussion with A R T employees look for A R T on the Internet. Look for the A R T folder on America Online in Craig Andertons Stage Studio and Sound (keyword SSS) under the Manufacturer Supported Forums. Email us at artroch@aol.com Look for the A R T supported area in the MIDI Forum B area on Compuserve (Go MIDI). Compuserve address: 76702,3700. Email us at artroch@cis.compuserve.com Check out our Web Page at: http:\\www.artroch.com

Connections

Its easy to interface the Dual MP with other equipment. XLR input and output connectors are located on the rear panel. Additional 1/4 unbalanced outputs are located on the rear panel and 1/4 instrument/ line inputs are located on the front panel for accessibility. The Dual MPs XLR connectors follow the AES standard of: Pin 1 = Ground, Pin 2 = Hot (+), Pin 3 = Cold (-). Ideally, one input per channel should be used at a time. However, because of its design the Dual MP can be hardwired into a rack without having to disconnect the XLR inputs when using the front panel jacks. If no load is placed on the XLR input (no instrument or microphone connected) the front jack will function as if there was nothing connected to the XLR input. Both Dual MP inputs may be used simultaneously. However, the two signals will sum and the signal present at the XLR jack will tend to attenuate the signal of the 1/4 input. Both balanced and unbalanced output connections may be used simultaneously. This is particularly useful when using the Dual MP as a direct box for instruments or line level signals. **Note: If you experience a grounding hum when using both output connectors (one to the console, one to an instrument amp) simultaneously, a ground loop may be the problem. To remedy this problem, disconnect the ground wire (pin 1) from the XLR cable plugged into the Dual MPs output. This interrupts the ground path and therefore breaks the loop.

Controls, Switches and Indicators
Power The Dual MP is powered by an internal power supply. The Power switch and indicator LED are located on the front panel. If the attached power cord ever becomes damaged, discontinue use until you can have it repaired. Phantom Power Switch Each channel of the Dual MP can power any microphone needing +48 volts DC of Phantom power. The Phantom power is engaged and disengaged with this switch. Phantom power is supplied to pins 2 and 3 of the XLR input jack.
Input Control The input control sets the amount of input gain of the Dual MP. Turn the control clockwise to increase gain and counterclockwise to decrease gain. You may control two ranges of gain with this control, +26 to +60dB and +6 to +40dB. Selection of the gain range is made with the +20dB gain switch. Sonic Character LED Array Four LEDs are provided on each channel which display how the tube gain is affecting the input signal. These LEDs are calibrated with the tube circuitry to give you an accurate visual of its output signal (**Note: these LEDs are pre - output level control). The first LED is labeled Cln (clean). The tube is producing a clean output when this LED is lit. The next two LEDs are labeled warm. This is the normal operating range for the Dual MP. At this level, the tube is producing an output signal which most would call warm or (those ever over-used) tube/ retro/ vintage/ rich/ etc/ etc. Whatever you would like to call it is fine. Youll find the output signal has an enhanced bottom to low mid quality with smooth high frequency detail. The last LED is labeled Clp (Clip). This LED will light at approximately 6dB before audible distortion occurs. If this light flickers, do not panic. The unique design of the Dual MP causes the tube to distort well before any other gain stage. When a tube goes into distortion it is a gradual process and tends to sound pleasing for a range before it turns into a distortion box. After some use youll find the sweet spot of the Dual MP is with this light flashing fairly regularly. +20dB Gain/ Norm Switch Use the +20dB Gain/ Norm switch to set the gain range of the Input control. When the switch is in the out (Normal) position the gain range is +6 to +40dB. Depressing the switch adds 20dB of gain. With the switch in, the gain range is +26 to +60dB. With most microphone applications youll find using the Dual MP with the +20dB gain switch in is needed in most situations. Use the setting that best fits your application.
**Note: Be sure to turn down or mute the output of the Dual MP when engaging or disengaging Phantom power. Additionally, when disengaging, allow 30 - 45 seconds for the power to completely dissipate. Most microphones will make a sound like air leaking from a tire when phantom power is disconnected, but some can make some very nasty low rumbles and whines as well. **Another Note: Dynamic microphones should not be affected or damaged if they are plugged into a line where Phantom power is present. However, if the mic doesnt need it, dont use it. Some things are best left untested! Phase Switch The Phase switch is provided to reverse the phase of a signal. This switch works on Pins 2 and 3 of the XLR Output jack of the channel. In the Normal position, the signal is in-phase. In the Reverse (or in) position, Pins 2 and 3 are reversed as the signal is changed to 180 degrees out of phase. In multiple microphone applications, the placement of the microphones can affect the phase of a signal. If two microphones pick up the same signal from different locations, the result can be a hollow or frequency shifted sound. In some cases it may sound as if an instrument disappears if it happens to be 180 degrees out of phase. Depressing the Phase switch of one channel can remedy this problem. Likewise, if a microphone cable is wired incorrectly, when used with a properly wired cable the signal will be out of phase. **Note: for single microphone applications switching the phase switch in and out will produce little to no change in the output signal. Special Effects For industrial, metal, or just flavor textures experiment with the Dual MP. Cascading the channels can produce overdrive and tube distortion that can add interesting textures when blended with vocals and different instruments. Placing signals purposely out of phase can yield interesting results. No harm will come to the Dual MP with this type of experimentation however, be sure to have output and monitoring levels turned

Output Control The output control sets the output level of the Dual MP. When the control is fully counterclockwise, there is no output.Turning the control clockwise increases the level of the output to a maximum of +10dB of gain. This gain is in addition to the existing input gain. Design Overview A R Ts Dual MP circuitry is a hybrid design utilizing the latest and most advanced solid state and tube technology. Using a transformerless design throughout, the Dual MP maintains exceptional signal integrity and extremely low noise. The Active balanced input utilizes a hybrid multiple paired transistor design providing extremely low noise and excellent CMRR. A second stage 12AX7A tube running on a regulated DC voltage of +50volts provides additional gain. The tube will overload before the input or output stage. This allows the user to manipulate the tube gain to meet their sonic requirements. The 1/4 input has a high impedance preventing the loading of any device connected to it, making the Dual MP perfect for DI applications. Applications Preamp The main application of the Dual MP is a microphone preamplifier. Plug any microphone directly into either input and set the input and output controls to provide a healthy level into the next stage of your system. DI The Dual MP is ideal for use as a DI box. Plug the instrument into either input and use the XLR or 1/4 (or both) outputs to connect to your recorder, board or PA system. 2-mix Because of its low noise and excellent tonal qualities, the Dual MP is ideal for running mixes through before recording to DAT or cassette. Used as a mastering device, the Dual MP is capable of adding warmth and, set properly, gentle tube compression to the incoming signal.
DOWN before testing the sound. When running one channel into another (cascading) you have the potential for upwards to 120 to 140dB of gain.
A R T Dual MP Specifications
Dimensions: 1.75 H x 19 W x 6.5 D Input Connections: XLR (balanced), 1/4 unbal. Output Connections: XLR (balanced), 1/4 unbal. Input Impedance: XLR, 1/4 2K ohms, 840K ohms Output Impedance: XLR, 1/ohms, 300 ohms Maximum Input Level: XLR +14dBu Maximum Input Level: 1/4 +22dBu Maximum Output Level: XLR +28dBu Maximum Output Level: 1/4 +22dBu CMRR >75dB (typical @ 1kHz) Frequency Response 10Hz to 20kHz (+0, -1dB) Dynamic Range >100dB (20Hz to 20kHz) Total Harmonic Distortion(THD) <0.1% (typical) Maximum Gain: XLR to XLR 70dB (typical) 1/4 to 1/4 54dB (typical) XLR to 1/4 64dB (typical) 1/4 to XLR 60dB (typical) Equivalent Input Noise (EIN) XLR to XLR -129dBu (A weighted) 1/4 to 1/4 -105dBu (A weighted) Power Requirements: 95-125VAC, 10W - (USA) Internal fuse Other power requirements configured for country of destination.

Warranty and Service Information
Limited Warranty Warranty service for this unit will be provided by Applied Research and Technology, Inc. in accordance with the following warranty statement. Applied Research and Technology, Inc. (A R T) warrants to the original purchaser that this product is free from defects in workmanship and materials for a period of three years from the date of purchase. A R T will, without charge, repair or replace, at its option, defective product or component parts upon prepaid delivery to the factory service department or authorized service center, accompanied by proof of purchase date in the form of a valid sales receipt. EXCLUSIONS: This warranty does not apply in the event of misuse or abuse of the product or as a result of unauthorized alterations or repairs. This warranty is void if the serial number is altered, defaced or removed. A R T reserves the right to make changes in design and make additions or improvements upon this product without any obligation to install the same on products previously manufactured. A R T should not be liable for any consequential damages, including without limitation damages resulting from the loss of use. Some states do not allow limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to you. This warranty gives you specific rights and you may also have other rights which vary from state to state. For units purchased outside the United States, service will be provided by an authorized distributor of A R T products.

Service

The following information is provided in the unlikely event that your unit requires service. Use this procedure to return units in the United States only. For service outside the United States, please contact your authorized A R T distributor. 1) Be sure the unit is the cause of the problem.Check to make sure the unit has power supplied, the proper power supply is being used (note the output specification of the power supply make sure you are using the proper AC or DC voltage), all cables are connected correctly, and the cables themselves are in working condition. 2) If you find the unit to be at fault, write down a description of the problem, including how and when the problem occurs. 3) Call the factory for a Return Authorization (RA) number. 4) Pack the unit in its original carton or reasonable substitute. The packing box is not recommended for a shipping carton. Put the packaged unit in another box for shipping. Print the RA number clearly under the address. 5) Include with your unit: a return shipping address (we cannot ship to a P.O. Box), a copy of your purchase receipt, a daytime phone number and the description of the problem. 6) Ship the unit to: Applied Research and Technology, Inc. 215 Tremont Street Rochester, NY 14608 Atten: Repair Department R.A.# _______________ 7) Contact our Customer Service department at 716/436-2720 for your Return Authorization number or questions regarding your repair. Customer Service hours are Monday through Friday 8:30AM to 4:30PM Eastern time.

Additional Information

If you are planning to purchase additional equipment for your audio needs, please consider the following A R T Products. Recording/ Live Sound MR-1, Personal Reverb Processor Tube MP, Personal Microphone Preamplifier MDM-8L, Eight channel compressor/limiter Pro Gate, Eight channel programmable Noise Gate SC-2, two channel compressor/limiter/gate MDC-2001, Stereo dynamics processor FXR and FXR Elite (II), Two channel Digital multi-effects processors Effects Network, Digital Dedicated and multi-effects processor Multiverb Alpha, Digital multi-effects processor HD-15, Two channel 15 band EQ HD-31, 31 band EQ Pro MP, Professional two channel microphone preamp Instrument applications XTREME, Personal guitar processor with digital effects DST-4, Programmable guitar preamp with digital effects Power Plant, Studio guitar preamp DST 8080, 80 watt/ channel powered guitar preamp with effects The Acoustic, Personal acoustic guitar processor with digital effects SGX-2000, Analog and digital preamp/ processor for guitar SGX-Nightbass, Analog and digital preamp/ processor for guitar ECC, Guitar floor processor BCC, Bass floor processor MIDI X-15, MIDI foot controller with two expression pedals X-12, MIDI foot controller with optional Power Pedal controller For a full line catalog, write, call in, or email us to request one. For up to date information on new products send in your User Registration card NOW!

DUAL LEVELAR

Two Channel Tube Compressor/Leveling Amplifier

USERS GUIDE

Introduction Thank you for purchasing the Dual Levelar and congratulations! You now own one of the most sophisticated pieces of audio signal processing gear available. Similar in design philosophy to classic tube limiters, the Dual Levelar utilizes a VCA-less design for premium, musical performance. This design features electro-optical (Vactrol) and vacuum tube electronics which deliver classic sound without the old noise. Features Two channel tube and Vactrol-based Leveling Amplifier Stereo linking of channels Hand selected 12AX7 Tubes Vactrol - Optical electronic isolators Non-VCA design = transparent, classic sound Balanced XLR and 1/4 TRS inputs Balanced XLR and 1/4 TRS outputs Limiting and Compression ratios Auto or Fast release characteristics Variable Threshold rotary controls Variable Output level rotary controls Gain reduction LED ladder 10Hz to 20kHz Frequency Response >100dB Dynamic Range Extremely low noise All steel construction Designed and manufactured in the USA Fill in the following for your future reference: Date of purchase: ___________________ Purchased From: ____________________ Serial Number: 256-________ This a great time to fill out the User Registration card included with your Dual Levelar to become a completely informed A R T Artist. Returning the card to us ensures you of becoming the first to know about new A R T products as well as any further developments from A R T.

256-5004-101

Overview Compression is used to alter the dynamic range of a signal. In recording and live sound situations, compression and limiting is necessary to manage sounds with wide dynamic ranges. Dynamic Range is measured as the difference between the loudest and softest level of a signal. (i.e. from a scream to a whisper). Once a signal rises above or falls below the set threshold (selectable signal level), the compressor automatically changes its gain to raise or lower the overall signal level. Think of this as manually moving a fader up and down to try to keep a signal at a consistent level. Limiting can be described as a ceiling. When using a limiter, once the signal level reaches the threshold, it is unable to go any louder - it is limited to a desired level. In addition to making signal levels more manageable, it is common practice to apply compression or limiting to a signal to make it louder or more in-your-face. The benefit of using the Dual Levelar for these applications is in its design. By utilizing opto-electronics, the Dual Levelar allows you to add more compression without sounding like youre squashing the daylights out of the signal. Unlike typical compressors that use VCAs to control level detection, the Dual Levelar is very musical. The nature of its operation is much like the way your eye adjusts to light. Just as your eye transparently adjusts to changes in light, the Dual Levelar adjusts to changes in signal level.
unbalanced signals by simply plugging in an unbalanced cable. The inputs are designed for use with line level signals ranging from -30dBm to +15dBm. While it is possible to plug an instrument directly into the Dual Levelar, it is desirable to run the instrument into a preamp before the signal runs into the Dual Levelar. This will provide a stronger signal and will keep noise to a minimum. Microphones must be run into a microphone preamplifier (like A R Ts Tube MP) before being run into the Dual Levelar. Use the XLR input for use with equipment that provides an XLR output (like the Tube MP). Use the 1/4 input jack for balanced or unbalanced 1/4 applications. XLR pin configuration: pin 1 = Ground, pin 2 = Positive (hot), pin 3 = Negative (cold). The 1/4 TRS configuration is: Tip = Positive (hot), Ring = Negative (cold), Sleeve = Ground. Do not use both inputs at the same time. Outputs The outputs of the Dual Levelar are active balanced. You may use it in an unbalanced configuration without harm to the output circuitry. Use the unbalanced 1/4 jack for sending your signal to amps, processors or other unbalanced configurations. Use the XLR output to send signals to equipment which accepts XLR connections. Both outputs may be used at the same time. **Note: If you experience a grounding hum when using both output connectors (one to the console, one to an instrument amp) simultaneously, a ground loop may be the problem. To remedy this problem, disconnect (lift) the ground wire (pin 1) from the XLR cable plugged into the Dual Levelars output. This interrupts the ground path and therefore breaks the loop.

Connections

Its easy to interface the Dual Levelar with other equipment. All connections are made at the back of the Dual Levelar. Standard XLR and 1/4 inputs and outputs make patching simple. Note: for best audio quality, always use high quality cables. Inputs The Dual Levelar provides both an XLR and 1/4 input jack. Both jacks are balanced. The 1/4 jack can be used with
Controls, Switches and Indicators
Power The Dual Levelar is powered by an internal power supply. The Power switch and indicator LED are located on the front panel. If the attached power cord ever becomes damaged, discontinue use until you can have it repaired or replaced. Like all tube equipment, the Dual Levelar must be allowed to warm up before use. Upon power up you will see all the LEDs light, then turn off. This is normal and the Dual Levelar is ready for use once the LEDs have turned off. The 12ax7 tubes will reach normal operating temperature within one to three minutes. During this warm up period you may experience variations due to the THD of the tubes stabilizing. Again, this is normal and the Dual Levelar will provide consistent results once this warm up period is over. Threshold Control The Threshold control sets the point at which the Dual Levelar will act on a signal. Turning this control counterclockwise lowers the threshold (adding more compression to a signal). Turning this control clockwise raises the threshold. Setting the Threshold control is dependent on the input signal. The output from a guitar might be -20dB to -10dB, where the level from an insert on a console might be -10dB to +10dB. The easiest way to set the threshold control is to start with the control fully clockwise. Slowly turn the control counter-clockwise (lowering threshold) until you see the Threshold LED light. Now adjust the control (either lower or higher) until you have the amount of compression you desire. Active/Bypass Switch The Active/Bypass switch must be pressed in for the Dual Levelar to process a signal. In its out position, the Dual Levelar is bypassed and signal runs from the input jacks to
the output jacks with no processing. Use the Active/Bypass switch when setting the Dual Levelars output level to achieve unity (no boost or cut) gain. Unity gain is achieved when the active level is the same as the bypassed level. Limit/ Comp Switch In its out position, the Dual Levelars compression ratio is an active 2.3:1 ratio. This means that for every 2.3dB over the threshold the input signal rises, the Dual Levelars output will change by 1dB. This is a very mild and musical compression ratio which is ideal for smoothing all types of signals. In its in position, the Dual Levelars compression ratio is greater than 6:1. This is typically called soft limiting as it allows only a 1dB change in signal level for any signal reaching over 6dB over the set threshold. This setting is ideal for applications where exceeding a set level is not desirable (mixing, popping bass, etc.). Auto/Fast Switch The position of the Auto/Fast switch selects the release characteristics of the Dual Levelar. The out position allows the Dual Levelar to recover quickly once the signal falls below the threshold. The in position allows the Dual Levelar to adjust itself depending on the characteristics of the signal being processed (sometimes called program dependent). Use the fast setting when the signal has repetitive, consistent characteristics (kick drum, snare, vocals, etc.). Use the auto setting when the signal has varying characteristics (long decaying notes alternating with quick notes, mix material, etc.). Output Control The Output control sets the output gain of the Dual Levelar. When the control is fully counterclockwise, the output level of the Dual Levelar is attenuated by -83dB (off). Turning the control clockwise adds gain (sometimes called make-up gain). Since levels can be decreased when compression is applied, the Dual Levelar has the ability to

apply gain to bring the processed signal back up to unity (same as input level). To properly set the output level, adjust the control while switching between Active and Bypass. When these two levels are equal in volume, the output control is set properly. Gain Reduction Meter The four-LED meter is provided to give a visual indication of how much compression is taking place. The Threshold LED will light when the input signal reaches the set threshold level. The remaining three LEDs indicate how much the signal is being compressed. Their values are -3dB, -6dB and -12dB.
A R T Dual Levelar Specifications
Dimensions Weight Input Connections Output Connections Input Impedance XLR, 1/4 Output Impedance XLR, 1/4 Maximum Input Level, XLR Maximum Input Level, 1/4 Maximum Output Level, XLR Maximum Output Level, 1/4 Frequency Response Dynamic Range THD @ 0dB out: Equivalent Input Noise (EIN) XLR to XLR 1/4 to 1/4 Attack Time Release Time Slope Max. Attenuation Power Requirements 19W X 6.50D X 1.75H 5.5 Lbs balanced XLR & 1/4 TRS balanced XLR & 1/4 TRS 20K ohms, 1M ohms 600 ohm, 300 ohms +15dBm +15dBm +26dBm +20dBm 10Hz to 20KHz (+/-.5dB) >105dB (20-20kHz) <0.1% (typical) -100dBm (A weighted) -100dBm (A weighted) 6.5ms Fast-200ms, Auto-70ms-1sec. Comp - 2.3:1, Limit >6:1 28dB 95-125VAC 10 W (USA) Internal fuse. Other power requirements configured for country of destination.

Applications

Compressor/ limiter The main application of the Dual Levelar is to control the dynamic range of a signal level. Plug a line level (post preamplifier or other gain stage) source into either input and set the threshold and output controls to provide the desired amount of compression to the input signal. Stereo mix and mastering Because of its low noise and excellent tonal qualities, the Dual Levelar is ideal for running mixes through before recording to DAT or cassette. Used as a mastering device, the Dual Levelar is capable of adding warmth and impact to the overall signal level. Vocal and instrument levelling The musical nature of the Dual Levelar makes it ideal for use on a wide range of instruments and vocals. Place the Dual Levelar into a channel insert, after a preamplifier, or from a direct output of a channel of a mixer. Adjust the controls of the Dual Levelar to achieve the desired amount of compression.

A R T retains a policy of constant product improvement; therefore, specifications are subject to change without notice. A R T reserves the right to make changes in design or make additions to or improvements upon this product without any obligation to install the same on products previously manufactured. Were Online! For Product information, questions, applications, tips, answers and general discussion with A R T employees look for A R T on the Internet. Check out our Web Page at: http://www.artroch.com. email: artroch@aol.com
Warranty & Service Information
Limited Warranty Warranty service for this unit will be provided by Applied Research & Technology, Inc. in accordance with the following warrant statement. Applied Research & Technology, Inc. (A R T) warrants to the original purchaser that this product and the components thereof will be free from defects in workmanship and materials for a period of three years from the date of purchase. Applied Research & Technology, Inc. will, without charge, repair or replace, at its option, defective product or component parts upon prepaid delivery to the factory service department or authorized service center, accompanied by proof of purchase date in the form of a valid sales receipt. EXCLUSIONS: This warranty does not apply in the event of misuse or abuse of the product or as a result of unauthorized alterations or repairs. This warranty is void if the serial number is altered, defaced, or removed. A R T reserves the right to make changes in design or make additions to or improvements upon this product without any obligation to install the same on products previously manufactured. A R T shall not be liable for any consequential damages, including without limitation damages resulting from loss of use. Some states do not allow limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to you. This warranty gives you specific rights and you may also have other rights which vary from state to state. For units purchased outside the United States, service will be provided by an authorized distributor of Applied Research and Technology, Inc.
Service The following information is provided in the unlikely event that your unit requires service. 1) Be sure that the unit is the cause of the problem. Check to make sure the unit has power supplied, all cables are connected correctly, and the cables themselves are in working condition. 2) If you find the unit to be at fault, write down a complete description of the problem, including how and when the problem occurs. Please write down a description of your complete setup before calling Customer Service. 3) Call our Customer Service department for a Return Authorization (RA) number or questions regarding technical assistance. Customer Service hours are 9:00am to 6:00pm Eastern Time, Monday through Friday. 4) Pack the unit in its original carton or a reasonable substitute. The packing box is not recommended for a shipping carton. Put the packaged unit in another box for shipping. Print the RA number clearly on the outside of the shipping box. Print your return shipping address on the outside of the box. 5) Include with your unit: a return shipping address (we cannot ship to a P.O. Box), a copy of your purchase receipt, a daytime phone number, and a description of the problem. Keep your manual! 6) Ship your unit to: APPLIED RESEARCH AND TECHNOLOGY, INC. 215 TREMONT STREET ROCHESTER, NEW YORK 14608 ATTN: REPAIR DEPARTMENT RA#_______________________