ART SOLOMPA Solo MPA Multivoice Tube Preamplifier User Manual

SOLO MPA
MULTIVOICE TUBE
PREAMPLIFIER

User’s Manual

IMPORTANT SAFETY INSTRUCTIONS

CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER (OR BACK). NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
The lightning flash with arrowhead symbol, within equilateral triangle, is intended to alert the user to the presence of uninsulated “dangerous voltage” within the product’senclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance (servicing) instructions in the literature accompanying the appliance.

WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE.

1. Read these instructions.

2. Keep these instructions.

3. Heed all warnings.

4. Follow all instructions.

5. Do not use this apparatus near water.

6. Clean only with dry cloth.

7. Do not block any ventilation openings.
   Install in accordance with the manufacturer’s instructions.

8. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat.

9. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one wider than the other.
   A grounding type plug has two blades and a third grounding prong. The wide blade or the third prong are providedfor your safety. If the provided plug does  not fit into your outlet, consultan electrician for replacement of the obsolete outlet.

10. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from the apparatus.

11. Only use attachments/accessories specified by the manufacturer.

12. Use only with the cart, stand, tripod, bracket, or table specified by the manufacturer, or sold with the apparatus. When a cart is used, use caution when moving the cart/apparatus combination to avoid injury from tip-over.

13. Unplug this apparatus during lightning stormsor when unused for long periods of time.

14. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.
    • The apparatus draws nominal non-operating power from the AC outlet with its POWER or STANDBY/ON switch not in the ON position.
    • The mains plug is used as the disconnect device, the disconnect device shall remain readily operable.
    • Caution should be taken when using earphones or headphones with the product because excessive sound pressure (volume) from earphones or headphones can cause hearing loss.

CAUTION

• Do not expose this apparatus to drips or splashes.
• Do not place any objects filled with liquids, such as vases, on the apparatus.
• Do not install this apparatus in a confined space such as a book case or similar unit.
• The apparatus should be located close enough to the AC outlet so that you can easily g rasp the power cord plug at any time.
• If the product uses batteries (including a battery pack or installed batteries), they should not be exposed to sunshine, fire or excessive heat.
• CAUTION for products that use replaceable lithium batteries: t here is danger of explosion if a battery is replaced with an incorrect type of battery. Replace only with the same or equivalent type.

WARNING

• Products with Class I construction are equipped with a power supply cord that has a grounding plug. The cord of such a product must be plugged into an AC outlet that has a protective grounding connection.

WARNING

• To prevent possible hearing damage, do not listen at high volume levels for long periods.

RACK-MOUNTING THE UNIT
Use the supplied rackmount screw kit to mount the unit in a standard 19-inch rack, as shown below.
Remove the feet of the unit before mounting. CAUTION

• Leave 1 U of space above the unitfor ventilation.
• Allow at least 10 cm (4 in) at the rear of the unit for ventilation.

CAUTIONS ABOUT BATTERIES
This product uses batteries. Misuse of batteries could cause a leak, rupture or other trouble. Always abide by the following precautions when using batteries.

• Never recharge non-rechargeable batteries.
  The batteries could rupture or leak, causing fire or injury.

• When installing batteries, pay attention to the polarity indications (plus/ minus(+/-) orientation), and install them correctly in the battery compartment as indicated. Putting them in backward could make the batteries rupture or leak, causing fire, injury or stains around them.

• When you store or dispose batteries, isolate their terminals with insulation tape or something like that to prevent them from contacting other batteries or metallic objects.

• When throwing used batteries away, follow the disposal instructions indicated on the batteries and t he local disposal laws.

• Do not use batteries other than those specified. Do not mix and use new and old batteries or different types of batteries together. The batteries could rupture or leak, causing fire, injury or stains around them.

• Do not carry or store batteries together with small metal objects. The batteries could short, causing leak, rupture or other trouble.

• Do not heat or disassemble batteries. Do not put them in fire or water. Batteries could rupture or leak, causing fire, injury or stains around them.

• If the battery fluid leaks, wipe away any fluid on the battery case before inserting new batteries. If the battery fluid gets in an eye, it could cause loss of eyesight. If fluid does enter an eye, wash it out thoroughly with clean water without rubbing the eye and then consult a doctor immediately. If the fluid gets on a person’s body or clothing, it could cause skin injuries or burns. If this should happen, wash it off with clean water and then consult a doctor immediately.

• The unit power should be off when you install and replace batteries.

• Remove the batteries if you do not plan to use the unit for a long time. Batteries could rupture or leak, causing fire, injury or stains around them. If the battery fluid leaks, wipe away any fluid on the battery compartment before inserting new batteries.

• Do not disassemble a battery. The acid inside the battery could harm skin or clothing.

For European Customers
Disposal of electrical and electronic equipment and batteries and/or accumulators
(a) All electrical/ electronic equipment and waste batteries/accumulators should be disposed of separately from the municipal waste stream via collection facilities designated by the government or local authorities.
(b) By disposing of electrical/electronic equipment and waste batteries/accumulators correctly, you will help save valuable resources and prevent any potential negative effects on human health and the environment.
(c) Improper disposal of waste electrical/ electronic equipment and batteries/ accumulators can have serious effects on the environment and human health because of the presence of hazardous substances in the equipment.
(d) The Waste Electrical and Electronic Equipment (WEEE) symbols, which show wheeled bins that have been crossed out, indicate that electrical/ electronic equipment and batteries/accumulators must be collected and disposed of separately from household waste. If a battery or accumulator contains more than the specified values of lead (Pb), mercury (Hg), and/orcadmium (Cd) as defined in the Battery Directive (2006/66/ EC), then the chemical symbols for thoseelements will be indicatedbeneath the WEEE symbol. Pb, Hg,Cd (e) Return and collection systems are available to end users. For more detailed information about the disposal of old electrical/electronic equipment and waste batteries/accumulators, please contact your city office, waste disposal service or the shop where you purchased the equipment.

Wireless Equipment Precautions

Compliance of radio transmitter and interference This product has the function of broadband transmitter using 2.4 GHz Band.
Use frequency range: 2400 MHz – 2480 MHz Maximum output power: Bluetooth® Class2 (less than 2.5 mW)

CAUTION
Use only in the country where you purchased the product.

• Authorization of wireless devices are different in countries or regions.
• Depending on the country, restrictions on the use of Bluetooth wireless technology might exist.

Radiation Exposure requirements
This equipment meets the regulation, which is recognized internationally, for the case of human exposure to radio waves generated by the transmitter.
Radiation Exposure requirements
This equipment complies with EN.6231 1; Assessment of electronic and electrical equipment related to human exposure restrictions for electromagnetic fields; the harmonized standard of DIRECTIVE 2014/ 53/ EU.
Laser Information
This product contains a solid state laser system within its enclosure and is classified as a “CLASS 1 LASER PRODUCT”. To avoid exposure to the laser beam, do not attempt to open the box. tJ•W•Ma

WARNING

• DO NOT OPEN THE PROTECTIVE HOUSING WITH A SCREWDRIVER.
• USE OF CONTROLS, ADJUSTMENTS OR FOLLOWING PROCEDURES OTHER THAN AS DESCRIBED HEREIN MAY RESULT IN HAZARDOUS RADIATION EXPOSURE.

This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy, and if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.

CAUTION: Changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.
This device complies with Industry Canada licence-exempt RSS standard(s).
Operation is subject to the following two conditions: (1) This device may not cause interference, (2) This device must accept any interference, including interference that may cause undesired operation of the device.

Introduction

Thank you for purchasing Applied Research and Technology’s Solo MPA. For users ready to take the next step, the ART Solo MPA Multivoice Tube Preamplifier picks up where built-in preamps drop off. Combining the best of both worlds, the Solo MPA allows users to blend between a pristine low-noise/low-distortion solid state transistor circuit and a warmer Class-A tube mic preamp. Along with the flexible EQ controls, users can voice the Solo MPA to create their own signature sound.
Featuring 48V phantom power and a variable input impedance control, users can tailor the Solo MPA to suit their microphone of choice, be it a high-quality dynamic, a studio grade condenser or a low-level ribbon. A Low-Cut control allows vocals to be sculpted for clarity while the Tilt EQ can be used to emphasize high presence or low-end warmth.
Housed in a compact 1U space rack-mountable chassis with a CNC milled aluminum face plate, the Solo MPA is designed to deliver years of reliable operation in the studio or at the venue.

The Solo MPA’s feature set

• Adjustable input impedance for flexible microphone voicing (600 to 80K ohms).
• Flexible Tilt EQ
• Tunable Lowcut Filter
• Variable Voice Tube/Solid State Control
• Analog VU meter
• Front accessible meter trim
• Backlit function switches
• Discrete class A FET input microphone preamplifier
• Low noise at low gains
• Low THD
• Wide frequency response
• Front mounted Instrument/DI Input
• Very high input impedance
• +4dBu/-10dBV output level selection
• Automatically switches to the instrument input when you plug in
• 1U Rack mount aluminum front plate
• Removeable IEC cord
• Internal power supply
• 3-year parts and labor warranty

Installation

The ART Solo MPA may be used in a wide variety of applications and environments. In a rack-mountable, all-steel enclosure, the unit is designed for continuous professional use. Mounting location is not critical, however for greater performance reliability we recommend that you not place the unit on top of power amps, or other sources of heat and/or strong magnetic fields. The tube circuitry needs about a minute to “warm up” and stabilize from a cold power up.

AC Power Hookup

The Solo MPA has an internal power supply designed to operate from 100/120V~ or 220/240V~, 50/60Hz 25W. Units manufactured for use outside of North America have been modified to comply with the required electrical specifications.
Under no circumstances should the power cable be altered. If the cable becomes cut or damaged, discontinue its use and have it replaced before operating the Solo MPA.
The power source must provide a good ground connection, and the ground pin on the mains plug should never be defeated.

Audio Connections

Audio connections to and from the Solo MPA are:Unbalanced 1/4-inch cables may be used with no damage to the Solo MPA. We recommend using only high-quality cables equipped with the appropriate connectors.

Front Panel

1. Power Switch
   The Power switch turns the power on and off to the unit. The Solo MPA should be turned “on” with all monitor levels turned down to protect against any “thumping” caused by power up. Likewise, the Solo MPA should be turned “off” after turning all monitor levels down.
   When the Power switch is turned on, the VU meters will light. Switch LED’s will light if its associated switch is in the “in” position. Power on the Solo MPA before any monitoring outputs or power amps are turned on.
   Like all tube-based equipment, the Solo MPA needs to warm up to operating temperature. The 12AX7 tube will reach operating temperature within one to three minutes. During this warm-up period you may experience sound variations due to the bias of the tubes stabilizing. This is normal and the Solo MPA will provide consistent results once the warm-up period is over.
   If the Solo MPA fails to power up when the POWER switch is turned on, check to see that its power cord is plugged into an active outlet. Locate the fuse installed in the IEC connecter, verify that the fuse is not blown, replace if blown with the same type and value fuse. If the unit still fails to operate properly, turn it off and unplug it. Then consult your dealer or the ART Customer Service Department.

2. Instrument Input
   The ¼-inch jack on the front panel serves as an instrument input. The input impedance is always >1M ohm and the gain can be adjusted by the Input gain control. The maximum input signal level is +17dBu (5V RMS) @ minimum input gain.
   When you plug into this jack it DISABLES the balanced input on the rear of the unit. This feature allows you to keep the rear input patched in, and use the instrument input to switch to a different source. The instrument input allows the Solo MPA to serve as a great DI device as well.

3. Gain Control
   This control optimizes the input signal level before the tube gain is applied. Both Microphone and Instrument input gainsremain the same and are affected by this adjustment. Input gain can be adjusted from 0dB (for line level signals) to 40dB of gain. The analog meter is used to see the effects of the input gain setting. Additional gain is available via the Gain switch (+20dB) and the Master Output control (+15dB) for a maximum of 75dB total.
   The combination of these controls allows the user to adjust the signal level through the tube section, providing more or less “tube” sound as needed. To obtain more “tube’ sound, increase input gain, use the +20dB Gain switch and less Analog output gain.
   Both the microphone and instrument inputs are optimized for their respective sources as far as signal levels and noise performance. Running most of the gain on the input generally provides the best performance of the Solo MPA.
   Refer to the section titled “Obtaining the best noise performance with the Solo MPA for more detailed instructions on setting the Input Gain control for the best results.

4. Impedance Control
   This knob controls the Mic/line input amplifier impedance. This function allows variable voicing of any microphone. Refer to the section titled “Adjusting the Input Impedance” for more information on making the most of this function.
   The ¼-inch instrument input is NOT affected by this control, and remains high (>1M ohm) impedance.

5. Low Cut Control
   The Low-Cut Filter is a single tuned High Pass Filter that is frequency tunable. The input signal can be filtered to remove “pops” or other extraneous low frequency information. This control moves the rolloff frequency from 10 Hz (fully CCW) to 200 Hz (fully CW). Since it is single tuned, it preserves some low frequency content so its use is less obtrusive. It is especially useful in close mic’d applications.

6. Tilt EQ Control
   The Tilt EQ control can be used to emphasize a high presence or low-end warmth in the audio signal.

7. Voice Control Solid State/Tube
   The Voice control can be used to blend the Solid-State and Tube stages.

8. Gain Switch
   The Gain switch is used in conjunction with the input gain control to adjust signal levels through the Solo MPA. When depressed, the tube circuit provides 20dB more gain in the signal path. This also has the effect of driving the tube harder and making the tube the dominant source of gain and overload character.

9. Phantom Switch
   Phantom power on the microphone input is turned on and off with this switch. Depressing the switch will power condenser microphones and other 48volt phantom powered devices. Phantom power is supplied to pins 2 and 3 of the input jack.
   NOTE: Dynamic microphones are NOT affected by Phantom power, although it should be turned off when using dynamic microphones or line level inputs.
   Note: It’s suggested to mute the output of the Solo MPA when engaging or disengaging phantom power, this will help prevent damage to other equipment connected to the Solo MPA.

10. Phase Switch
    The Phase switch, when engaged, will invert the phase of the audio signal. The Phase switch is located after the tube circuit in the signal path, so you can hear slight differences between different phase selections in the “normal” plate voltage mode near saturation. There are a number of reasons why adjusting the phase is needed these include, wiring errors and inversions in some audio equipment. Some microphones sound different depending on the phase chosen.
    If two microphones are out of phase, they may cancel at various frequencies (depending on the distance between them). If this happens, try changing the phase of one of the microphones and see if there is an improvement.

11. VU Meter
    The analog meter is used for monitoring signal levels at the balanced output as well as previous stages.

12. Meter Trim
    The Meter Trim is used to adjust the Meter’s “0” point. This may change if the unit is NOT mounted with the front panel perpendicular to the floor.
    Using a small flat-blade screwdriver you can mechanically fine-tune the meter indicator position if, for example, it does not rest at the leftmost position when the unit is OFF.
    The Output level of the Solo MPA can be monitored by selecting the function you want displayed on the VU meter.

13. Master Output Control
    The output signal level at the rear output jacks is adjusted by this control. It can provide from +15dB of gain (fully clock- wise) to completely muted. You can see the effects of this adjustment reflected in the analog meter.

Rear Panel

1. I/O Level Switch
   +4dBu/-10dBV
   The +4dBu/-10dBV switch is used to set the output level of the Solo MPA for the appropriate system levels. This feature allows you to match 0 VU on the meters of the Solo MPA and your mixer or other equipment.
   When depressed, 0 VU on the output meter corresponds to +4dBu on the outputs. In –10dBV mode, the output level measures –10dBV.

2. Balanced Inputs
   The Solo MPA’s XLR connectors follow the AES standard of Pin 1 = Ground, Pin 2 = Hot (+), Pin 3 = Cold (-). The Balanced inputs have an input impedance that is variable from 150 to 3K ohms via the front panel control. The Maximum input level is +19dBu balanced and +17dBu unbalanced.

3. Balanced Outputs
   The Solo MPA’s flexible active balanced outputs are available on both ¼-inch and XLR connectors. They offer low impedance for driving long cable runs and are intelligent enough to maintain the same output level whether it is balanced or unbalanced.
   The Solo MPA’s XLR connectors follow the AES standard of Pin 1= Ground, Pin 2= Hot (+), Pin 3= Cold (-). The balanced ¼-inch phone jacks are typical Tip = Hot (+), Ring = Cold (-), Sleeve = Ground Maximum output level is +27dBu balanced and +20dBu unbalanced.

4. IEC Power Connector
   This is a fused variable voltage selectable IEC connector. The fuse drawer can be removed for fuse replacement and used to set for the correct incoming voltage 100-120V or 220-240V. Rotate the fuse drawer so that the arrow from the drawer lines up with the IEC block for the mains voltage.

Operating Instructions

Obtaining the Best Noise Performance

1. Start by turning down the Input Gain knob and centering the Analog Output knob. The Analog meter will now indicate how much tube headroom there is. Set the +20dB switch to the out position.
2. Increase the Input Level knob until the meter reads above –10dB.
3. If you have turned the input knob fully clockwise and the indicated level is still below –10dB on the meter, center the input knob and depress the Gain switch. Increase the Input Gain until there is sufficient level.
4. This procedure optimizes the gain elements to provide the widest dynamic range possible.

Adjusting the Input Impedance
The same microphone can sound different on various pre-amps. One reason is that every pre-amp presents a different load to on its’ input, some even change as gain is changed! Our third-generation discrete front end was designed to be absolutely transparent. Every nuance of the microphone is maintained providing detail masked by inferior pre-amps. The Input Impedance control is one key element in providing new versatility in voicing microphones.
Note: the Input impedance control only affects the XLR connector inputs. The ¼-inch instrument input on the front panel is NOT affected by this control in any way. The instrument input impedance is ALWAYS >1M ohm.
Dynamic microphones are affected as much as phantom powered microphones are. We provide a continuously variable impedance control to allow you to fine-tune the voicing, finding the perfect interaction between microphone and pre-amp.

1. Start by setting the centering the Input Impedance knob. This provides a 20K ohm load.
2. Lower impedance loads will reject more noise picked up by cabling, and dampen microphone resonance.
3. Higher impedance settings provide a more “open” sound. Lower impedances tend to focus the sound more.

Specifications

mode)
Low Cut Filter| single pole, 10-200Hz adjustable
Tilt EQ| +/- 12dB adjustable
Power Requirements| 100-120V 60Hz / 220-240V 50Hz
Dimensions: (HxWxD)| 1.75-inch x 19-inch x 6.0-inch 4A5 cm x 48.3 cm x 15.2 cm
Weight| 5.6 lb / 2.5kg

ART maintains a policy of constant product improvement. ART reserves the right to make changes in design, or make additions to, or improvements upon, this product without any obligation to install same on products previously manufactured. Therefore, specifications are subject to change without notice.

Block Diagram

WARRANTY INFORMATION

Limited Warranty
Applied Research and Technology will provide warranty and service for this unit in accordance with the following warrants:
Applied Research and Technology, (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 and Technology 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 limitations 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 have other rights, which vary from state to state.
For units purchased outside the United States, an authorized distributor of Applied Research and Technology will provide service
Fill in the following information for your reference:
Date of purchase ………………………………………
Purchased from ……………………………………….

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, all cables are connected correctly, and the cables themselves are in working condition. You may want to consult with your dealer for assistance in troubleshooting or  testing your particular configuration.
2. If you believe that the ART unit is at fault, go to www.artproaudio.com.
3. Select “Support”, then “Return Authorization Request” to request a return authorization number.
4. If you are returning the unit for service, pack the unit in its original carton or a reasonable substitute. The original packaging may not be suitable as a shipping carton, so consider putting 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 note with the RA number and your contact information, including a return shipping address (we cannot ship to a P.O. box) and a daytime phone number, and a description of the problem, preferably attached to the top of the unit. Also include a copy of your purchase receipt.

www.artproaudio.com
Email: support@artproaudio.com
©2023 Applied Research & Technology / Yorkville Sound
Manual-Owners-ART-SOLOMPA-00-1v2
• January 11, 2024
111-5004-200

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