A-Designs MP-2A Series Specifications

A Designs Audio, Inc.
“Quality without Compromise”
P.O. Box 4255  West Hills, CA 91304 USA  (818)716-4153www.adesignsaudio.com
Before you start your new MP-2A Series True Tube Microphone preamp
please read the following:
ANY real tube product is sensitive to a high SPL environment. This may cause
microphonics in a recording situation. Make sure you are able to shock
mount and or place the unit in isolation if need be. Direct light will also effect
tubes, as well.
PLEASE, be sure to have at least one rack space between any tube products
from the product above and below the unit. This will ensure your tube unit will
not over heat. Over heating will cause damage to the tubes and shorten their
life span. If possible place, the MP-2A Series unit in the top rack space to
allow air flow.
If you have received your unit via UPS/Fed-Ex/DHL, or any other courier, your
MP-A should have been double boxed for protection. If it was not double
boxed, please contact your dealer and return the unit to them for a
We demand ALL our units to be double boxed to help prevent damages during
Thank you,
Peter Montessi
A Designs Audio LLC
Fill out and Return Warranty Card to A Designs Audio, Inc.. Warranty begins the day of purchase. Your
name will be placed on our mailing list (unless otherwise requested) for future updates and new product
A Designs Audio, Inc. reserves the right to make improvements or changes at any time to this product.
Published by: A Designs Audio, Inc.
P.O. Box 4255
West Hills, CA 91304 U.S.A.
Edition 4.0 2009
Copyright 2009 A Designs Audio, Inc. All Rights Reserved.
WARNING: Removing Cover Will Void Your Warranty.
1 Year Limited Warranty Internal Parts, 30-Day Limited Warranty Labor, 30-Day Limited Warranty Tubes
A Designs warrants that our hardware conforms substantially to the specifications contained in this
manual when used in accordance these specifications for a period of 1 year from the date of original
purchase from A Designs or its authorized dealers. In case of a valid warranty claim, your sole and
exclusive remedy and A Designs' entire liability under any theory of liability will be, at its option, to repair
or replace the product without charge, or, if not possible, to refund the purchase price to you. The
warranty is not transferable and applies only to the original purchaser of the product.
For warranty service, contact A Designs Audio at 818-716-4153 to obtain a Return Merchandise
Authorization (RMA) number.
Warranty is void if product serial numbers have been removed or if the product has been damaged by
abuse or unauthorized modification and repair. There are no user serviceable parts inside.
This warranty is in lieu of all warranties whether oral or written, expressed or implied. A Designs Audio
makes no other warranty either expressed or implied, including without limitation, any implied warranties
of merchantability, unless for a particular purpose or noninfringement. purchasers sole and exclusive
remedy under this warranty shall be repair or replacement as specified herein.
In no event will a designs audio be liable for any direct, indirect, special, incremental or consequential
damages resulting from any defect in the product, including lost profits, damage to property and, to the
extent permitted by law, damage for personal injury, even if A designs audio has been advised of the
possibilities of such damages.
A Designs, A Designs Audio, Inc., and MP-2A are trademarks of A Designs Audio, Inc. All other
trademarks are the property of their respective owners.
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
Welcome to the Analog Sound of the MP -2A. This is an all tube product, and there are some basics you
should come to understand before using this product for the first time.
Tubes are a component that have specialized and unique features. If you are a "pre" or baby boomer,
born before 1957, you may recall using tubes in various products, such as radios, amplifiers, and
televisions. So, this is just to refresh your memory. If you are a "post" baby boomer, this could be your
first experience with tubes, so please pay close attention! (You will be tested at the end of this manual).
Tubes are most efficient and effective when "warmed up." This means, upon starting the MP-2A, you
should allow the tubes to become fully heated before attempting to operate. The minimum amount of
warm up time is approximately 15 to 20 minutes.
Set up your instrumentation layout before powering up the MP-2A. Plug in your instrument or microphone
while the unit is off. This will prevent unwanted noise such as "pops." The same applies when you shut
down. Allow a minimum of 25 seconds for the power to drain from the tubes properly. Then you can
unplug your instrument or microphone. Always turn your Phantom switch to the off position before
plugging or un-plugging your Microphone.
Placing the MP-2A Series in a rack, we recommend using the first tier or allow one x space in order to
properly ventilate. Avoid overheating! Too much heat will reduce the life-span of your tubes. We also
recommend strongly that you observe SPL and shock mount any tube product.
A Designs has scoured the earth for the perfect combination of tubes for this unique quality sound. Go
ahead, get started. Read the following pages carefully to become acquainted with the warmth and clarity
that the MP-2A can deliver to your recordings.
Please feel free to email A Designs Audio, Inc. via the website with any creative applications for the use
of the MP-2A. We have included some applications in this manual. We may just include your suggestion
on our website!
Congratulations on the purchase of your MP-2A all tube microphone preamplifier!
Most of all, have fun.
Peter Montessi, President
A Designs Audio, Inc.
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
Legal Notice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 2
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 5
Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 6
Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 11
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
Vacuum-tube design
Two (2) Level Volume Controls
Two (2) Polarity Switches
Two (2) Tone Switches
Two (2) Phantom Switch
Two (2) Backlit True VU Meters
Red Jewel Lamp On/Off
Two (2) Neutrik Combo XLR 1/4" Input Connectors
Two (2) XLR Output Connectors
Zero Feedback Loop
Two (2) U-Rack Space
Two (2) CineMag Input Transformers
Two (2) Custom Wound Output Transformers
Two (2) 6NI-P Tubes
Two (2) EF86 Tubes
Clean and airy high end
Warmth, transparency, and quality sound.
In line with our company policy of continuous development, the above features are subject to change
without notice.
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
Input Impedance
Gain Range
Noise (EIN)
Mic Phantom
Mic Input Phase
1.4k Ohm
-128 Weighted
Switchable 48 Volt Power Source
Switchable 0-180
Instrument Jack Input
Input Impedance
1/4 phono
Min > 100k Ohm
Balanced XLR Output:
Output Impedance
Maximum Level
600 Ohm Switchable to 10k
+22 dBu
Frequency Response
Low-Z, transformer-balanced
20 Hz - 60k Hz
THD: > .08 @ 1 Khz
Power Requirements:
100/120/230 VAC - 42 Watts
Dimensions (W x H x D)
19" x 3.5" x 10"
18 lbs. 8.16kg (Shipping weight 20 lbs.) MP-1 17 lbs.
In line with our company policy of continuous development, the above specifications are subject to
change without notice. Testing was performed BE Labs Oxnard, CA
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
* Channel 1&2 VU Meters - Meters provide general indication of level. They are set to -4dB.
* Level control knobs are just that. They will control the level/pad of the incoming signals.
* Polarity - 0 to 180
* Tone Switch ½ and 3/4 - This switch will allow you to set your outputs to your configuration.
* Phantom-On/Off - The Phantom Switch is there to give you the option of using various kinds of
Microphones. If you are using a Condenser Microphone please make sure you have the Phantom Switch
in the on position. If you turn the Phantom Power Switch off while the Mic is still plugged in there will be
a 5 second delay before it is completely off.
* Heat Vents - Allow the flow and circulation of air to cool the tubes and transformers.
* Power Switch - Large size for easy operation up and down (on/off).
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
* Power Light Indicator - Red Jewel light indicator. When power is on... the light will illuminate.
*Heat Vents - Allow the flow and circulation of air to cool the tubes and transformers.
*XLR outputs Balanced
*XLR inputs Balanced
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
* AC Plug - For electrical outlet (caution: please check to see what Voltage your MP-2A is set to). If the
Voltage Box is not marked according to your country's code please notify A Designs before powering up.
* Fuse Amperage - These are placed on the MP-2A to indicate which voltage your unit is set up for. USA
Voltage should be set to 120v. For export to countries with 220v, the correct box should be marked at
the back of the unit. If not marked or marked incorrectly, please notify A Designs before you turn your unit
* Fuse Box - This box acts as a fuse container draw. The Fuse draw will slide in and out for easy access
to change your fuse, as necessary.
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
Caution - Caution Sign is a warning that extreme heat will create damage to the Tubes. Please make sure
you have proper spacing in the Rack. We recommend 1x spacing if used in a Rack mount. Or you can
place the MP-2A on the top tier of your Rack. Not allowing proper air flow voids the factory warranty.
XLR Outputs - The XLR output is balanced out and you have the option to change the output ohms from
the face of the MP-2A (600 ohms/ 10k) by using the OUTPUT Switch located on the front panel of the
MP-2A. XLR's are clearly marked indicating which Channel is being used.
XLR Inputs - The XLR input is used for Microphones. You can use the inputs for other instruments. If you
are using a condenser Microphone, please make sure your Phantom Power is in the on position. The
Phantom Power switch is located on the front panel. (See Illustration 1). XLR's are clearly marked
indicating which Channel is being used.
Serial Number - If this serial number is removed or tampered with, your warranty will be void.
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
The MP-2A has a 2U rack space which fits nicely into any Studio Rack and will compliment your
Width: Standard 19 inches for easy Rack Mount installation.
Height: Standard 3.50 inches or 2U Rack Space.
Depth: 10 inches
Weight: 18 lbs 8.16 kg.
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
A good, quality microphone preamp will add a full, warm sound to any type of
recording or live performance.
Generally, we begin by setting our input signal to unity, then concentrate on
other devices such as compressors or effects for modifying the sound. But, this
does not always have to be the case.
You will notice this unit is not cluttered with bells and whistles. Less is more.
The MP-2A was designed for simplicity. This has not restricted the sound, but
enhanced it. This unit was designed to free your imagination to create music
with unencumbered tonal qualities.
Mic-pre settings, as a rule, begin with gain structure, unity or 0db. Although this
seems a great place to start, this may not always have the best application for
your particular project. Try, what we call, "driving the tubes" on the MP-2A,
instead of introducing effects into a chain. Simply stated, try sending the input
signal well into the red. Many producers and engineers use this technique for
bass guitars in rock/pop songs, and more recently, vocals in chorus.
Another technique audio engineers use, when recording an instrument in
stereo, is to run one side in- phase and the other side out-of-phase. This trick
tends to deceive the stereo image and also defuses bass boom by canceling
out frequencies. It may sound unusual, but surprisingly, there are large
numbers of published Audio CD's where this technique has been employed to
improve the overall sound.
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007
Apart from creating special effects, the MP-2A can be used to fix problematic
recordings. An example of this would be a drum track that has gone
Try the following:
(1) Send the individual tracks to the MP-2A.
(2) Change the phase switch on one of the tracks.
(3) Compare this with the bass response.
You will then be able to determine which tracks are in-phase and out-of-phase.
This allows you to hear how much of the sound you are missing.
Above all, it is important to experiment. Do not to leave the controls "set in
stone." Most professional audio engineers and producers modify the mic-pre
controls first, before moving on to a secondary unit.
Note: If you have a trick or tip that you would like to share with us, contact A
Designs Audio, Inc. through our website or mail us at:
Attention: Applications, P.O. Box 4255, West Hills, CA 91304.
We will publish it on our website with your name, if you choose.
A Designs Audio  Owners Manual MP -2A  Edition 4.0  January, 2007