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Vintage Audio
Dual Channel Class A
Discrete Preamplifier
Vintage Audio
M73 Dual Channel Discrete Preamplifier
Congratulations on your purchase of your new Vintage Audio M73 Dual Channel
all discrete Microphone Preamplifier
The M73 is based on the British classic 1290 preamp and is a faithful reproduction
using original Carnhill/St Ives input and output transformers coupled with an all
discrete design.
We put tremendous effort into all of our preamps and compressors to make your
music more enjoyable and your sessions less droll. Each unit is hand built to our
specifications and is constructed of nothing but the highest quality parts. As with
all of our preamps the M73 uses remote relay switching which shortens the signal
path and lowers noise making the preamps performance even better. Excellent
filtering is also provided to lower ripple and thus lower the noise floor even further
making them extremely quiet in terms of self noise.
Our M73 model comes with a full one year warranty and is built to the highest
standard using the highest quality components.
As with all professional equipment, please be sure to read all necessary
literature prior to hooking devices up and powering them on. All units are
set for voltage based on the original sale destination. Please consult the tag
below the AC inlet if you purchased a unit “used” or second hand to make
sure it is set for the right voltage before applying AC voltage.
About Vintage Audio
Vintage Audio is a small group of folks who love electronics and music. All are
musicians and nerds at heart. Johnny Five is a screen saver and Star Wars and Star
Trek share the airspace. We have been building pro audio gear for years and have a
real passion for offering affordable, extremely well made reproductions to the
audio community.
We are not re-inventing the wheel; Vintage Audio’s mission is to recreate the best
sounding modern reproductions of some of the most sought after classic circuits in
the world. We have a lot of experience on what it takes to make an excellent
sounding preamp or compressor. We hand select all of our components, pieces and
parts based on the character they impart, reliability. Most parts are Mil Spec, are
designed to last and provide years of unparalleled performance.
On to the good stuff!
All of our designs are set up to be extremely simple to use and to obtain great
So about your new preamp
The M73 is a 1290 style, dual channel, discrete, Class A, transformer coupled
preamp. The M73 offers a Direct Input on channel one and two as well as
Phantom, Phase, Pad and Impedance switching.
The M73 is a three stage preamp that offers fantastic headroom and a ton of
character making them a favorite on guitars, vocals, you name it.
The three stages of amplification provide the user with 80+db of gain at the output.
The M73 offers an impedance switch at the microphone input between 300 ohms
and 1.2k. The variable impedance is really nice for Ribbon microphones but works
well as a color option also. The use of Carnhill UK transformers keep the sound as
close as is possible to the original and simply sound beautiful.
These wonderful preamps impart a thick footprint and make everything sound
large and focused. The Phase shift in the transformers coupled with the
saturation make the M72 and M73 track stacking monsters making mixes full
with little effort.
These beautiful Dual Channel Class A Hot Rod preamps are handmade here in our
shop in the USA and are completely hand wired like all of our models.
The design is very simple and easy to use to obtain excellent results.
In the next section you will find a list of all controls to help
you get started.
Front Panel Controls Overview
Gain Control: The gain control is a 12 step Grayhill attenuator that controls the
amount of gain that the preamplifier can deliver. At 50db and below, the switch
merely controls the gain of the first two preamp stages. Once the control is
switched to over 50db, the third amplifier stage is added to achieve a maximum of
80+db. When miking drums, vocals or when using hot condensers we recommend
a 20db pad before reducing or adding any gain to the input signal to lower the
amount of possible distortion.
Phase Switch: This switch, when engaged, flips the polarity of the input pre input
transformer and essentially switches pins 2 and 3 for 180 degrees of phase
correction. This is particularly nice on drums and other instrument where this type
of phase correction is necessary.
Pad Switch: This switch engages a 20db pad pre input transformer for those
instruments with a high dynamic range.
48V (Phantom switch): This switch simply engages the 48V on board phantom
for condenser microphones requiring a phantom power supply.
Output control: The output control is set up to control the amount of level hitting
the last stage of the amplifier and output transformer. This allows the user to
effectively drive the preamp harder without clipping the input of your converter,
Tape machine etc.
Impedance switch: This switch in its normal (low) position sets the input
impedance that the microphone sees at 300ohms. When engaged to the high
position, the impedance is switched to 1.2K, which also increases the amount of
gain capable of the preamp on higher impedance microphones.
Hi-Z input: HI-Z direct inputs on the M73 for instruments and line signal.
Back Panel Overview
Input: Signal input for channel one and channel two respectively. Microphone as
well as line signals can be inputted into the M73. When using line level signals
make sure to have the 20 db pad engaged.
Outputs: Signal output for channel one and channel two. The signal here, as well
as at the input, is transformer balanced and isolated.
Please note: that transformer coupled outputs (as in the M73) require a balanced
connection either: electronically, with a transformer or Psuedo-balanced. Failure to
use a balanced connection to interface with the output of your M73 will result in
the absence of audio at the output. Please consult you owners manual of any
devices you are planning on interfacing with the M73*.
AC power inlet: Please consult the tag by the Ac power inlet for the correct
voltage and fuse rating. Voltages are set upon assembly and the label will indicate
which voltage it is set for as well as the appropriate fuse rating.
*Psuedo-balancing is fairly simple and merely requires that pins 1 and 3 be tied
together in either the cabling or at the jack. For ¼ and TT connections this equates
to Ring and Sleeve. This is the easiest and most cost effective solution though
balancing is best for the lowest noise and best performance
Input Impendence: 300-1.2k Ohm Floating, transformer coupled.
Output Impedance: 600 Ohm Floating transformer coupled
Gain: 80 db of total gain
Pad: -20db
Fuse: 250V Slow Blow 5x20mm, 315ma (120vac), 175ma (240vac).
Dimensions: 19x3.5x12 inches
Weight: 14 lbs boxed
Note: Mains voltages are set when the unit is constructed. All units are wired for
their Destination.
The Serial label contains information on what voltage the unit is wired for as
well as the correct 250v fuse rating.
Vintage Audio
All Vintage Audio products come with a full One Year
warranty against defect and are built to the highest
standard. For more info on this or other Vintage Audio
products or to request service, please see us at
Again, Thanks for your purchase!
We are confident that you will enjoy your new Vintage
Audio unit for years to come.
Made in the USA
Vintage Audio
Copywrite 2013
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