Millennia STT1 User Manual

INTRODUCTION (see block diagram)

The STT-1 Origin is a collection of Millennia's essential product line combined into one box. You might
call it our "greatest hits" compilation. The STT-1 is a single channel (mono) processing chain with various
signal path topologies (vacuum tubes, discrete transistors, audio transformer, transformerless) all
selectable at various functions. The STT-1 offers an entirely discrete, entirely Class-A direct signal path
from input to output. The signal path can be variously selected to use vacuum tubes or transistors, trans­former or non-transformer coupling. The STT-1 also offers additional monolithic utility outputs. We
show (yes, we counted) at least 134 different product combinations available in the STT-1 Origin —
ranging from the most musically transparent, sonically accurate, and dynamically stable audio circuits, to
sublime levels of vacuum tube and transformer 'euphony', and everything in between. The possibilities
afforded the creative engineer, producer, and musician are virtually endless. The STT-1 includes the
following functions, employing the essential topology of Millennia products as noted by name:

1.) HV-3 discrete hybrid solid state microphone preamplifier -or-

2.) M-2 vacuum tube microphone preamplifier

3.) Vacuum tube instrument DI input, routable into M-2 vacuum tube -or- HV-3 solid state gain amplifiers

4.) Balanced line level (+4) input, routable into M-2 vacuum tube -or- HV-3 solid state gain amplifiers

5.) NSEQ four-band parametric EQ, selectable via vacuum tube -or- discrete solid state audio topology

6.) TCL opto-compressor/limiter/de-esser, selectable via vacuum tube, solid state, or non-amplifier topology

7.) All paths selectable via transformer -or- transparent transformerless input signal path

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The STT-1 Origin has three available audio inputs.

1.) Line Input (XLR or 1/4" phone, rear panel)

2.) Mic Input (XLR, rear panel)

3.) Instrument DI Input (1/4" phone, front panel)

A user must select one of the above three inputs via the "SOURCE" rotary switch. The above inputs cannot
be combined or mixed internally. Polarity of any input can be flipped 180 degrees, if desired. The mic
input can also receive +48V Phantom power, if required.

All input sources (mic, line, DI) are routed directly to the front-end gain amplifiers. A front-end gain
amplifier is selectable as either vacuum tube (M-2) or solid state (HV-3). Each front-end gain amplifier has
its own gain adjustment potentiometer (approximately +10 dB to +50 dB solid state range and +20 dB to
+40 dB vacuum tube range). A user can select one front end gain amplifier, only (VT or SS) — front end
gain amplifiers cannot be mixed or used simultaneously. Additionally, a Millennia MIT-01 audio-path
transformer is selectable at all inputs (mic, line, DI) to the gain amplifiers. Use the transformer when you
want to add an enhanced, "in-your-face" euphonic personality to high-level input signals. The MIT-01 input
transformer remains relatively uncolored and sonically neutral with nominal signal levels.

The front-end amplifiers feed two areas simultaneously: (1) a direct utility ouput and (2) the EQ/Dynamics
section. The direct output is placed before the EQ and Dynamics sections. The direct output is FET-based,
monolithic, balanced, and always active. The EQ and Dynamics sections can share the same amplifier stage
(selectable as vacuum tubes or field effect transistors), which opens up some interesting operational fea­tures. The ORIGIN's Dynamics functions can be used with vacuum tube amplfication, solid state amplifica­tion, or with no amplification whatsoever. See this manual's specific operating sections for important detail
on EQ and Dynamics co-operation.

The STT-1 has three other 'main' outputs: (1) monolithic XLR balanced, (2) discrete pure Class-A 1/4"
unbal, and (3) discrete pure Class-A XLR unbalanced. Main outputs sit at the back end of the STT-1,
following all functions. An additional RCA phono jack provides a linking function for stereo operation of
two STT-1 Dynamics sections. The Selco VU meter is a true audio responding level meter which can be
selected to measure the main output level or Dyanamics gain reduction.

STT-1

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STT-1 REAR PANEL

(1) MICROPHONE INPUT "MIC INPUT"

Conventional 3-pin female XLR input jacks for use with all standard balanced microphones, both phantom
and non-phantom powered. Provides +48 Volts DC Phantom powering via front panel switch. Input
impedance is approximately 6,200 ohms with phantom power switched in. Microphone input is selected
via a front panel rotary switch marked "Source - MIC." Pin 2 is positive polarity. Pin 3 is negative polarity.
Connector contacts are Neutrik Galvatronic gold plated. It is suggested that XLR cable connectors used
with the STT-1 employ identical plating. This input feeds either the vacuum tube gain amplifier (M2) or
solid state gain amplifier (HV-3), with or without transformer coupling, depending on the status of front
panel Twin Topology "TT" and "XFMR" switches. With non-transformer coupling, the maximum micro­phone input levels are +3 dBu (vacuum tube) and +14 dBu (solid-state). For reference, a Neumann U87Ai
directly in front of a screaming vocalist (127 dB SPL) will output approximately -6 dBu. (NOTE: Do not let
the front panel "overload indicator" LED fool you. It begins to turn on with a mic preamp output of +6
dBu. When you first see the red LED turn on dimly, you have 20 dB of output headroom remaining!)

(2) LINE LEVEL INPUT "LINE INPUT"

Conventional 3-pin female XLR connector for use with balanced line level audio signals. A line level signal
is defined here as nominal +4 dBu operating level. Pin 1 is ground. Pin 2 is positive polarity. Pin 3 is
negative polarity. A 1/4" phone jack is wired in parallel with the XLR (Tip=pin 2, Ring=pin 3, Sleeve=pin

1). Input impedance is approximately 2,200 ohms (x2). Line level input is selected via a front panel rotary
switch marked "Source - LINE." This input feeds either the vacuum tube gain amplifier (M-2) or solid state
gain amplifier (HV-3), with or without transformer coupling, depending on the status of front panel Twin
Topology "TT" and "XFMR" switches. Minimum line input gain is achieved when amplifier gain controls
are set fully counter-clockwise. Maximum line level input level is +30 dBu into the solid state gain
amplifier and +19 dBu into the vacuum tube gain amplifier. Unbalanced "semi-pro" (-10 dBv) signals should
be tried in both the front panel DI input and the line level input — select the input which sounds best. Line
level input XLR connector contacts are Neutrik Galvatronic gold plated. It is suggested that XLR cable
connectors used with the STT-1 employ identical plating.

(3) FRONT END DIRECT OUTPUT "DIRECT OUT"

Conventional three pin male XLR connector providing balanced, line level output directly from the front-end
amplifiers (MIC, LINE, DI). This output is configured before the EQ, Compressor, De-esser, and main
outputs. This direct output is essentially equivalent to the output on an HV-3 micamp and can be used in
addition to the main outputs (below). Pin 1 is ground. Pin 2 is positive polarity. Pin 3 is negative polarity.
This line level output is capable of driving <600 ohm loads and long, high capacitance cables. Outputs
may be configured in an unbalanced configuration by grounding pin 3, or taking pin 2 directly as an
unbalanced signal while floating pin 3. In the former configuration, the output is automatically increased by
6 dB. Connector contacts are Neutrik Galvatronic gold plated. It is suggested that XLR cable connectors
used with the STT-1 employ identical plating.

(4) MAIN OUTPUT #1 "MAIN OUT - BAL"

Conventional three pin male XLR connector providing balanced, line level output from all stages of the STT-1.
Can be used simultaneously with all other outputs. Pin 1 is ground. Pin 2 is positive polarity. Pin 3 is negative
polarity. This monolithic-based, balanced line level output is capable of driving <600 ohm loads and long, high
capacitance cables and has a maximum output level of +32 dBu. Outputs may be configured in an unbal­anced pin-2-hot configuration by either grounding pin 3, or taking pin 2 directly as an unbalanced signal
while floating pin 3. In the latter configuration, the output is decreased by 6 dB relative to the former
configuration. Connector contacts are Neutrik Galvatronic gold plated. It is suggested that XLR cable
connectors used with the STT-1 employ identical plating.

STT-1

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STT-1

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(5) MAIN OUTPUT #2 "MAIN OUT - UNBAL"

Conventional three pin male XLR connector providing unbalanced, line level output from all stages of the
STT-1. Can be used simultaneously with all other outputs. Pin 1 is ground. Pin 2 is positive polarity. Pin 3
is ground. This output is all discrete, pure Class-A, and is capable of driving < 600 ohm loads and long,
high capacitance cables. This output should drive a balanced destination with no interface concerns. In the
rare instance where a balanced destination exhibits difficulty with an unbalanced source, use the balanced
output (#4 above). Connector contacts are Neutrik Galvatronic gold plated. It is suggested that XLR cable
connectors used with the STT-1 employ identical plating.

(6) MAIN OUTPUT #3 "MAIN OUT - UNBAL"

Conventional 1/4" female phone connector providing unbalanced, line level output from all stages of the
STT-1. Can be used simultaneously with all other outputs. Tip is signal positive polarity, Sleeve is ground.
This output is all-discrete, pure Class-A and is capable of driving < 600 ohm loads and long, high capaci­tance cables. This output should drive a balanced destination with no interface concerns. In the rare
instance where a balanced destination shows difficulty with an unbalanced source, use the balanced output
(#4 above). This output is paralleled with Output #5 (above).

(7) DYNAMICS LINK "Dyn Link"

Conventional RCA-style phono jack providing a connection to the dynamics side chain circuit. Use to link dual
STT-1 units for stereo operation. Any conventional RCA phono cable should work appropriately.

(8) EARTH/AUDIO GROUND JUMPER

A barrier terminal which ties earth ground to audio ground. If ground "hum" loops are experienced when using
the STT-1, removing this jumper may help. Using this jumper to lift ground, the integrity of the chassis/earth
ground connection is never compromised. Do not defeat the earth grounding pin on the AC plug.

(9) AC VOLTAGE MAINS SELECTION "100-120" or "200-240"

A power entry module with a removable fuse holder block. This fuse holder block is selectable for 100 ­120 Volt or 200 - 240 Volt worldwide mains powering. The fuse block contains two fuses — one fuse is in
series with the hot power line while the other fuse is in series with the neutral power line. Both fuses must
be installed. To change the mains voltage selection, remove IEC power connector and assure that the STT-1
is not connected to mains power. With a non-conductive tool, gently pry the fuse block away from the
power entry module. Remove the two fuses and replace both with type as shown below. Slide out the
internal PC Board, turn it over, and reinsert the PCB so that the desired AC mains voltage appears in the
viewing window. Double check that the fuses installed correspond to the AC mains voltage range which
appears in the viewing window. Gently push the fuse block back until flush and snug.

FUSES:
For 100-120 VAC mains, use two 5 x 20 mm, 1A, slow blow, 250 V, Littelfuse 218 or equiv.
For 200-240 VAC mains, use two 5 x 20 mm, 500 mA, slow blow, 250 V, Littelfuse 218 or equiv.

(10) POWER ENTRY "IEC Power Receptacle"

An IEC-type AC line-power receptacle for use with removable cords. Use only the power cord provided with the
STT-1 unit or equivalent U/L approved type SV, SVT, SJ, or SJT AC power supply cord. Do not defeat the third pin
earth ground. If ground lifting is desired, remove the Earth/Audio Ground Jumper strap (topic number 8 above).

STT-1

STT-1 FRONT PANEL — FRONT END

(1) FRONT-END AMPLIFIER SELECT SWITCH "TWIN TOPOLOGY"

Pushbutton switch which selects the front-end gain amplifier as either entirely vacuum tube (VT) or entirely
solid state (SS). When used as a microphone preamp, the solid state amplifier is essentially identical to the
front-end found on Millennia's acclaimed HV-3 — used by a who's who in critical acoustic recording
worldwide. The vacuum tube amplifier is essentially identical to the front-end of Millennia's sublime M­2b. The DI instrument input uses a tested and selected low noise, high voltage (300+ Volts) 12AT7 vacuum
tube for impedance buffering, which then feeds either the VT or SS gain amplifiers. There's also an unusual
twist here. To further enhance the Origin's sonic palate, we have included something that Millennia has
historically avoided — a switch selectable audio path transformer. Here's why...

Audio designers know that audio transformers add various types of sonic color (distortion) to an audio path
— especially at high dynamic levels and wide frequency excursions. This is why, to date, Millennia has
avoided audio path transformers. In our opinion, audio transformers simply have no place in a critical
signal path when acoustic realism and dynamic stability are primary objectives.

That said, it is also widely known that audio transformer distortion can add "artistic personality" to audio
signals. For decades, creative engineers and producers have selected various transformer-coupled audio
paths to achieve a marked sonic signature. A good example is found in Rupert Neve's original Class-A, all­discrete designs from the 1960s. Mr. Neve's early console modules (1272, 1073, etc.) are in demand today
due to their ability to "cut through" a mix and present a "bigger than life" sonic signature. Hugely unnatural,
and delightfully so! What causes these audio artifacts? It's predominantly the transformers. We can thank
Rupert's old audio path transformers for most of that familiar euphonic coloration and pleasing distortion.

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Millennia enjoys a fine collection of these 1960's era console modules. We use them on pop recording dates
(by choice, however, more than 90% of our recording schedule remains acoustic classical, jazz, and ethno­eclectic; where we use HV-3 and M-2b micamps exclusively). We know intimately the "sound" that a
purposefully designed audio path transformer can deliver. It is with this understanding and mission that
Millennia presents our first product with (gasp!) an audio path transformer.

Numerous listening tests were performed on a wide range of off-the-shelf transformers. We couldn't find a
stock transformer that had the particular "sound" we were searching for. We then embarked upon a design
effort to create our own unique transformer. Developed for its ability to deliver a "bigger than life" sonic
signature when hit hard (high input levels), the new Millennia MIT-01 audio input transformer is not
intended for acoustic reality nor accuracy. Rather, when used with higher input levels, the MIT-01 offers a
colorful sonic personality that engineers and producers of popular music will likely find both highly artistic
and eminently useful. This transformer can be switched in and out of the front-end audio path; selectable
via a front panel switch (see #4). The transformer can be used with all input types (microphones, line-level,
and instrument-DI). When used with nominal input levels, the transformer exhibits minimal sonic colora­tion. The remaining functional areas of the STT-1, including the vacuum tube or solid state EQ, dynamics,
and output sections, remain inherently transformerless.

(2) PHANTOM POWER SELECT SWITCH ("+48V")

Pushbutton switch which provides phantom power (+48 Volts DC) to the microphone. When this switch is
depressed (illuminated red), phantom power is applied simultaneously through dual 6.81k ohm resistors to pins 2
and 3 of the three pin female XLR mic input. Use phantom power with condensor and other microphones
requiring traditional phantom supply. CAUTION: Applying phantom power to ribbon microphones could
damage them. Do not use phantom with ribbons, moving coil, and other microphones which do not require
phantom power. Use care, as well, not to insert or extract mic cables from the STT-1 when phantom power
is active. This could damage both the microphone and the sensitive HV-3 front end.

STT-1