Summit 2BA-221 Operating Manual
Summit Audio Model 2BA-221
Microphone Preamp and Line Module
Operation Manual
Summit Audio, Inc.
P.O. Box 223306
Carmel, CA 93922
(831) 728-1302
email: sound@summitaudio.com
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Introduction
Introducing the 2BA-221 continuously variable impedance
microphone preamp from Summit Audio. Featuring microphone level, line level, and Hi-Z instrument inputs, the 2BA221 utilizes separate and individually controlled solid state
inputs to mix the microphone input with the Hi-Z or line input
into the variable vacuum tube stage. Mix the signals through
DANGER!
HIGH VOLTAGE
IMPORTANT: Check
the bottom sticker to
make sure the
2BA-221 is manufacture for the voltage
used in your country.
This is done at the
factory ONLY.
the 12AX7A/ECC83 vacuum tube output or output them
separately through multiple solid state outputs. The 2BA-221
also features a stackable input design; multiple 2BA-221’s
can be linked together to form a modular mixing device with
individual outs, inserts per channel, and a final vacuum tube
gain stage. Its swept high pass filter, multiple simultaneous
tube and solid state outputs, insert jack, and internal power
supply makes the 2BA-221 a powerful tracking and mixing
tool.
Features
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Variable microphone impedance
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High quality mic preamp with polarity, pad and level control
Channel insert
Highpass filter
1 balanced input, 1 mic input, 1 instrument input
Balanced outputs
Hand Crafted in the U.S.A.
Model 2BA-221 Microphone Preamplifier
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Carefully unpack the 2BA-221 and it’s power cord. Save the
carton and packing material for possible future use. Before
powering up the unit, read this manual and observe the cautions for
HIGH VOLTAGE
.
Important Warranty Information
For your 3 year warranty, register your 2BA-221 on line
today at www.summitaudio.com .
Introduction
Model 2BA-221 Microphone Preamplifier
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Front Panel
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Front Panel
Hi Z Input (Solid State)
This input can be used to mix in a musical instrument or
other high impedance signal.
Line/Hi Z Input Gain Control
This control simultaneously adjusts the solid state gain of the
front panel Hi-Z input and the rear panel line input. Use more
of this control for a cleaner, less vacuum tube sound. Adjust
this control along with the Tube Output gain to get the proper
output level and to get the desired sound.
Signal LEDs
Green - - Signal is present at the input.
Amber - Proper input signal level.
Red - - - Signal is at the threshold of Clipping.
Set the input gain controls so that the red LED only lights
occasionally. The green and amber LEDs should be on most
of the time.
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Summit Audio, Inc.
Tube Output Gain Control
This control varies the tube output gain, including the XLR
and balanced TRS outputs. Turn this dial up for more vacuum
tube sound and to get more gain. Both the Line/Hi Z input
and the Mic Preamp gain controls feed this control. For the
most vacuum tube sound, turn this dial up to 2 or 3 o’clock
and adjust the solid state input gain (Line/Hi Z or Mic) for
the proper signal level. This control has no affect on the
stacking output.
Mic Preamp Gain Control
This control adjusts the gain of the solid state microphone
input. Use more of this control for a cleaner, less vacuum
tube sound. Adjust this control along with the Tube Output
gain to get the proper output level and to get the desired
sound.
Front Panel
Mic Preamp Loading Control
This knob controls the loading or impedance for the microphone input. The input can be set from 100 ohms to 10K
ohms. You can set this control to match the 2BA-221 to the
impedance of your microphone or as a "tone" control. Try
sweeping the impedance control to hear the different sounds
available from a single microphone.
Check the manual for your microphone to find the output
impedance or check the charts on page 18 which shows the
output impedances for many commonly used microphones.
The loading impedance should be about four times the microphones output impedance. Check the users manual of your
microphone for more information.
If you are in doubt on how to set the Mic Loading control, set
it fully clockwise to the 10K
Ω
position.
Model 2BA-221 Microphone Preamplifier
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Front Panel
Pad Switch
This switch engages or disengages a –20dB pad to set the
input sensitivity of the microphone input. If enough gain is
available with your microphone, use with the pad set to –20
for quieter operation.
Polarity Switch
This switch inverts the polarity of the microphone input in
order to compensate for out of phase equipment or wiring.
+48V Phantom Power Switch
This switch enables +48 volt phantom power to the microphone input. Phantom power is present whenever the blue
LED is illuminated. Turn the unit off to bleed off the voltage.
Warning:
power and may be damaged. Check the microphone’s specifications and requirements before using phantom power.
Some microphones cannot tolerate phantom
Highpass Filter Frequency Control
This control adjusts the frequency of the highpass filter from
20Hz to 200Hz. The highpass filter is used to remove low
frequency rumble from the mic input.
Important - Please Read!
The 2BA-221 contains a vacuum tube which
generates heat.
Do not block the cooling holes on the top of the
2BA-221 and always allow adequate ventilation
when mounting the unit in a rack enclosure.
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Summit Audio, Inc.
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