Signal Audio Workshop CH-2 User manual

CH-2 Vacuum tube
2-Channel Microphone pre
OWNER’S MANUAL
Signal Audio Workshop
Abarbanel ST.53
Tel Aviv 66089 IsraelP.O.B 5169 TLV 61051Office: 972-3-6820892
Fax: [phone]
www.signal-audio.com

CH-2 Owner’s Manual
Content:
Preface______________________________
Front & rear panel controls___________
Construction options ______________________
Signal chain_________________________
Tips & Tricks__________________________
Installation____________________________
Maintenance __________________________
Specifications _________________________
Warranty___________________________
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www.signal-audio.com
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Dear customer,
I’d like to personally thank you for the
confidence that you have shown in Signal
Audio Workshop by purchasing the CH-2.
You acquired the latest generation of
Microphone pre amp which is unequal in its
design and specification.
I am confident that working with the CH-2
will open new worlds of manipulating audio
signals with a tool like no other. In order to
produce the full potential of this sophisticated tool I strongly
encourage you to read and understand this manual thoroughly.
The CH-2 is truly a unique piece of equipment with Tube heart
and analog soul.
Every peace of gear Signal AWS makes is meticulously hand
crafted in our workshop. We consider the development and
assembly as a form of art and take great pride in the final
product.
The CH-2 is a result of a two year development period in which
we researched the fundamentals of Microphone pre amps
topologies. In an effort to innovate and achieve the CH-2
outstanding Sonic capabilities.
For the input stage we designed a custom Mu-metal input
transformers for maximum signal linearity along with the sonic
benefits of the transformer’s character. We specially designed a
Tube CLASS A input stage for its second harmonic performance
in order to match the needs of digital recording to the warm
sound of analog equipment.
All signal path stages are pure CLASS-A with tubes circuitry and
transformers for each channel take this uncompromising
structure to the highest level of sonic excellence.
These features make this revolutionary tool out stand any other
in today’s market!
I hope you will enjoy working with the CH-2 as much as
we enjoyed making it for you!
With Honor.
Oded Levy
Signal AWS
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Front panel controls:
1) 48v phantom switch.
2) Phase reverse switch.
3) -20db pad (reduction of high level input signals).
4) Input select switch – selects input source
microphone/DI.
5) Direct input specially designed for high impedance
sources (input impedance 4.7m).
6) Tube gain knob from +22db to 60db.
7) H.P.F. selectable five frequency rotary switch –
changes low cut frequencies at 12db/oct.
8) Power Standby switch.
9) Tube filaments light indicator.
10) +300v power light indicator.
Rear panel:
Rear panel elements:
PIN1 GND
PIN2 HOT
PIN3 COLD
4 XLR balanced line input/output
connectors with the same pin standard
as shown in the diagram.Mains voltage 220/115 VAC input select
switch. Mains power socket with mains
fuse.
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Construction options:
)optional(step rotary gain selector12
12 step rotary gain selector optional with
3.3db steps constructed with metal film
1% resistors and sealed rotary selectors
with silver coated contacts.
Signal chain:This chapter details on the signal chain’s structure in order to help
you better understand the CH-2.
(1) INPUT SECURITY:
Designed for maximum optimization of all microphones with
all standard features like +48v (phantom), phase reverse
switch and -20db pad, especially designed for minimum sonic
degradation. All these functions are preformed with special
silver coated toggle switches for maximum rigidness of
operation.
(2) INPUT TRANSFORMER:
High gain 200 ohm microphone input transformer matching to
a high input impedance. Design for optimal reduction of most
kinds of noise caused when microphones are connected.
Ensure Electromagnetic Compatibility (EMC) standards
compliance. Feature Mu-metal core for minimal harmonic
distortion. Internal electrostatic shields for maximum common
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mode noise rejection at high frequencies. Multiple interleaved
windings ensure low leakage inductance for excellent ultra
high frequency response. Mu-metal can for magnetic
shielding.
(3) TUBE GAIN STAGE:
Vacuum tube class A topology gain amplifier ranges from
+22db to 62db (typical). Designed especially to deliver a
constant sonic performance at all gain levels. This stage was
especially tailored to preserve the delicate balance between
transparency and 2nd harmonic THD. An optional 12 step
rotary gain selector can be added with 3.3db steps, made with
metal film 1% resistors and silver coated contacts.
(4) PASSIVE HIGH PASS FILTER:
12db/oct passive H.P.F. filter with five cutoff frequencies and
hard wired bypass. Cutoff frequencies are 65, 110, 180, 250,
450 Hz. All frequencies filter electronics made from passive
components with audio grade capacitors in order to preserve
sonic excellence.
(5) OUTPUT STAGE:
Design to deliver a delicate balance between signal
transparency and tube second harmonics. This stage was
carefully tailored to provide all advantages of both tube
oriented warm sound and solid state signal transparency.
Highest grade of solid state electronics with +/-24v power
supply. Transparently delivers full advantages of all previous
stages.
All signal stages are made from metal film resistors and audio
grade capacitors to preserve maximum sonic performance.
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Tips & Tricks:
1. stereo recording: one of the most common methods of recording
stereo signals is done by locating two identical microphones in an
x/y mode and the calibration of the gain should be done by the
following steps:
A. Calibrate channel 1 gain to optimum
recording level by viewing the “in level”
meter on your recorder.
B. Repeat step A on channel 2.
C. Reverse the phase on channel 2.
D. Press mono on your control room
monitoring system.
E. Re trim the gain on channel 2 to maximize phase cancellation
between the two sides.
F. Return to normal phase and stereo mode.
2. As a rule of thumb: calibrate record level will be done by viewing
the recording level of the recorder and not other meters that may
be on the recording chain (such as compressor etc`).
3. Some microphones may produce very high output level,
therefore we recommend using the -20db pad switch, in cases of
high S.P.L. recorded otherwise the channel may clip while
recording.
4. Cutting environmental rumbles with the 65 Hz H.P.F. on male
vocals is preferably done even without compensating low
frequency with external EQ by wisely manipulating the proximity
effect of cardioid microphones.
5. M-S recording technique: place 3 microphones (center, left &
right) according to the diagram:
Reverse phase on left microphone.
Combine the three microphones on
your mixer. The sides channels
should be hard panned L<>R, and
center panned to the center. The
center microphone level in the
resulted mix will affect the stereo
images width
according to the balance between sides and center microphones.
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Installing the unit:
Always install this unit in a properly grounded environment!
Do not expose the unit to humidity or dusty environment!
Do not expose the unit to heat sources and unventilated places!
Always make sure that the unit operates on the correct mains
voltage. (230/115 VAC) before applying mains voltage!
Signal AWS will not be responsible for damages created by
improper mains voltage issues.
PIN1 GND
PIN2 HOT
PIN3 COLD
All audio connections are
balanced threw XLR connectors
with the pin list:
Maintenance:
Cleaning:
Do not clean the unit with water or with water soaked cloth.
Cleaning is best made with dry dusting brush and vacuum cleaner.
Dust and moisture are the primer enemy of switches and contacts
within this unit. Avoiding them as much as you can will prolong the
unit’s life significantly.
Maintenance:
There are no user’s serviceable parts inside the unit.
Opening and servicing this unit by someone who is not authorized by
Signal AWS is strictly prohibited.
Technical service is made only by those who are authorized from
Signal AWS.
We recommend replacement of vacuum tubes only when
The unit has proven to not function correctly and according to
the type of problem discovered.
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Specifications:
):from in to out(Electronics structurePhantom power (+48 V) switches.Phase reverse & -18db pad switches.
Custom 200 ohm microphone input step-up transformers in
Mumetal cases.
12AX7 tubes CLASS A design 62db gain amplifier.
Fully passive 12db/oct 5-state high-pass filters + bypass.
Filter frequencies: 65Hz, 110Hz, 180Hz, 250Hz & 450Hz.
Solid state transformerless design balanced output stage.
Input Impedance: 200 Ohms Balanced, (PIN 2 HOT).
Output Impedance: >50 Ohms Balanced, (PIN 2 HOT).
MAX Gain: 62 db (typical).
MAX Input level: +2dbm (for THD < 2%).
MAX Output level: +31dbm/600 ohm (on balanced output).
Noise Floor: -70db @ 22-22khz (typical).
Frequency Response: 20-20kHz +/- 0.3db, 15-40kHz +/-
2db.
Gain: 62db continuously variable from +22
to +62db.
Operating Voltage: 230Vac @ 50Hz / 115Vac @ 60Hz.
Dimensions CH-2: H= 3 units, W= 19”,D=13.4”.
Shipping weight:
All spec’s at RL=600Ohm.
Info subject to change without prior notice!
All legal rights reserved to Signal Audio Workshop!
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Limited Warranty
LIMITED WARRANTY: This product is warranted to the original
consumer purchaser to be free from defects in materials and
workmanship under normal installation, use and service for a
period of one (1) year from the date of purchase as shown on the
purchaser’s receipt. The obligation of Signal AWS under this
warranty shall be limited to repair or replacement (at our option),
during the warranty period of any part which proves defective in
material or workmanship under normal installation, use and
service, provided the product is returned to Signal AWS,
TRANSPORTATION CHARGES PREPAID. Products returned to us or
to an authorized Service Center must be accompanied by a copy of
the purchase receipt. In the absence of such purchase receipt, the
warranty period shall be one (1) year from the date of
manufacture. This warranty shall be invalid if the product is
damaged as a result of defacement, misuse, abuse, neglect,
accident, destruction or alteration of the serial number, improper
electrical voltages or currents, repair, alteration or maintenance by
any person or party other than our own service facility or an
authorized Service Center, or any use violative of instructions
furnished by us. This one-year warranty is in lieu of all expressed
warranties, obliga-tions or liabilities. ANY IMPLIED WARRANTIES,
OBLIGATIONS, ORLIABILITIES, INCLUDING BUT NOT LIMITED TO
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICU-LAR PURPOSE, SHALL BE LIMITED IN DURATION
TO THE ONE YEAR DURATION OF THIS WRITTEN LIMITED
WARRANTY. Some states do not allow limitations on how long an
implied warranty lasts, so the above limita-tion may not apply to
you. IN NO EVENT SHALL WE BE LIABLE FOR ANY SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES FOR BREACH OF THIS
OR ANY OTHER WARRANTY, EXPRESSED OR IMPLIED, WHATSO-
EVER. Some states do not allow the exclusion or limitation of
special, inciden-tal or consequential damages so the above
limitation or exclusion may not apply to you. This warranty gives
you specific legal rights, and you may also have other rights which
vary from state to state.
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Warranty registration form
Please take the time to fill out this registration Form and send it to
the address mentioned below. Or send this page threw e-mail to:
[email protected]
Signal Audio WorkshopAbarbanel ST.53
Tel Aviv 66089 IsraelP.O.B 5169 TLV 61051
Fax: [phone]Or send it by
Registering your product will allow you to get full warranty service
plus product upgrades if there will be any at the warranty period,
according to Warranty rules.
We would like to seize these opportunity to thank you once again
for choosing Signal AWS as your product leader.
PRODUCT INFO:
Model: __________________________________________________
Serial No: ________________________________________________
Manufacturing date: ________________________________________
Supplier: _________________________________________________
OWNER INFO:
Owner’s name: ____________________________________________
Company: ________________________________________________
Address: _________________________________________________
City: ____________________________________________________
State: ___________________________________________________
Zip: _____________________________________________________
Country: _________________________________________________
Phone: ___________________________________________________
Fax: _____________________________________________________
e-mail: ___________________________________________________
Comments:
__________________________________________________________
__________________________________________________________
__________________________________________________________
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