Iron Age Audioworks Channel Strip CS1 User manual
User’s Manual
Channel Strip CS1
©2019 by IronAgeAudioworks
Thank you for your purchase of an Iron Age Channel Strip. Iron Age Audioworks is a small team
of engineers and designers and we truly appreciate your business. We hope you enjoy using
this as much as we enjoyed making it.
Safety
Safety with audio equipment is normally a matter of common sense, but we want to make sure
you get the best use out of your equipment. So please, use common sense including...
●Use typical practices for using electrical and audio equipment.
●Don’t clean this with water or use it around water.
●Any ventilation openings in the case need to remain open.
●Don’t use this around anything that’s hot (such as a radiator or space heater).
●Don’t defeat the ground pin on the plug or use a ground-lift device that does.
●Don’t use a cut or damaged power cord, and keep the cord from getting pinched or
stepped on.
●Don’t service the box unless you’re a qualified technician.
Power
The unit is powered by an internal linear power supply and will accept standard 110 VAC
power. A user-accessible fuse is located on the IEC connector at the rear of the case. It will
come set at +/-22V and +48V for phantom power. Please contact us if you would like to
change the supply voltage for use with other op amps.
©2019 by IronAgeAudioworks 1
Overview
The Iron Age Channel Strip was designed as a powerful front end tracking and mixing solution
featuring three modules in a one rack unit space, each with a custom-wound Cinemag output
transformer.
Block Diagram
The input section features a discrete op amp fed by three different modes. In mic input mode
it is a classic mic pre using a Jensen input transformer and providing up to 64 dB of clear,
warm gain. The mic preamp features switchable phantom power and a -20 dB pad. In line
input mode a second discrete op amp is used as a balanced transformerless input for a
balanced +4 dBu nominal input. The third mode uses a front-panel accessible high impedance
instrument input. Phase and mute are available for all functions. The input amplifier feeds a
custom Cinemag output transformer followed by a continuously variable attenuator, allowing
you to drive the input stage and transformer to get the right amount of gain and color. A
post-attenuator "mic pre out” is available.
©2019 by IronAgeAudioworks 2
The equalizer module is a three-band, sweepable frequency design using two discrete op
amps and a second output transformer. Inspired by a late seventies console that became a cult
classic, our spin takes the design to a whole new level. There are 15 center frequencies divided
into three bands (Low, Mid, and High) as shown below:
Low
Mid
High
OFF
OFF
OFF
20 Hz
250 Hz
4.8k Hz
40
500
7.5k
90
1.2k
9k
200
2.4k
12k
40
4.8k
12k (shelving)
Each band features 15 dB of boost or cut with a Q of approximately 1.2. A transformer
balanced +4 dBu insert point is available post-EQ. Additionally, the EQ section features a
buffered two position second-order high pass filter (12 dB/octave) at 50 and 80 Hz.
Finally, the output line amp uses a balanced input stage using another discrete
transformerless amplifier to feed a "fader" with 12 dB of gain "in hand," followed by a
console-style discrete line amplifier with a transformer balanced output.
As with all Iron Age products, the Channel Strip uses the M2 discrete operational amplifier,
designed and built in-house by us.
The combination of the input gain, attenuator, and fader knob gives a wide range of sonic
possibilities, and with up to seven op amps and four transformers in the signal path, you'll
never want for massive mojo. This is Iron Age at its finest!
Through the IAA Custom Shop, we also offer a variety of input transformers, output
transformers, op amps, and even voltages to give you the sound you want. Whether you're
looking for quiet and clear, warm and smooth, or edgy and rock and roll, this channel strip can
do what you need.
Reach out to us with to whiteboard your idea!
©2019 by IronAgeAudioworks 3
Controls
Front Panel
The POWER switch turns the unit on and off.
The SOURCE switch is a three position toggle. In MIC mode the microphone input is engaged
and a Jensen mic input transformer is inserted to the signal path before the input stage
operational amplifier. In LINE mode the line input is engaged and a balanced transformerless
amplifier is inserted to the signal path before the input stage. In DI mode the front panel 1/4"
jack is engaged and a high impedance circuit is inserted to the signal path before the input
stage.
The input GAIN knob drives the gain over the op amp in the input stage for all modes (5-40 dB).
The PAD button engages a -20 dB pad with a characteristic impedance of approximately 2300
ohms. This only affects the mic input mode.
The +48 button provides 48V phantom power to the microphone through the XLR connector.
This only affects the mic input mode.
The MUTE button turns the input stage signal to the output transformer off for all input modes.
The PHASE button inverts the signal being sent to the primary side of the output transformer,
inverting the phase of the output signal by 180 degrees for all input modes.
The TRIM knob attenuates the signal after the input module’s output transformer for all modes.
The post-attenuator signal is available at the MIC PRE OUT jack in the rear panel.
The HPF switch is a three position toggle. It can be set to OFF, 50, or 80 for 50 and 80 Hz high
pass filtering, respectively.
Each of the three EQ bands has identical controls. The center frequency for each band is
selected by the six-position frequency switch. The amount of boost or cut is selected by the
©2019 by IronAgeAudioworks 4
knob to the right of the frequency selection switch. The full counter-clockwise position of the
frequency switch is OFF. In this position, there is no gain across that band, which eliminates
the need to center the boost/cut knob. A post-EQ transformer balanced insert point is available
at the normally closed INS SND switching jack in the rear panel.
The line amplifier can be used as a stand-alone module by sending a signal into the INS RET
jack on the rear panel. It is a normally closed switching jack fed by the post-EQ insert send
signal.
The FADER knob controls the level of the output signal, which is equivalent to a post-fader
direct out on a console channel strip. For lowest noise and distortion, and maximum
headroom, the fader should be operated near its 0 dB point. At its full clockwise position, the
FADER allows for a 12 dB boost using the output line amplifier for gain.
Optimum gain staging and a wide variation of tones can be obtained through the use of the
input GAIN knob, the input TRIM knob, and the output FADER knob.
Inputs and Outputs
The mic input is balanced by a Jensen transformer to receive a nominal -60 dBu balanced
input via an XLR jack on the rear panel of the unit.
The line input is a nominal +4 dBu balanced line input via a TRS jack on the rear panel.
The DI input is a nominal -42 dBu high impedance instrument input via a TS jack on the front
panel.
The mic pre output is a nominal +4 dBu Cinemag transformer balanced line output via a TRS
jack on the rear panel.
The insert send is a nominal +4 dBu Cinemag transformer balanced line output via a normally
closed switching TRS jack on the rear panel.
The insert receive is a +4 dBu balanced line input via a normally closed switching TRS jack.
The channel out is a +4 dBu Cinemag transformer balanced line output via a TRS jack.
©2019 by IronAgeAudioworks 5
Back Panel
Chassis
The Iron Age Summing Mixer uses a standard 19” 1RU. The unit is powered by an IEC power
cord and an internal bipolar and +48V power supply.
Technical Specifications
Gain Range
Mic Preamp 28 - 64 dB (8-44 dB with PAD)
DI 10 - 46 dB
Line Input 0 - 36 dB
Maximum Input Level
Mic Preamp -3.5 dBu
DI +21 dBu
Line Input +20 dBu
Maximum Output Level +26 dBu, all outputs
Input Impedance
Mic Preamp 2300 Ohms
DI >1 MOhms
Line Input >10 kOhms
Output Impedance (all) <75 Ohms, transformer balanced
Frequency Response +0.10, -1.4 dB 20Hz-20kHz
Actual Measured Noise -96.4 dBA line input to channel output
THD @ +4 dBu output 0.002% typical, line input to channel output
Power Consumption 125 mA max
©2019 by IronAgeAudioworks 6
Frequency Response
Low Frequency
Mid Frequency
©2019 by IronAgeAudioworks 7
High Frequency and Shelf
High Pass Filter
©2019 by IronAgeAudioworks 8
Warranty
We warrant this product to be free from defects of materials and workmanship for a period of
one (1) year from the date of purchase. We will remedy any defect identified within this period
by repairing or replacing the product at our option. It will be your responsibility to pay for
shipping the product to us, and if the product is determined to be defective, our responsibility
to pay for shipping the product back to you.
LIMITATIONS AND EXCLUSIONS. This warranty, and any other express or implied warranty,
does not apply to any product which has been improperly installed, subjected to usage for
which the product was not designed, misused or abused, damaged during shipping, or which
has been altered or modified in any way. This warranty is extended to the original purchaser
only. THIS EXPRESS, LIMITED WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESS OR IMPLIED, TO THE EXTENT ALLOWED UNDER APPLICABLE STATE LAW. IN NO
EVENT SHALL IRON AGE AUDIOWORKS BE LIABLE FOR ANY SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OF THIS PRODUCT.
If you suspect a defect in this product, please contact us to discuss the problem (it is possible
that a suspected defect could be due to improper usage).
Contact us with any issues, to say hi, or share the music you’ve made. We love this gear and
want you to love it too.
©2019 by IronAgeAudioworks 9
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