Awesome Transistor Amplifier is an 500 series channel Amplifier with a possiblity of a passive mix buss. We were able to use the extra set of I/O jacks for a mix buss.
The AwTAC Channel Amp has an LCR passive mix buss (left - center- right selectable just like most consoles had up to the late 60s, no pan pot) in the unit. Since it is a double wide module, we were able to use the extra set of I/O jacks for a mix buss. With a standard XLR cable, you can connect one Awesome into another and *POW* now you have a mixer. Just like that. The buss level, just like the paradigm of all lust worthy classic consoles with a passive buss, is conveniently set at mic level. After you've chained all your Channel Amps together, we've devised a special (awesome if you will) breakout cable that plugs into the standard XLR jack and delivers the Left and Right buss to the mic pre's of your choice. This obviously sets you up for a myriad of tonal choices when both tracking with multiple mic's mixed to a mono source (there are still *some* people that track guitars like this, right) and mixing your stems (or tracks) from your DAW.
The mixing functionality is designed to work with all (every) 500 rack currently on the market. If it has a male and female XLR, you can use that rack to build a mixer out of Channel Amps. Please inquire if you have a rack with TT jacks and we'll come up with an easy solution for you.
But wait, there's more!
You may be saying to yourself, "Im never going to have long throw faders, this is silly and will never apply to me." Well, it is lovingly called Awesome Channel Amplifier for a reason and we want that to apply to everyone, so check out what else you can do with the fader loop:
While we designed the loop to be used with a fader, ultimately all it is is an unbalanced insert, and it can absolutely drive 600 ohms, so you can totally use the insert to stick any piece of gear in there, most conveniently: a compressor.
You can connect a Compressor or Limiter to the AwTAC Channel Amplifier post EQ and post fader, pre output, pre buss assign. This means of course, that whatever piece of gear you use on the insert will show up on both the main direct out and on the buss as well. Just when you thought it could get no more Awesome.
Surely there are some people that may have reservations about an unbalanced send and return, but do realize that most of the consoles that built the sound of rock in 1970 had insert points that were unbalanced, identical to this. If your wiring and grounding is solid, it shouldn't be an issue.
The signal on the send sits at nominally 9dB below line level while being able to drive 600 ohm compressors to +20dBm. This is not a problem for the vast majority of compressors out there past and present, simply adjust any input, threshold, and output controls to compensate.
Certainly any compressor with modern bridging input will have no problem receiving the send signal as well.
1. Input Selector Switch is the global input sensitivity control which selects the amplification level for both mic and line level signals on a 12 position rotary switch. Five line positions (-6dB to +15dB) are available inside the bounded portion of the switch (11-3 o'clock on the dial) with Unity Gain at line level denoted by the open circle at 12 o'clock.
Mic Positions begin at 4 0'clock and provide a maximum gain of +65dB in the 10 O'clock position.
Via the state of the 1970 art magic of the sensitivity switch, input signals are routed throughout the custom wound Sowter AW27 input transformer for Mic, Line and Direct input signals.
Important to note, our line input is not simply a pad in front of the input transformer. The mic pre amp and the line pre amp are two completely discrete amps that are tuned differently from each other for specific use. The Line pre amp is as full bandwidth as reasonable, designed with mixing in mind. The mic amp is in comparison bandwidth limited for a much more "in your face" sound. Bandwidth limited, why would you want that Because it sounds *incredible*. You'll see.
2. Phantom Power Switch sends 48v Phantom Power to the XLR output for powering microphones and direct boxes when switched to the right.
2A. LED will illuminate to indicate Phantom Power is on. It is a good practice to engage this switch only after your mic is plugged in and off before unplugging the microphone. Consider this step to your work flow especially if you are using a TRS (phone or TT) patch bay with the units. It is optimal for your mic to see 48v on both its hot (XLR pin 2 in most places in the world these days) and cold (XLR pin 3) legs simultaneously. When using a mic with a phone patch bay, the tip of the connector (hot, pin 2 equivalent) will make contact before the ring of the connector (cold, pin 3 equivalent) which, over time, can lead to damage to your mics if "hot patching" with phantom power on.
3. Direct Instrument Input Jack is a DC coupled switched jack actuated by inserting a 1/4 phone plug for any high impedance, low level signal: instruments. This input is optimized for passive pickups (guitars, basses, pedal steel, electric pianos, clavinets, etc) and also works well with instruments with active outputs like synths, mellotrons, combo organs, etc. Referencing the block diagram, you can see that the Instrument Input Amp is located before the Input Transformer whose gain is selected via the Input Selector Switch just like the mic and line level inputs.
4. Output Fader Pot sets the level for the audio sent to the final amplifier stage. Unity Gain is "Full On" in the three o'clock position. Unlike a fader on most consoles, there is no "gain in hand" and will only attenuate your signal as you turn the knob counter clockwise from the "Full On" designator. For Expert Level operation, experiment with the carefully crafted distortion available in the Channel Amp by dialing down the output fader counter clockwise and adjusting the input sensitivity switch for Maximum Awesome. Those familiar with guitar amplifiers that have a "gain" and "master volume" control will find this fader works to achieve a similar end effect. The Fader Pot fully counterclockwise in the six o'clock position will mute your channel amp in a mix scenario. The taper of this pot lends itself wonderfully to creating beautifully smooth fadeouts on program material.
5. High Pass Filter Switch engages a 12dB / Octave high pass filter (or low cut filter) at 130 Hz when switched to the right. The high pass filter is critically located at the output of the EQ network and is much much more than a simple "rumble filter" in the front end of the mic preamplifier, here's why:
Elaborate saturation can be achieved with the strategic use of this switch. Experiment with boosting the low shelf to the maximum and then engaging the high pass filter: this will allow the Low Frequency Shelving Amplifier to saturate while cutting the low frequency output to a more "usable" level. This is a very very handy tool to not overlook and opens the door for creative gain staging possible with the Awesome Channel Amp.
6. Polarity Reverse Switch flips the phase of the signal when engaged to the right. The location of the flip is also critically located after the Line Level Output Amplifier so any nonlinear distortion generated is flipped as well, turning the Polarity Reverse function into yet another tone shaping device beyond its immediate function.
7. Output Transformer Loading Switch is a three position toggle which places a 1200 ohm load on the output transformer in the up position, 600 ohm load in the down position and removes the loading resistor in the center position. With modern high impedance inputs, a more traditional load can be placed on the output to make the output of the Channel Amp work a little harder, approximating a more classic tone via a modern bridging input (as seen on an A-D converter for instance).
8. Passive Mix Buss Switch assigns a secondary winding of the AW26 Output Transformer to the Left (up) Center (middle) or Right (down) mix buss for passive mixing. Just like the best designed vintage consoles, the passive buss is set at 150 ohms and at Mic Level, so any standard mic pre can be used to make up the gain on the summing buss. The feed for the buss is taken from a secondary winding of the output transformer that is in every way identical to the main direct out, so all of the tone that has been carefully dialed in on the mains gets fed to the buss.
The most practical use for the mix buss will likely be summing stems from a DAW. Set up your submix in stems and output to your Awesome Mixer and you have a VERY powerful system at your fingertips. A completely self contained 8x2 mixer for summing a DAW can be setup with ten AwTAC Channel Amps and two ten space racks.
During my initial testing with the Awesome Mixer, I gravitated towards using two mics on a guitar cab, each plugged into a Channel Amp and then bussed through the mix network to a third Channel Amp and got some of the best guitar tones I have ever been able to create to date. I could easily see this being a standard mode of operation on tracking sessions for myself in the future.
Why not just record those two mics through the Channel Amps to two separate tracks and combine in the mix Well, first off, that eliminates a whole set of decisions to struggle with during a mix. For my work flow, streamlining mix decisions is absolutely advantageous. Second, and most important, the mix buss has a sound and it is epic (epic as in truly Epic, not Bedford Ave epic), when you take a listen to it you'll see... By using three of these in a 2x1 configuration, that guitar sound is passing through 18 discrete amplifiers, 6 transformers and 2 inductors. The sound that can yield is gargantuan and thick. A sound that Ray Harryhausen would have animated (replete with four heads, dreaded fur and talons dripping stop motion poison). The Channel Amps were tuned to get bigger and bigger when adding more channels in series and a 2x1 summing arrangement is the fastest conclusive experiment you can conduct to prove this to yourself.
9. Equilizer Network Control Switch engages the Awesome EQ to the right and bypasses the EQ to the left. For maximum amplifier saturation, it is suggested to "zero" the EQ pots and leave the EQ engaged if you don't want the EQ, yet want the largest sound possible out of the box. Bypassing the EQ removes three amplifiers in series from your signal path.
This switch (like all the switches on the AwTAC Channel Amplifier) is a super high quality, gold plated switch designed to provide years of noise free operation. Audio does however, pass through this switch (ie, this switch does not control a relay) and as a result can induce a "click" when operating the switch just like every single classic discrete transistor desk from the 70's did. This circuit is not designed to be switched in and out "on the fly" while recording a track or mix.
10. Baxandall High Frequency Shelving Amp Pot for dialing 12dB of boost or cut, frequency selected by
10A. High Shelf Frequency Select Switch is a three position toggle which selects 11Khz in the up position, 6Khz in the down position and a 17khz "air" band in the center position.
11. Mid Amp Pot for dialing 12 dB of boost or cut, frequency selected by
11A. Mid Frequency Select Switch is a ten position rotary switch which selects eight frequencies (300hz - 8 Khz) available on the inductor based mid band EQ. 1K and 3K each have two positions on the rotary dial for a wide (normal) and narrower Q.
12. Baxandall Low Frequency Shelving Amp Pot for dialing 12dB of boost or cut, frequency selected by
12A. Low Shelf Frequency Select Switch is a three position toggle which selects 70hz in the up position, 35Hz in the down position and 130Hz in the center position.
13. Forward / Back Switch is our expert level control which alters the coupling of the EQ network to the output stage of the channel amp. As a result, this switch will only have an effect when the EQ is engaged. This is a very subtle control which directly effects the way your track will "sit" psycho acoustically in your mix. It is most noticeable as a cumulative effect. A good way to strategically learn the most effective use of this switch is by assigning it to groups in your mix. For example: Track or Mix all of your drums and bass "Back" with guitars and vocals "Forward". Now reverse. You should notice that your mix will sit with a different image or tilt. It's very handy for adding some "space" to your mix without having to plug in a different amplifier type. This "space" should be typically most noticeable in how the low end will sit in your mix. This can be used to subtly add depth or bring things forward in a way that EQ or high pass filtering wont do. Be patient and creative experimenting with this switch, rewards are to be discovered.... Switching in real time on a single track will not produce an epic change but it's cumulative effect is quite obvious to hear over the landscape of a full mix.
IMPEDANCE (Nominal 1kHz)
I/P LINE = 12k
I/P MIC = 900
I/P INSTRUMENT = 200k
O/P = 80
BUSS = 7.5k
Mic Input: Transformer balanced
Line Input: Transformer balanced
1/4 Input: Unbalanced
Line Output: Transformer balanced
Buss Output: Transformer isolated, unbalanced
Mic Input Mode*
Nominally 900 transformer balanced, floating
Gain adjustable from +21 to +65 in 7 steps
Maximum input 0 dBu for %1 THD+N @ 1kHz
Line Input Mode*
Nominally 12,000 transformer balanced, floating
Gain adjustable from -6 to +15 in 5 steps
Maximum input +27dBu to produce max output condition (below)
*Mic and Line input modes can be used interchangeably for loud mics and quiet lines, or to experiment with distortion and impedance effects. 48V phantom power can be engaged regardless of the mic/line or gain settings.
Instrument Input Mode
Nominally 200,000 unbalanced
Gain adjustable from -12 to +59 dBu in 12 steps
Maximum input +16 dBu for %1 THD+N @ 1kHz
Nominally 80 transformer balanced, floating
Output level continuously adjustable from 0 dBu (FULL ON) to -infinity
Maximum output is +20 dBu into 600 for %1 THD+N @ 1kHz
L-R Buss Outputs
Nominally 6,600 unbalanced, transformer isolated
Maximum output depends on buss termination and summing amp headroom
Unit crosstalk TBD
Channel separation TBD
Noise (w/EQ bypassed)
WTD 10Hz to IEC-A
Not more than -94dBu @ minimum gain
Not more than -57dBu @ maximum gain
Equivalent Input Noise -122 dBu
Distortion (w/EQ centered)
THD+N at +18dBm
0.025% @ 10kHz
0.02% @ 1kHz
0.15% @ 100Hz
@ 0 dBm, unity gain
± 0.5 dBu 20 Hz to 20kHz (w/EQ bypassed)
± 1 dBu 20 Hz to 20kHz (w/EQ centered)
-1 dB @ 10Hz
+3 dB @ 100kHz
Actual Q and boost/cut amounts vary per frequency selected
HF tone control (quasi-shelving)
± 10 dBu @ 6k, 11k, and 17kHz
Q = 1.6 nominal (from 1.3 to 2)
MF presence control (peaking)
± 17 or 12 dBu @ 330, 470, 590, 790, 1.2k, 1.4k, 2.5k, 3k, 5.6k, and 7.8kHz
Q = 1.15 nominal (from 0.3 to 3)
LF tone control (quasi-shelving)
± 12 dBu @ 35, 70, and 130Hz
Q = 0.33 nominal (from 0.2 to 0.5)
12dB/octave @ 130Hz
The AwTAC Channel Amplifier is an analog audio signal processor conforming to the industry standard API 500 Series modular form-factor. It was designed according to API VPR Alliance specifications, and will thus install in any API or compatible 500 Series enclosure having two or more conjoined module slots. Such an enclosure, typically called "lunchbox" or "rack", is required to operate an Awesome EQ, providing the necessary DC power and rear panel input/output connectors. While we at AwTAC have found the Purple Audio Sweet Ten Rack, a heavy-duty 10-slot 3RU enclosure which houses up to five Channel Amplifiers to be our favorite sounding rack, to the best of our knowledge at the time of writing the following third-party 500 Series enclosures should also suffice.
Dimensions: 5.25 x 3 x 6 (h x w x d, inches)
Weight: 2 lbs
Power Requirements: ±86mA @ ±16VDC
+ 4mA @ +48VDC (Only if using phantom-powered microphones)