UTA UnFairchild 670M II User Manual
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UTA UnFairchild 670M II User Manual

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UnFairchild 670M II User Manual Version 1.1
UT A
UnderToneAudio
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Summary of Contents for UTA UnFairchild 670M II

  • Page 1: Table Of Contents

    UT A UnderToneAudio UnFairchild 670M II User Manual Version 1.1 1. INTRODUCTION 2. SAFETY/ POWERING UP 3. REAR CONNECTIONS 4. FRONT PANEL CONTROLS 7 - 8 5. CALIBRATING PROCEDURES Balancing Calibrating The Audio Levels Matching Channel Compression VU Meter Output Level Calibration 6.

  • Page 2: Introduction

    From our sound lab to yours, we sincerely hope you will find the results as useful and satisfying as we have. What’s different about the UnFairchild 670M II from an original Fairchild? We are using Cinemag recreations of the original transformers used in the audio path. They are extremely close to the originals with only small adjustments made to accommodate a more desirable gain structure.

  • Page 3: Safety/Powering Up

    2. SAFETY/POWERING UP SAFETY   I NSTRUCTIONS         WARNING:   T o   r educe   t he   r isk   o f   f ire   o r   e lectric   s hock,   d o   n ot   e xpose   t his                                                                   product  ...
  • Page 4 12. Do   n ot   u se   t his   d evice   w ith   w all   o r   c eiling   m ounts   n ot   s pecified   b y   t he   m anufacturer.   13.
  • Page 5 2. RACK MOUNTING and POWERING UP Before powering up, be sure you are plugging in to a properly grounded outlet. The standard setup for the UnFairchild is for a 110V-120V 60hz AC power source. It can be setup for 220V-240V op- eration upon request.

  • Page 6: Rear Connections

    3. REAR CONNECTIONS AUDIO INPUTS/OUTPUTS You are now ready to plug in cables to the rear of the unit. All audio connections on the unit are XLR. INPUT • Plug the source signals you want to be processed into the INPUT LEFT and INPUT RIGHT XLR input jacks on the back (see figure 1).

  • Page 7: Front Panel Controls

    4. FRONT PANEL CONTROLS UNFAIRCHILD UNFAIRCHILD UNFAIRCHILD DESCRIPTION OF FRONT PANEL CONTROLS 1. POWER SWITCH - Use this switch to turn the UnFairchild on and off. Push the switch UP to the “ON” position to turn the unit on and push the switch down to power the unit off. 2.
  • Page 8 7. BYPASS/VU SWITCH - This 4-position switch allows you to bypass the active circuitry and control the meter functionality. • BYP: When set to the bypassed BYP mode, the signal plugged to the input jacks will be connected directly to the output jacks; bypassing all of the active electronics. • VU: When set to the VU mode, the input signal will be processed by the compression circuit and the VU will show the resulting output level. • GR: When set to the GR mode, the VU meters will show the amount of gain reduction. • BAL: When set to the Balancing BAL mode, the unit is put into a special mode used for balancing the circuitry for optimal performance with the particular set of 6386 tubes that are installed.

  • Page 9: Calibrating Procedures

    5. CALIBRATION PROCEDURES BEFORE YOU CALIBRATE: As the UnFairchild warms up, the calibration will typically fall into place. This can take any- where from 10 to 30 minutes. BALANCING WITH THE METER Balancing is important for the overall performance of the UnFairchild. When the tubes are out of balance typically you will hear a thumping sound when the compressor is reacting to transients.

  • Page 10: Matching Channel Compression

    5) Adjust the GAIN TRIM potentiometer until the VU reads “0dB” (All UnFairchilds have “0dB” on the meter calibrated to a +4dB output level). IMPORTANT! There is another aspect to the level gain trim adjustments; the gain trim control adjusts the bias current of the 6386 tubes. It is a great way to adjust the level, but it will affect the sonic character of the compression.

  • Page 11: Vu Meter Output Level Calibration

    1) Power up the UnFairchild and let it warm up for 5-10 minutes. 2) Set the BYPASS/VU switch to GR. 3) Set the channel mode switches to IND. 4) Set the INPUT GAIN controls to your UNITY GAIN setting (typically 12). 5) Turn the THRESHOLD”controls to 10 (fully clock-wise).

  • Page 12: Using The Side Chain

    6. USING THE SIDE CHAIN There are many ways to make use of the side chain feature on the UnFairchild. In this manual, there are 2 common approaches that we will discuss. USING THE LOOP In this application, the SC SEND - L and SC SEND - R outputs on the back panel send signal to an ex- ternal processing device (typically an equalizer).

  • Page 13: Feedback Vs. Feedforward

    7. FEEDBACK VS. FEEDFORWARD One of the advantages of having a side chain insert on the Fairchild circuit, is that you can set up the com- pressor to be FEEDFORWARD instead of its intended FEEDBACK design. FEEDBACK compression means that the compressor is using the signal from the final output of the device to trigger the compression.

  • Page 14: Time Constant Presets

    8. TIME CONSTANT PRESETS PRESET # ATTACK RELEASE .2 ms .3 Sec. .2 ms .8 Sec. .4 ms 2 Sec. .8 ms 5 Sec. .4 ms 2 sec. for individual peaks, 10 seconds for multiple peaks .2 ms .3 sec for individual peaks, 10 sec. for multiple peaks and 25 sec.

  • Page 15: Example Settings

    DRUMS There are a lot of cool applications for the UnFairchild with drums. The UnFairchild 670M II is liter- ally the tube compressor I had been looking for... for 20 years. I had never found a tube compressor that had the right combination of the smoothness, that is inherent in tube circuitry, with the flex- ibility and aggressiveness I need for making modern records.

  • Page 16: Bass

    BASS Bass is one of the instruments that has always worked well with the original Fairchild. You will find that settings 1,2 or 3 feel very similar to an original 660 or 670. Settings 4 and 5 always had to slow of a release for bass guitar in my opinion.

  • Page 17: Piano

    PIANO For piano I have two types of recordings I typically do. Either a bigger more open natural sound or a really aggressive affected sound. For the big open sound VAR4 (ATK5/REL3) is great. For the really aggressive sound I like to use the FEEDFORWARD mode. You can get this really cool effect of the sound almost imploding on itself.

  • Page 18: Maintenance

    You can acquire tubes yourself and follow the balancing instructions in section 5 or you can contact us about purchasing a replacement tube directly from UTA. 11. SPECIFICATIONS Input Impedance..........

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