UTA UnFairchild 670M II User Manual Download Page 6

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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.

• 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).

Use the provided splitter cables as describbed on

page 13 if you would like to implement the Feed Forward option.

• Plug the OUTPUT LEFT and OUTPUT RIGHT signal from

the UnFairchild into the inputs of the device that will be either

recording or monitoring the processed signal.

SIDE CHAIN CONNECTIONS

• Connect the signal from the UnFairchild SC SEND - L and

SC SEND - R into the input of an external processing device (typi-

cally an equalizer).

• Connect the signal from an external source or process-

ing device into the SC RCV - L and SC RCV - R inputs on the back

of the UnFairchild

(see figure 2).

(Find more information on applications for the side chain feature

see the “USING THE SIDE CHAIN” section on page 12)

INPUT

SC SEND

GND

LIFT

SC RCV

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

WARNING: SHOCK HAZARD - DO NOT OPEN
AVIS: RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR

6386

ECC99

ECC81/12AT7

ECC83/12AX7

ECC99

ECC81/12AT7

ECC83/12AX7

6386

Voltage select

in fuse drawer

110V - T2A

240V - T1A

MAINS FUSE:

Serial #

Model: 670M II

Designed and built in California by

UnderToneAudio

UTA

AC LINE

50/60Hz

150VA

OUTPUT

INPUT

SC SEND

GND

LIFT

SC RCV

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

WARNING: SHOCK HAZARD - DO NOT OPEN
AVIS: RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR

6386

ECC99

ECC81/12AT7

ECC83/12AX7

ECC99

ECC81/12AT7

ECC83/12AX7

6386

Voltage select

in fuse drawer

110V - T2A

240V - T1A

MAINS FUSE:

Serial #

Model: 670M II

Designed and built in California by

UnderToneAudio

UTA

AC LINE

50/60Hz

150VA

OUTPUT

INPUT

SC SEND

GND

LIFT

SC RCV

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

WARNING: SHOCK HAZARD - DO NOT OPEN
AVIS: RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR

6386

ECC99

ECC81/12AT7

ECC83/12AX7

ECC99

ECC81/12AT7

ECC83/12AX7

6386

Voltage select

in fuse drawer

110V - T2A

240V - T1A

MAINS FUSE:

Serial #

Model: 670M II

Designed and built in California by

UnderToneAudio

UTA

AC LINE

50/60Hz

150VA

OUTPUT

UNF V2.0, CMB REAR SILKSCREEN, RevB2

LAYER 1 BLACK

VIEW #1 COMPLETED PART

VIEW #2 COMPLETED PART INSTALLED

NOTES:
PART:

UNF V2.0, CMB REAR SILKSCREEN, RevA

COMPOSITE VIEW (FOR REFERENCE ONLY):
SILK SCREEN LAYER 1 BLACK

Undertone Audio
323-208-1566

(figure 1)

(figure 2)

Summary of Contents for UnFairchild 670M II

Page 1: ...PROCEDURES Balancing 9 Calibrating The Audio Levels 9 Matching Channel Compression 10 VU Meter Output Level Calibration 11 6 USING THE SIDE CHAIN Using the Loop 12 Side Chain Compression FX 12 7 FEEDBACK VS FEEDFORWARD 13 8 TIME CONSTANT PRESETS 14 9 EXAMPLE SETTINGS Drums 15 Bass 16 Guitar 16 Piano 17 Vocals 17 Mix Buss 17 10 MAINTENANCE 18 11 SPECIFICATIONS 18 1 ...

Page 2: ...l Fairchild manual recommends that you should change the tubes every 6 months We lowered the plate voltage going to the 6386 tubes to help extend their life and reliability 6386 tubes can cost anywhere from 120 500 each and the unit uses 8 of them Best case you re looking at 1 000 every 6 months to be sure an original Fairchild is running up to spec This is one of the reasons so many of them sound...

Page 3: ...fluid on the device 5 Vents are provided for heat dissipation on the sides and the rear of the device Maintain at least 2 5cm space around these vents to provide sufficient ventilation 6 Keep the device away from sources of heat and open flame such as heaters radiators stoves lit candles etc 7 Make sure the power cord is intact before plugging it into the device Do not use cords with visible damag...

Page 4: ... 240VAC operation packed separately Open the fuse drawer on the AC receptacle on the rear of the device and replace the T 0 4A fuse with the T 0 2A accessory fuse 4 In the fuse drawer change the AC Mains switch from the 110V position to the 240V position 5 Assure that the fuse drawer is secured closed before attaching the power cord INSTRUCTIONS POUR 220 240VAC FONCTIONNEMENT 1 Avant de commencer ...

Page 5: ...he selected voltage PROPER VENTILATION IS ESSENTIAL TO ENSURE THE UNFAIRCHILD DOES NOT OVER HEAT There are important ventilation holes on the top and bottom of the chassis that help keep the unit within the proper operating temperature If there vent holes are covered up the unit WILL over heat When mounted in a rack be sure to leave at least a 1 3 rack space gap above and below the unit When sitti...

Page 6: ...T signal from the UnFairchild into the inputs of the device that will be either recording or monitoring the processed signal SIDE CHAIN CONNECTIONS Connect the signal from the UnFairchild SC SEND L and SC SEND R into the input of an external processing device typi cally an equalizer Connect the signal from an external source or process ing device into the SC RCV L and SC RCV R inputs on the back o...

Page 7: ...monic distortion See Calibrating the Audio Levels under the CALIBRATING PROCEDURES section on pg 9 10 for more details 5 BALANCE TRIM POT This trim pot is used to balance the circuit for optimum performance based on the particular set of tubes installed See balancing under the CALIBRATING PROCEDURES section on pg 9 for more details 6 GR ZERO These trim pots are used to set the meters to 0dB on the...

Page 8: ...ontrol is sen sitive to and it changes the ratio or knee of the compression In the fully counter clockwise position the UnFairchild will be sensitive to the lowest range of input levels and have the softest knee or lowest possible ratio As the control is turned clockwise the ratio increases and the threshold becomes less sensitive and requires a higher setting to maintain the same amount of compre...

Page 9: ...lications but there are circumstances in which balancing by ear may achieve better results The balance between a set of tubes can be different based on the amount of compression If you are using the UnFairchild to do some very ex treme compression on transient sound sources such as drums you may hear some sonic artifacts such as thumping You can solve this simply 1 Play the sound source with the c...

Page 10: ...ix buss or for mastering If you want the softer thicker more saturated sound set the INPUT GAIN to 9 or 10 This will force you to set the GAIN TRIM much lower to achieve unity gain with a 4dB output level This can add some beautiful coloration when using the UnFairchild for tracking or mixing individual instruments The higher bias current calibration settings can shorten the life span of the 6386 ...

Page 11: ...re calibrated at the factory with Audio Precision test equipment to make sure 0dB on the meter is exactly 4dB when metering output level If these drift or if you would like to have a different calbration for the meters manual calibration can be accessed through small holes on the right side of the chassis 1 Power up the UnFairchild and let it warm up for 5 10 minutes 2 Set the BYPASS VU switch to ...

Page 12: ...he drum mix heavily without changing the balance of the kick drum in the blend When using the UnFairchild on vocals you can boost higher frequencies on the side chain signal and make the gain reduction circuit more sensitive to the higher frequencies This creates a de esser type result when compressing vocals These are just a few examples There are many more applications for this frequency based m...

Page 13: ...e 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 Counterintuitively when the compressor starts compressing the signal triggering the compression gets quieter In a way it gives the compressor an awarenes...

Page 14: ... consequently the fastest attack release setting when the attack release controls on the lower panel are set to 1 You can then make either the attack or release longer resistively with the attack release controls on the lower panel If you select VAR2 then BOTH the attack and release will get slower You can then make either of them even slower with the attack release controls on the lower panel Bot...

Page 15: ...e been loving using either VAR1 or VAR2 with a slower attack time setting around 7 12 and a faster release time setting around 1 4 This gets that wonderful effect of enhancing the transient attack of the drums while pulling the ambience forward for a thicker more explosive sound If you are looking for a more vintage Fairchild type sound settings 1 or 2 are great for getting a more Beatle esque dru...

Page 16: ...lace after that For this sometimes the FEEDFORWARD mode is really effective It gets even more of that dbx 160 smack when the guitar first comes in For clean elec tric guitars there is a cool thing that happens with the really fast attack times Sometimes I find clean electric guitars to be to pointed sounding and I like to use a limiter type setting to smooth the attacks For this the attack needs t...

Page 17: ...ondenser mic There are two ways to go with the UnFairchild on the mix buss If all of the individual tracks in the mix have already been compressed to taste then the slower attack times VAR2 ATK5 REL2 have been great This setting is slow enough to not alter the attack on the drums in the mix while add ing some glue additional pumping and presence to the overall mix EQ ing out low end in the side ch...

Page 18: ...r sure what is better until these units have been around long enough for people to start reporting back to us with their results either way The second issue is the eventual replacement of tubes They should last a long time under normal circum stances but there is always the possibility of a tube getting smashed or unexpectedly failing prematurely You can acquire tubes yourself and follow the balan...

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