Avalon VT-747SP Operation Manual Download Page 1

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D E S I G N

AVA L O N

U R E

L A S S

A M

U S I C

E C O R D I N G

Y S T E M S

V T - 7 4 7 S P

Operation Manual

Pure Class A Stereo Spectral Opto-Compressor Equalizer

Summary of Contents for VT-747SP

Page 1: ... I G N AVA LON P U R E C L A S S A M U S I C R E C O R D I N G S Y S T E M S VT 747SP Operation Manual Pure Class A Stereo Spectral Opto Compressor Equalizer 2001 Avalon Industries Incorporated Release 1 0 ...

Page 2: ...N DESIGN P U R E C L A S S A M U S I C R E C O R D I N G S Y S T E M S VT 747SP Operation Manual Avalon Industries Inc PO Box 5976 San Clemente CA 92673 Tel 949 492 2000 Fax 949 492 4284 www avalondesign com ...

Page 3: ...747sp 18 4 5 Six Band Passive Equalizer 18 4 6 Using the Equalizer 18 4 7 Using the Side chain 19 5 0 Applications 19 5 1 0 Typical Set ups 19 5 1 1 Recording 20 5 1 2 Stereo Mixdown Buss 20 5 1 3 Mixdown Mastering DAW 20 5 1 4 Mastering 21 5 2 0 Application Settings 21 5 2 1 Stereo Buss for Mixdown 21 5 2 2 Stereo Buss with De ess 22 5 2 3 De ess on Vocals 22 5 2 4 Stereo Keyboards 23 5 2 5 Extre...

Page 4: ...high quality service Please take a moment to read this manual and enjoy your Avalon experience 1 1 Overview The Vt 747sp combines a stereo tube discrete Class A opto compressor with a musical six band program equalizer as well as Left Right output level gain reduction metering and an internal regulated power supply in a 2U space Ideal for high performance DAW digital audio workstation input signal...

Page 5: ...ete amplifiers are utilized for the input and output drive interface with 36dB input headroom A high quality analog VU meter indicates accurate gain reduction Twin LED meters provide a 60dB range with fast L R output status of all levels 1 2 Features Class A optical compression 100 discrete Pure Class A operation Built in side chain for spectral control Six band discrete graphic passive EQ TSP Tub...

Page 6: ...ard 4 Operation Manual Keep the packing materials in case you need to ship your unit for any reason Note You must fill out and send in your warranty card in order to receive warranty and technical support If you have not already filled out your warranty card please take the time to do so now Page 6 Avalon Vt 747sp Operation Manual AVALON DESIGN Introduction Vt 747sp contents and packaging ...

Page 7: ... source XLR type connectors pin 2 is hot You can use the Vt 747sp in mono however the Left and Right will always work together as one dedicated stereo pair 3 Turn on the power and allow 60 seconds while the soft start procedure commences You may hear a relay click at about 45 seconds During the soft start procedure the Vt 747sp is in hard wire bypass mode and will pass signal but the controls will...

Page 8: ...ore compression at the frequencies set by the LF low frequency and HF high frequency spectral frequency controls located directly below THRESHOLD Sets compressor input threshold from 30dB to 20dB COMPRESSION Sets ratio of compressor from 1 1 to 20 1 COMPRESSOR Switch in engages compressor into signal path hard wire bypass SIX 6 BAND PASSIVE CLASS A PROGRAM EQUALIZER EQ to COMP Inserts the six 6 ba...

Page 9: ... all of the functions of the Vt 747sp Start by plugging a stereo source CD player stereo keyboard Submix output etc into your Vt 747sp If possible run directly out of the Vt 747sp to powered monitors bypassing the console or mixing board Choose a musical selection loop patch sample or instrument with wide dynamic range so you can experiment with the compressor Set push button switches to their off...

Page 10: ...tails on each specific control or switch please refer to Chapter 4 Operations and Controls 3 0 Safety and Grounding The following chapter describes how to safely install your Vt 747sp for optimal sonic performance 3 1 Safety Instructions This unit contains voltages that can cause serious injury or death Do not operate with the covers removed Improper connection of the equipment grounding cable can...

Page 11: ...ever be used with this unit 3 3 AC Voltage Selection Before connecting the Vt 747sp to the AC supply check the OPERATING VOLTAGE located on the rear of the chassis in the AC inlet connector Voltages available are 100 120 220 240VAC 5 50 60Hz at 60 watts USA uses 120V To change the AC voltage for your location 1 Make sure there is no AC power cable connected to the AC inlet 2 Insert a small flat he...

Page 12: ...ver from left to right 3 Pull fuse casing labled with an arrow straight out 4 Replace fuse in casing Insert casing into casing slot Close AC voltage selector cover 3 5 Rack Mounting and Cooling The Vt 747sp is designed to be mounted in a standard 19 equipment rack As vacuum tubes and Class A circuitry can generate heat it is highly recommended that an additional rack space above and below the unit...

Page 13: ...e Vt 747sp is well shielded against moderate electrical and magnetic fields care should be taken to avoid areas that are in proximity to large motor or power transformers Locations near sources of high RFI radio frequency interference such as computers or digital effects devices should also be avoided Because of the microphonic nature of vacuum tubes areas of extreme vibration or sound levels shou...

Page 14: ...threshold level Continuously variable from 30dB to 20dB EQ COMP Switches six band passive equalizer before pre the compressor This gives flexibility to achieve different sounds Putting the EQ before the compressor will give the signal a more squashed and narrow sound than if the EQ follows the compressor LF SIDE CHAIN THRESHOLD Controls the increase of compression for the LF specified frequency ra...

Page 15: ...The frequency turnover Q and amplitude ranges have been carefully chosen for each band to provide extremely smooth musicality Pushing the faders up from center detent will boost and pushing the faders down will cut OUTPUT Continuously variable output control This controls the overall program level of the Vt 747sp The Vt 747sp is calibrated so that 0 on the LED output meters accurately shows 4dBu A...

Page 16: ...high mid frequency range 10dB 5kHz shelf HIGH RANGE EQUALIZER BAND Controls high frequency range 20dB 32kHz shelf AC Power Switch Turns the power on and off You must allow approximately 60 seconds from the time you turn on the power switch for the Vt 747sp to complete the entire soft start turn on proce dure For more details on the soft start pro cedure please refer to Chapter 3 5 Turn on Procedur...

Page 17: ...r contact your authorized Avalon dealer For instructions on changing the fuse see Chapter 3 4 Fuse Replacement page 12 4 2 Connections The LINE INPUTS are an electronically balanced Class A circuit with a nominal 20k ohm input impedance Can be used unbalanced by shorting pin 3 to ground on the cable connector The connectors are female XLR 3 The OUTPUTS are a low impedance electronically balanced c...

Page 18: ...west phase change while offering simple and effective tone control The following is a description of the six fre quency bands From Low to High left to right 1 24dB 15Hz shelf response 2 8dB 125Hz selected Q response 3 4dB 500Hz selected Q response 4 4dB 2kHz selected Q response 5 10dB 5kHz shelf response 6 20dB 32kHz shelf response 4 6 Using the Equalizer The equalizer section of the Vt 747sp has ...

Page 19: ...ontrol section of the compressor 5 0 Applications The first thing to remember is that there are no specific rules The Vt 747sp was designed to be extremely flexible and filled with endless colors textures and tones TRUST YOUR EARS 5 1 0 Typical Set ups The following setup diagrams are a few typical ways not the only ways to insert the Vt 747sp in the audio chain during a recording project Much of ...

Page 20: ... or DAW Inputs Outputs Inputs Outputs Mixing Console for Monitoring Inputs Mixing Console for Monitoring Inputs Analog or Digital Tape Machine Mixing Console Multiple Outputs Multiple Line Inputs Stereo Submix or Main Insert Inputs DAT or CD Burner Inputs Vt 747sp DAW Rt and Lft Stereo Submix Outputs Inputs Record Two New Tracks Inputs Outputs Stereo Mix on DAT CD or Tape Mach Final Media DAT or C...

Page 21: ...o chain The output control is designed to be sonically invisible This means that you can set the output level based on what signal level you want coming out of the Vt 747sp and you will not color the signal by turning this control up or down Therefore the output level is not included in the example settings 5 2 1 Stereo Buss for Mixdown Input 3 Gain Out TSP Out Compressor In EQ Comp Out Compressio...

Page 22: ...qualizer In EQ Faders from left 1 to right 6 1 1 2 1 3 0 5 4 0 5 5 1 6 1 5 2 3 De ess on Vocals Input 2 High Gain Out TSP In Compressor In EQ Comp In Compression Ratio 20 1 Compression Threshold 20 Attack Fast Release Fast Make up 2 Side Chain In Side Chain LF Threshold 15 Side Chain LF Frequency 200Hz Side Chain HF Threshold 15 Side Chain HF Frequency 7kHz Equalizer In EQ Faders from left 1 to ri...

Page 23: ...izer In EQ Faders from left 1 to right 6 1 0 2 1 3 1 4 2 5 2 6 1 5 2 5 Extreme Compression Input 0 Unity Gain Out TSP In Compressor In EQ Comp In Compression Ratio 20 1 Compression Threshold 20 Attack Fast Release 12 O clock Make up 10 Side Chain Out Side Chain LF Threshold bypassed Side Chain LF Frequency bypassed Side Chain HF Threshold bypassed Side Chain HF Frequency bypassed Equalizer In EQ F...

Page 24: ...ers from left 1 to right 6 1 1 2 2 3 1 4 2 5 1 6 1 5 5 2 7 Acoustic Guitar Input 3 Gain Out TSP Out Compressor In EQ Comp Out Compression Ratio 9 1 Compression Threshold 15 Attack 10 O clock Release Fast Make up 0 Side Chain In Side Chain LF Threshold 10 O clock Side Chain LF Frequency 250 Hz Side Chain HF Threshold 3 O clock Side Chain HF Frequency 7 kHz Equalizer In EQ Faders from left 1 to righ...

Page 25: ...l so that the volume is consistent whether the singer is whispering or screaming During mixdown compressors are used to tighten up the tracks so that nothing pops out of the mix uncontrollably During the mastering process compressors are used very slightly to tighten up the entire mix and can give the mix a bigger sound The way a compressor works is like an automatic fader When the input signal ex...

Page 26: ...ry beginning of a sound is usually the loudest and most difficult to record smoothly for example vocals slap bass guitar etc In many cases you want to let these initial transients pass through before pulling down the gain other times you want the compression to start right away To help make adjustments to this specific event the attack control adjusts the length of time it takes for the compressio...

Page 27: ...stions about the Vt 747sp Q Can I use the Vt 747sp as an insert for compression and EQ A Yes the Vt 747sp is perfect as an insert for a recorded stereo signal such as keyboards acoustic piano drum overheads acoustic guitar etc Q What s the main difference between the Vt 747sp s compressor and Avalon s AD2044 compressor A The Vt 747sp is a dedicated stereo compressor that is loaded with many differ...

Page 28: ...id Band as a peak dip then simply cut turn down the High Frequency band to bring down the ultra high end giving you more creative possibilities Q Why does the needle in the VU meter sometimes drift to the left of 0dB after the Vt 747sp warms up A As the unit warms up after approximately 30 minutes the resistance of the meter coil is increased with heat and the needle then settles into its operatin...

Page 29: ...our recorded music will sound bigger It works wonderfully for synths drum machines and keyboards that would otherwise sound thin and lifeless Q Can I use the SIDE CHAIN LISTEN func tion as a parametric EQ A Yes Press in the SIDE CHAIN LISTEN button and use the Threshold controls as cut boost and the two frequency selectors to select the frequencies of interest Note that the Threshold controls will...

Page 30: ... the volume Once you have isolated the problem to the Vt 747sp please check the following list for suggested solutions Page 30 Avalon Vt 747sp Operation Manual Trouble Shooting AVALON DESIGN Problem No Power No Power Lights dim no sound No sound Hum or buzzing noise Distorted sound Distorted sound Cause Power cable on back of chassis not securely plugged in Fuse blown due to power surge or imprope...

Page 31: ...9 492 2000 1 Background noise a crackling or sizzling sound 2 Ringing noise 3 Low output volume 4 Distorted sound Other problems Please call your nearest dealer or the Avalon factory at 949 492 2000 if you have any technical questions or are experiencing problems not listed in our Trouble Shooting Table Page 31 Avalon Vt 747sp Operation Manual Trouble Shooting AVALON DESIGN ...

Page 32: ... tubes should be performed by an authorized Avalon technician Meter Calibration and Alignment The VU meter can be easily adjusted to 0 VU when no signal is present To adjust the VU meter to zero 1 Turn the unit on 2 Let unit warm up for at least 30 minutes 3 Unplug all inputs 4 From the front of the unit use a small flat head screwdriver to turn the recessed trim pot so that the needle reads zero ...

Page 33: ...0 segment LED VU meters with 27dB to 30dB range Compressor type optical passive attenuator Make up gain Variable 0dB to 10dB stereo tracking Compression ratio Variable 1 1 to 20 1 Threshold Variable 30dB to 20dB Attack Variable 2mS to 200mS Release Variable 100mS to 5 seconds Side chain spectral contour Variable threshold 15dB to 15dB frequency 70Hz to 9kHz Equalizer type Discrete Class A passive ...

Page 34: ...MPRESSION 1 20 4 7 8 3 10 2 6 5 dB THRESHOLD 20 20 0 6 10 10 16 15 3 2 DESIGN AVALON 0 1 2 3 3 2 1 CLASS A PROGRAM EQUALIZER LEVEL SIGNAL dB OUTPUT 0 20 6 2 2 3 4 4 8 1 1 EQUALIZER R dB L 30 0 24 18 12 12 6 6 18 24 30 20 10 3 2 AVALON VA C U U M T U B E 7 5 3 1 0 1 2 d e c i b e l s VU IN IN IN IN IN IN IN HF v747 sp t dB 15 15 15 15 0dB 2 6 10 SIDE CHAIN THRESHOLD CONTOUR GR SC LISTEN SIDE CHAIN ...

Page 35: ... IN LF HF 2 BAND EQ COMP TSP TSP COMP OPTO IN IN TIMER 40 sec STANDBY BYPASS EQ PRE COMP EQ PRE COMP MAKE UP GAIN METER BUFFER LINK INPUT LEFT Class A Vacuum Tube STEREO SPECTRAL OPTO COMPRESSOR WITH TSP VT 747SP Avalon Design is a division of Avalon Industries Inc 2001 c TSPTWIN SIGNAL PATH EQ PRE COMP BALANCED 20K OHM 36dB OUTPUT RIGHT BALANCED 600 OHM 30dB BALANCED CLASS A INPUT AMP DISCRETE CL...

Page 36: ... accident or transit damage 6 Proof of purchase in the form of a bill of sale or invoice to provide evidence that the unit is within the warranty period must be presented to obtain warranty service 7 This warranty is only valid if the serial number appears on the product Outside of the USA Please check www avalondesign com for your nearest authorized service center 11 1 Returns If your Vt 747sp ha...

Page 37: ...ertz or in musical octaves channel A single functional path in an audio circuit clipping A cause of audio distortion that is the result of excessive gain requiring the peaks of the audio signal to rise above the capabilities of the circuit compressor In effect an automatic fader When the input signal exceeds a predetermined level called the threshold the gain is reduced by the compressor and the s...

Page 38: ...cies filter A simple equalizer designed to remove certain ranges of frequencies A high pass filter also called a low cut filter reduces or eliminates frequencies below the cutoff frequency There are also high cut low pass filters bandpass filters which cut both high and low frequencies but leave a band of frequencies in the middle untouched and notch filters which remove a narrow band but leave th...

Page 39: ...s then recorded to a master recording device such as a DAT recorder monaural Confined to a signal channel One microphone is a mono pickup many microphones mixed to one channel is a mono mix Several mono sources however can be panned into a stereo or at least two channel mix mono short for monaural noise Unwanted sounds Hum buzz or hiss could be crosstalk or digital hiss noise floor The residual le...

Page 40: ...ustic waveform side chain A function on a compressor where a specified frequency range is compressed more than the overall musical program Many compressors have a jack for an equalizer to be inserted into the compressor drive electronics shelving filter A rise or drop in frequency response at a selected frequency that tapers off to a preset level and continues at the level to the end of the audio ...

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