AVA L O N P URE C LASS A DESIGN M USIC R ECORDING S YSTEMS V T- 7 3 7 S P P u r e C l a s s A M o n o Va c u u m Tu b e / D i s c r e t e P r e a m p l i f i e r, O p t o - c o m p r e s s o r & E q u a l i z e r Operation Manual © 2016 Avalon Industries Incorporated. Release 2.
V T- 7 3 7 S P Operation Manual Avalon Industries, Inc., 3715 Cahuenga Blvd, Studio City, CA 91604 Tel: 949-492-2000 www.avalondesign.
Table of Contents 1.0 Introduction . . . . . . . . . . . . . . . . . . . . . .5 5.2 Application Settings . . . . . . . . . . . . .24 1.1 Overview . . . . . . . . . . . . . . . . . . . . .6 5.2.1 Vocals . . . . . . . . . . . . . . . . . . . . . .25 1.2 Features . . . . . . . . . . . . . . . . . . . . . .7 5.2.2 Vocals with De-ess . . . . . . . . . . . .26 1.3 Unpacking and Inspection . . . . . . . . .8 5.2.3 Bass Guitar . . . . . . . . . . . . . . . . . .27 5.2.4 Acoustic Guitar . . . . . . . . . . .
Introduction 1.0 Introduction Welcome to Avalon and the world of Pure Class A music recording systems. The Vt-737sp is an extremely powerful, versatile and musical direct recording path for combining the essetial elements needed for professional music recording: Class A vacuum tube preamplifier, vacuum tube opto-compressor and discrete parametric equalizer.
Introduction 1.1 Overview The Vt-737sp combines three essential fuctions needed for professional recording: preamplifier, compressor and equalizer. The Vt-737sp is designed to completely bypass the mixing board during input to deliver the purest and cleanest signal possible to your recording device. It works wonderfully for recording directly into a digital device giving the signal a richer and fuller sound.
Introduction It has +/-16dB amplitude control and a high/low Q (bandwidth) swtich which musically sharpens the filter’s response from a Q of 0.2 (wide) to 0.85 (medium). The High Mid band filter section is of the same type and covers a frequency band of 200Hz to 2.8kHz. With the X10 switch engaged, the filter covers the 2kHz to 28kHz range. A high/low Q switch changes the bandwidth in the same way as the Low Mid band.
Introduction 1.3 Unpacking and Inspection Your Vt-737sp was packed carefully at the factory. Check to make sure that the shipping carton contains the following items: 1. 2. 3. 4. Vt-737sp Power cable Warranty card Operation Manual Keep the packaging materials in case you need to ship your unit for warranty service. Note: Your must fill out and send in your warranty card in order to receive warranty and technical support.
Quick Start-up 2.0 Quick Start-up The following chapter is designed to help you get started using your Vt-737sp right away without having to read the entire manual. Make sure however to take time to read the manual at a later date as there are many safety aspects and features of the Vt-737sp that will not be discussed here. If you are familiar with this type of equipment you can also familiarize yourself with your Vt-737sp and the functions with the Quick Start-up Guide on page 10.
Quick Start-up 2.
Quick Start-up 2.2 Tips UNITY LEVEL - The VT-737sp is calibrated so that unity level is 0dB VU=+4dBu output. PREAMP GAIN - Use the preamp gain control as a gain control, not a level control. Turning up the PREAMP GAIN will drive the tubes harder for different tonality. OUTPUT - Use the output control as the overall level control. EQ->COMP - Inserts the four band parametric EQ before the compressor in the signal path. SC-MID - Engages the built in side-chain.
Safety and Grounding 4. COMPRESSOR - Press in the COMPRESSOR switch and turn the main compression controls to the following: COMPRESSION - full clockwise (20:1) THRESHOLD - full counter clockwise (-30dB) ATTACK - full counter clockwise (Fast) RELEASE - full clockwise (Slow) This is full compression with fast attack and slow release. You can probably hear the compressor “pumping” or “breathing”. Play with the compression controls to get a feel for the compressor. 3.
Safety and Grounding This product is equipped with an AC power inlet and must be connected to a three-wire grounded plug. Voltages available are 100-120-220-240VAC +/-0.5% 50-60Hz at 75 watts (USA used 120V). The AC power cable must be plugged into an appropriate outlet that is correctly installed and grounded in accordance with all local electrical safety codes and ordinances.
Safety and Grounding 3.4 Rack Mounting and Cooling The Vt-737sp is designed to be mounted in a standard 19” equipment rack. As vacuum tubes and Class A circuitry generate heat, it is highly recommended that an additional rack space above and below the unit be kept empty to allow for adequate cooling. Avalon Design has developed 1U ventilation panels (VP-1) specfically to keep your rack-mounted gear cool. Always use all four front panel-mounting holes when mounting the Vt-737sp in a rack enclosure.
Operation and Controls 4.0 Operation and Controls The following chapter describes the details of your Vt-737sp and how to operate each function. 1 PREAMP GAIN Continuously variable rotary control adjusts input level of signal. This control will drve the tubes harder to get more tube tone into the preamp. The input has +36dB of headroom before overload. You can use this control at minimum and maximum levels for different sounds and colors.
Operation and Controls 7 COMPRESSION (RATIO) Sets the compression ratio. Continuously variable from 1:1 to 20:1. 8 COMPRESSOR When switch is engaged, the compressor is inserted into the signal path. When disengaged, the compressor section is hard bypassed by a sealed silver-contact relay. 9 VU METER Can be selected with the METER switch to indicate either output level (non-illuminated) or compressor gain reduction (illminated). The VU meter’s needle is also speed sensitive for measuring gain reduction.
Operation and Controls 21 EQ->COMP Switches the signal so that the equalizer section is before the compressor. This gives flexibility to achieve different sounds. Putting the EQ before the compressor will give the signal a more squashed or tighter sound than if the EQ follows the compressor. 22 ATTACK Varies attack time of compressor from 2ms to 200ms. 23 VU METER (0dB calibration screw) Recessed screwdriver adjustment for setting of 0dB on the VU meter when set to read the compressor’s gain reduction.
Operation and Controls 4.1 Rear Panel Description 1 GROUND LINK 2-terminal barrier strip. Isolates chassis ground from audio ground. To lift ground, simply unscrew both phillips-head screws and remove the metal strip held down by the screws. Do not remove this link unless you experience hum or AC noise. 2 AC INPUT & FUSE Combination IEC socket, voltage selector and fuse location. AC Voltage is factory set as ordered.
Operation and Controls 4.3 Unbalanced Operation The Vt-737sp can also be used in unbalanced system by grounding the unused input or output pin. For mic or line input, tie pin 3 to pin 1 (ground). For output from the Vt-737sp to an unbalanced input leave pin 3 floating. Either the high or low pins can be used to carry the unbalanced signal. 4.
Operation and Controls Creating Distortion or Overdrive You can achieve interesting distortion sounds ranging from loose tube overdrive to tight discrete distortion. Be very careful experimenting with this because the Vt-737sp can get very loud and can cause serious damage to your speakers or ears. Avalon recommends that you first experiment using a line level input such as a guitar or bass plugged into the front panel instrument jack (not a microphone).
Operation and Controls 8. Fine tune controls for desired effect. 9. THRESHOLD is interactive with the PREAMP GAIN control; boost or cut the PREAMP GAIN level if the THRESHOLD control becomes out of range (swapping the equalizer before the compressor may also necessitate re-adjusting the threshold level). 4.4.4 Using the Equalizer 4.4.3 Linking Two Vt-737sp’s Two Vt-737sp’s can be linked for stereo operation. The compressor sections of both units are linked and controlled by one set of controls.
Operation and Controls When engaged, the frequency band selected is multiplied by a factor of ten. This means that the frequency is shifted upward by a multiple of ten. In the case of the LOW MID, this shift is from the range of 30Hz- 450Hz to the frequency range of 300Hz-4.5KHz and in the case of the HIGH MID, the shift is from the range of 200Hz-2.8KHz to the range of 2KHz-28KHz. Try experimenting with these different range settings to see how effective they are at covering the full audio spectrum.
Applications frequency only in the side-chain path and no longer hear the harsh “sss” sound in the audio path. At the same path time it now makes the compressor 10db to 15db more sensitive at the frequency you selected and boosted by +10 to +15dB (on the HIGH MID). The gain reduction meter should show -3dB to -10dB or more at the “sss” frequencies only.
Applications Figure 5.1.2 - Mixdown Tape Based Figure 5.1.5 - Mastering Tape Based Analog or Digital Tape Machine Stereo Mix on DAT, CD, or Tape Machine Right Output Left Output Multiple Outputs Link Line Input Line Input Multiple Line Inputs Output Mixing Console Main Outputs Inputs DAW or CD Burner Output Output Right Input Left Input Insert One Channel (Y-connector) Line Input two Vt-737sp’s linked Final Media - DAT or CD Outputs Inputs Monitoring System 5.
Applications 5.2.
Applications 5.2.
Applications 5.2.
Applications 5.2.
Applications 5.2.
Applications 5.2.
Applications 5.2.
Applications 5.2.
Applications 5.2.
Basics 6.0 Basics This chapter is intended to help the relatively new recording engineer understand many of the basics involved in recording. Included are information on impedance and cables as well as general information on microphones, preamplifiers, compressors, and equalizers. The information does not necessarily apply directly to the Vt-737sp, but many of the topics discussed will help you understand how to better utilize your Vt-737sp. 6.
Basics 6.3 Cables and Connectors Regardless of how high the quality of your mics, mixing console, singal processors, recording devices and monitors, the entire system can be degraded or silenced by a bad cable. Hum, crackles and lost signal due to open circuits, or failed outputs due to shorted circuits can be caused by cable problems. You should never try to save money by cutting corners with cables or connectors. High price alone does not guarantee a good product.
Basics Condenser microphones are typically more sensitive than dynamic mics and are useful for recording the harmonic details of instruments and voices at lower volume levels such as acoustic guitars, acoustic piano, and vocals. Condensers also typically cover a wider frequency range and pick up the complex harmonics and overtones that come from instruments such as acoustic piano, vocals, horns, xylophone, vibes or cymbals.
Basics 6.6 Compression Compression Variables Defined A compressor is one of the most widely used signal processors in the recording studio. Compressors are used during the recording process as well as during mixdown and mastering. During the recording process compressors are used to control the dynamic range or volume of a signal. For example, a singer may vary his volume level from a whipser to a scream during a particular song.
Basics Release: Once the signal falls below the threshold, the Release control determines how quickly the compressor “lets go” of the volume control and lets the level rise back to unity gain. Just as the Attack control sets the volume of the start of a sound, the Release control sets volume of the end of a sound. The release can be used creatively to make sounds cut-off sharply or sustain longer. Compressors usually have built-in metering to allow monitoring of the amount of gain reduction taking place.
FAQs Keyboard - Bottom at 80Hz to 120Hz; body at 240Hz; presence at 2k5Hz. Bass guitar - Bottom at 60Hz to 80Hz; attack/pluck at 700Hz to 1kHz; string noise / pop at 2kHz to 3kHz. Electric guitar - Fullness at 240Hz; bite at 2kHz to 3kHz Acoustic guitar - Bottom boom at 80-120Hz; body at 240Hz; clarity at 2k5Hz to 5kHz. Horns - Fullness at 120 to 240Hz; shrill at 5kHz to 8kHz.
FAQs Q: Can I damage the Vt-737sp by turning the preamp gain up too high? A: No. The Vt-737sp has enourmous headroom (+36dB on Line Input). Crank it up and check it out. Q: Why does Avalon use opto-compressors? A: Avalon uses opto-compressors because they are the most musical of all compressor types. Q: Can I do mastering with a pair of Vt-737sp’s? A: Yes. The Link jack in the back enables you to link the compressors of two Vt-7337sp’s. You will have to adjust the EQ controls separately on each unit.
FAQs Avalon does not recommend that you experiment with different types of tubes because it can lead to extreme damage to your Vt-737sp. Q: If I am using a digital recording system, is it worth going out of my digital system for mixdown and mastering even if I don’t have to? A: Yes. The Vt-737sp is known to breath life into digital recordings. It will add air to the highs and open up the bottom end. This process is very effective if you have high quality A to D and D to A converters.
Trouble Shooting 8.0 Trouble Shooting If you experience any problems with your Vt-737sp, please make sure to first isolate the problem to your Vt-737sp. In many cases the problem can be a bad cable instrument, or another piece of equipment in the signal path. It is easiest to isolate the problem by removing as many pieces of extraneous gear in the signal path as possible. If you believe that your Vt-737sp has problem, please set up the following test system: 1.
Trouble Shooting 1. Plug your input source (microphone, instrument or line input) into Vt-737sp; make sure to check your cable. 2. Output of Vt-737sp directly to powered monitors or monitor system. Use the OUTPUT control on the Vt-737sp to adjust volume and check this cable as well. Once you have isolated the problem to the Vt-737sp please check the following list of problems and corresponding suggested solutions. Tube Related Symtoms The following list are symptoms of a failing vacuum tube.
Service Information 9.0 Service and Contact Information Maintenance and Tube Life Because of the exceptional build quality of the Vt-737sp, the unit will perform for many years to come. But just like any musical instrument, it needs care and maintenance to keep it in top shape. Vacuum Tube Replacement For peak performance, Avalon Design recommends changing these tubes every 5000 hours of run time. Selected, performance-matched vacuum tubes are available directly from the factory.
Technical Information 10.0 Technical Information Your Vt-737sp is built to withstand many years of high performance music making. If you experience any malfunctions or problems, please contact the dealer where your unit was purchased. If your Vt-737sp has outlasted your dealer, please contact Avalon.
Technical Information 10.
Technical Information 10.
Warranty and Safety Standards 10.3 Vt-737 (purple) vs Vt-737sp 11.0 Warranty As of Jaunary 1999 the original Vt-737 was discontinued and is no longer in production. Avalon Industries, Inc. warrants this product against deflects in material or workmanship as follows: 1. For a period of time (1) year from the date of purchase Avalon will pay the labor charges to repair the defective product. After this one (1) year period, all labor charges will be paid by the customer. 2.
Warranty and Safety Standards 11.1 Returns 12.0 Safety Standards If you Vt-737sp has become defective within the one (1) year period as specified above, please contact the place of purchase to arrange for warranty repair. If you would rather directly with Avalon, please call the factory at 949-492-2000. To return a unit to Avalon for repair or exchange you will need to obtain a Return Authorization Number (RA) from Avalon. To obtain an RA number (in the USA only) 1. Visit www.avalondesign.
Glossary Appendix A - Glossary amplification - The process by which a signal level is increased. amplitude - The distance above or below the centerline of a signal’s waveform. The greater the distance from the centerline, the larger the pressure variation or electrical signal. attack - The initial transient or first part of the envelope of a signal. The beginning of a note. attenuate - To reduce the signal level.
Glossary dBm - Decibels referenced to 1 milliwatt. dBu or dBv - Decibels referenced to 0.775 volt. dBV - Decibels referenced to 1 volt. de-ess - Using a frequency-dependent function in a compressor to reduce excessive sibilance (”sss, “sh”, and “ch”) sounds. detent - A point of slight physical resistance (a click stop) in the travel of a knob or slide control. dynamic microphone - A microphone that operates by electromagnetic induction to generate an output signal.
Glossary gain - The measure of how much a credit amplifies a signal. Gain may be stated as a ratio of input to output values, such as decibels from line amplifier. gain stage - An amplification point in a signal path, either within a system or a single device. Overall system gain is distributed between the various gain stages. graphic EQ - A type of equalizer where the frequency bands for cut/boost and bandwidths are fixed. Graphic EQs are usually controlled by faders instead of knobs.
Glossary overload - The distortion that occurs when an applied signal exceeds a system’s maximum input level. parametric EQ - A parametric EQ allows continuous control of each of the three primary EQ parameters (frequency, gain and bandwidth) independently. peak amplitude - The maximum instantaneous amplitude of a signal. phantom power - Power for a condenser mic from a preamplifier supplying a positive DC supply voltage of +48V through a balanced XLR mic cable.
Glossary unbalanced - An electrical circuit in which the two legs of the circuit are not balanced with respect to ground. Unbalanced circuit connections require only two conductors (signal “hot” and ground). Unbalanced audio circuitry is less expensive to build, but under certain circumstances is more susceptible to noise. volume - Electrical or sound level in an audio system. waveform - A graph of a signal’s sound pressure or voltage level versus time.
Glossary Avalon Vt-737sp Operation Manual Page 55
Glossary Page 56 Avalon Vt-737sp Operation Manual
Avalon Industries, Inc., 3715 Cahuenga Blvd. Studio City, CA 91604 Tel: 949-492-2000 www.avalondesign.
