1. Úvod
Thank you for choosing the Avalon VT-737sp Tube Channel Strip. This professional audio device integrates a microphone preamplifier, instrument direct input (DI), opto-compressor, and a sweepable equalizer into a single 2U rack-mountable unit. Designed for superior audio performance, the VT-737sp provides a versatile and high-quality signal path for recording, mixing, and mastering applications. This manual provides essential information for the safe and effective operation of your unit.
2. Bezpečnostní informace
Please read and understand all safety instructions before operating the VT-737sp. Retain this manual for future reference.
- Zdroj napájení: Připojte jednotku pouze k určenému střídavému proudu.tage as indicated on the rear panel. Ensure the power cable is securely connected and not damaged.
- Větrání: The VT-737sp contains vacuum tubes that generate heat. Ensure adequate ventilation around the unit. Do not block ventilation slots or operate in an enclosed space. Maintain at least 4 inches (10 cm) of clear space around the unit.
- vlhkost: Do not expose the unit to rain, moisture, or excessive humidity. Do not place liquid-filled objects on or near the unit.
- Servis: Refer all servicing to qualified service personnel. Do not attempt to open the chassis or perform repairs yourself, as this may expose you to dangerous voltages and will void the warranty.
- Manipulace s trubkou: Vacuum tubes are fragile and can be hot. Allow the unit to cool down before moving or servicing. Tube replacement should only be performed by qualified personnel.
- Základy: Always ensure the unit is properly grounded to prevent electrical shock.
3. Vlastnosti
The Avalon VT-737sp offers a comprehensive set of features designed for professional audio production:
- Circuit Topology: Utilizes four dual triode vacuum tubes (Sovtek 6922) with high-voltage discrete Class A circuitry for optimal sonic performance.
- Mikrofon Preamp: Transformer-balanced input with a gain range of 0dB to +58dB, suitable for various microphones. Includes +48V phantom power for condenser microphones.
- Instrument DI: Front panel unbalanced jack socket for direct connection of instruments, offering a maximum input level of +30dB.
- Řádkový vstup: Balanced XLR input with a maximum input level of +36dB.
- Opto-Compressor: Class A vacuum tube opto-compressor with adjustable Threshold, Ratio, Attack, and Release controls. Features a side-chain function for de-essing using the dual sweep mid EQ.
- Ekvalizér: 100% discrete Class A transistor equalizer section with a musical passive filter design. Includes sweepable Bass, Low Mid, High Mid, and Treble bands.
- Výstup Ampživější: Tube-driven, 100% discrete, Class A low-noise output ampživější.
- Měření: Onboard VU meter switchable for output level monitoring or gain reduction display.
- Stereo propojení: Two VT-737sp units can be linked for stereo operation.
4. Ovládací prvky a připojení
4.1 Ovládací prvky na předním panelu

Obrázek 1: Přední panel View of the Avalon VT-737sp
The front panel provides access to all primary operational controls and the instrument input.
- PŘEDAMP ZÍSKAT: Adjusts the input gain for the microphone and line inputs.
- VSTUPNÍ REŽIM: Selects between Instrument (front panel DI), Line (rear panel XLR), or Mic (rear panel XLR) input.
- VYSOKÝ ZISK: Engages an additional gain stage for low-level signals.
- FÁZE: Invertuje fázi vstupního signálu.
- HIGH PASS FREQUENCY: Sets the cutoff frequency for the high-pass filter (30Hz, 60Hz, 120Hz).
- FILTR: Engages the high-pass filter.
- THRESHOLD (COMPRESSION): Sets the level at which compression begins.
- RATIO (COMPRESSION): Determines the amount of gain reduction applied once the threshold is exceeded.
- ATTACK (COMPRESSION): Controls how quickly the compressor reacts to signals exceeding the threshold.
- RELEASE (COMPRESSION): Controls how quickly the compressor returns to its original state after the signal falls below the threshold.
- VU METER: Displays either output level or gain reduction, selectable via a switch.
- BASS (EQ): Controls the gain of the low-frequency shelving equalizer.
- LOW MID (EQ): Controls the gain and sweepable frequency of the low-mid band.
- HIGH MID (EQ): Controls the gain and sweepable frequency of the high-mid band.
- TREBLE (EQ): Controls the gain of the high-frequency shelving equalizer.
- VÝSTUP: Adjusts the overall output level of the unit.
- VYPÍNAČ: Zapíná nebo vypíná jednotku.
4.2 Připojení zadního panelu

Obrázek 2: Zadní panel View of the Avalon VT-737sp
The rear panel houses all audio input/output connections and the power inlet.
- AC VSTUP: Standard IEC power inlet for connecting the AC power cord.
- ZEMNÍ ODKAZ: Terminal for connecting an external ground wire if required to reduce hum or noise.
- COMPRESSOR LINK: 1/4-inch mono jack for linking the compressor section of two VT-737sp units for stereo operation.
- OUTPUT LINE: Balanced XLR and 1/4-inch TRS outputs for connecting to mixers, audio interfaces, or other processing equipment.
- INPUT LINE: Balanced XLR input for connecting line-level audio sources.
- INPUT MICROPHONE: Balanced XLR input for connecting microphones. Includes +48V phantom power.
5. Nastavení
Proper setup ensures optimal performance and longevity of your VT-737sp.
5.1 Vybalení a umístění
- Carefully remove the VT-737sp from its packaging. Inspect for any signs of damage during transit.
- Place the unit in a well-ventilated area, preferably in a standard 19-inch equipment rack. Ensure sufficient airflow around the top, bottom, and sides of the unit. Avoid placing it near heat sources.
5.2 Připojení napájení
- Ujistěte se, že je vypínač na předním panelu v poloze VYPNUTO.
- Connect the supplied IEC power cable to the AC INPUT on the rear panel of the VT-737sp and then to a grounded AC outlet of the correct voltage.
5.3 Audio připojení
Before making any audio connections, ensure all connected equipment is powered off to prevent potential damage or loud pops.
- Vstup pro mikrofon: Connect your microphone to the INPUT MICROPHONE XLR connector on the rear panel. If using a condenser microphone, activate +48V phantom power via the front panel switch.
- Vstup přístroje: For direct instrument connection (e.g., guitar, bass), use the 1/4-inch jack on the front panel. Select 'Instrument' on the INPUT MODE switch.
- Řádkový vstup: Connect line-level sources (e.g., preamps, synthesizers) to the INPUT LINE XLR connector on the rear panel. Select 'Line' on the INPUT MODE switch.
- výstup: Connect the OUTPUT LINE XLR or 1/4-inch TRS connectors to your audio interface, mixer, or other destination.
- Stereo Linking (Optional): To link two VT-737sp units for stereo compressor operation, connect a standard 1/4-inch mono cable between the COMPRESSOR LINK jacks of both units.
6. Operating the VT-737sp
The VT-737sp offers a flexible signal chain: Preamp > Compressor > Equalizer > Output. Each section can be bypassed independently.
6.1 Zapnutí
After all connections are made, turn on the VT-737sp using the front panel POWER switch. Allow a few moments for the tubes to warm up and stabilize.
6.2 Vstupní sekce
- Select the appropriate input source (Mic, Instrument, Line) using the VSTUPNÍ REŽIM přepínač.
- Upravte PŘEDAMP ZÍSKAT to achieve a healthy signal level without clipping. Use the VYSOKÝ ZISK switch for very low-level sources.
- Zapojte se FÁZE switch if phase inversion is required.
- Aktivujte FILTR a vyberte a VYSOKÁ FREKVENCE PRŮCHODU (30Hz, 60Hz, 120Hz) to remove unwanted low-end rumble or noise.
6.3 Compressor Section
The opto-compressor provides smooth and musical gain reduction.
- Upravit PRÁH to set the point at which compression begins. Lowering the threshold increases compression.
- Nastavte POMĚR to determine the intensity of compression (e.g., 2:1 for subtle, 10:1 for more aggressive).
- Control the compressor's response time with ÚTOK (fast for transients, slow for overall level) and UVOLNĚNÍ (fast for punch, slow for smooth sustain).
- For de-essing, engage the side-chain function and use the EQ's mid-bands to boost the sibilant frequencies, which will then trigger the compressor more effectively at those frequencies.
6.4 Equalizer Section
The passive EQ offers broad tonal shaping capabilities.
- Použijte BASS a ZTROJNÁSOBIT controls for shelving boosts or cuts at the low and high ends of the spectrum.
- The NÍZKÝ STŘED a VYSOKÝ MID bands feature sweepable frequency controls, allowing you to pinpoint and adjust specific frequencies. Adjust the gain for boost or cut.
- Experiment with subtle adjustments to achieve desired tonal characteristics.
6.5 Output and Metering
- Upravte VÝSTUP knob to set the final signal level sent from the unit.
- Použijte VU METER to monitor either the output level (0 VU = +4dBu) or the amount of gain reduction applied by the compressor.
7. Údržba
Regular maintenance helps ensure the longevity and optimal performance of your VT-737sp.
- Čištění: K čištění vnější strany jednotky používejte měkký, suchý hadřík. Nepoužívejte tekuté čisticí prostředky ani rozpouštědla.
- Větrání: Periodically check that the ventilation slots are clear of dust and debris. Ensure the unit has adequate airflow during operation.
- Životnost trubice: The vacuum tubes have a finite lifespan. If you notice a degradation in sound quality (e.g., increased noise, reduced clarity, inconsistent performance), the tubes may need replacement. This should only be performed by qualified service technicians.
- Skladování: If storing the unit for an extended period, ensure it is in a dry, temperature-controlled environment, protected from dust and physical shock.
8. Řešení problémů
If you encounter issues with your VT-737sp, refer to the following common troubleshooting steps:
| Problém | Možná příčina | Řešení |
|---|---|---|
| Žádná síla | Power cable disconnected; Power switch off; Blown fuse; Power outlet issue. | Check power cable connection; Ensure power switch is ON; Check fuse (refer to service manual for location/type); Test power outlet with another device. |
| Žádný výstup zvuku | Incorrect input mode selected; Gain set too low; Cables faulty or incorrectly connected; Compressor/EQ bypassed or set to extreme. | Verify INPUT MODE; Increase PREAMP GAIN and OUTPUT; Check all audio cables and connections; Ensure compressor/EQ are not bypassed or set to extreme values. |
| Hučení nebo šum | Ground loop; Faulty cables; Nearby electrical interference; Worn tubes. | Ensure proper grounding; Try different cables; Move unit away from other electronics; If persistent, tubes may need inspection by a technician. |
| Zkreslený zvuk | Input signal too hot; Gain set too high; Output clipping; Faulty tubes. | Reduce input signal level; Lower PREAMP GAIN or OUTPUT; Check levels on connected equipment; If distortion persists, tubes may need inspection. |
| Kompresor nefunguje | Threshold set too high; Ratio set too low; Compressor bypassed. | Lower THRESHOLD; Increase RATIO; Ensure compressor is engaged. |
If the problem persists after attempting these solutions, please contact Avalon customer support or a qualified service technician.
9. Specifikace
Detailed technical specifications for the Avalon VT-737sp:
| Specifikace | Hodnota |
|---|---|
| Rozměry položky (D x Š x V) | 23.3 x 18.8 x 8.5 palce |
| Hmotnost položky | 28.3 libry |
| svtage | 48 Volts (DC) Maximum Supply |
| Počet kanálů | 4 (Internal processing channels, not discrete inputs) |
| Topologie obvodu | Four dual triode vacuum tubes (Sovtek 6922), high-voltage discrete Class A |
| Microphone Gain Range | Transformer balanced 850/2500 ohm, 0dB to +58dB |
| Instrument Input Max Level | +30dB unbalanced front panel jack socket |
| Line Input Max Level | +36dB balanced XLR |
| Maximální výstupní úroveň | +30dB balanced 600 ohms, DC coupled, discrete Class A |
| Typ montáže | Rack Mount (2U) |
| Dodržování | FCC (Partial) |
| Datum první dostupnosti | 13. dubna 2004 |
10. Záruka a podpora
Avalon Design products are manufactured to the highest standards. For information regarding warranty coverage and technical support, please refer to the warranty card included with your product or visit the official Avalon Design webUschovejte si účtenku jako doklad o koupi pro případ reklamace.
For technical assistance, troubleshooting beyond this manual, or service inquiries, please contact Avalon Design customer support directly. Contact information can typically be found on their official webmístě nebo na obalu produktu.





