Instruction/ maintenance manual of the product 386 dbx Pro
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® 386 Dual V acuum T ube Preamp w/Digital Out User Manual.
W ARNING FOR Y OUR PRO TECTION PLEASE READ THE FOLLOWING: KEEP THESE INSTRUCTIONS HEED ALL WARNINGS FOLLOW ALL INSTRUCTIONS CLEAN ONL Y WITH A DAMP CLO TH. DO NOT BLOCK ANY OF THE VENTILA TION OPENINGS. INST ALL IN ACCORD ANCE WITH THE MANUF ACTURERS INSTRUCTIONS.
U.K. MAINS PLUG W ARNING A molded mains plug that has been cut off from the cord is unsafe. Discard the mains plug at a suitable disposal facility . NEVER UNDER ANY CIRCUMST ANCES SHOULD YOU INSERT A D AMAGED OR CUT MAINS PLUG INTO A 13 AMP POWER SOCKET .
T able of Contents 386 Intr oduction 0.1 Defining the 386................................................i 0.2 Service Contact Info .........................................ii 0.3 W arranty ............................................................ii 0.
INTRO CUSTOMER SER VICE INFO 386 DEFINED W ARRANTY INFO ® INTRODUCTION 386.
Intr oduction ® 386 User Manual i 386 Congratulations on your pur chase of the dbx 386 Dual V acuum Tube Preamp with digital out - put capabilities. For over 25 years, dbx has been the industry leader in dynamics processing.
® Intr oduction 386 386 User Manual If you r equire technical support, contact dbx Customer Service. Be prepared to accurately describe the problem. Know the serial number of your unit - this is printed on a sticker attached to the rear panel.
Intr oduction ® 386 User Manual iii 386 Install the 386 in your rack with the provided rack scr ews. I t is essential that when the 386 is being mounted in a rack mounting enclosure, the unit should be positioned with enough ro om (at least one centimeter at the top and one centimeter at the bottom of the unit) to allow prop - er ventilation.
Getting Started ® Getting Started Section 1 386.
Getting Star ted ® 386 User Manual 2 Section 1 386 Power Switch Tu rns the 386 on and off . IEC Power Cord Receptacle This is the power cord receptacle of the 386. An IEC cord is included with the shipped prod - uct. AES/EBU Digital Connector The 386 provides AES/EBU digital output formating through the XLR connector .
® Instrument Input This unbalanced high-impedance input connection is used to insert an instrument signal direct- ly into the preamp. Use the LINE switch to make instrument input or the rear panel line input active. Plugging into the instrument jack will override the rear panel 1/4” input jack (line input must be selected).
Getting Star ted ® 386 User Manual 4 Section 1 386 Meter Select Switch This switch allows you to select display metering of either the digital or analog output signal. The analog level is scaled in dBu, while the digital level is scaled in dBFS. LightPipe™ Meter This meter displays either the analog or digital output signal.
ANALOG APPLICA TIONS ® ANALOG APPLICA TIONS Section 2 386.
Analog Applications ® 3 386 User Manual 6 Section 2 386 • Turn of f all equipment before making any connections. • Install the 386 in your rack with the provided rack scr ews.
® 1). Make microphone connections, being careful to keep the DRIVE control in the minimum (+30 dB) position. 2). Connect the 386’s Line outputs directly to the audio inputs of your r ecorder .
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DIGIT AL APPLICA TIONS ® DIGIT AL APPLICA TIONS Section 3 386.
Digital Applications ® 10 Section 3 386 Dither Switch This switch is used to select the dither type algorithms including: TPDF , SNR 2 , or None. Dither is random noise that is added to the audio signal which effectively eliminates the harmonic distor- tion created by truncation.
® AES/EBU Digital Connector The 386 provides AES/EBU digital output formating through the XLR connector . Be sure to use short lengths of 110 Ω digital cables rather than standard XLR to XLR cables. Using the correct cables will pre- vent digital dropouts and other interconnection problems.
Digital Applications ® 12 Section 3 386 Rear P anel Connections • Connect the source to the desir ed 1/4” TRS or XLR input. • Connect the AES/EBU or S/PDIF output of the 386 and run into the AES/EBU or S/PDIF input inter face of the DA W (CPU).
® Rear P anel Connections • Connect the source to the desir ed 1/4” TRS or XLR input jack. • Connect the AES/EBU or S/PDIF output of the 386 and run into the AES/EBU or S/PDIF input of the digital mixer . Fr ont Panel Digital Output F eatures 1).
Digital Applications ® 14 Section 3 386 Rear P anel Connections • Connect the source to the desir ed 1/4” TRS or XLR input. • Connect the AES/EBU or S/PDIF output of the 386 and run into the AES/EBU or S/PDIF input interface of the DA W (CPU). Fr ont Panel Digital Output F eatures 1).
® Rear P anel Connections • Connect the source to the desir ed 1/4” TRS or XLR input jack. • Connect the AES/EBU or S/PDIF output of the 386 and run into the AES/EBU or S/PDIF input of the digital mixer . Fr ont Panel Digital Output F eatures 1).
Digital Applications ® 16 Section 3 386 The 386 gives you the unique option of utilizing the analog and digital outputs simultaneously. This option is ideal for using the analog output section as a r eference monitoring signal of the dig- ital signal.
APPENDIX Sync Input Info Block Diagram dbx T ype IV™ White Paper Noise-Shaping Algorithms T runcation Specifications ® APPENDIX Appendix 386.
Sync Input Info ® 18 Appendix A 386 The dbx 386 comes with the word input 75 Ω te rminated. For certain configurations, you may wish to have the sync input be unterminated. Certain "house sync" configurations will r equire you to change the default position of the termination jumper on the main circuit board.
® Microphone Input +48V Low 20dB Pad Phase In vert Low Cut dbx TYPE IV Conversion System DSP Dither Sample Rate Wo r d Length Output Format Shape Peak LED Line/Mic 12AU7 T ube Drive Analog Output Lev.
T ype IV™ White P aper ® 20 Appendix C 386 dbx T ype IV™ Con version System White P aper b y Roger Johnson The dbx Type IV™ Conversion System is a proprietary analog-to-digital (A/D) conversion.
® to-noise performance since the signal is now closer to the noise floor . Because users of digital equipment have to be extremely car eful not to exceed 0 dB FS (full-scale), they must use peak-reading headroom meters.
T ype IV™ White P aper ® 22 Appendix C 386 Fig. 2 illustrates the mapping function in a differ ent way. Input levels are shown on the left of the graph, while con- verted levels are shown on the right. Notice the mapping of lar ge signal excursions to the 4 dB “Type IV™ Over Region.
® Figure 3b - Signal of Fig. 3a Going Bey ond the A/D Clip Lev el Amplitude Time A/D Clip Lev el A/D Clip Lev el Figure 3a - Signal Having Low and High F requency Content Amplitude Time T ype IV™ W.
T ype IV™ White P aper ® 24 Appendix C 386 Now you’re p robably wondering, “What’s the catch? I can’t get something for nothing so what did I give up?” Y ou may be worried that your A/D noise floor got 4 dB worse because we borrowed the top 4 dB of your converter .
® 16-Bit TPDF dither . (a) Shape “off”, (b) with shape set to “S1”, (c) with shape set to “S2.” Parameters: Input -60dBFS, 1 kHz; FFT Length= 2048, Sample Rate= 48 Khz, A verages= 32; Graph Steps= 1024. (a) 24-Bit word, (b) 16-Bit truncated output, no dither .
Appendix ® 26 Appendix D 386 Microphone Input Connector: Female XLR Pin 2 Hot Type: Electronically balanced/unbalanced Impedance: 330 Ω Maximum Input Level: -9 dBu or +11 dBu with 20 dB pad engaged.
® ® 8760 South Sandy Pkwy . Sandy , Utah 84070 Phone: (801) 568-7660 F ax: (801) 568-7662 Int’l F ax: (603) 672-4246 Questions or comments? E•mail us at: customer@dbxpr o .
An important point after buying a device dbx Pro 386 (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought dbx Pro 386 yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data dbx Pro 386 - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, dbx Pro 386 you will learn all the available features of the product, as well as information on its operation. The information that you get dbx Pro 386 will certainly help you make a decision on the purchase.
If you already are a holder of dbx Pro 386, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime dbx Pro 386.
However, one of the most important roles played by the user manual is to help in solving problems with dbx Pro 386. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device dbx Pro 386 along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
