Aphex 1100 MkII Owner's Manual
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Aphex 1100 MkII Owner's Manual

Dual class a discrete tube microphone preamplifier with integrated 24-bit 192khz a/d converter
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Owner's Manual
Model 1100 MkII
Dual Class A Discrete Tube Microphone
Preamplifier with Integrated 24-Bit
192kHz A/D Converter
Document No. 999-4200
Aphex
Thermionics
- Division of Aphex Systems Ltd.
Copyright 2003 Aphex Systems Ltd. All rights reserved. No portion of this manual may be reproduced without permission.
Page A-1
Manual designed and written by Donn Werrbach 02/03. Creation tool: Adobe InDesign 1.5 for Windows. Printed in U.S.A.

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  • Page 1 Thermionics - Division of Aphex Systems Ltd. Copyright 2003 Aphex Systems Ltd. All rights reserved. No portion of this manual may be reproduced without permission. Page A-1 Manual designed and written by Donn Werrbach 02/03. Creation tool: Adobe InDesign 1.5 for Windows. Printed in U.S.A.

  • Page 2: Declarations

    Declarations Model 1100 MkII Mic Preamp - Owner’s Manual Safety Declarations A MESSAGE FROM THE PRESIDENT Dear Aphex Customer, We are very pleased to present the new Mark II version of our highly acclaimed For protection against electric shock, do not remove the cover. No user CAUTION: Model 1100 Microphone Preamplifier.

  • Page 3: Aphex Thermionics: The Story

    For The first product to apply an RPA circuit was emission by heating the metal example, the Model 1100 MkII Mic Preamp incor- our model 107 Thermionic Mic Preamplifier. cathode to incandescence. porates a very low noise second stage opamp...

  • Page 4: Block Diagram

    Block Diagram Mic Input LoCaf Tuning Return Jack Send Jack Phantom Power Source Preamp Gain Impedance Compensator MicLim Element MicLim Detector S/PDIF and TOSLINK Digital 20dB Pad Reflected Plate Amplifier Output Stage Outputs Phase Reverse Headroom Meter Class A PNP Input Stage 24 Bit A/D Converter Reflected Plate Amplifier Second Stage AES/EBU Output...

  • Page 5: Introduction

    A switched input resistance has been To complement the technical achievements inside, dual optocoupler to provide noiseless switching added to the Model 1100 MkII to extend the we styled it with a beautiful new look. Chromed and high attenuation.

  • Page 6: Table Of Contents

    Contents Declarations Aphex Thermionics: The Story Block Diagram Introduction Front Panel Features Back Panel Features Understanding & Using MicLim Interfacing & Cables Installation Instructions Service & Warranty Specifications Tube Topics White Paper: More Gain, No pain Appendix A: Word Clock Wiring Page A-6...
  • Page 7 Model 1100 MkII Mic Preamp - Owner’s Manual useful for calibrating the drive to an external A/D converter. 1.4 Phantom This button turns on and off the 48 volt phantom power to the microphone jack. The 48 volt source ramps up and down very slowly to avoid thumps.

  • Page 8: Front Panel Features

    BNC clock input jack. The peak level below the point of clipping, thus it 1100 MkII will go into a hunt mode until it finds 1.12 Gain shows you how much headroom is left at all the word clock parameters and locks on.
  • Page 9 Model 1100 MkII Mic Preamp - Owner’s Manual With LoCaf you get as much as 20dB of improved faces begin to oxidize including these points of headroom below the low cut corner frequency contact. When that happens, metal oxide point...
  • Page 10 Front Panel Features Model 1100 MkII Front Panel Summary 22 26 12 Input Gain: 4dB steps, 21 to 65dB 20 Line Output Calibrate: 3-Turns, 0 to -12dB 13 Low Cut Filter: Off, 30, 36, 44, 63, 77, 92, 111, 134, 162, 195 Hz.
  • Page 11 Model 1100 MkII Mic Preamp - Owner’s Manual Aphex Thermionics - Division of Aphex Systems Ltd.

  • Page 12: Back Panel Features

    In the absence of a suitable external clock through. The final unit should have a 50 or source, you can use one Model 1100 MkII as a 75 ohm (as dictated by your distribution cable 2.4.2 Clock Out clock master and slave everything else to it. For...
  • Page 13 For everyone else, please trust us. It works and it power is turned on by the front panel button. The Model 1100 MkII balanced output is a special works very well. There is little more to say about this jack. The type known as “impedance balanced”...
  • Page 14 Back Panel Features tances become the dominating noise resistance, 1/4” phone jacks allow you to insert outboard Open Switch Mutes thus the generated noise is much higher. The audio processors between the mic preamp and preamp can’t tell whether a mic is there or not, the A/D converter as well as between the preamp it just amplifies whatever signal is there even if it and the analog line output.
  • Page 15 With ference, the interference will be cancelled. the Model 1100 MkII all you have to do is make sure pin 2 wires to the patch plug tip, and you’ve Look at figure 2-8 showing a conventional line got full signal.
  • Page 16 Back Panel Features Model 1100 MkII Back Panel Summary POWER Digital Line Out Z Comp Line Out Z Comp AES/EBU Line & A/D Insert Mute Insert Mute Audio 24-Bits OPEN TIP OPEN CIRCUIT Return Send Return Send MUTES MUTES +4dBu...

  • Page 17: Understanding & Using Miclim

    Model comprises a specially developed optically coupled it. Everybody is familiar with the clipped overload 1100 MkII mic preamp, even under severe con- load resistor that is loaded across the mic input that’s heard when a performer suddenly gets on ditions.
  • Page 18 Using The Z-Comp Switch (CdS) photocells causes oscillatory clipping: then the limiter will act on the micro- The 1100 MkII has an impedance compensa- reactions. Only feed forward optocoupler limit- phone signal to prevent the peak from reaching tion (Z-Comp) switch near each mic input jack ers have been produced.

  • Page 19: Interfacing & Cables

    Model 1100 MkII Mic Preamp - Owner’s Manual Because of its impedance balanced output stage, the Model 1100 MkII is unusually easy to interface with balanced and unbalanced outboard gear. We have subscribed to the “pin-2 high” AES wiring standard so the only problem you should possibly encounter would be with interfacing cables wired using the older and sometimes still seen “pin-3 high”...
  • Page 20 A/D converter will violate the rules we have been outlining here, with too much level. You can use the 1100 MkII’s but don’t despair. You probably won’t experi- 4.10 Insert Jacks headroom meter to verify. It monitors the signal ence any problems.

  • Page 21: Installation Instructions

    Model 1100 MkII Mic Preamp - Owner’s Manual 5.1 Unpacking Your Model 1100 MkII was packed carefully at the factory in a container designed to protect the unit during shipment. Nevertheless, Aphex rec- ommends making a careful inspection of the shipping carton and the contents for any signs of physical damage.
  • Page 22 The most common ground problems come from may become lucky and find a pesky hum problem The Model 1100 MkII is not any more prone to the a.c. house wiring. The wall outlets of adja- can be eliminated simply by getting the right two...

  • Page 23: Service & Warranty

    Service & Warranty Model 1100 MkII Mic Preamp - Owner’s Manual Aphex Systems supports its customers with spare parts and technical assistance. You may contact us by phone, fax, and the Internet. Out-of- warranty repair work should be performed by qualified service personnel only.

  • Page 24: Limited Warranty

    Any and all warranties are limited to the duration of the warranty stated above. EXCLUSION OF CERTAIN DAMAGES Aphex Systems’ liability for any defective unit is limited to the repair or replacement of said unit, at our option, and shall not include damages of any other kind, whether incidental, consequential, or otherwise.

  • Page 25: Specifications

    Specifications Model 1100 MkII Mic Preamp - Owner’s Manual These specifications are ascertained mostly through laboratory measurements and are believed by the manufacturer to be true and accurate. Nevertheless, the manufacturer dis- claims any liability for damages, direct or consequential, resulting from errors. It is the sole responsibility of the user to determine the suitability of the product.
  • Page 26 Specifications Digital Audio Specifications Output Resolution: 24-Bits Output Sample Rate: 44.1, 48, 88.2, 96, 192 KHz Selectable Clock Source: Internal Low Jitter Crystal and external word clock Digital SNR: 98dB typical for ref level = 0dB(fs), 80dB typical for ref level = -18dB(fs) Dithering: Due to the microphone and preamp noise floor, dithering is inherent.

  • Page 27: Tube Topics

    Model 1100 MkII Mic Preamp - Owner’s Manual The Model 1100 MkII contains two dual triode tubes, one per channel. One triode of each tube is used in the low noise second stage and the other is used in the impedance balanced output stage. Thanks to the Aphex exclusive Reflected Plate Amplifier (RPA) circuits, you can substitute different tube types with equal success.
  • Page 28 6 Volt Tubes 8.6 Relevant Base Diagrams gassy tube. In our RPA circuits, a well manufac- The tubes that work in the Model 1100 MkII tured tube will probably never become weak or follow the industry standard base diagrams 9A gassy even in 100 years of use.
  • Page 29 That low output level will have to be boosted in a following gain stage. This, how- maximum output level of +27dBu the dynamic range of the preamplifier is 95dB (68 + 27) at that gain setting. Page 9-1 Aphex Thermionics - Division of Aphex Systems Ltd.
  • Page 30 MicLim to trigger earlier than necessary from excessive low frequency 1. Noise energy. One of the primary design goals of the Model 1100 MkII was to have as wide a dynamic range as possible. Several key inventions combined with a no-compromise c. Drift Stabilized A/D Converter...
  • Page 31 Precision Three Turn Output Level Attenuator One of the technology improvements comprising the model 1100 MkII is a highly In order to match the analog output of the model 1100 MkII to the user's system efficient switchmode/linear hybrid power supply. Switchmode design is used to level, the output gain is adjustable from zero dB (max gain) to -14dB.
  • Page 32 Rear panel XLR and quarter-inch phone jacks are both provided for balanced output. VI. Summary Every circuit and component that went into the Model 1100 MkII was studied and scrutinized for optimum performance. The result of the innovations and careful engineering is a uniquely excellent preamplifier.
  • Page 33 This is something ance. In most cases, unmatched word clock lines Page 10-1 Aphex Thermionics - Division of Aphex Systems Ltd.
  • Page 34 A length of coax driven by a brute forced output mented in much of the digital audio equipment MkII’s or other equipment. If the 1100 MkII is the driver will cause edge ringing and wave distortion presently available. This leads to real clocking last unit in line, the best option for terminating of the clock pulses.
  • Page 35 Model 1100 MkII Mic Preamp - Owner’s Manual the transmission characteristics. Maximum Brute Force cable length depends on several factors, but you probably shouldn’t attempt distances greater than 4 feet. Figure 5 End-of-Line Termination NOTE ON CONVERTING TO A Last Unit In Line MATCHED LINE: because of the 1100 MkII’s automatic input level...
  • Page 36 Model 1100 MkII Mic Preamp - Owner’s Manual Notes...

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