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Argiriadis Analogue Electronics DU User Manual

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DU USER GUIDE
T: +44 203 146 8779
www.tube-electronics.co.uk

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Summary of Contents for Argiriadis Analogue Electronics DU

  • Page 1 DU USER GUIDE T: +44 203 146 8779 www.tube-electronics.co.uk...

  • Page 2: Table Of Contents

    AAE Distortion unit Table of Contents DESCRIPTION & FEATURES ......................... 5 Input and output stages .......................... 5 Distortion 'tone’ in relation to frequency ....................6 Differences between triode and pentode sound................... 6 Off Load' mode operation ........................7 Positive feedback (PFB) ........................... 7 FRONT PANEL CONTROLS AND SWITCHES ....................
  • Page 3 AAE Distortion unit HOW OFTEN AND WHEN IS IT NECESSARY TO REPLACE TUBES ............ 34 FUSES ..............................35...
  • Page 4 AAE Distortion unit...

  • Page 5: Description & Features

    The DU consists of an input stage and an output stage. The signal level that enters the input stage is set by the input gain control, and the output signal level is set by an output control plus an attenuator.

  • Page 6: Distortion 'Tone' In Relation To Frequency

    At low input signals triode mode produces predominantly second harmonic distortion which is more musical. Drive and gain controls must be set low to drive the DU softly to avoid clipping if this kind of sound coloration is desired. As the drive level is turned up, more distortion will be generated, first low even, then low odd (like third) and a smaller amount of higher orders both even and odd, until eventually clipping occurs.

  • Page 7: Off Load' Mode Operation

    AAE Distortion unit Off Load' mode operation In 'off load' mode the load that is connected to the output of the DU is removed (reduced to zero) and this alters the characteristics of the amplified sound wave, introducing high distortion that is extreme, harsh and shrill.
  • Page 8 AAE Distortion unit...

  • Page 9: Front Panel Controls And Switches

    XLR input converter, and thus the signal that enters the DU input stage. The balanced to unbalanced converter does not amplify the signal, it has a gain of 0dB TRI/CASC: this switch selects the input stage operating mode.
  • Page 10 XLR output socket is connected to the output of the unit so you get the DU processed sound. As far as the balanced XLR inputs and outputs are concerned this is a true BY-PASS switch, but it only affects the balanced (XLR) input/outputs.
  • Page 11 AAE Distortion unit (13) UL: a large toggle switch that selects between triode and ultra-linear mode, situated on the left of MUTE switch. (14) PHASE: a miniature toggle switch, it reverses the phase of the output signal. (15) OUTPUT ATT this is a four-step rotary attenuator switch to extend the range of the OUTPUT control due to the fact that there can be a considerable variation of signal level that the unit can generate.
  • Page 12 AAE Distortion unit...

  • Page 13: Preparation Before Switching On

    (b) Even if the unit below the DU runs cool, there must still be a distance of at least a 2U (3 1/2) inches, 90mm) of empty air space between the DU and the unit below. If the unit below gets warm this gap must be increased by least 4U (7 inches 18 ohm).

  • Page 14: Stand-By Switch

    AAE Distortion unit unit's electronic circuits so that it (the metal case) works as a shield against external interference but also prevents internal instability and oscillation. In most studios and especially if the balanced (XLR) inputs and outputs are used it may never be necessary to operate this ground switch, so there is a piece of tape to keep it in the ON position at all times.

  • Page 15: The Output Attenuation Switch

    AAE Distortion unit However, If the signal at the input is below the -7.8dBu level, the unit may not to be able to distort as much. * For input signal levels higher than the 0dBu level the INPUT control may need to be set lower for a clean sound.

  • Page 16: Precautions

    AAE Distortion unit PRECAUTIONS PLEASE DO NOT LEAVE THE UNIT SWITCHED ON WHEN NOT IN USE Each time: (a) you increase the input gain settings (b) change from triode to ultra linear or pentode, (c) operate in OFF LOAD mode (d) operate in positive feedback (PFB) mode Ensure that you decrease the OUTPUT or the stepped attenuator OUTPUT ATT...

  • Page 17: Bias Control And How It Affects Distortion And Clipping In The Output Stage

    AAE Distortion unit (15) fully anticlockwise (first step) and use the OUTPUT(9) control to fine tune the level coming out of the unit. However, if the output of the unit is not high enough you can first turn the OUTPUT control down to zero then turn the OUTPUT ATT (15)

  • Page 18: How To Use The Bias Control (6) In Triode Ultra-Linear And Pentode Modes

    AAE Distortion unit (a) In triode mode : An electrode at the input of this tube called the grid starts drawing current and this is called grid clipping. *Grid clipping in most control settings starts abruptly and is hard. (b) In pentode mode: (i) the same grid current effect that occurs in triode mode (ii) the output signal in the power tube is entering its saturation region.
  • Page 19 So at low BIAS settings and with careful use of the DRIVE control (so that the signal entering the power tube does not get too high) it is possible to operate the DU so that grid clipping does not occur.

  • Page 20: Switching On

    AAE Distortion unit (c) At maximum BIAS (=10) (i) In triode and ultra-linear modes when the signal reaches a certain level grid clipping will occur first which sounds harsh, and that happens well before cut off clipping. The transition from a clean (TRI or UL) sound to grid clipping distortion is very abrupt, as already mentioned in (1).

  • Page 21: Testing The Unit And Operating Guidelines

     and beats and finally complex signals made out of different frequencies. For the first tests use the DU in clean mode (low tube distortion amplifier) and gradually move  into higher distortion modes of operation. To do this you must set the DRIVE...

  • Page 22: Cascode Versus Triode

    AAE Distortion unit By gradually turning up the OUTPUT control you should be able to hear the signal from the speakers. Try cascode operation: (a) Set the INPUT control to zero first (b) Set the TRI/CASC switch in CASC (down position). To avoid any clicking noises while you operate you can press the MUTE...
  • Page 23 AAE Distortion unit On very low INPUT(1) control settings ( for less intermodulation distortion), mild sound coloration is also possible in cascode mode if a fair amount of third harmonic distortion (on top of the second) is preferred. Overdriving the output stage : (a) Set DRIVE and OUTPUT controls to zero first...
  • Page 24 AAE Distortion unit (c) Set DRIVE control to zero (momentarily) and the output attenuation switch ATT (15) to its lowest position (max, attenuation) which is the first dot clockwise. Set the BIAS control to zero, the ATT switch in the up position and turn up the DRIVE control to overdrive the output stage.
  • Page 25 AAE Distortion unit Also, the output level will always be higher in pentode mode so always turn the OUTPUT control down a bit when you switch from triode (TRI) to pentode (PE). Alternatively, you can use the OUTPUT ATT (15) switch by turning it one dot anticlockwise.
  • Page 26 AAE Distortion unit BUT FIRST In order to avoid premature tube failure please make sure that before you use the TRI/PE (12) switch Disconnect the high voltage (B+) from the unit by setting the S-BY switch in the UP position ...
  • Page 27 AAE Distortion unit Ultra-Linear (UL) mode To operate in UL mode you must first set the rotary mode select switch (12) to triode (TRI L or H) and then press the UL (13) switch in the down position. BUT FIRST *In order to avoid premature tube failure please make sure that before you use rotary mode (12) and/or...
  • Page 28 (1...3) and gradually turn up the PFB control until the DU starts oscillating, it will start oscillating in high PFB settings 7...10. If you turn the DRIVE down (to a lower setting) the oscillation will start at lowers PFB...
  • Page 29 AAE Distortion unit The PFB control is a logarithmic potentiometer so that at low settings (0...4) makes it possible to increase the in-phase signal gradually. The way to use this control is to turn it up until oscillation starts and then back it off a bit. The PFB mode is very unpredictable and it does not depend on the PFB control setting alone.

  • Page 30: Technical Notes

    AAE Distortion unit TECHNICAL NOTES SAFETY The chassis and metal case of every electrical appliance must always be securely and permanently connected to the mains ground. This is the middle pin of the IEC mains input socket, and the connection between the chassis/metal case and mains ground is the safety earth bond.

  • Page 31: Balanced And Unbalanced Lines

    AAE Distortion unit It is very important to turn the output control to zero first, because the are many reasons why hum appears when two units are connected to one another, badly shielded interconnecting cables to name one. If a ground loop is not the reason of the hum operating the ground lift switch for the wrong reasons could increase the hum/noise to a much higher level.

  • Page 32: Tube Issues

    AAE Distortion unit TUBE ISSUES NOISE, MICROPHONY & AGE Tube noise often manifests itself as excessive hiss and intermittent crackling noises a condition that gets worse with time, but this type of noise (unlike microphony) is not caused by vibration. Excessive hiss is often caused by emission loss due to age.

  • Page 33: Emission Loss

    The first tube in the DU is the small signal triode section of the PCL86/14GW8 triode/pentode tube which is electrically the same as a 12AX7. Now, because the unit is designed to accept studio line level signals (0dBu, 0.775Vrms) if it becomes noisy its noise will be low in low DRIVE...

  • Page 34: Ionization

    AAE Distortion unit IONIZATION Ionization is a serious problem as well as gas currents and electrical leakage between different tube elements which cause it. These problems can develop with age but can also happen to new tubes especially if they operate too close to their maximum ratings. They are not common in pre-amp tubes but they occur in power tubes and can damage other circuit components too, because ionization can cause internal and external arching plus high current surges.
  • Page 35 AAE Distortion unit FUSES Fuse choice is based on estimates and some of the fuses in the power supply unit have slightly low ratings on purpose to ensure that they blow if something goes wrong and protect the circuits that they are connected to.
  • Page 36 AAE Distortion unit...

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