DRAWMER OPERATORS MANUAL. CONTENTS: SAFETY CONSIDERATIONS INTRODUCTION APPLICATIONS INSTALLATION AUDIO CONNECTIONS. Vacuum tube compressor, Operators manual • Read online or download PDF • Drawmer Electronics Mic-Pre/Tube Compressor User Manual. Download DRAWMER MIC PRE COMP SCH service manual & repair info for electronics experts.

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Because the compression system is based on the Soft Knee principle, the onset of compression is progressive, so no Ratio control is necessary. This stage may be deliberately overdriven if required to add tonal coloration to an instrument, and with the addition of an external speaker simulator, overdriven guitar sounds may be Directly Injected “DI’d” into the mixing console.

Avoid mounting the unit directly above power amplifiers or power supplies that radiate significant amounts of heat and always connect the mains earth to the unit. As with other Drawmer products, the by-pass switch offers a choice of Normal, By-pass and Side Chain Listen modes so that if you have patched in any additional side chain processing, you can easily monitor what effect it is having.

The microphone input stages feature extremely low noise, balanced input circuitry with additional tube amplification, enabling modern microphones to take on the characteristics of older tube models. For mono use, each channel may be considered as being completely independent and set up accordingly. Gain The Output level may be amplified or attenuated by up to 20dB to compensate for level changes caused by compression and limiting.

Three switchable Attack settings are provided giving Fast, Medium and Slow attack times. Replace with a correctly rated fuse for the selected operation voltage.


Using a number 1 size pozidrive screwdriver, remove the two self-tapping screws holding the voltage selection switch cover plate on the rear panel. Avoid running at excessively high output levels as this reduces the available amount of signal headroom and could lead to distortion in extreme cases. Determines the input level above which gain reduction will be applied manuwl may be set in the range dB to infinity.

This is judged partly by ear and partly by observing the gain reduction meter. Remove the cover plate and slide the switch fully to its opposite end.

DRAWMER 1960 Operator’s Manual

There is little doubt in the minds of many engineers and producers that vacuum tubes possess a unique sound quality providing a “warmer, more alive” sound. This rotary switch selects the compressor input source. In addition, the incorporates two low-noise microphone preamplifiers with provision for phantom powering, plus a versatile instrument preamplifier with passive EQ and brightness switch. Averages the left and right channel control settings drawme the unit is used for processing a stereo signal.


Phantom power is individually switchable on the two channels and a peak overload LED warns when clipping is imminent. Because the tube circuitry generates more heat than an equivalent solid-state design, it is advisable to leave space above the unit to allow the heat to dissipate.

The fully conforms to the EMC standards, if you propose to use the unit where it maybe exposed to high levels of disturbance such as found close to a TV or radio transmitter we suggest that the screen of the signal cable is connected to the chassis connection on the XLR type connector.

Setting up is simplified by the soft-knee compressor action which means that it is only necessary to adjust the Threshold control until the desired degree of gain reduction is achieved. Because the compressor is a soft knee type, it requires few controls. The Gain control may be set to provide the required output level using the level meter as a guide. Switch settings 1 through to 4 provide progressively increasing release times, while positions 5 and 6 cause the release times to vary in a manner which automatically adapts to the dynamics of the incoming signal.

With the programme material playing, adjust the Threshold control until the desired amount of gain reduction registers on the meters. The adjacent Clip LED illuminates when excessive mic gain has been applied and there is a danger of clipping.

If necessary, change the Attack and Release settings to suit the material. If more gain reduction appears necessary, it is worth considering applying a conservative degree of compression during recording and then further compression while mixing. Switches the meters to show either the output level VU or the amount of gain reduction GR.

Positions one to four have fixed release times whilst positions five and six are two different programme dependent release time modes making the unit ideally suited to programme material with complex dynamics such as complete stereo mixes and vocals.

In Normal mode, the signal is passed through the compressor. Re-connect to mains power source. The unit should always be connected to the mains supply earth using this cable.

Equalization is provided along with sufficient gain to overload the tube pre-amp for sustain effects. The actual attack time is further modified by the release setting chosen. Interestingly, the attack times are further modified by the choice of release setting so the range of choices are wider than it might first appear.

The intended use of the audio insert jacks would be to patch in EQ egreverb or similar processing. For use with stereo signals such as complete mixes or submixes, the unit should be switched to Stereo Link mode and both sets of channel controls set to the same position.


Because guitar sounds are so subjective, and because they vary so much with instrument and playing style, there are no hard and fast rules to setting up, but a good starting point is to switch Bright ‘On’ and set the compressor for ‘Med’ attack and ‘6’ release.

Because the meter has VU characteristics, it closely reflects what is actually being heard, though will not respond quickly enough to register short signal peaks. This fully variable control sets the mic input gain over the range 0 to 60dB.

There are four, dual-stage tubes in the audio signal path and the compressor section is designed to provide a soft-knee characteristic which contributes both to the sweet sound of the unit and to its ease of use. Soft-knee compressors are generally preferable for unobtrusive level control and the system used in the provides firm control without the side-effects of a fixed, hard-knee design.

The Drawmer is a two channel unit with each channel comprised of a completely natural sounding “soft knee” vacuum tube compressor and an extremely low noise microphone pre-amplifier with switchable 48 volt phantom power. Combining eight manusl tube stages and the low noise and reliability of solid state electronics, the Drawmer provides the ultimate direct interface between the sound source and the recording medium.

Drawmer – Manual

The VU meters may be switched to monitor either the amount of gain reduction taking place or the output signal level and the two channels may be used either independently or as a stereo pair, depending on the setting of the stereo link switch.

Attack simply offers a choice of slow, medium and fast 19960 release has six settings. The Aux input is a valuable addition as it combines the virtues of a D. The two auto release switch settings continually optimise the compressor action to suit the dynamics of the material being processed, setting 5 kanual optimised for percussive material and setting 6 for general purpose use.

A further auxiliary instrument pre-amp with EQ is also provided. The Aux ddawmer may also be used for processing the output from a dedicated guitar preamplifier, where the EQ can be used to further tailor the sound before it is compressed.

Fibre or plastic washers may be used to prevent the front panel becoming marked by the mounting bolts. Two sets of insert points on the rear panel allow additional effects to be added either before or during compression.