Comp-54 manual - Golden Age Music
Contents
1. COMP 54 Vintage Style Compressor THRESHOLD RATIO ATTACK RELEASE iis Em r Lal m L a r a a a a a iii E i s a Lal L INL T INTRODUCTION Congratulations on choosing the Golden Age Project COMP 54 Compressor The COMP 54 is a one channel vintage style compressor The signal path uses only discrete components like resistors capacitors and transistors The input and output are transformer balanced and the unit also uses a third interstage transformer This is the way audio components were built before integrated circuits became available IC s are small and cheap and they are widely used in most modern designs It is clear though that audio components built with modern technology doesnt always provide the best perceived sound quality or character that the modern user desires On the contrary the subjective sound quality delivered by vintage equipment is often prefered over the one delivered by modern units This is the reason why so many vintage audio components are cloned and pro duced again and also why the vintage originals are often very expensive on the second hand market The class A circuit used in the COMP 54 is similar to the one in the classic 2254 compressor that was de signed in 1969 It quickly became a legend due to it s totally unique sound character that is warm smooth sweet and musical These characteristics have been heard on countless recordings through the years and it is a versatile sound that wo2. Care must be taken to protect the meter from physical overload not the least when it is set to show output level If the needle is hitting the end of it s travel hard or for prolonged periods there is a risk that the meter will be damaged This is not covered by warranty The unit is calibrated from factory to show 0 VU when the output level is about 4 dBu or 1 23 volts This is a common reference level in pro audio but most equipment will be able to handle much higher levels Since the COMP 54 will be used in different setups it is possible to adjust the meter reference level with the trim potentiometer on the circuit board marked Meter Out If the needle hits the end of its travel you should adjust the trimmer so that the needle stays within its normal travel you will then have raised the reference level If the COMP 54 is used in a semi professional 10 dBu environ ment you can decrease the VU reference level by adjusting the trimmer the other way Another way to stop the meter needle from hitting the end of it s range is to switch the meter to show gain reduction since the full scale will usually seldom be reached unless you compress very hard There is a trim potentiometer also for this meter mode marked Meter GR WARRANTY The COMP 54 come with a one year parts and labor limited war ranty It is built to last but components can break down There is a slow blow fuse located inside the unit If the unit
3. dies please check this fuse If it has blown replace it with a new one If this doesnt help the unit will need repair and you should then contact the dealer where you bought the unit Please note that repairs and warranty issues are handled through your dealer by the distributor in the area where you bought the unit Damages caused by misuse is not covered by warranty REGISTRATION You are welcome to register your unit at our website www goldenageproject com would like to thank you for chosing the COMP 54 wish you much joy with the unit and I hope that it will help you in making a lot of great sounding music Yours Bo Medin Create music Be happy II
4. dynamic range of a signal more or less invisible or it can be used as a crea tive tool affecting the sound in a big way You will find a lot of infor mation about how to use and adjust compressors on the internet CONNECTING THE COMP 54 Connect the power adaptor to the AC outlet please note there are different adaptors used for 115V and 230V and the 24V AC output to the jack on the back panel Connect the audio source to any one of the input jacks XLR or TRS They are wired in parallell the same is true for the output jacks The output stage will easily drive two modern units connected at the same time Since the unit is transformer balanced it usually doesn t matter if you use balanced or unbalanced units before and after it CONTROLS THRESHOLD This sets how high the signal must reach before the compressor kicks in RATIO This sets how much compression is applied in ratio to the dB rise in Signal level above the Threshold ATTACK This sets how fast the compressor kicks in once the Thresh old has been breached RELEASE This sets how fast the compressor lets go once the input signal has dropped back below the threshold HPF This adds a high pass filter in the sidechain circuitry Frequen cies below the filter cut off will trigger compression to a lesser degree GAIN This changes the make up gain so that the ouput level can be adjusted to a suitable level LINK Is used to synchronize the compressor action in
5. only three transistors the last one in the chain is a hefty 2N3055 power _ transistor running in class A mode driving the output transformer So all in all the complete signal chain only contains a maximum of ten active elements Compare that to the big number of transistors that are usually used in one single integrated circuit MODERN VERSUS OLD It is true that there are some great IC s available today that achieves very low levels of static and dynamic distortion The simple circuits that the COMP 54 uses and even more so the transformers cannot match the low distortion specifications of modern IC s It is the distortion components that imparts a sound character to the audio signal and if the distortion components are of the right sort this is a good thing since it makes the recorded voice or instrument sound better more musical more pleasing to the ear This is one reason why vintage style units are so popular today Sometimes transparent units are prefered over colored ones It s all about taste and it depends on the genre For most modern music styles though color and character is definitely a good thing And isn t it great to use audio components built according to the old minimalistic approach where one can follow the signal flow from one discrete component to another USING THE COMP 54 The best way to learn using a compressor is by experimentation A compressor can be set to do its job which is to lower the
6. rks very well on many sound sources and in many genres The essence of this sound is now available at a surprisingly low cost making it available to nearly everyone FEATURES Vintage style electronics Based on classic diode bridge designs Transformer balanced I O s Prepared for transformer upgrade Flexible control range for Ratio Attack and Release All controls except the Gain make up one are stepped Three selectable Sidechain filter frequencies Separate Bypass and Compression IN OUT switches Meter selectable for Output and Gain Reduction Possibility to Link two units for stereo operation Separate in and output XLR and TRS jacks for flexible connections Back panel switch for 600 Ohm termination External power power supply to avoid interaction with the audio circuitry and the transformers Great sound that suits most sound sources and genres Asolid build quality that will last many years of normal use MNW GO LJ Der NEARG ESR ReOxILE C T COM CIRCUIT DESCRIPTION The signal first enters the input trans former a damping network and is then passed on to the diode bridge where the actual gain reduction is taking place it is followed by balanced FET transistor stage Then follows an interstage step up transformer that feeds the sidechain circuitry and a three transistor gain stage followed by the GAIN potentiometer The signal then goes to the output stage This stage again uses
7. two COMP 54 units working as a stereo pair This is usually done to prevent image WAV GO LIpebeNTA G EPR OUE CT C O M shifting that could occur if each channel is compressed individually and content on one channel is louder than that on the other Simply connect an unbalanced TRS cable between the LINK jacks on the back panels press the LINK switches and match the controls on both units IN OUT Pressing this switch removes the compression action the signal still passes through the circuitry though so you can compare the sound with and without compression METER Switches the meter to show output level or gain reduction BYPASS This is a hardwire bypass meaning that the signal is directed from the input jacks directly to the output jacks if this switch is pressed You can then easily compare the sound with or without the COMP 54 in the signal chain 600 OHM TERM The output transformer is designed for having a load of 600 ohms The input impedance of most modern equipment is 10 kohm or more If the transformer isnt properly loaded the output level will increases the square wave response will worsen and the higher frequencies will be accentuated So if you connect the COMP 54 to a modern unit the switch should normally be engaged so that the output transformer is properly ter minated You can always let your ears decide which position works best the switch can be used as a two position high frequency eq LEVELS AND METER CARE
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