A COMPRE SS OR H PH OMPRESS O C A R AL AL P
The information in this document is subject to change without further notice and shall not be deemed as an obligation or warranty of any kind by the manufacturer. No warranties, express or implied, are made with regard to the quality, suitability or accuracy of this document. The manufacturer reserves the right to change the contents of this document and/or the associated products at any time without the provision of prior notice.
WARNING: High Voltage • Risk of electric shock. • Do not open chassis. • Refer service to qualified service staff only. • Before connecting the device to the main power supply, check if the right voltage is selected. • Replace fuse with the same type and value only. • This device must be connected to ground. • Do not use a damaged power cord. • Never place containers with liquid, e.g. beverages or a vase, on the unit. • Do not expose this device to rain or moisture. • Do not use this device near water, e.g.
Dear friend of audio culture, First of all, we would like to thank you sincerely for choosing the alpha compressor as your new mastering tool. From now on, you not only have the maximum possible audio quality in dynamics processing at your disposal, but also a complete arsenal of flexible and effective tools which will shift the fruit of your work to a new level.
BASICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BASICS Controls Both channels of the alpha compressor are absolutely identical regarding their electronic design. Therefore both sides of the front panel have exactly the same controls and switches. Continuative information on the specific functions can be found on the pages in brackets.
EQ On: activates the Niveau Filter. In the signal path, this special EQ is placed after the compressor section, thus it will not influence this section’s behavior. (p. 17) EQ Freq: the center frequency of the Niveau Filter. Around this reference point, bass is boosted and treble is cut or vice versa. (pp. 17, 31) x10: shifts the frequency range of the Niveau Filter. The printed values from 20 Hz to 2.0 kHz are multiplied by 10 to 200 Hz and 20 kHz. (pp.
BASICS Connectors Voltage 220 - 240 VAC ~ 50 Hz 110 - 120 VAC ~ 60 Hz Power Consumption 100 W Controller Brightness Made in Germany WARNING! RISK OF ELECTRIC SHOCK - DO NOT OPEN! Fuse Type 1.5 A Slo-Blo @ 220 - 240 VAC 3.
Getting Started Never fear! With its many options and quite a lot of controllers the alpha compressor might look a little tricky at first sight. In practical experience, however, it is a clearly structured and easy to use tool. The control elements are divided into three layers, whereas the left and the right channel sides are completely identical. +4 Thresh 0 +11 -6 +15 70 -13 dB 0.01 800 150 ms 60 1.9 2.1 1.2 1k8 ms 1.8 1.3 1k5 Auto Fast 1.7 1.4 1k1 75 1.
BASICS In the middle of the unit, right below the gain reduction meters, there are three buttons to set the distinct operating modes of the alpha compressor: M/S Mode Active Channel Link M/S Mode If this button is pressed, the alpha compressor will work in M/S mode in which the controls on the left side affect the middle channel and those on the right side belong to the side channel. Otherwise the unit will work in stereo mode.
Thresh Attack Release Feed Forward Ratio Auto Fast On Attack x10 Gain dB ms Auto Fast Ratio ms EQ Gain EQ Freq SC Gain SC Freq Hz Release Feed Forward Auto Fast EQ Gain EQ Freq Mix Thresh Soft Clip On On Mix Soft Clip Auto Fast 1:X SC Gain SC Freq x10 Gain dB On Soft Clip Gain Reduction Direct Compressed Transformer On M/S Mode Active Channel Link Direct Compressed Transformer On Link Mode In link mode, both channels of the alpha compressor can be coupled and
BASICS Thresh Attack Release Feed Forward Ratio Auto Fast On Attack x10 Gain dB ms Auto Fast Ratio ms EQ Gain EQ Freq SC Gain SC Freq Hz Release Feed Forward Auto Fast EQ Gain EQ Freq Mix Thresh Soft Clip On On Mix Soft Clip Auto Fast 1:X SC Gain SC Freq x10 dB On Soft Clip Gain Gain Reduction Direct Compressed Transformer On M/S Mode Active Channel Link Direct Compressed Transformer On Stereo Compression In order to get a first impression of the sonic quali
Auto Fast (Attack) The Auto Fast function causes an automatic shortening of the attack time on fast and loud signal peaks. This effect is easy to comprehend when compressing a preferably dynamic drum loop, for example. Please set the following values as a starting position: • • • • Attack: Release: Ratio: Threshold: 50 ms 300 ms 1:1.8 Set to a position that results in approx. 3-4 dB of gain reduction Because of the quite long attack time the snare and bass drum will be processed very moderately.
BASICS Feed Forward This function makes it possible to switch the junction of the sidechain alternatively behind (feedback) or in front (feed forward) of the actual compressor section. This has an enormous effect on the character of the compressor. Again, our drum loop can be used for demonstration: While processing in feedback mode is smooth and even, switching into feed forward mode will result in a clearly more aggressive and harder kind of compression.
Thresh Attack Release Feed Forward Ratio Auto Fast On Attack x10 Gain dB ms Auto Fast Ratio ms EQ Gain EQ Freq SC Gain SC Freq Hz Release Feed Forward Auto Fast EQ Gain EQ Freq Mix Thresh Soft Clip On On Mix Soft Clip Auto Fast 1:X SC Gain SC Freq x10 Gain dB On Soft Clip Gain Reduction Direct Compressed Transformer On M/S Mode Active Channel Link Direct Compressed Transformer On M/S Matrix One of the most powerful features of the alpha compressor is its swit
BASICS Thresh Attack Release Feed Forward Ratio Auto Fast Attack x10 Hz Gain ms Auto Fast Mix Soft Clip Auto Fast 1:X SC Gain SC Freq On On dB ms Ratio EQ Gain EQ Freq SC Gain SC Freq Mix Release Feed Forward Auto Fast EQ Gain EQ Freq On Thresh Soft Clip x10 dB On Soft Clip Gain Gain Reduction Direct Compressed Transformer On M/S Mode Active Channel Link Direct Compressed Transformer On Sidechain Filter The sidechain filter allows frequency-dependent shaping
Thresh Attack Release Feed Forward Ratio Auto Fast On Attack x10 Gain dB ms Ratio ms Auto Fast EQ Gain EQ Freq SC Gain SC Freq Hz Release Feed Forward Auto Fast EQ Gain EQ Freq Mix Thresh Soft Clip On On x10 Mix Soft Clip Auto Fast 1:X SC Gain SC Freq dB On Soft Clip Gain Gain Reduction Direct Compressed Transformer On M/S Mode Active Channel Link Direct Compressed Transformer On Audio Filter The audio filter is placed behind the compressor in order to avoid
BASICS Thresh Attack Release Feed Forward Ratio Auto Fast On Attack x10 Gain dB ms Auto Fast Ratio ms EQ Gain EQ Freq SC Gain SC Freq Hz Release Feed Forward Auto Fast EQ Gain EQ Freq Mix Thresh Soft Clip On On x10 Mix Soft Clip Auto Fast 1:X SC Gain SC Freq Gain dB On Soft Clip Gain Reduction Direct Compressed Transformer On M/S Mode Active Channel Link Direct Compressed Transformer On Mix Controller The mix controller makes it possible to cross-fade betwee
Thresh Attack Release Feed Forward Ratio Auto Fast Attack x10 Hz Gain dB ms Ratio ms Auto Fast EQ Gain EQ Freq SC Gain SC Freq Mix Release Feed Forward Auto Fast EQ Gain EQ Freq On Thresh Soft Clip On On Mix Soft Clip Auto Fast 1:X SC Gain SC Freq x10 dB On Soft Clip Gain Gain Reduction Direct Compressed Transformer On M/S Mode Active Channel Link Direct Compressed Transformer On Soft Clip Limiter The Soft Clipper was designed to limit short, loud transients
SCENARIOS +4 Thresh 0 -6 +15 1,0 dB 0,3 2,0 Feed Forward 0,3 EQ Gain EQ Freq 1,6 2,2 2,2 2,7 Auto Fast 50 20 60 20 % LP 3,5 4,5 3,0 3,0 Hz 6,0 6,0 7,5 8,5 8,5 3k3 12 1,0 dB 0,3 2,7 5,5 Gain Reduction 60 On M/S Mode Active Channel Link % Direct 3,5 4,5 0,5 HP 800 2k0 30 On 16 14 Hz 3k3 11 8,0 5,5 24 12 dB Compressed 500 40 21 11 0 430 50 19 10 1:X 280 340 2,4 80 Soft Clip 6,0 8,0 Com Auto Fast -12 dB 2,2 1,1 SC Gain SC Freq -12
+4 Thresh 0 -6 +15 1,0 dB 0,3 2,0 Feed Forward 0,3 EQ Gain EQ Freq 1,6 2,2 2,2 2,7 Auto Fast 50 20 60 20 % LP 3,5 4,5 3,0 3,0 Hz 6,0 6,0 7,5 8,5 8,5 3k3 12 1,0 dB 0,3 2,7 5,5 Gain Reduction 60 On M/S Mode Active Channel Link % Direct 3,5 4,5 0,5 HP 800 2k0 30 On 16 14 Hz 3k3 11 8,0 5,5 24 12 dB Compressed 500 40 21 11 0 430 50 19 10 1:X 280 340 2,4 80 Soft Clip 6,0 8,0 Com Auto Fast -12 dB 2,2 1,1 SC Gain SC Freq -12 1,5 100 m
SCENARIOS +4 Thresh 0 -6 +15 1,0 dB 0,3 2,0 Feed Forward 0,3 EQ Gain EQ Freq 1,6 2,2 2,2 2,7 Auto Fast 50 20 60 20 % LP 3,5 4,5 3,0 3,0 Hz 6,0 6,0 7,5 8,5 8,5 3k3 12 1,0 dB 0,3 2,7 5,5 Gain Reduction 60 On M/S Mode Active Channel Link % Direct 3,5 4,5 0,5 HP 800 2k0 30 On 16 14 Hz 3k3 11 8,0 5,5 24 12 dB Compressed 500 40 21 11 0 430 50 19 10 1:X 280 340 2,4 80 Soft Clip 6,0 8,0 Com Auto Fast -12 dB 2,2 1,1 SC Gain SC Freq -12
+4 Thresh 0 -6 +15 1,0 dB 0,3 2,0 Feed Forward 0,3 EQ Gain EQ Freq 1,6 2,2 2,2 2,7 Auto Fast 50 20 60 20 % LP 3,5 4,5 3,0 3,0 Hz 6,0 6,0 7,5 8,5 8,5 3k3 12 1,0 dB 0,3 2,7 5,5 Gain Reduction 60 On M/S Mode Active Channel Link % Direct 3,5 4,5 0,5 HP 800 2k0 30 On 16 14 Hz 3k3 11 8,0 5,5 24 12 dB Compressed 500 40 21 11 0 430 50 19 10 1:X 280 340 2,4 80 Soft Clip 6,0 8,0 Com Auto Fast -12 dB 2,2 1,1 SC Gain SC Freq -12 1,5 100 m
SCENARIOS +4 Thresh 0 -6 +15 1,0 dB 0,3 2,0 Feed Forward 0,3 EQ Gain EQ Freq 1,6 2,2 2,2 2,7 Auto Fast 50 20 60 20 % LP 3,5 4,5 3,0 3,0 Hz 6,0 6,0 7,5 8,5 8,5 3k3 12 1,0 dB 0,3 2,7 5,5 Gain Reduction 60 On M/S Mode Active Channel Link % Direct 3,5 4,5 0,5 HP 800 2k0 30 On 16 14 Hz 3k3 11 8,0 5,5 24 12 dB Compressed 500 40 21 11 0 430 50 19 10 1:X 280 340 2,4 80 Soft Clip 6,0 8,0 Com Auto Fast -12 dB 2,2 1,1 SC Gain SC Freq -12
+4 Thresh 0 -6 +15 1,0 dB 0,3 2,0 Feed Forward 0,3 EQ Gain EQ Freq 1,6 2,2 2,2 2,7 Auto Fast 50 20 60 20 % LP 3,5 4,5 3,0 3,0 Hz 6,0 6,0 7,5 8,5 8,5 3k3 12 1,0 dB 0,3 2,7 5,5 Gain Reduction 60 On M/S Mode Active Channel Link % Direct 3,5 4,5 0,5 HP 800 2k0 30 On 16 14 Hz 3k3 11 8,0 5,5 24 12 dB Compressed 500 40 21 11 0 430 50 19 10 1:X 280 340 2,4 80 Soft Clip 6,0 8,0 Com Auto Fast -12 dB 2,2 1,1 SC Gain SC Freq -12 1,5 100 m
REFERENCE Threshold Offset The analog audio level of the alpha compressor depends on the studio environment it is used in. In the majority of cases it depends on the D/A converter used, because the output stages of the converter determine the analog level. As there is no binding norm for it, this level can be at +4 dB, +6 dB, +10 dBu, +12 dBu or even +15 dBu. To make sure that the threshold controller actually covers its complete adjustment range it can be adjusted to those different levels.
Attack Here a burst signal (a sine tone that is boosted by 12 dB for a period of 100 ms) is used to demonstrate the effectiveness of the attack controller. The different curves show how fast this level jump is reduced by 4 dB. On fast settings the reduction takes only a few milliseconds, on longer settings the reduction does not only take longer, but it is also smaller. Therefore the amount of gain reduction is always higher on fast attack settings than on longer settings.
REFERENCE Release This figure is based on a very fast attack time; the gain reduction is about -7 dB. The burst lasts for 25 ms and then follows the release phase with time parameters of different length. The linear characteristic of the release curve is very easy to see here. Because of the utilized circuit, the attack time must always be added to the release time.
Ratio Feedback The alpha compressor works with a soft knee characteristic and increasing ratios at rising gain reduction values. The scale on the front panel is based on a measured gain reduction of 6 dB. Strictly speaking, the ratio values become noticeably higher on stronger reductions: If there is 17 dB of gain reduction the ratio value will shift from the printed 1:2.5 to actual 1:4.5 after all.
REFERENCE EQ Gain Low For this measurement the center frequency was set to 1.8 kHz and the EQ gain controller was set to different positions between 0 and full left (-3 dB). The diagram shows the effectiveness of the filter: The lower frequencies are boosted up to 3 dB, at the center frequency they cross zero, and the higher frequencies are cut up to 4.5 dB. Depending on the setting of the EQ gain the level might need some make up with the gain controller.
EQ Frequency This diagram shows a variation of center frequencies with the EQ gain controller turned fully clockwise (HI). The x10 button shifts the complete frequency area by a factor of 10. With settings in the border areas of the covered frequencies it is also possible to realize ‘almost’ shelving filters, but in these cases the level has to be adapted with the gain controllers.
REFERENCE SC Low Pass This diagram shows some settings of the sidechain frequency controller (SC Freq) in low pass mode (LP). If the filter is set at 100 Hz for example, full gain reduction will still occur at these 100 Hz and the high frequencies will have lesser influence the higher they get. Therefore in this mode of operation the filter should always be set to the highest frequency you just about want the compressor to react to.
Mix This measurement diagram shows a fade from the original to the compressed signal (direct and compressed buttons active). The gain controller was set at 8 dB, which is also the reason for decreasing levels in the more clockwise areas of the controller range. In case that only the direct or alternatively only the compressed signal is switched in, the mix controller does not have any influence on the level.
APPENDIX Level Problems No Signal This problem might be caused by balanced wiring. If the signal almost completely drops when the alpha compressor is activated, it is probable that a pin of the XLR connector at the input is not connected. As the input stages feature transformers, both pins have to be connected. The classic case for this problem would be a balanced XLR connection that is connected to an unbalanced output that only uses ground and pin 2. Connecting pin 3 to ground should solve this problem.
Frequency Response: <10 Hz – 200 kHz (-0.5 dB) THD+N @ +15 dBu, 20 Hz - 22 kHz: Stereo Mode (Direct) Stereo Mode (Compressed) M/S Mode (Direct) M/S Mode (Compressed) 0.0039 % 0.009 % 0.014 % 0.034 % Noise Floor, 20 Hz - 20 kHz (A-weighted): Stereo Mode (Direct) Stereo Mode (Compressed) M/S Mode (Direct) M/S Mode (Compressed) -95.8 dBu -89.3 dBu -95.6 dBu -92.
APPENDIX Warranty Conditions and limitations The alpha compressor is covered by a limited warranty for a period of 5 years against defects in parts and labor from the date of purchase. Natural wear is not covered by this warranty. elysia will remedy problems caused by material or workmanship either by repair or replacement to restore the product to full performance without charge for parts and labor. Repairs or replacements will not extend the warranty period.
dB dB 0.01 Hi % x10 dB 12 dB HP -12 24 21 19 25 -5 -2 Soft Clip Transformer 10 8.0 11 6.0 LP 1.1 16 dB 14 On 3.0 5.5 8.0 30 4.0 11 40 50 80 1.7 On Hz 5.0 6.0 2k0 11 9.5 8.5 4307.5 2.4 12 4.0 2.1 1.9 2.2 1.8 3k3 1:X 280 340 1.6 14 3.0 18 20 M/S Mode 16 2.0 1.5 1.0 Active Gain Reduction Soft Clip 18 1.5 16 2.0 14 3.0 Channel Link 20 1.0 12 4.0 11 Lo 1.0 +20 2.7 9.5 8.5 7.5 6.0 5.
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