Crossfader circuit - Revision history

Rasteri: /* Discrete JFET-based VCAs */

2016-02-05T03:09:00Z

‎Discrete JFET-based VCAs

2016-02-05T03:02:50Z

‎Discrete JFET-based VCAs

2016-02-05T03:02:10Z

‎Monolithic VCA ICs

2016-02-02T00:47:15Z

‎Monolithic VCA ICs

2016-02-01T15:15:55Z

‎Introduction

2016-02-01T14:59:38Z

‎Generating the control voltage

2016-02-01T05:04:18Z

‎Discrete JFET-based VCAs

2016-02-01T04:57:10Z

‎Ground pulldown

2016-02-01T04:49:52Z

2016-02-01T03:59:23Z

@@ Line 105: / Line 105: @@
 Mixers using JFET-based circuitry include :
-* '''Vestax [[PMC Pro|PMC ProA]]''' series, also the [[PMC Pro|PMC ProVCA]] series despite the name
+* '''Vestax PMC05ProII/ProIII/ProIIIVCA, 06ProA/ProVCA
 ====Monolithic VCA ICs====

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 Mixers using JFET-based circuitry include :
-* '''Vestax [[PMC Pro|PMC ProA]]''' series, manufactured around the turn of the century
+* '''Vestax [[PMC Pro|PMC ProA]]''' series, also the [[PMC Pro|PMC ProVCA]] series despite the name
 ====Monolithic VCA ICs====

@@ Line 119: / Line 119: @@
 Mixers using this approach include :
 * '''Technics [[Technics SH Series|SH-EX1200]]
 * '''Rane TTM Series''' (except the TTM57)
 * Essentially all modern analog performance mixers

@@ Line 120: / Line 120: @@
 * '''Vestax [[PMC Pro|PMC ProVCA]]''' series
-* '''Technics [[Technics SH Series|Technics SH-EX1200]]
+* '''Technics [[Technics SH Series|SH-EX1200]]
 * '''Rane TTM Series''' (except the TTM57)
 * Essentially all modern analog performance mixers

@@ Line 13: / Line 13: @@
 ====Decay time====
-''Full Article with awesome waveforms and harmonic analysis : [[Decay]]''
+''Full Article with awesome waveform diagrams and harmonic analysis : [[Decay]]''
 Muting an audio signal is not as simple as immediately returning the channel to zero, as this would result in clicks and pops. The signal should instead decay over a few tens of milliseconds. However, if this decay is too large, the signal will take too long to mute and make rhythmic cutting impossible. An ideal decay time would be in the region of 10 to 20 ms.
-Some mixers aimed at turntablists have been afflicted with overlong decay times, presumably as a result of turntablists not having been fully consulted in the design process. These include :
+Some mixers aimed at turntablists have been afflicted with overlong decay times, presumably as a result of turntablists not having been fully consulted in the manufacturing process. These include :
 *[[American Audio QD5 MK2]]
 *Stanton SA Series
 *[[Vestax Samurai Series|Vestax PMC05ProD Samurai]]
 ==Design Approaches==

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 This control voltage can come from a number of different places -
-* It can be generated directly by the fader itself. This requires no additional components, and can still be filtered using a capacitor, but does not allow for
+* Generated directly by the fader itself. This requires no additional components, and can still be filtered using a capacitor, but does not allow for any processing. This approach is used in some Allen & Heath mixers.
+* Generated by some analogue circuitry. This allows advanced features such as curve control, and the ability to combine the crossfader and input fader control so a single VCA can be used per channel. This is the approach taken by the Vestax PMC Pro series, and the Rane [[TTM54]].
-it can be generated by some analogue circuitry based on a number of factors including fader position, or for even more flexibility it can be generated by a digital microprocessor such as in the [[Rane TTM56]].
+* Generated by a digital microprocessor such as in the [[Rane TTM56]]. This allows for maximum flexibility, and can be modified during the production run should that be necessary.
-−
-−
 There are a number of different approaches to VCA circuit design :

@@ Line 97: / Line 97: @@
 ====Discrete JFET-based VCAs====
-Another type of VCA circuit can be made using a JFET :
+Another type of VCA circuit can be made using a [[wikipedia:JFET|JFET]]:
 [[File:VCAJfet.png]]

@@ Line 54: / Line 54: @@
 [[File:Fader_circuit_2.png]]
-This has much reduced crosstalk and again requires only one resistive element per output channel, but also significantly attenuates the signa, so will adversely affect the [[Wikipedia:Signal-to-noise_ratio|signal-to-noise ratio]] of the circuit. It also requires a sigmoid-taper fader as before.
+This has much reduced crosstalk and again requires only one resistive element per output channel, but also significantly attenuates the signal, so will adversely affect the [[Wikipedia:Signal-to-noise_ratio|signal-to-noise ratio]] of the circuit. It also requires a sigmoid-taper fader as before.
 Mixers that use this topology include :

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 ===Requirements===
-Turntablists have the following requirements in a mixer circuit:
 ====Sharp Curve====
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 ====Decay time====
-Silencing an audio signal is not as simple as immediately returning the channel to zero. If this is tried
+''Full Article with awesome waveforms and harmonic analysis : [[Decay]]''
-When the fader is moved, the appropriate channel should change volume at a rate quickly enough to allow rhythmic cutting, but slowly enough to eliminate any clicks and pops which would be caused by an instantaneous decay
+*[[American Audio QD5 MK2]]
 ==Design Approaches==

← Older revision		Revision as of 03:59, 1 February 2016
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	====Decay time====		====Decay time====
		+
		+	Silencing an audio signal is not as simple as immediately returning the channel to zero. If this is tried
		+
	When the fader is moved, the appropriate channel should change volume at a rate quickly enough to allow rhythmic cutting, but slowly enough to eliminate any clicks and pops which would be caused by an instantaneous decay		When the fader is moved, the appropriate channel should change volume at a rate quickly enough to allow rhythmic cutting, but slowly enough to eliminate any clicks and pops which would be caused by an instantaneous decay