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Transistor vca. Dec 15, 2021 · ICs and Transistors.

  • Transistor vca. Mar 22, 2018 · FET compresion is better suited for aggressive and heavy sounds like electric guitar and drums. The MiniMod Discrete Cascaded VCA is a 10hp wide Eurorack format module. It uses FET transistors to amplify or attenuate the signal. This is super simple and not a lot of components. More specifically: their usage in common emitter amplifiers plus their two central flaws (variations between seemingly identical samples & temperature dependence). Or you could even knock up something with a vactrol, even lower parts count. It features two fully discrete transistor VCA cores which are hardwired in series. The PNP pair for the VCF is located at the very top, to the right of the oct/V trimmer. Easy to build and small enough for Eurorack. Jun 24, 2024 · Two Transistor VCA Now we get two outputs, which are in opposite phase: Two Transistor VCA Output Adding a couple more transistors and the second op amp (in the same IC package as the first one), we can combine the two signals, subtracting them to produce the difference between them (hence, differential pair). The AS3046 is a matched transistor array. 3 on which you can find more info here. How-ever, NPNs should only be replaced with NPNs and PNPs with PNPs, and within each of the following sets, all the transistors should be of the same type: fQ3,Q6,Q7g fQ4,Q10g fQ5,Q8,Q9g fQ11,Q15,Q16g The transistors are well suited to a wide variety of applications in low power systems. Again, the BCM56DS is an excellent and affordable choice. Apr 25, 2020 · As to running this VCA on a dual 12 Volt power supply; I don't think there will be any problems with that. Positive CV's will clip and distort the signal. However, there is a fundamental difference in the transistors: In a VCA compressor, the transistor is housed within an integrated circuit (an IC) which responds to the voltage of your incoming signal. 1 x LM13700 IC; 1 x TL072; 1 x BC559; Hardware. I’ve come up with a compromise that’s not too bad: I use a resistor (4. It’s indeed as boring as it sounds, but it’s invaluable in any synth. Support the channel through Patreon: https://www. Mar 12, 2019 · As in our simpler subtractive synthesis examples, an envelope generator runs to the first VCA's control input, creating the sound's overall dynamic contour. The schematic is based on a classic long-tailed-pair VCA design. The AS3360 VCA schematic typically includes a combination of op-amps, transistors, resistors, capacitors, and other passive components. This VCA can act as a variable volume, variable amplifier, mixer… Oct 30, 2019 · I’ll probably post more approaches to the VCA issue in the future. Jul 23, 2014 · VCA Transfer Function . It's a good idea to glue the matched transistors together, to keep them roughly at the same temperature. I call it passive because it doesn't need a eurorack power connector. I left the cv attenuate pot out mki x es. 2x 50K 16mm Potentiometer 4x 100K ohm resistors 5x 10K ohm resistors 1x 47K ohm resistor 3x 220K ohm resistor 2x 1K ohm resistor 3x 22K ohm resistor 1x 100K ohm trimmer May 9, 2024 · I’m trying to make a VCA with as few components as possible, normally the CV part requires an additional op-amp. Mar 10, 2021 · Although the stacked-FET topology can improve the insertion loss and power handling capability as compared to the conventional single transistor VCA, the main obstacle that limits the usage of stacked-FET in VCA is the low dynamic range caused by the significantly higher resistance. It runs on the power of the CV. U1a (1/2 TL072) sums up and inverts the two inputs. In reference to Figure 1 and from the Ebers Moll equation for a bipolar transistor, the transfer function of the differential pair amplifier is: Here's the MiaW video and here's a schematic (the actual VCA is in the middle, and relies on the LED driver circuit at the bottom and the inverting amplifier in the upper middle/right. This filter really sounds sweet. It’s the ideal chip for building Moog ladder filters. There are two audio inputs each with their own level controls along with two CV inputs which control the gain of VCA 1 and a Master CV input and level control which controls the gain of VCA 2. Kassutronics VCA, one opamp and three transistors and a few passives. On the way we'll learn the very basics about how transistor circuits work, and we'll learn how to turn currents into voltages using op-amps! Schematic: Support the channel! :) https://www. 7k on the OTA’s Ibias input) as a voltage/current converter. It consists of two independent, high-gain operational transconductance amplifiers (OTAs), which can be configured in various ways to create different VCA circuits. 5V from the contour generator hits the transistor emitter the LFO swings fine between -15 and -12 at the collector. VCAs have many applications, including audio level compression, synthesizers and amplitude modulation. Buy Behringer 1006 FILTAMP VCF/VCA Module for Eurorack (16 HP) featuring Classic Filter / Amplifier from '70s, Authentic ARP 2500 Circuitry, 24 dB Transistor Ladder LP Filter + VCA, Manual + 3 CV Control Inputs, Variable Attenuators, Resonance at Filter Peak Cutoff, 2 Audio Signal Inputs + Ext VCA Controls, VCA Exponential or Linear Switchable, Includes Ribbon Power Cable, Includes Mounting Feb 23, 2024 · Understanding VCA in FET Compressors. May 31, 2019 · Would a Sallen-Key filter and transistor "swing-VCA" driven from the same CV be equivalent, or is there a magic circuit that can be an LPG in just one circuit (without having to split the CV)? I know it won't have the "ringing" characteristics of a vactrol LPG, but that's okay in this case. The VCA (voltage-controlled amplifier) is the heart of a FET compressor. Reply reply Sep 28, 2017 · So you may now be asking yourself what these circuit types are. As with VCA #2, matched transistor pairs are used to preserve the critical balance, but they’re needed only for the bottom pair below the ladder. However, it was a good example to learn about transistor amplifiers, and I write down what I learned below. Indeed, so fundamental is the VCA that it has its counterparts in every type of synthesis: digitally controlled analogue synths have 'DCAs', while pure digital synths and samplers have all manner of time-variant Nov 6, 2016 · Re: 1 transistor "passive" VCA-ish thingy Post by HZR » Fri Mar 18, 2022 7:27 am Look Mum No Computer had a design with just teo parts: a transistor (bc106) and a diode, but you can omit the diode as well. Changing connections of LM13700 inputs shows that OTA side of the circuit is working fine and something about the transistors is wrong. I fixed the clipping. Aug 23, 2023 · I’ve been trying to find a decent diy vca for the lm13700. Some of the designs that use a similar approach are Kassutronics Discrete VCA, Yusynth Simple VCA and Klein Mortiz' Classic Transistor VCA, among many others. I built a slightly-more-complex version of a single-transistor VCA a while back. 6, but instead of shunting signal to GND, the pull-up / pull-down transistors just apply currents to a switching BJT, into base and out of emitter, while C-E is the switch terminals. 2 x B100k potentiometers (RV09AF-40-20K-B100K) 1 x 8-pin DIP socket; 1 x 16-pin DIP socket; 4 x 3. Feb 7, 2022 · The reason this works is that the waveforms with steep sides going into the VCA CV input are asking the VCA to open and close extremely rapidly and this exposes the mismatch among the transistors -and the resistor tolerances in the duplicated parallel channels- here. 5mm audio jack; 1 x 2x8 IDC PCB header for power (for standard Eurorack supplies) 1 x 6-pin JST PCB header for power (what I use in my system) If building PCB. The schematic is rather simple. It has the classic Minimoog sound and noise is quite low. Thank you for taking the time to write this! I’ve been referencing it for the past few weeks with a circuit I’m currently working on. Here's a schematic. [3] These attenuators, which were state of the art in the early 1970s, were successfully used in professional Dolby A and consumer Dolby B noise reduction systems but did not Learn to design a classic transistor-based VCA from scratch, exploring BJTs, common emitter amplifiers, differential amplifiers, and voltage control techniques for audio applications. Recorded straight output without effects and processing. VCA. You can even use a mixture of di erent transistor types. 1x diode 1N4004 1x op-amp TL072P 1x BC547 NPN transistor 1x BC847BS NPN general purpose double transistor . How can I remove clicking sound from transistor VCA ? I made a dual VCA copying Moritz Klein's design and it works fine on smooth transitions but on fast changes in volume it makes a really loud licking noise. After all the opamps and transistors all work fine on 12V so I think it's just a matter adjusting the trimmers. I just got into the lm13700 and I’ve been trying to hunt down a useful diy vca for it. Most audio compressors operate using either VCA (Voltage Controlled Amplitude), FET (Field-effect Transistor), OPTO (Optical), or VARI-MU (Variable-MU). The earliest solid-state VCA topology was an attenuator rather than an amplifier; it employed a junction field-effect transistor in voltage-controlled resistance mode. It contains five matched transistors, with two connected as a differential pair. Under normal VCA operation it would be -15V closed and -12V open at the same point. IC's, diodes, transistors. BC557C PNP silicon transistors, but it should work with almost any common transistor types. VCA-2 is a more streamlined version of VCA-1, the circuit has also an inverting input to simulate ringmodulation via a nulling method. This vid. Matched pair of npn transistors Nov 14, 2023 · Re: Erica Synth EDU VCA / Transistor HFE Question Post by guest » Sat Dec 02, 2023 6:37 pm it controls the current to the base, but less so the current to the leds. FET compressors are designed to maintain more transients, so they add an extra punch in contrast to the variable. A voltage divider pot between -12v and +12v if nothing is plugged into the CV input to control the gain. Quick question, does anybody know a simple VCA circuit which includes Control voltage and a potentiometer to change the volume? and specially, a VCA able to get to volume 0, my circuit didnt work well enough, it couldnt mute completely the sound. 4 HP Front panel. The version shown in the VCA Techniques article uses a current mirror as the load for the long-tail pair (LTP). We specifically select our transistors to add harmonics and give a rich and thick Eurorack Dual Triple Response VCA Assembly Instructions. Nov 19, 2020 · Is there any theoretical analysis of the early Korg "angular transistor" VCA? I suppose it was conceived by Mieda-sama, in which case it should better be named "Mieda-style VCA". The Eowave Germania 241 is a discrete VCA/warmer module build around with the sound characteristic of the vintages Russian germanium transistors. I like the n-channel jfet “I am o” and the vactrol vca too (both passive). They may be used as discrete transistors in conventional circuits however, in addition, they provide the very significant inherent integrated circuit advantages of close electrical and thermal matching. You do need an oscilloscope to calibrate it though. Prototype of discrete transistor filter and VCA made with ultra matched transistor pairs. These extra punches are known as mu and VCA compressors. The output of this VCA is then passed into a second VCA. com/moritzklein by buying my DIY kits: Aug 8, 2013 · It's something in the middle of a VCA/distortion/waveshaper. TIS97 transistors for the Moog Minimoog VCA, VCF, and preamp sections. I’ve done the differential pair transistor vca (tough for me to match the pairs). All available circuits have limitations, and this article looks at the various techniques used. com/TheAudioPhoolThis is a continuation of last time, where we learned how a simple differential amplifier (diff A variable-gain (VGA) or voltage-controlled amplifier (VCA) is an electronic amplifier that varies its gain depending on a control voltage (often abbreviated CV). This is Alfa’s new-production clone of the venerable CA3046, which is now pretty hard to find and getting expensive. com :: View topic - Single transistor VCA circuit) Minus the coupling capacitors, both seem to follow the same one transistor plus diode approach. Each component plays a crucial role in shaping the VCA’s behavior, such as determining the control voltage response, dynamic range, and distortion characteristics. One problem of these discrete VCAs is thermal drift of the transistors, this causes the CV rejection to vary (As was pointed out by Jörgen Bergfors). this video is a long one, because there's a lot to talk about. What’s a VCA: For those yet unclear about the concept, it’s a voltage controlled amplifier. I’ve run into strange non-linear traits with the voltage-to-current converter/PNP section. This initial gain stages brings the large modular signals down to small signal level. For better or worse, it's not completely passive as there are a few places where a voltage source is needed: it has a bias network to pull the input voltage up, so both positive and negative voltages get passed through. Potentiometers, trimmers and resistors. 1 x 1x16 P2. It’s a nice first DIY VCA that you can build in very short time, with very few, off-the-shelf, components. Dec 12, 2018 · The 2n3904 is considered a small signal transistors and tends to be more linear at lower signal levels. 1 - Circuit description 2 - Assembly guide 3 - Documentation. BJTs (bipolar junction transistors) work surprisingly well, provided the input level is kept 'reasonable' (which in this context means no more than 500mV RMS). Warm things up: That fat Analog Character: It's not question here be in the area of the "most transparent VCA ». Collector of PNP transistor doesn't go as low as the first VCA. We're not only designing a VCA – we're also looking at NPN transistors and their idiosyncrasies in detail. Inputs of the second VCA are normalled to the first one which allows to split the audio signal to both VCA or control both VCAs with a single … Feb 26, 2020 · This electronics video tutorial provides a basic introduction into NPN and PNP transistors which are known as BJTs or Bipolar Junction Transistors. When using it to attenuate the VCA, the VCA output seems to jump in amplitude when going from a CV input of 0v to 1v. So an OTA chip is pretty similar to what you'd be doing with transistors, just with a some of it done for you. This could also be accomplished with a simple voltage divider, but there are benefits to buffered inputs. Sep 6, 2022 · The Simple VCA is a single-chip Voltage Controlled Amplifier module, in Eurorack format. Oct 20, 2015 · This is a very simple Voltage controlled amplifier (VCA) module, using a classic differential amplifier. Nov 8, 2022 · This circuit is also balanced to avoid thumps and clicks at the audio output when the control voltage changes the frequency. If you look at the bottom left of the simplified schematic of the inside of a 13700 you can see the same differential pair of transistors that appears on pretty much all discrete VCA schematics. Jul 20, 2022 · \$\begingroup\$ @JavierSoto Balanced as in currents -- actually, like the diode switch on the link, Fig. The VCA transistor pair is the one between the 470 ohm resistors, next to the AMORE connector. Negative CV's give a normal VCA-ish behaviour. May 17, 2023 · By perfectly capturing every nuance of the classic Moog oscillators and ladder filters and harnessing discrete transistor VCA modeling, the Minimoog UAD Instrument faithfully captures every detail of this classic instrument used by everyone from Parliament-Funkadelic, to Kraftwerk, Dr. Kassutronics' webpage entry describes how it works in nice detail and with some simple math. By learning to differentiate these circuit types, you will gain far more control over your mixes. patreon. If you're building this as a module, you can skip the stuff at the bottom left, that's just generating a virtual ground so it can run off of single supply). The Minimoog VCA is using only discrete transistors as active components. When compression is needed, a control voltage is applied to lower the gain. The first field The analog bits, developed in partnership with the ultra-serious folks at Pittsburgh Modular Synthesizers (a very serious synthesizer company) and are comprised of a voltage controlled amplifier circuit (VCA) as well as an extra juicy old-school transistor ladder filter, perfect for those of you who are not afraid of ladders or transistors. The waveshaping/distortion is controllable by the CV or attenuating the audio. It's a take on the single-NPN-VCA as seen in MS-10/20, or JX-3P. Long-tailed pair Dec 12, 2019 · A very simple, old school, transistor based VCA circuit that's tried and tested. There are two audio inputs each with their own level controls along with two CV inputs which control the gain of VCA 1 and a Master CV input Field effect transistors, also known as FET, are a type of dynamic audio effect. If a jack is plugged into the CV input Dec 15, 2021 · ICs and Transistors. This module runs on +/-12V as standard so a very Eurorack friendly design. EDU VCA is a simple yet efficient dual VCA for your eurorack system. THAT Corporation manufactures a range of high performance integrated circuits, including our industry-leading digitally controlled and analog Microphone Preamplifiers, Blackmer® VCAs, Analog Engine® Dynamics Processors, InGenius® balanced (differential) Line Receivers, OutSmart® Line Drivers, Phase Locked Loop ICs, and Transistor Arrays. It's the Voltage Controlled Amplifier, or 'VCA', and it is an important element in the operation of any analogue synthesizer. FETs act as voltage-variable resistors that change in response to the control voltage. This is an intermediate to advanced build, so please follow the instructions in order and use the bill of materials and the not the photos alone as the BOM will have the most up-to-date and best functioning part list. Generally, the slowest attack time on the FET compressor is much faster than the fastest attack time variable mu compressor. The design comes from Yusynth, and I implemented it without significant changes. Dre, and more. Designing a classic transistor-VCA from scratch. Q1 and Q2 are connected as a differential stage, it is a good practice to have these two trannies matched or to use a dual transistor such as a 2SC1583. It has DC-coupled inputs so you can use the VCA both for audio and CV signals. When the full 4. NOTE: this module has been discontinued and replaced by VCA 1. 54 Pin The LM13700 is a versatile voltage-controlled amplifier (VCA) that can be used in a wide range of audio applications. Thank you for purchasing our Eurorack VCA Kit. This second VCA is controlled directly by the velocity signal (whether it originates from a keyboard, computer, or elsewhere). Mar 6, 2021 · Hello, I was looking for a very simple VCA solution and I found this: But then I found also this one: (on this website: electro-music. Features. I don't have genuine Minimoog to compare, but maybe my filter is a little quieter thanks to the BC550C low noise transistors. First VCA is fine, second VCA doesn't fully close at logaritmic response. A VCA (voltage controlled amplifier/ attenuator) is the heart of any compressor or peak limiter circuit, and there are quite a few different approaches. And the second has biasing for the base, which seems a good idea anyway? What puzzles me though: The first feeds CV VCA-2 is a more streamlined version of VCA-1, the circuit has also an inverting input to simulate ringmodulation via a nulling method. Let me break each of them down Jan 30, 2024 · An example implementation of electronic gain control circuit in the form of a Voltage-Controlled Attenuator (VCA) designed with Op Amp and BJT transistors is Sep 24, 2013 · \$\begingroup\$ The voltage swing noted in the scope view is at the connection of the transistor collector and the 10K resistor. htqjdug zilc fznrv djpu hwbjh kblgfok rtagcdj kuvfw wdhenj nphkx