Questions tagged [synthesizer]

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Synth PSU ripple/noise filtering

Noob alert. I'm building a modular synthesizer (musical instrument) and I'm having a problem with building a good power supply for this use. I bought a +12/-12 VDC power supply and read that ...
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1 answer
36 views

How should I go about overriding or switching between an internal control voltage source when an external source gets connected?

For example, I'm using a potentiometer to modulate an internally generated +5v audio signal, and I'm sending the output signal down to the next part of my circuit. If I were to add an external input ...
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3 votes
1 answer
686 views

Headphone output - what is the function of these resistors going to ground between the decoupling capacitors and headphones

The Korg Monotron Duo synth uses the TPA6111A2 headphone amp. The circuit they use is largely the same as the one from the datasheet - except for R78, the 470ohm resistor going to ground right after ...
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46 views

Using components (in a modular synthesizer) that contain vactrols -- safe for the end user?

I am looking to purchase a MakeNoise modular synthesizer whose modules use vactrols (I've been told). I was told that the "Optomix" module, which is discontinued, uses them, but other ...
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3 votes
1 answer
160 views

Analog synthesizer- Add second VCO

I am working on reviving an old synth design (Transcendent 2000), but I would like to add a second oscillator. I was thinking of doubling the circuit highlighted below, and sharing the pitch control (...
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1 answer
82 views

~3400 ppm/C resistor replacement/substitute?

I am working on reviving an old synth design (Transcendent 2000 for those interested) and the VCO and VCF both rely on high ppm/C resistors to compensate for temperature changes. I can include the ...
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1 vote
1 answer
72 views

Purpose of PNP transistors connected base to base in 1V/Octave synthesizer keyboard circuit

The circuit below (found here) is designed to be used in a 1V/octave keyboard used to control a synthesizer. When the potentiometer is adjusted properly, pressing the buttons produces output voltages ...
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3 votes
1 answer
160 views

How can this 74 series Inverter circuit be analyzed?

I'm trying to analyze the keymech scanning / sampling circuit in the WASP synthesizer So far I understand that the keymech is sampled one key at a time by the 74 series logic driven by the dual ...
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How to stabilize this CV triggered toggle (555 timer latching switch) when fed with two gates?

I created the prototype for a modular synthesizer module. The project goal is an AND gate that is fed with two control voltage inputs (A and B with an Vpp around 5V). There will be two outputs: the ...
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2 votes
3 answers
78 views

How do different octaves sound different in the presence of a low-pass filter in a synthesizer?

Per my understanding, when playing a certain pitch, say 440 Hz (middle C), the VCOs will produce their corresponding waveforms (say sawtooth) at that frequency. Because of the characteristics of the ...
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220 views

A voltage controlled diode ladder filter for a modular synthesizer by Moritz Klein

Designing a diode ladder filter from scratch: Designing a diode ladder filter from scratch "Complete project on falstad: ..." Turning my diode ladder filter into a eurorack module "...
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3 answers
526 views

Understanding sawtooth wave harmonics

I've been playing synthesizers for a while and I'm trying to understand their math and electronics better. The sawtooth is one of the three common waveforms on most subtractive synths. The waves are ...
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2 answers
76 views

Could an analog synthesiser be made to run on USB power 2.5W?

5V USB is now standard and very convenient. But I see a lot of synths and audio projects working with higher voltages ... from 9V to 12V to 22V etc. Are there physics reasons for this? In that ...
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Custom breadboard manufacturers [closed]

I'm not sure if this is the right StackExchange for this, but I'm interested in whether it's possible to get some custom breadboards made. That is some solderless prototyping breadboards with a couple ...
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2 answers
84 views

Help identifying circuitry diagram

Now first and foremost, I know absolutely nothing about circuitry - joined an computer science chatroom and they couldn't help, I have cross referenced the symbols to the internet to try and ...
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-1 votes
2 answers
93 views

Identifying missing component from vintage synthesizer [closed]

I acquired a Hillwood C-1A synthesizer with a burnt circuit board with 3 empty holes where a part needs to go. I'd like to repair the board but I don't know what component to look for... Help? The ...
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3 votes
2 answers
151 views

A triple voltage supply from a dual supply

I have build a dual power supply for an analog synth (see image below). The input source is a 12 VAC - 1.7A adapter. It is based on the Wall Wart power supply from Music from Outer Space. Now I would ...
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0 votes
1 answer
251 views

Difference between a frequency synthesizer and a frequency mixer

I have tried looking a couple different places but cannot find a concise explanation on the difference between a frequency synthesizer and a frequency mixer. My goal is to take a signal at 915 MHz and ...
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0 answers
51 views

Connect multiple bipolar PSUs to one torroidal transformer with center tapped secondary winding

I'm currently starting my ventures into building a modular synthesizer in eurorack format and am currently using a single power supply like this with a 12V AC wall wart: Source: http://...
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0 votes
1 answer
84 views

Can I add a Sense connection to this power supply?

I have a synthesizer (Yamaha CS-50) and the power supply is broken. I don't know why but it always blows the fuse. I tried everything, changing components, testing the transformer, etc. The fault is ...
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1 vote
1 answer
75 views

What is the "input" being fed into a Delta-Sigma Modulator in a Fractional-N PLL? Are bits needed for a specific resolution at the input or output?

I'm doing some reading into Fractional-N PLL design and I have a bit of conceptual confusion regarding a delta-sigma modulator used to toggle the modulus of a divider. If you're trying for a certain ...
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1 vote
4 answers
117 views

Is an MPU capable of equal quality digital synthesis as a dedicated DSP chip? [closed]

Is there any factor which would cause a modern microprocessor ( such as an ARM Cortex A/M ) to be inferior at performing digital synthesis compared with a dedicated DSP chip of comparable speed? At a ...
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3 votes
0 answers
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Sawtooth VCO DC offset issues

[Apologies in advance for possible misuse of terminology. I don't have any formal education in EE and am mostly self taught, so I may be lacking in some fundamentals.] I am trying to design a discrete ...
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1 vote
4 answers
1k views

Audio output voltage range

I'm working on a synthesizer project and I'm confused on what the final audio output voltage should be. The idea is that I would send the audio to a speaker or headphone amplifier, so I don't have to ...
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0 votes
1 answer
78 views

Why 90VAC from a synth's chasis that uses 12VDC PSU?

I have Korg's Wavestate synth. https://www.korg.com/us/products/synthesizers/wavestate/ It uses 12VDC PSU with two prongs, hence it has no ground pin. My power outlet is 220VAC. When I connect the ...
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2 answers
293 views

How will wire wound resistors affect the synth's sound?

I am soldering up Music from Outer Space: Noise Toaster synthesizer. The guy who designed it said that carbon resistors should be used ("The resistors should be carbon composition or carbon film&...
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2 votes
3 answers
124 views

FET Written Inside Comparator/Op-Amp Symbol

I'm in the process of importing a bunch of old schematics from a 70's era synthesizer into KiCAD. In the process I've come across a symbol that I can't make sense of. It looks like this: Does anyone ...
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1 answer
132 views

Power Line Decoupling in Eurorack

Can some please suggest if I am doing this right ? The intended circuit is to used with opamp (TL072) Have I understood the decoupling right ?
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295 views

Using an Audio Signal for a Control Voltage for an Analog Synthesizer

I have a Moog Sub 37 Analog Synthesizer and a Korg SV-1 keyboard. Can I take the audio out of either the line outs or headphone out of the Korg and plug it into the volume or filter Control Voltage (...
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1 vote
1 answer
671 views

Trying to make fuzz factory with CV inputs

I'm trying to construct some kind of fuzz factory modular from regular fuzz factory pedal. Circuit of the original pedal is pretty easy, but I've tried to add some VCAs based on LM13700. Honestly, I'...
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21 votes
6 answers
6k views

Where do overtones in a 555 generated square wave come from?

I have built a 555 oscillator and connected it to a speaker. Using an oscilloscope I adjusted the 555 to generate a 2.5kHz square wave. I then held a microphone up to the speaker and fed the input ...
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1 vote
1 answer
595 views

Analog exponential convert for MFOS VCO

I'm trying to understand the exponential converter in the MFOS VCO. Here is a link to the complete MFOS Noise Box synth schematic. http://musicfromouterspace.com/analogsynth_new/NOISETOASTER/...
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3 votes
2 answers
2k views

Grounding Vcc and Vee?

I recently started electronics as my hobby. I'm working on this v/oct modular synth and in the schematic that I was working on, it did not make sence to me when all the Vcc and Vee are connected to ...
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52 votes
5 answers
7k views

Why does music synthesizer built from chain of astable multivibrator circuits get "out-of-tune" after a few hours?

I built a prototype keyboard/sound synthesizer using a chain of 13 astable multivibrator circuits whose outputs are connected to an audio amplifier chip (LM386) and speaker, all powered off a 9V DC ...
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4 votes
1 answer
232 views

How can I get this circuit to "make noise"

I designed this noise generator circuit that uses a 1N514 Schottky diode with a VDB transistor amplifier(note: the upper VDB resistor is actually 15kOhm). Looking at the oscilloscope trace it seems to ...
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1 answer
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Measuring Frequency Synthesizer specifications

I need to measure all the electrical specifications of the Frequency Synthesizer KSN-2346A+ from Mini Circuits that appears in this datasheet: https://www.minicircuits.com/pdfs/KSN-2346A+.pdf but the ...
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1 vote
1 answer
7k views

Can I change a capacitor with one with a higher capacitance?

Hi I have just joined after lurking a lot because I haven't found an answer that was specific enough for me. I have a Soviet synthesizer (TOM 1501) and it has some odd defects such as clicking noises ...
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1 vote
3 answers
3k views

Standard ways to make a variable low pass filter

I tried out a basic low pass filter on one of my analog synthesizers: simulate this circuit – Schematic created using CircuitLab and this seems to work. I was wondering how I can create a ...
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1 answer
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PCB key contact [closed]

Hi! anyone knows how to design a pcb like this in the photo with eagle? Someone has a guide to do it? I don't know how the resistor should be placed. It is basically a pcb for a synth, the key ...
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0 votes
0 answers
274 views

How to fix LFO sync by changing component values

I've built an LFO with a sync output for a modular synth project. The LFO circuit is based on http://www.electro-music.com/forum/topic-31166.html and the reset part I added into that one using https:/...
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7 votes
3 answers
1k views

Amplify a signal having a DC component without using an opamp

I am building a simple modular synthesizer. I would like to keep everything simple and prefer to use discrete components over integrated circuits. My goal is to improve my knowledge about electronics. ...
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1 vote
1 answer
128 views

Choosing Component Values for DCO Design

This is a sawtooth DCO, the comparator U1A resets the ramp at the desired frequency (thus controlling the frequency), and the voltage V7 applied to integrator U2A determines the rate of change of the ...
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1 vote
1 answer
184 views

Function of diode in the following circuit schematic?

I feel that I have a semi-solid understanding of op-amps (and the circuit above) after reading quite a few explanations online. Where I'm starting to get quite lost is the function of the two diodes ...
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4 votes
2 answers
626 views

Can someone help me to find the right transformer for this power supply?

So my current project is building a replica of the ARP Pro Soloist synthesizer from the 70’s. The project is mostly going very smoothly, but I am having some issues with the power supply section of ...
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3 votes
3 answers
944 views

How to drive a speaker/microphone from a digital circuit?

I’m having a hard time understanding how to use speakers or microphones. My end game here is a sequencer I’m going to lay out what I think so that you guys can correct me and help me understand why ...
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1 vote
1 answer
1k views

Is it possible to replicate the Thomas Henry X-4046 circuit using the PLL_Virtual component in Multisim?

The part of the circuit I'm having trouble implementing is the transistor pair that are used to control the output frequency (going into pin 11 of the 4046). I have removed the Exp FM, Linear FM, ...
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6 votes
3 answers
1k views

Exponential amplifier thermal stabilisation

I am currently trying to build a DIY analog synthesizer. I've looked at a lot of different designs and I am quite stuck on understanding how some exponential amplifier designs work. In analog ...
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1 vote
1 answer
596 views

Correct note frequency for STM32 based MIDI synth

I have been playing about with the EasyMXPro for STM32 dev. board from Microelektronica. I am trying to create a simple monophonic wavetable synth using the DAC, playable via. a MIDI keyboard, however,...
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-1 votes
2 answers
936 views

What do I solder to a 3.5 mm jack to make sound come out of it? [closed]

I am trying to make a simple Atari punk console.i am new to electrical engineering. I am trying to figure out what to solder to each pin of the jack to make the finished product work.
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-3 votes
2 answers
51 views

2 outputs of clock synthesizer connected together [closed]

Can anyone explain what is the purpose of the following schematic? Why are outputs Y1 and Y3 connected together?
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