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Audio Electronics

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- Thu, 09 May 2013 10:25:57 EST 5EiDjcTO No.5631
File: 1368109557306.jpg -(697015B / 680.68KB, 1600x900) Thumbnail displayed, click image for full size. Audio Electronics
I would be very grateful if anyone with any knowledge of audio engineering could give me a hand here. Even basic electronic descriptions would be great.
Could someone please explain to me the purpose of Capacitors, Resistors, and other components within a mixing console?
I understand there's a total "we wont do your homework for you" and that's fine, but I'm struggling to find a description of what these components actually do when in the context of an analogue recording desk.
Thanks for the help guys, I'll probably try cross posting this in /m/ but I'm not sure about the expertise of the guys over there.
>>
Samuel Clammerstone - Thu, 09 May 2013 14:57:47 EST buTeoEHV No.5632 Reply
I'm a former audio engineer turned EE, and while I haven't built any substantial audio circuits in a while, I'll try to help you out.

I'll start from the basics.
Microphones have a transducer which consists of moving a diaphragm inside a magnetic coil to convert acoustic sound waves into corresponding electrical signals.

From here, the signal is amplified using a preamplifier to bring the signal up to line level, allowing for a greater signal to noise ratio.

In short, capacitors can be used for many things inside a mixing console. Capacitors only allow AC voltage signals through and as such they are used to filter DC out of the audio chain, they are useful for isolating certain frequencies in EQs so that they can be boosted seperate from other parts of the signal, and they are also a fundamental component of power supplies in amplifiers and other active electronics.

I don't know enough to give you all the roles, but that's some of the main ones.

As far as resistors, resistors are used to limit current flow, and can be needed in a TON of roles for the mixing console. Most circuits in a given application use anywhere from a few resistors to hundreds because it's so important to limit the current in a circuit.
Probably the main feature they are used for besides allowing all the other circuits to work without buring up from overcurrent is potentiometers.

Potentiometers are variable resistors which can be implemented either as a varying current controller or more commonly, as a voltage divider.
Voltage division is something that occurs when you arrange resistors in a certain fashion, and potentiometers allow you to change how much voltage is taken out of the circuit.

This concept is perfect for making volume controls, so almost all the analog knobs in the EQ, Compression, gating circuits, even the faders are potentiometers wired in this way.

Some boards use digital potentiometers, but old analog mixing consoles like the one in your picture use analog ones like described above.

There are other components like transformers which are used in the input stage, but I'm not completely familiar with how they work. Hope that's been a good start for ya.
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William Chollerlock - Sat, 11 May 2013 18:27:02 EST 5EiDjcTO No.5640 Reply
>>5632
Thanks for the post man, a little tipsy right now and just about to go to bed, but I'll give a proper look through your post tomorrow man.
Cheers!
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Hannah Sengerwack - Sun, 19 Jan 2014 22:41:03 EST aB7CcMJn No.6100 Reply
>>5632
>Potentiometers are variable resistors which can be implemented either as a varying current controller or more commonly, as a voltage divider.

Cool fact: Potentiometers are sold with "linear taper" or "audio taper". We percieve loudness on an exponential scale, so the "audio taper" is a logarithmic scale.(so the first 20 degress is 10 ohms, then the next is 100 Ohms, the next is 1kohm, etc.)
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Betsy Blopperwater - Mon, 20 Jan 2014 06:33:58 EST XCQJbXtu No.6101 Reply
Alright time for a math lesson.

Do you remember complex numbers? Sqrt(-1) = i

Yeah it turns out that shit is really useful for electrical engineers. In short, the role that capacitors, inductors and resistors play in a circuit can be modeled using equations on the complex plane.

So remember how functions were described in highschool? Like a machine that transforms one number into another.

Well imagine that capacitors and inductors and resistors do that, they act as a function that manipulates the incoming wave to do whatever.

These are generally called filters.

Now you're also going to see capacitors and inductors in the power supply section of whatever it is you're looking at and those are used for largely the same reason, except it's dropping the voltage usually and making the sinusodial ac curve just a stright dc line.

And you might see capacitors and inductors in timing circuits and this is again related to how inductors and capacitors can be used to manipulate a wave form, this time for timing purposes, by manipulating the frequency of oscillations.

So yeah, that's what those candy looking things on your circuits do.
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Angus Turveyforth - Wed, 22 Jan 2014 08:37:48 EST n3nxs0ss No.6102 Reply
>>6101
that mother fucker.


my 11th grade math teacher litterally said "dont bother asking me when you will use this, you still have to learn it" when we were talking about complex(imginary) numbers.
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Graham Mevingwut - Thu, 23 Jan 2014 23:46:45 EST SMgEF33p No.6104 Reply
>>6102
>my 11th grade math teacher litterally said "dont bother asking me when you will use this, you still have to learn it" when we were talking about complex(imginary) numbers.

Sin(x) +Cos(x) have equivalent expressions with e^(a*x) . Every function can be represented with sums of sin and cos functions. It's usually easier to work with the exponential function, though. I think I fucked up the exponential function, but the point remains. Imaginaty numbers are cool beans.
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Simon Genderfield - Mon, 03 Feb 2014 04:39:36 EST U0IJI7OT No.6112 Reply
>>6101

What.

A power supply generally works like this:
-Firstly you have the diode bridge that makes a pulsating voltage of your AC sine wave.
-After that you have a condensator leveling the voltage out
-After that you have an IC which levels and caps your voltage on a certain value.

Filters in the power supply are mainly used to stop the pollution that these power supplies give to the rest of your electrical installation. These filters are a combination of condensators and inductors in series or parallel. Due to resonance they'll filter out a certain range of frequencies (Fourier analysis of the current/voltage signal tells you which frequencies fuck up the most).
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Simon Genderfield - Mon, 03 Feb 2014 04:42:44 EST U0IJI7OT No.6113 Reply
>>6112

Obviously there is a transformer to bring the AC voltage to a decent lower value, which I forgot to mention.
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Doris Cricklespear - Mon, 10 Feb 2014 22:12:36 EST kU/b2Op8 No.6129 Reply
>>6112
Filters are also used in D-Class amps, where a signal is converted to a digital pwm signal. the digital is converted back to analogue at a different voltage using a low pass of some kind.
filters dont need to be LRC circcuits, opamps do it as well or better, with a steeper frequency response and less phase shift. just fyi
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Eliza Semmlefure - Fri, 14 Feb 2014 06:37:04 EST PDTgKfh5 No.6132 Reply
>>5631
Go to khanacademy.com and watch everything in the Calculus and Differential Equations sections, then go to libgen.info and torrent a few EE textbooks.
Do you really think you're going to learn four years of EE in an image board post?
Granted you only really need to learn basic circuits, electronics, and signals, but if you're not willing to put in the time, you're never going to really understand what's going on.

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