please define some electrical terms for me...

[Tragabigzanda]

Hey all...

So I'm doing my best to understand the electronic guts of making good recordings, but I can only read so much on wikipedia before my brain starts to burst; folks here seem to put things in simple terms fairly often, so without further ado, some phrases/ideas that I'm having a difficult time fully grasping; I've got a general idea on most of these, but don't quite have the "total picture"...Any help would be useful.

-solid state

-AC vs. DC

-discrete electronics

-Class A, Class AB, etc...

-coupling

-balanced vs. unbalanced (and any related dangers)

-transformerless design (why is this a good thing, other than that it makes for a simpler signal path?)

That's all for now; more to follow later...

Thanks.

[rockstudio]

Tragibigzanda - I am no tech, but here are some clues.

Solid state - describes a circuit that does not use vacuum tubes, but instead uses transistors or other bits of silicon.

AC vs DC - Alternating Current (like from your wall [in the USA 60hz 120v]) where the two terminals reverse their polarity many times per second (in usa, 60 times per second or 60hz) vs Direct Current (like from your battery) where there is one positive terminal that is always positive and one negative terminal that is always negative.

Discrete Electronics - generally refers to high quality electronic circuits designed with high voltage components (not 9v battery circuits, but probably +/- 18v or +/- 24v) generally using symmetrical power rails and optimized for critical audio applications.

Class A and Class AB - are types of amplifier circuits. very basically, class A means the device (a tube or a transistor) is biased so it will conduct throughout the entire input cycle. In Class AB there will be a pair of devices (tubes or transistors) that will function together to achieve a complete cycle but not in the same way as class A, and not in the same way as class B, but in between. Thus achieving high linearity and mid level efficiency.

got to go, hope this helps so far.
Ant

[Randy]

-discrete electronics- I think low-voltage stuff can be made discrete. I think the term relates to each of the components being of single function- ie. no integrated chips or opamps which combine components like transistors, resistors and capacitors. The advantage of discrete circuits would be in the ability to tune the circuit with great precision and to be able to repair or modify them with relative ease.

-coupling- It simply means connecting two electrical elements together. If you use a capacitor to connect a circuit to ground it is considered a coupling cap, because it is connecting one thing to another. Coupling amps can have two amplifiers connected together to amplify one signal.

-balanced vs. unbalanced (and any related dangers)- Balanced signals tend to have less noise than unbalanced signals, especially over long distances of cable (ie. 100 ft.) Sometimes an unbalanced signal patched into a balanced system can produce a ground loop, which is hum, usually at about 60 Hz- the frequency of the line current.

-transformerless design (why is this a good thing, other than that it makes for a simpler signal path?)- Transformers add distortion to a signal. A good example is that the old AKG c414 that was transformerless model had more accurate representation of a signal's low end compared to the one with transformers. Some people like the sound that transformers impart.

[thunderboy]

I'll go with Randy's definition of "discrete electronics". rockstudio's sounds like it came from a marketing manual.

Unbalanced - a two-conductor system, with the reference to ground carried on one and the signal on the other. The "DC" of audio. Long runs can get noisy. Guitar cables are unbalanced.

Balanced - a three-conductor system, with reference to ground carried on one (pin 1), the signal carried on another (pin 2) and a polarity-reversed signal carried on the last (pin 3). The "AC" of audio. Mic cables are balanced. The pin 3 polarity-reversed signal is flipped again on the receiving end, where it is combined with the pin 2 signal. This effectively doubles the signal strength while cancelling any noise picked up along the way - a process called "common mode rejection".

jt

[GooberNumber9]

+1 on Randy's definition of "discrete". Literally it means "not integrated". The term didn't even exist until integrated circuits and op-amps came about.

Also, before you post more questions, try:
http://en.wikipedia.org

This place is a regular font of technical knowledge. You might start off reading about chroma sampling and end up looking at Stokes' theorem and have no idea how you got from one to the other.

Todd Wilcox

[rockstudio]

awesome dudes. I have been told in the past that I sound like a marketing manual!

[earl parameter]

ignore the class (A or/and B) war and just listen ? there are plenty of bad class A designs

discrete ( definition = separate ) - refers to designs using individual components that?s all. passives, transistors etc... as opposed to I.C.'s which are entire circuits in a single package. if a discrete circuit is designed well then it will sound better then an IC design but they are generally very expensive

coupling - is actually a method of using single capacitors to remove DC offset between two separate operations. even inside the same circuit sometimes. if a capacitor is sent to ground it is generally meant for filtering out either noise or in conjunction with a resistor it will filter out specific frequencies designated by the value of the two components.

- another merit of transformerless design is cost - another negative is that generally transformers are used to create balanced signals and if you remove it from the design you will in most cases have to replace it with an amp stage and if it needed a step up then 2 stages to recreate the balanced signal. so in some cases a design with a transformer is actually simpler. for the record i prefer transformers - and the term ?distortion? gets a bad rap. it is used as a general term to describe ANY change in the signal, good or bad.

i don?t think its been mentioned yet but balanced refers to a setup using 3 conductors instead of 2 for unbalanced. the third is a separate ground used to keep it separate from the negative and results in lower noise and less signal loss over longer runs. if you test a unbalanced and balances cable yourself at exactly the same level through the entire signal path you will notice an enormous difference between the two in noise and level ( if all the stages are balanced of course ). as for balanced circuit designs they either fake being two separate circuits for each +/- with things like summing, transformers, and adding inverting amps to the output or they are actually two entirely separate circuits (also called dual mono) which is obviously better in most cases.


ignore ALL marketing bullshit - !!!!!! - use your ears - failing that the ears of someone you can actually respect is a good start ( until you can hear it yourself ), but those people can be hard to find


steven

[Tragabigzanda]

Hey, thanks for all the help everybody...

I'm still really stumped by the concept of AC/DC. That is, if AC is both positively & negatively charged particles, and they are coming through the wall into my amp (for example), and they hit this grid that allow a certain amount of positive particles through, then where the hell do the negative particles go? Back to the power company? Or do they sit in my amp (or whatever) and contribute to the deterioration of sound quality?

On a side note, I just want to let everyone know about this Ebay seller, TheWellReadBook, who was supplied me with nearly every back issue of Tape Op available (just missing a few of the early ones). It's so great to have this mag that is forever re-readable; articles that made no sense to me once can be read six months later once I've got a better grasp on stuff...Some of the really old Geoff Farina articles and "Behind the Gear" stuff is finally making sense to me!

[Recycled_Brains]

i think this would make for a good sticky. then people can continue to post questions about other terms. it would be nice way of creating a reference for this kind of thing.

whatcha think

-ryan

[Randy]

Wikipedia has a good explanation of alternating current:

http://en.wikipedia.org/wiki/Alternating_current

It's not that there are positively and negatively charged particles moving back and forth, it's that the net sum of electrons in the molecules making up the conductor alternate between extra electrons and fewer electrons than the conductors natural state.

[earl parameter]

the way that i think of electricity is more like a flowing river - not individual little particles (regardless of how much closer that is to the truth). there each thing you add to the path will alter the flow in some way.

DC is just using the "top half of the river" so to speak, ignoring the bottom. this doesn't have any negative side effects like "contributing to the deterioration of sound quality" it just doesn't get used. lots of devices actually use DC ( the power supply splits and regulates AC down to either one or two separate DC lines using regulation and filtering to clean it up ). AC is just what gets sent to the house.


its tough to explain, which is why its so hard to find a good explanation,


steven

[earl parameter]

i think this would make for a good sticky.

then maybe brian could jump in and do a much better job of explaining. i'm sure he has a better manner to get all of this to sink into people heads. probably has a correction or two as well

[Electricide]

where the hell do the negative particles go? Back to the power company?

yep. I think of it like a pulley: you are the power company/wall socket. You have one end of the rope in each hand, and the rope goes through a pulley out in front of you (pulley=your gear). You move you hands back and forth and the rope travels through the pulley. You pull with your right arm, and your left arm travels forward. Then the opposite. How hard you pull is Voltage, how many pulleys determines resistance, and how much rope you can get through in one pull is Amperage.

Except, you are pulling back and forth 60 times each second.

So yes, the electrons all flow back through the socket, through the wire, up to the power pole, through the mega transformer, back to the power company. Then a 60th of a second later, they head back toward your gear. It's all very exhausting!

[Randy]

I like where you are going with that Electricide,

Then the transformers would be block and tackles, the capacitors springs, resistors would be friction spindles.

Direct current would simply be tension across the string with no back and forth motion.

Transistors and tubes would be hard to place in the physical world. Maybe they would be these things that magically transfer the motion of a thin string over to the thick string.

[Andy Peters]

I'm still really stumped by the concept of AC/DC. That is, if AC is both positively & negatively charged particles, and they are coming through the wall into my amp (for example), and they hit this grid that allow a certain amount of positive particles through, then where the hell do the negative particles go? Back to the power company? Or do they sit in my amp (or whatever) and contribute to the deterioration of sound quality?

The proper distincition between AC and DC is that a DC voltage (current, too!) is static -- it does not change with time. AC does change with time.

So, yes, the terms "alternating current" and "direct current" are misnomers.

-a