Glossary of relevant terms:

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Glossary of relevant terms:

Post by VelvetGeorge » Wed Oct 27, 2004 5:17 pm

As per JF's great suggestion, here are the terms we throw around on this forum and they're meanings.
Some may be based on our personal opinions, so take them FWIW.

Bias: the quiesent(idle) plate current drawn by vacuum tubes with no signal going through them.

Clipping:

A tube can be made to draw more current or less current. If it draws too so current, that no matter how positive the grid goes, the tube cannot pass any more current, then the tube is saturating and the top of the wave is "clipped" off. Instead of being round, it is flat. This is called clipping. It can also happen if the tube draws too little current because if you keep drawing less and less, you will eventually get to the point of no current. This condition is called cutoff. If you reach cutoff during a portion of a signal, then the bottom of the wave is "clipped" off and clipping is said to have occurred.

Linear/non linear range:

The tube's response is the most linear when it is operating exactly half way between saturation and cutoff. When it operates close to the limits of cutoff or saturation, it is operating in the most non-linear portion of the tubes operating curve.

Parasitic Oscillation: Uncontrollable, unusable form of feedback or any other tones self generated by an amplifying device.

plexi: affectionate term used to describe Marshall amps from the 1960's with plexiglass control panels. More recently used to also describe Marshall's reissue amps. SLP commonly refers to the Super Lead Plexi.

rectumfrier: not so affectionate term used to describe Mesa Boogie Dual Rectifier amps.

SAG:
Sagging is the result of the power supply delivering it's maximum amount of current when you play hard. Since it's out of current, but the amp is still demanding more, the voltage drops. This creates a compression affect on harder playing.

The amp will have headroom on lightly played parts and seem to smooth out on harder parts. This is due to that voltage symapthetically dropping or "sagging" or if you want....

When you play a note, the amp will respond to the note. At first, it will compress slightly ( some amps more than others), then, as the circuit begins to recover, the volume will rise slightly. This is happening as the string is beginning to die out, so you get a singing quality here. The envelope of how any particular amp does this and how pronounced it is loosely referred to as sag. Sometimes it is also referred to as "meow".





Please add suggestions in the thread and I'll edit them into the list.

George
Last edited by VelvetGeorge on Thu Oct 28, 2004 2:35 am, edited 2 times in total.
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Post by flemingmras » Thu Oct 28, 2004 1:32 am

Parasitic Oscillation: Uncontrollable, unusable form of feedback or any other tones self generated by an amplifying device.

Bias: What people often do to minority groups...uh...err...uh...I mean...the quiesent(idle) plate current drawn by vacuum tubes with no signal going through them.

Solid State: Shitty tone

All Tube: Great Tone!!!


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Post by Zoso » Thu Oct 28, 2004 5:07 pm

I'd like someone to explain what the choke is and does, so if someone will do that you could add that to the list.
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Post by Country Boy Shane » Thu Oct 28, 2004 6:31 pm

Yea really! Doesn't the lower the value of the choke mean that the amp gets more distorted?
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Post by 5150loveeddie » Thu Oct 28, 2004 7:07 pm

George! should bold the words in the list (ex. scrotum tone: very ballsy tone.......bla bla bla...)
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Post by flemingmras » Thu Oct 28, 2004 9:24 pm

The choke, commonly called a "smoothing choke", helps to smooth out the "ripple" in pulsating DC. Pulsating DC is created by the rectifier as AC passes through it. Your main B+ supply(plate voltage) rectifier allows the positive half of the AC sine wave coming from the power transformer to pass through, but not the negative side of the wave. This creates a bunch of positive pulses pulsating at a frequency of 120Hz, or 120 cycles per second.

This is unusable, since we want DC to maintain a constant voltage at all times instead of pulsating.

Basically what happens is as the DC pulse goes more and more positive, this creates a building magnetic field surrounding the choke coil. As the pulsating DC wave falls back to 0 volts, the field collapses, regenerating a countervoltage into the coil that is pretty close to the max value of the pulsating DC to bring the power supply voltage back up. Then, the pulsating DC wave rises back up before this voltage has a chance to drop again. This gets rid of the "ripple", or the pulses, in pulsating DC to help hold the voltage constant.

Hope this helps.

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Post by Zoso » Sun Oct 31, 2004 1:49 am

Thanks Jon! So does that mean that the choke is acting like an inductor as opposed to a straight ahead transformer? I always assumed it was just a little mini-transformer, since that's what it looks like. I know transformers use inductance to do what they do, but what you're saying is that the choke just acts as a straight inductor without stepping anything up or down. Right? Or am I way off base? :?
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Post by Guest » Sun Oct 31, 2004 3:43 am

You are correct Zoso,a choke is an inductor,not a transformer

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Post by Guest » Sun Oct 31, 2004 3:48 am

Sorry that last post was from me,forgot to log in :o

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Post by Flames1950 » Sun Oct 31, 2004 7:42 am

Anonymous wrote:Sorry that last post was from me,forgot to log in :o
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Post by 5150loveeddie » Fri Nov 05, 2004 5:24 pm

Overdrive: Used to be called Distortion but that isn't descriptive enough. It is the idea of using one small amplifier (preamp) to push another one very hard, causing it to overdrive and distort. When done properly, it is controllable to the limit...

Distortion: The difference between what goes into an electronic device and what comes out.

Gain: The amount of voltage amplification in the preamp section of an amp. This voltage amplification ultimately drives the power tubes which do not add any more gain. The power tubes add current (power).
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Post by 5150loveeddie » Fri Nov 05, 2004 10:29 pm

Anode: The part of a tube or semiconductor diode that the electrical current flox exit. Also call the plate on tube amps, the anode (not to be confuse with anus...) is always more positively charged than the cathode

Cathode: This is part of the tube or semiconductor diode where the electrical current flow enter
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Post by 5150loveeddie » Fri Dec 03, 2004 11:17 pm

Diode: an electronic device that is the equivalent of a check valve(oneway only). Electrons can go one way only. The diode can be a vacuum tube (full wave rectifier tube) or solid state rectifier (semiconductor format).

So a rectifier is made up of diodes (a tube or semiconductors) and its main purpase is to convert the AC (250-600volts AC) from the power transformer, to DC that the tubes needs to operate.
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Post by 5150loveeddie » Mon Jan 10, 2005 8:28 pm

Saturation: A condition in which maximum current is reached and no more current can possibly flow.

Transformer: An electrical device made from two or more windings of wire wrapped around an iron core. They are primarily used to create power supplies and match impedances between output tubes and speakers.

Vacuum tube: A tube whose major components would include an anode and a cathode in an evacuated envelope(the vacuum...). It performs as an amplifier, oscillator, or rectifier in audio circuits.

Sag: The amount of decay in the envelope before a played note is sustained at a constant volume level. It is caused by the resistance of the power supply and that resistance would include the rectifier tube resistance as well as the internal resistance of the power transformer.

Capacitor: Device made from two conductors separated by a non-conductor. Whatever is between these conductors is called a dielectric. Capacitors store electricity. They will block D.C. current but pass A.C. current.

Electrolytics:Another name for a capacitor whose dielectric is an electrolyte. These are very small for the amount of capacitance and are therefore used in the power supply.

Capacitive coupling: A type of coupling between two adjacent stages that uses capacitance. Usualy this is done with a capacitor; however, adjacent component/wires could have enough capacitance to couple A.C. signal.

Dielectric: The non-conductor substance that separates the two conductors of a capacitor. Paper, air, electrolyte, mica, polyester, ceramic are some of the dielectrics that are used.

Buffer: A buffer is like a barrier so that one section of a circuit does not "see" the other section. In the case of our ABC Box switcher, a quad OP amp is used. The first section amplifies the guitar signal and sends its output to the other three sections. Each of the other three sections has its own output. So each output could go to an amp. The amp would not "know" about the guitar or the other outputs. The other outputs would not "know" about each other. The signal is said to be buffered.

Now what if you had a ABC Switcher whose input directly was connected to three output jacks. In this scenario the signal would not be buffered. The input impedance of each amp would combine with the other input impedances to load down the signal. The guitar would "know" about the amps, the amps would "know" about each other and the guitar.
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Post by Billy Batz » Tue Mar 28, 2006 9:50 am

I figure this could be very helpful for newbs with terminology and all that

Tube pinouts

12AX7 Dual Triode tubes (any 12A-7)
Pins
1- Side A Anode/Plate (DC voltage)
2- Side A Grid (AC Audio Signal is applied)
3- Side A Cathode (to ground)
4- Filament - 4+5 for one side of parallel hookup to 6.3v supply
5- Filament - 4+5 for one side of parallel hookup to 6.3v supply
6- Side B Anode/Plate (DC voltage)
7- Side B Grid (AC Audio Signal is applied)
8- Side B Cathode (to ground)
9- Filament - 9 for other side of parallel hookup to 6.3v supply

Pentodes - EL34, 6L6, 6V6, 6550, 5881, KT88, KT66 etc..
Pins
1- Suppressor Grid - only on EL34 otherwise not connected in other tubes (grounded in most amps)
2- Filament - one side of 6.3v supply
3- Plate (DC voltage)
4- Screen Grid (DC Voltage) (tied to plate in triode opperation)
5- Control Grid - AC Audio Signal applied + (-)Bias Voltage
6- no connection (usually used as tie point for B+ and Screen grid resistors between pins 4 and 6)
7- Filament - other side of 6.3v supply
8- Cathode - to ground (via cathode pair in cathode biased amps)

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