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Where can I find recording resources? - Posted By: Luigi On: 10/2/2006
- Resource Web Sites -
KVR Audio
Hit Squad
- VST Plugin Sites -
Intergalactic (various)
VST Central (various)
Battery (drum)
EZ Drummer (drum)
FXpansion BFD (drum)
- Recording/Editing/Production/Sequencing Software -
(software that doesn't say "free" usually has a"demo" available)
Audacity (free)
Audio/Sample Editor Software (free)
Reaper (free)
Kristal Audio Engine (free)
LUNA (free)
QuickAudio (free)
Acoustica BeatCraft (drum editor)
Acoustica MixCraft (editor)
Tracktion
Cubase
Pro Tools
SoundForge
Acid
Sonar
Magix
- Recording Tips/Links -
Guitar/Amp Mic'n
Guitar/Amp Mic'n 2
Home Recording Primer
- Interfaces -
PreSonus
M-Audio
Edirol
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What is an Effects Loop? - Posted By: Luigi On: 10/6/2006
- The Effects Loop -
An effects loop is located between the preamp and output section of an amplifier's circuitry and is used to locate an external effect(s) between the preamp stage and the power stage of an amplifier. Typically, there will be Send (or Effects Out) and Return (or Effects In) jacks on the back of an amplifier head to accept a 1/4" jack... common to most effect signal chains.
Here is a diagram of a typical effects loop...
An Effects Loop enables the application of further processing for a signal as it comes out of a preamp section. Perhaps one has some ambient or color effects such as flange, echo, chorus, or reverb that would get lost in the gain/EQ preamp section of an amplifier. Think of it as a post processing a preamp signal,before amplifying it. Gain units, such as overdrive/boost/distortion typically do not work well in an effects loop, as they are designed to clip or boost signal at the preamp input.
- Series/Parallel Loops -
Some amplifiers have both a series and a parallel effects loop - or one or the other. A series loop means that the effects loop comes straight from the preamp, throught the effects loop and direct into the power stage section of an amplifier. A parallel loop runs alongside the signal path and usually has a blend control, to apply more or less of the loop signal to the power stage,sometimes referred to as 'wet' signal.
The following illustration demonstrates the series/parallel concept...
- Using a Preamp in an Effects Loop -
An external preamp can be used through an Effects Loop to replace an amplifiers existing preamp stage.
Note: The external device MUST have a preamp level signal output, most floor pedals and many rack units are not preamp signal qualified,plugging one of those devices into the Retrun/In of an effects loops will not yield desirable results.
Typically, a rack unit preamp is used in this application, such as a Rocktron Voodu Valve, Carvin TN100, etc... The last image in the above illustration describes the use of an external preamp. The following image details that process.
- Additional -
Most soundboards/mixers have loop circuits as well, to apply/blend some type of ambient/color effect into the final mix for selected channels.
An effects loop can also be used to quickly determine which section of an amplifier has failed if zero output is available in normal use. Using a gain pedal, plug into the Return/In jack of the Effects Loop, turn the pedal up and play through it. If an audible signal is present where no signal was present before - you have a problem in the preamp stage of your amplifier.
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Ohms/Watts and Speaker Matching? - Posted By: Luigi On: 10/18/2006
Terms used in this FAQ:
- AC: Alternating Current
- DC:Direct Current
- RMS: Root Mean Squared or average continous operating value
- Ohm: A unit of measurement for electrical resistance
- Watt: The standard unit of measurement of electrical power
- Resistance: Measured in ohms, opposition to current flow (DC)
- Impedance: Measured in ohms, impedance is the combination of resistance, inductance and capacitance of the circuit (AC).
Ohms is a measurement of either resistance or impedance - in the case of a speaker cabinet/amplifier - its impedance. The reason the two are different is... resistance is constant (found in DC circuits) and impedance changes with frequency (found in AC circuits). The signal from an amplifier to a speaker cabinet is an AC signal.What you see printed on speaker label is typically the 'nominal' impedance, or average impedance, unless otherwise noted by the manufacturer. Note: Using an ohm-meter to measure a speaker circuit will yield close, but false results (some speaker makers supply a DC resistance value for this measurement) - since it is a DC static measurement and speakers are rated for impedance (AC) not resistance alone.
Better safe than sorry: Match the impedance of your speakers/cabinets to the output printed on the speaker output jack of the ampflifier it is connectd to. An 8 ohm speaker may fluctuate between 4 and 30 ohms of impedance depending on the frequency input, but will be rtaed at 8 ohms, which of coure, should be connected to an 8 ohm amplifier output..
Once you have that in hand... Wattage - many schools of thought on this, and many arguments, no one seems to agree, at any level of expertise. If you have have 4 speakers wired together (wired in series, parallel or series/parallel), rated at 65 watts each - you have a total load capacity of 260W. Hopefully, the speakers you may have, are rated at their continous or RMS value. So while a speaker is rated at 65W RMS - it can likely handle surges 40%-50% more, depending on speaker design, in this example possibly up to 100W Peak/Max.
My school of thought is this... severely underpowering a speaker cab - lets use an amp of 50W RMS and a cab of 260W RMS, will not move the voice coils in a speaker for the way they are designed - not only may it sound like arse, many techs swear that underpowering a speaker will burn up speaker voice coils faster than anything else. Claimed because the source level is not supplying the continous signal level that is being expected, and thus the signal distorts (clip) - causing overheating in the voice coil(s).Overpowering speakers has pretty much an obvious opposite effect, it can fry them, not enough capacity to handle the signal. But, remember the RMS and Peak/Max (those specs are sometimes available in a data sheet at the vendor) - if a cab is rated at 260W RMS, it could probably handle a 300W amp, since the peak load may be around 400W and the amp would seldom be run at full continously.When matching speaker cabs to amps:
- Match the impedances - always
- Underpowering speakers by more than 50% 'may' produce undesirable results
- Overpowering speakers by more than 15% 'may' produce undesirable results.
Those numbers are very generic (safe) as there is a lot more that goes into designing cabs than one might think - including the type of amp tube/soild state, the ablility of an amp to keep up with frequency, demand/signal output, surge factors present and the speaker design itself.
If amplifier/cabinet numbers look too lopsided, they probably are.
When in doubt - exercise common sense.
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How do I measure the output of a guitar pickup? - Posted By: Luigi On: 10/24/2006
I've seen this question a few times... so I decided to answer it here in this FAQ.
DC resistance, measured with a simple DC meter on the ohms scale, seems to be popular, but folks read much more out of that than they should. At any rate, zero'ing an ohm meter and connecting the probes to each end of the pickup coil will give you the DC resistance. It should be noted that the pickup leads should be disconnected from any other circuitry before performing this measurement.
DC resistance is basically useful for roughly bench matching pickups on hand and continuity checks, I wouldn't use those numbers against any vendor provided data - as the conditions for the measurement from one place to another may be different.
This IS the problem in the market world of pickups - there is NO standard that vendors use. So, when researching pickups... only use data from a particular vendor against different pickup data from the same vendor.
Millivolts and Inductance (Henries) is what you want to measure for output and tone.
Bill Lawrence has shared his thoughts on this up pretty well at this link.
Measuring MilliVolts and inductance of a guitar pickup is closer to black magic than anything else... because of the disparity of methods used... there really is no baseline data to work with. In order to perform any of that analysis though, you need the minimum of an ocilloscope at your disposal. This page details some of the equipment used in an analysis.
Lastly, if you really are a geek, and want to pursue this farther... this page is a pretty good article by Helmuth Lemme - he also has a book out, but it is German.
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Pinch Harmonic Basics - Posted By: Luigi On: 12/5/2006
This FAQ is designed to get those without a clue, up and running with pinch harmonics. First, I will give some background info on harmonics themselves and the later - move to pinch harmonics.
This section will only cover the technique required to produce neck harmonics - pinches later.
Basically there are a handful of different ways to produce harmonics, all of them really relying on the same basic principle. Any string that is touched at a harmonic node point while vibrating will produce a different, higher pitch than the fretted note. What pitch you get depends mainly on the harmonic node point that you are using. I'll get more into that in a minute, but first i'd like to just go over the different basic types of harmonics.
First off you have your basic Natural Harmonics. These are simply produced by using one of the fingers of your fretting hand to rest lightly, barely touching the string, directly over the harmonic node point. The easiest Natural harmonics to get to sound are the ones located directly over the fretwire of the 12th, 7th, and 5th frets.
The 12th fret natural harmonic is essentially the basis for Octave harmonics, also called artificial harmonics, these are produced by fretting any note before the 10th fret, or 12th on a 24 fret guitar, and then using your pick hand index finger to "fret" the harmonic similar to the technique used for the natural harmonic. To get this to sound you have to pick the string with your thumb or hold your pick between your thumb and middle fingers. I find just using the thumb is just easier. Now you actually can use this same technique to produce any harmonic interval, whether it be a 5 fret or a 7 fret distance you are using, or any other. Octaves are just the most commonly used with this technique.
Pinch Harmonics, is common a staple of the metal genre. Again pinch harmonics use the same basic principle of harmonics, and the technique is actually quite similar to the one used for artificial harmonics. However instead of using your index finger to "fret" a harmonic node point and then vibrating the string, you're going to use your thumb to hit the harmonic node point at the same time you pick the string. Using a pick you accomplish this by simply letting your thumb hang over the edge of the pick just slightly, it takes a little work to figure out just how much, but eventually it becomes almost second nature, if you use them often. If you fingerpick, they are also fairly simple once you get the hang of it, for this you need to use your thumb to hit the node point still and use another finger to pick the string, a little weird getting used to, but all in all not too hard.
- Technique wise: two things are involved - pick attack and finger or thumb touch/mute (some use the palm or edge of hand).
- Pinch harmonics are easier to get with heavier gauge picks
- Turn your pick at an angle to the strings, the plectrum should not be flat to the string when picking
- Use the tip of the plectrum and "dig" the string, allowing your thumb or first finger to touch the string simultaneously as you pluck it
- Pinch harmonics for beginners are easiest gotten by picking close to the neck pickup, find the "sweet" spot".
This following link demonstrates a few things:
Notes: Not much distortion was used, to give more of a "guitar" sound, I don't use a stomp box or much signal processing. Using more gain makes it easier for those starting out, or a distortion box that excites signal harmonics. Varying pick angles and attack will get you there, once you "have" it, it's pretty simple to get them anywhere, anytime.
http://www.youtube.com/watch?v=MKizp86ZUQI <--Video
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