Posts Tagged ‘amp’

This is just a quick tip I remembered whilst doing some live sound today that I thought I’d put on here.

If you’re in a live situation where you have to change between different bands/setups quickly, remember, a mic is a mic. This sounds silly but when you’re in a rush don’t worry too much about finding the right mic, if you chuck pretty much any mic on anything it will work. There are of course exceptions if you’re using large diaphragm condensers or ribbon mics or anything too sensitive (in which case just don’t put it on anything too loud) but if you’re using mics like those I would assume you know very well what you’re doing and time probably isn’t an issue. But for people who aren’t as clued up or trying to find ways to speed up changeovers, should you need to a kick drum mic will work on vocals, a piano mic will work on a guitar amp (this one I used today in fact) and the result will still give a useable result.

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Build a Triffusor

Materials (per triffusor):

  • 2x equilaterally triangular pieces of MDF wood
  • 2x rectangular pieces of MDF wood (width same as trianglar side)
  • 1x rectangular piece of MDF wood slightly shorter and thinner than other pieces
  • Acoustic foam rectangle the size of the 2 larger pieces of MDF wood
  • 5 long thin pieces of any kind of wood to be placed on one side for diffusion
  • A decent number of screws and some PVA glue (and some contact glue, though PVA will work)
  • Saw(s) and miter box (if cutting any of the wood yourself)
  • (Optional) beading for the edges

Process:

Attached larger pieces of MDF wood to two sides of one of the triangle. PVA glued, and then screwed them together.  Attached other triangle to other end of the rectangular MDF wood in the same way.

Used contact glue to attach acoustic foam to one side of the triangular prism.

Put smaller wood rectangle where third side of triangle would go and push it in so that it sits further back than the other sides.

Place long thin strips of wood against the side with the deeper wall and glue

Acoustic Properties:

–       Reflective side: The reflective side is smooth wood, allowing the sound to bounce off easily, creating direct reflections.

–       Absorptive side: The side with the acoustic foam is designed to absorb sound. When the sound hits the acoustic foam it enters any tiny gaps in the foam and bounces around inside it so many times that barely any of the sound manages to get reflected, most of it dies within the foam.

–       Diffusive side: The side with the further back wood and strips of thin wood running up and down it is designed to diffuse any sound that hits it. Either before or after the sound hits the back panel, much of it will reflect off the strips causing it to be reflecting off to the sides, known as being ‘diffused’, often used to stop early reflections from causing phase cancelation without killing the reflections all together and risking deadening the room too much.

Personal Uses:

  1. In parts of my room there are cupboards and dressers that would cause unusual reflections, reflective side could be placed in front of these to give more direct reflections.
  2. Diffusive or absorptive side could be placed at the back of my room where the first direct reflections would occur to send them in different directions of absorb them to reduce possible comb filtering in the listening position.
  3. Absorptive side could be placed facing out of the corners and be used as a bass trap.

Evaluation: Overall, each of the triffusor’s sides has the acoustic properties they were designed to have, and the triffusor itself is very sturdy and solid. If building more, the only thing I would do differently is take more time perfecting some of the measurements in attempt to get that really neat and tidy, professional look.

A synth is created through tone generation, manipulation, and amplification.

Generation:

A basic synth will often have a single oscillator (the generator) with the ability to generate some kind of sound wave, the most common being the square, saw, triangle and sine waves.

To start building a synth sound, first select your wave. The square wave has quite a ‘woody’ sort of sound, and is often good for bass synths, the saw wave is quite sharp and a common lead synth wave, the triangle wave sounds similar to the square wave but a bit more dull and harmonically weaker and the sine wave is very pure and lifeless. This is because the shape of the other waves creates harmonics, and if you were to filter out the frequencies around the note you were playing you would end up with something that sounds like a sine wave anyway.

These waves are often not the only choices, many synths offer you the choice of combining two waves, and some synths offer you noise waves, or even the ability to create your own wave shape.

So depending on your synth, these are your choices… for one oscillator. Very often synths will have multiple oscillators, giving you the ability to layer sounds on top of each other, and blend the volumes for an even or one sided combination, as well as a pitch control (often used to put an oscillator up or down and octave, but sometimes used for different intervals, be careful with using intervals other than an octave, it might sound cool at first but it could create problems in the harmonic progression of your song.) Individual detune controls are often available to add some crunch by putting oscillators slightly out of tune with each other.

Many synths also allow you to choose how many unison voices the synth has, which essentially means the synth adds multiple copies of itself onto itself, this is a great way to create a really huge sound, but don’t get carried away or you won’t leave any space in your mix for anything else!

If you’re just starting out I suggest you just use one or two oscillators, and stick with basic wave shapes, one of my favourite sounds is 2-3 oscillators all set to a basic saw wave. Which sounds kind of boring, but here’s where it gets more interesting.

Manipulation:

The first manipulator is the ADSR envelope (an envelope is where the signal passes through to be manipulated, feel free to call it the manipulator thing.) This stands for Attack, Decay, Sustain, Release.

The attack is how long it takes for the synth to go from no volume to peak volume

The decay is how long it takes to go from peak volume to sustain volume

The sustain is the volume from the end of the decay period to until the note you’re playing is released

And the release is the time taken for the sound to reach silence after the note is released

This is best shown using this graph:

Slow attack and release times are most common in pads to allow the chord to swell up and fade away.

Decay and release are only experimented with excessively for more unusual kinds of sounds.

The next manipulators are the filter and resonance:

The filter is used to roll of frequencies above a certain point, sometimes you are given control of how fast they roll off as well. This is often used to filter out unwanted harmonics or if the high frequencies are masking another sound in the mix and you feel you don’t need them. Another common use for it is to have the filter set low and automate it to open up gradually, allowing the synth to grow and fill out the audio spectrum. If you don’t know how to automate, leave a comment and I’ll do a post on it as I won’t be going into that in this post.

The resonance is a control to create a resonance at a certain frequency, making it more prominent in the sound. This is often used to create a bigger bass sound or to emphasise some interesting harmonics in lead sounds.

Other manipulators are –

The LFO: This stands for ‘Low Frequency Oscillator,’ but it doesn’t generate sound, however it is still a waveform, this waveform is just used to control other aspects of the synth. A common use is to have it control the volume on a bass synth so that the volume fluctuates at the rate the wave is set to, the wave is then often synced to the song tempo, and there we have… WUB WUB!

Other uses are to control things like the filter, the pitch, the resonance or anything really, and you can get some really insane sounds.

Effects: These can be anything from chorus, flange, delay, reverb, or many other things, but I won’t be going into these in this post either.

Unison Detune: This is often a single knob to control the detune for all the voices in the synth that aren’t given actual oscillators.

I’m sure there are lots of synths with manipulators I haven’t mentioned, but these are what I’ve found to be most common, but if I’ve forgotten an important one, let me know!

Finally, the amplifier:

This isn’t really something you need to think about unless you’re using a hardware synth that requires an amp to make sound, in which case you will just have to buy an amp and get familiar with it, because all amps are very different. Software synths are amplified by your DAW or your computer (if its a standalone synth) and played through your speakers.

There is also another kind of synthesis called FM or ‘Frequency Modulation’ synthesis, but I will save that for another post as it gets quite complicated.

Thanks for reading, hope you found this helpful, if theres anything you’d like me to do a post on, let me know!

Our lecture talked about the different dBs today and their common levels, 0 dBm being 1 mw in a matched 600 ohm load circuit creating .775v, +4 dBm being a 1.228v circuit for a stronger signal, meaning you have to pull your VU meters back so they’re not always maxed out, +4 dBu being a 1.228v signal in an unloaded circuit and finally -10dBV, a 1v signal regardless of impedance, reduced by 10dB, generally used by all consumer electronics.