A Sine wave is very smooth in character, and ultimately doesn't change much when passed through a filter. It is actually often missing on most vintage synths because a filter is able to smooth any wave in the direction of a sine wave. For example, a filter can smooth the squareness of a square wave so that it begins to emit the characteristic smooth sound of a sine wave. The transformation is not exactly from square to sine wave, but the similarity between a filtered square wave and a sine wave is definitely noticeable. Consequently a sine wave has a more limited use than other waveforms in vintage synthesis. It can however be used for very low, throbbing bass sounds and analogue percussion sounds like kick and tom drums.

A Triangle wave is slightly brighter than a sine wave, and is more susceptible to a filter. It can be used for flutey sounds, very synthetic cheap-synth sounds, and also extremely harsh, thumping bass drums, like TR909 kicks put through a bit of distortion. Remember the Casio VL1 VL-Tone keyboard? A mixture of triangle and square waves is the primary source of it's sounds. El-cheapo, here we come!!

The Square wave is extremely bright, almost to the point of being quite harsh. It can be used for very bright woody-flutey sounds, and is perfect for synth-pop sounds. This is a great waveform for emulating early 80's sounds, and especially Yazo, and Depeche Mode sounds from their Speak and Spell era. Remember that characteristic cowbellish sound from Soft Cell's Tainted Love? It's a Square wave! When filtered it can fit right up there in the mix with real retro synths.

The Sawtooth is the crux of vintage synthesis. It can be harsh and grinding in it's raw form, and used hand-in-hand with filters this is the epitome of retro-pop. It can be used for synth-bass and various string sounds, and for those sounds that I like to call the Zed (Zee) sounds - Roland MC202 bliss! Especially for those TB303 lovers out there, this is where samplers can become your resident TB303 master - Heavily filtered Sawtooth sounds on a sampler are TB303 heaven ... Sweep city!

The Pulse-width waveform is a modified Square wave and it doesn't vary much there from. It's sound is easily identifiable though because it has a square-wave sound with a more grungy edge to it. Generally it is a square wave with the width of the pulses altered in some way, causing a characteristic change in sound. It is often used as an alternative to the Square wave because it is variable and provides more interesting basic sounds, especially when filtering is used.

White Noise is a high-frequency random waveform. There is no structure at all to the waveform, except to say that it is a series of random pulses. In it's simplest form it sounds like the hiss of a radio which is not tuned to a station. There are different colours of White Noise which can be generated, like pink or brown noise. The reason we use the term colours as opposed to pitch is because White Noise, being random pulses, doesn't have a pitched waveform. It can however be altered quite easily using a filter. White Noise is used mainly in sound effects, as well as percussion instruments requiring noise (snares, hi-hats ... etc). It can of course also be used in the emulation of calliopes, steam-flutes, choirs, wind, sea ... etc.

By combining these oscillators together with filters, envelope generators (EG) and LFO's on a sampler, quite complex sounds can be generated. Since samplers have all the aspects of a vintage synth, all we need do is create the basic waveforms as shown in the diagram above, and then process them through the sampler. A simple way of doing this is to use Cool Edit to produce the waveforms, and then once we have these waveforms, your sampler has the power to perform many of the other functions which vintage synths are famous for.


Creating the Waveforms

The easiest way to create these waveforms is as I said before, to use Cool Edit. It generates all the above waveforms, except the Pulse-Width waveform. I won't go into detail as to how to create specific synth sounds, except to say that you should as far as possible try and limit your waveforms to 11/2 to 2 cycle wavelengths (the diagram above shows single wavelengths). This way you can loop the waveform and it will, despite its tiny size, give you an accurate representation of the original sound . This means you can cut your sound bank down to a fraction of the size you would normally encounter with sampling, but still have a workable sound. The White Noise is usually the only exception to the 11/2 - 2 length rule because of its random quality. You will have to determine the optimum loop length of a White Noise waveform yourself.

Although synth sounds are relatively simple to create, percussion sounds are an absolute nightmare to synthesize. The basis for vintage percussion on a sampler is a Sine Wave and White Noise. With these waveforms you can generally create a whole TR808 drum machine. Let me start with a discussion of what constitutes the basic structure of the main percussion sounds :

1) Bass/Kick and Tom Drums
The first sound emanating from a bass drum is the noise created by the pad hitting the drum skin, creating a loud, very short click. This is followed by the fading "hum" of the resonating drum cone. This hum goes from it's original pitch to a slightly lower pitch, although due to the very low frequency and the shortness of the sound this is often not consciously heard. The reason for the pitch change is very simple ... When you first strike the drum the skin is initially taught, but loosens after being hit. This causes a drop in frequency because the tighter skin has a slightly higher pitch, which lowers as the drum skin returns to it's original taughtness. Depending on the makeup of the bass drum, this effect may vary considerably, but it is generally not very noticeable on a kick drum. Thus there are 3 qualities needed (the first two being all important) :

a) The initial click as the pad hits the skin.  
b) The fading resonating boom after being hit.  
c) The lowering pitch.

a) and b) can be created in one go using a sine wave: Generate a sine wave at about 70-100 Hz. Clip it so that it starts at a maximum waveform value (as far away as possible from the zero crosspoint). Since the waveform starts away from the zero-crosspoint, it makes a click sound when the wave is output - This is the initial click of the kick drum. When looped beyond this click, you will have the resonating drum boom sound.

You can also just layer a very quick decaying White Noise wave to form the initial click rather than altering the Sinewave as in above, but for TR sounds this doesn't work well. The decreasing pitch can be obtained using the a pitch ADSR after the waveform has been successfully looped. Use a quick lowering of the pitch with the ADSR to create the right sound. For a TR808 kick, the above works perfectly, but for TR909 kicks the pitch ADSR on some samplers does not work well for that sharp, heavy kick sound.

2) Tom Drums
The Tom drum has the same format as the bass drum except that the pitch is higher and the decay time usually a bit longer. Also it is here that the pitch change becomes more noticeable, as well as the drop in frequency. An additional feature to the Tom scenario is to layer a very short White Noise wave at the start of the Tom, at a relatively low volume and low pitch. Depending on how you filter and pitch this White Noise, you can give the Toms a bit of a grungy, dirty sound rather than the usual clean boom sound. The TR808 Toms are clean, but add a little dirty White Noise and they sound really analog. The TR909 toms are a little more complex - it sounds as if there is more than one waveform at work there. You could also try using layered Sine Waves for Toms as well, in an attempt to introduce a bit of inharmonic content into the sound. This might bring you closer to the sound of TR909 toms.

3) Bongos
Bongos are simply a variation on the Tom sound. A little shorter, and perhaps a little dirtier, but all your need do is replicate a Tom, shorten the decay, and vary the pitch to your liking.

4) Snare Drums
For this you need White Noise and a kick drum from point 1 above. A Snare is similar to a bass drum, with the major difference being the noise generated by the springs attached to the underside of the drum skin, and the pitch and decay of the drum boom. Generally, use the above bass drum at a higher pitch (since a snare drum is smaller than a bass drum) and shorter decay, layered with a looped White Noise waveform decaying as desired. This is the basic building block of your snare drum. You can filter the White Noise to a desired colour, and also layer more White Noise at different pitches to vary the sound. I have found that higher frequencies (colours?!) of White Noise are the best for snappy snares like those of the TR808 and TR909. You can create a White Noise wave in Cool Edit, and then filter it with the quick filter, pushing up the high frequencies and excluding the lower ones. This generally gives the most impressive high-frequency White Noise waveforms rather than using your sampler's filter. Be careful not to over-filter the White Noise because this makes your snares sound puny, which is horrible unless you're looking for vintage Casio/Yamaha home keyboard drum sounds or mini-pops (remember the Casio PT-68 or old Yamaha PSR keyboards). Now to some this may not be great, but those old home keyboards have some excellent sounds - very different from the rest. The PT-68 in particular, has amazing hats. Adding a bit of reverb to the snares can be quite effective.

5) Hats and Cymbals
For the hats, use heavily filtered White Noise layered with an ultra-high frequency sine, square or triangle wave. The volumes of the White Noise and high-frequency wave will have to be jiggled a bit, but generally the hats sound better with the filtered White Noise louder than the high-frequency wave. If possible, use Cool Edit's Quick Filter to boost the highest frequency and remove all lower frequencies in the White Noise wave. The need for the sampler's filter may not even be necessary if you use this method. In fact, sometimes heavily filtered White Noise doesn't need another hi-frequency tonal wave layered alongside to make the hat sound convincing. The cymbals are similar, except I find it better to use more than one high-frequency wave and detune them. This improves the inharmonic quality (as opposed to the hissy quality) of the cymbal. Also, you can layer a slightly lower frequency White Noise waveform with a very short decay to imitate the actual striking of the cymbal.

6) Cowbells
Well, depending on what type of cowbell you're trying to emulate, you can rely on some additive waveforms in the shape of square and triangle waveforms, with the lower pitches of the additive wave set at volumes much higher than the high-pitched ones. You can also add a very short decay White Noise wave as well. Basically, for a TR808 cowbell you could use a mixture of square and triangle waveforms making up an additive waveform. Layer a minimum of 2 of these in a patch, and set one with a max volume and short decay, and the other at a much lower volume and longer decay. This will give you the general shape of the 808 cowbell output, which is a very sharp attack and decay, with no sustain and a longer release time.


General Vintage Considerations

When attempting to emulate vintage synths, it is important to note that there are several ways of creating convincing clones. Some have already been mentioned, but here is a more detailed list :

1) Chorus
There are two types of chorus which are most prevalent in modern synths and samplers. One takes copies of the original sound and plays them out-of-phase. This produces a richer and more evolving sound, which analogue synths are often characterized by. You can simulate this on a sampler by layering two identical sounds into one patch. The other method takes copies of the original sound and outputs them at a slightly different pitch. This produces an effect which is essentially identical to the first method. Technically they are very different, but the effect on our ears is often too similar to be noticed. I'm not sure which is the best method, but in any event it is an integral part of emulating vintage synths. My advice is to use lots of chorus on synth sounds, but hold back on the percussion sounds. Using chorus is an easy and effective way of getting that unstable quality which analogue synths are renowned for, and  you would be hard-pressed to find a modern sampler without chorus. The great thing about chorus is that it fattens up the sound - essentially making a single oscillator sound like several.

2) Detuning
Ahhhhh, this is where we reach an important, often overlooked part of analogue synthesis! Although chorus can sometimes achieve a detuned effect, for really tearing vintage sounds, detuning is a must. Many vintage synths have more than 1 oscillator per sound. Output these at slightly different pitches and they simulate a chorus effect. Fortunately further detuning allows wide variations in the pitches of these oscillators, and this can go way beyond a chorus effect. If you're looking for acid licks then this is your baby! Most samplers allow you to layer many oscillators, so the effect of detuning these can become monstrous at times! The method I frequently use is to layer 2 or more identical oscillators in an instrument. Use similar ADSR, filter and LFO properties for each of these oscillators. When I say similar, use slightly different rates of attack and decay of filters, LFO speeds and values ... etc. This will create a more evolving sound, almost to the point of being ever-changing - an analogue necessity! Then use your sampler's fine tune to detune some of these away from the base pitch. When the goose bumps settle after hearing this effect at work, you'll know that you've got what you wanted! If you don't detune enough then the effect won't be more than a chorus. Of course using both detuning and chorus will bring tears to your eyes, mark my words! You can of course utilize waveforms panned left and right as well to give you that ever-changing sound. Heavy detuning can give aggressiveness to your sounds.

3) Filters
You're not going to get very far in your vintage quest without this, believe me. Use it often and use it abundantly whenever possible. If oscillators are the voice of an analogue synth, then this is the mouth through which it speaks - literally! Opening and closing a filter is similar to opening and closing your mouth when you talk - it cancels and emphasizes frequencies. 

4) LFO'S
Here's another vintage necessity which must be used in abundance for strange and off-the-wall sound FX. Subtle use is of course necessary too, and it gives your sounds an animated feel.

So, to recap, some of the most important waveforms you could generate from Cool Edit are :