DX7 Brass

Released by Yamaha in 1983, the DX7 was an influential instrument in the mid-80s. One of the patches that stood out in lots of music was the DX7 Brass. Its warbly, full tone was elevated to sophistication with the addition of a vibrato tail-end, leading to its influence in synth pop.

The actual DX7 brass is made of the third combination ("algorithm 3" aka preset 3) of six operators that function as a mix of carriers and modulators. The specific configuration is a pair of trios of operators, each trio consisting of two modulators to a carrier.



Subtractive Analysis
This appears to be a waveform of an elusive timbre created by sine waves with an enveloped low pass filter, some resonance, EQ, and vibrato (frequency LFO but not exactly FM synthesis) that fades in after holding the key long enough. The attack is fairly high, but not enough to be playable at higher tempos.

Timbre Analysis
Some experiments to achieve that elusive timbre point to a sort of rounded "W" shape, which makes sense given the appearance of the black box algorithm on the right. There is a waveform in ZynAddSubFX labelled "Chebyshev," which seems to emulate the result of an analog filter on what might be a sawtooth. The second and third harmonics were boosted before applying that enveloped low pass filter and EQ.

This current version of the synth design breakdown is very messy and would need a simpler and cleaner approach from someone who can pull off a cleaner and more loyal-sounding result. Even so, you can still achieve a similar-sounding brass synth with the use of sawtooths and low-pass filters to knock out some of the buzz.

Recreations

 * The DX7 is available as a closely-emulated VST (engine developed by Raph Levien and many other contributors) that is loaded by a host in the DAW.