Yamaha 4OP Comparison

Here's a quick comparison of the classic Yamaha 4 operator FM synths. Created as inexpensive alternatives to the 6 OP DX7, when handled with care these synths are capable of some great sounds. First off, naturally, they all have four operators; one being the carrier frequency and the other three the modulating frequencies. Another thing is they all seem to have 8 note polyphony. So looking around a bit, the consensus on the difference in sound between these comes down to; multitimbrality or how many instruments it can play at once, the waveshape of the operators and the bit depth of the digital to analog converter (DAC).

DX-21

Multitimbral: Mono

Waveshape: Sine

DAC Bit Depth: 10 bit

DX-27 / DX-100

Multitimbral: Mono

Waveshape: Sine

DAC Bit Depth: 10 bit

FB-01

Multitimbral: 8 part

Waveshape: Sine and Noise

DAC Bit Depth: 10 bit

TX81Z / DX-11

Multitimbral: 8 part

Waveshape: 8 shapes

DAC Bit Depth: 12 bit

TQ-5

Multitimbral: 8 part

Waveshape: 8 shapes

DAC Bit Depth: 12 bit

So looking at this as a timeline we can see some changes occurred with the FB-01 with the addition of 8 part multitimbrality and the ability to set one of the operators as a noise generator. Then the TX81Z added the ability to change the waveshape outright. The other important thing folks seem to point out on this is the 12 bit DAC on the TX81Z. You might wonder how the bit depth at the input side of the DAC could really make any difference, and honestly I'm not so sure myself, but people claim that it gives the signal more breathing room resulting in a fuller sound. The 10 bit DACs seem to result in a more lo-fi gritty sound (and a really good bass sound). There are camps that swear by either side so it's definitely a personal preference thing.

Addendum: So the FB-01 actually is unique in the way it handles programming the voices. The volume of the operators is controlled on a 0 - 127 scale, all the other 4OP synths use a 0 - 99 scale. I think this is the main reason the stock voices are not up to par with the rest of the Yamaha 4OP synths. Basically the engineers at Yamaha had to relearn the whole system to program the voices; probably not worth it for a product that was supposed to be the cheapest of their synth range. So they probably pushed it through quickly to get something on the market. There are a handful of decent patches on there but most people prefer to program their own for this unit.

For an extremely in depth analysis, check this guy's page: http://www.angelfire.com/in2/yala/2fmsynth.htm

He refers to the FB-01 range as the "CX". I assume what he actually means is the "SFG-01 / SFG-05" which were the sound modules on the CX5M computer. I intend to follow this post up with a more in depth post on the FB-01 explaining the relationship of these units.