All of the the new workstations use compression algorithms to allow larger wave ROMs.

Yamaha Motif XS
"Wave: 355 MB (when converted to 16-bit linear format)"

Roland Fantom X
"Wave Memory: 128 M bytes (16-bit linear equivalent)"

Korg M3
"Preset PCM: 256 Mbytes (when calculated as 16-bit linear data)"

So the XS has 227 MB more Wave ROM data than the Fantom and 99 MB more Wave ROM data than the M3.

Anyone every wonder why Roland and Korg have nice, even numbers that are multiples of 128 and Yamaha always has these weird numbers- the classic Motif is 85 MB, the ES is 185 MB and now the XS is 355 MB ?
Here's the answer !

One of the things that is at the heart of the new Motif XS is the newest sound engine chip and it has some amazing features. One of the things that was signifcantly improved was it's ability to decode PCM in compressed format and the compression algorithms used.

Data compression is different from audio compression. Data compression is a way to store data in a compressed format and use a decoder in the chip to uncompress the data and play it back.

Done correctly it doesn't effect the sound quality, but some sounds are more sensitve to data compression than others.

The reason is there are differences in the way the compression is done. Korg has not released information on how they are doing their data compression which is new to the M3 (previous Korg models did not use compression at all ), but it likely works the same way as Roland where all the data is compressed in one scheme (say 2:1 data compression). That's why the spec is a nice round multiple of physical chip sizes which are 64 MB, 128 MB etc.

The Yamaha compression system is very flexible and decisions are done by the sound designers. It allows the sound designers to select what sounds are compressed , how much they are compressed and what compression algorithms are used. We can try different things to make sure that the sound quality is maintained and make the decision with our ears. If the sound designers decide a certain sound or area of a sound will be effected by the compression, we simply don't compress it at all. That's why we end up with odd numbers like 385 MB.

Data compression is a good thing because you get more wave data into the physical chip. More wave data means more sound (whether it's better or not depends on the sound data itself, but that's another blog). But it's great to have the flexibility in deciding on how that data compression is done.

So if you ever wonder why Yamaha has all those strange numbers in the catalog spec, there is a very good reason. It's so the sound designers can decide how the sounds get processed, what gets compressed and how much. It's one of the core technologies that make sure the XS sounds the best it possibly can.