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Cross Synthesis (クロス-シーサセス), often shortened in reference to "XSY", is a parameter that allows a voicebank to blend into another voicebank, in a gradual and progressive way. It is only available with the full version of the software.

How to useEdit

First, the users must access the Cross-Synthesis Web browser through the Singer Editor, and can assign a Primary Voice and a Secondary Voice to be used in Cross-Synthesis. This feature works with a selection of VOCALOID3 voicebanks when imported into the VOCALOID4 engine, however not all products are compatable.[1]

A chart of the voicebank packages that supports this feature is available in Yamaha's official website.

Cross-Synthesis will morph the Primary Voice using the Secondary Voice as an analytical data guide for the adaptation of the first. The cross-synthesis is not simply switching between two voices as the users draws a parameter curve, but is instead increasing the ratio of the Secondary Voice being combined with the Primary Voice, in a way more complex than a simple fade out. The Primary Voice is used as a "template" for the morphing, it means the vocal combination used in the Cross-Synthesis is not mutually exclusive or interchangeable, thus meaning the rendering and behavior will be slightly different depending on which voicebank is used as primary or secondary voice.

  • Example: A Power-Normal setting will not be equal to Normal-Power.

Users can also choose how much the second voice impacts the first, from subtle to extreme. XSY is very similar in concept to how the original VOCALOID engine used recorded analytic data to adapt the Vocaloid engine noise to sound like the vocalist behind the data.

Note that some packages, such as the Megpoid V4 vocals, may come with their respective pairs already set up for XSY within the feature.

Benefits of XSY?Edit

When used effectively, XSY expands the capabilities of the Vocaloid package in use, increasing its overall abilities beyond what any single vocal within the package offers.

As seen in the Megpoid V4 package, XSY has the potential to create many different results. By mixing vocals with more extreme results, the combination of the two creates an effect that mimics having an entirely different voicebank. XSY mixes in traits of the other vocal to create an entirely new sound. By mixing a "whisper" type vocal with a "power" type, one can achieve a "power-whisper" result. A Vocaloid with just two vocals can achieve the equivalent of a third and fourth voicebank via the XSY function.[2]

While the result can be used throughout the entirety of a song, multiple XSYs creates a more realistic vocal performance. The vocal can go from a normal "whisper" to singing a high ballad to express a joyful happiness, made achievable by a"power-whisper" mix. In the same song, a "dark-whisper" mix can creating a sad tone. In the case of the Megpoid V4 5 pairs, they were intended to use XSY to allow the user to ease from one vocal to another, allowing for easier/smoother switching between the two vocals in each intended pairing.

For Vocaloids with access to even just 1 more additional vocal expansion library and XSY will see their overall tone capabilities doubled. This makes them a much more attractive package then Vocaloids with just a single voicebank.

From Ver.4.3.0 of the VOCALOID4 engine "groups" were added, which allowed for the first time a certain number of vocals to XSY between them that were never able to do so before. It allowed vocals to XSY between multiple characters.[3][4]

A benefit of this expanded function is that multiple characters can be used to support the main Vocaloid. For example, Megpoid V4's 10 voicebanks can be switched around to act as "tone controlling", adding a slightly different tone to another vocal depending on if the user wants their primary vocal to alter to. This is possible due to all 10 having the same vocal range and tempo. Others such as Kokone can be used to bring a vocal to a more "falsetto" tone of voice. Then there are vocals like Macne Nana which can be used to give a vocal support during faster songs, due to her stability during high tempos.

Voicebank XSY variants calculationsEdit

The following calculations give an estimate as to how many major shifts in tone an XSY capable voicebank can produce.

Note that "α" represents the number of vocals that have the option to XSY with the intended vocal being used - this includes its usage both as a primarily and secondary vocal.

Equivalent potentially created additional vocals:

α x (α - 1) =

Theoretical total number of vocals is simply the previous result plus the original number of vocals thus the formula is:

α x (α - 1) + α =

For example, the Megpoid V4 release's 10 voicebanks work out as

10 x 9 = 90 additional possible results
10 x 9 + 10 = 100 total theoretical results

The following examples detail the results up to 15;

  • 2 voicebanks; produces 2 variations with XSY, 4 variations altogether including the original vocals
  • 3 voicebanks; produces 6 variations with XSY, 9 variations including the original vocals
  • 4 voicebanks; produces 12 variations with XSY, 16 variations including the original vocals
  • 5 voicebanks; produces 20 variations with XSY, 25 variations including the original vocals
  • 6 voicebanks; produces 30 variations with XSY, 36 variations including the original vocals
  • 7 voicebanks; produces 42 variations with XSY, 49 variations including the original vocals
  • 8 voicebanks; produces 56 variations with XSY, 64 variations including the original vocals
  • 9 voicebanks; produces 72 variations with XSY, 81 variations including the original vocals
  • 10 voicebanks; produces 90 variations with XSY, 100 variations including the original vocals
  • 11 voicebanks; produces 110 variations with XSY, 121 variations including the original vocals
  • 12 voicebanks; produces 132 variations with XSY, 144 variations including the original vocals
  • 13 voicebanks; produces 156 variations with XSY, 169 variations including the original vocals
  • 14 voicebanks; produces 182 variations with XSY, 196 variations including the original vocals
  • 15 voicebanks; produces 210 variations with XSY, 225 variations including the original vocals

Formula notes;

  1. It is worth noting that as XSY is a controllable variable, it is possible to create further variations than this chart displays by mixing more of one vocal with the other. For example, you may get a different result at 25% as oppose to 50% or 75% of the influence of the secondary vocal.
    1. However, the factors involved with how much you can get out of two vocal is dependent entirely on the two vocals involved. For example, two vocals which are relatively close in tone will give less varied results.
    2. These calculations are based on an "ideal setting" wherein the traits of both vocals are allowed to leak through enough to mimic the effect of having an entirely new voicebank. It does not factor in that more then 1 variable can be created, this is done so for simplicity sake.
  2. It is sometimes difficult to pinpoint the exact setting that gives the biggest difference.
  3. Note that the Vocaloid wikia's calculation will not take into account that some XSY compatible vocals are simply updates that add GWL. So some XSY combinations between older and newer versions of a software may show little response. However, the fact that GWL can change a vocals tone when combined with other GWL compatible vocals is why they are taken as "different" XSY combination despite being the same vocal.

XSY GroupsEdit

As mentioned elsewhere on this page Ver.4.3.0 of the VOCALOID4 engine added the "XSY group" assignments, extending the XSY usage beyond its previous capabilities. The XSY groups allow for vocals within them to XSY regardless of the character, while previously XSY had been restricted to one character only. This opened doors for very different vocal results from very different Vocaloids, with many even capable of producing a result that sounds like neither Vocaloid used in the process.

The same rules for XSY apply to this new group system, so nothing has changed except the potential number of vocals that are compatible.

Arranged by: Seller Tab / Group Name / Singer Name / Product Name

  • nemurion
    • yumemi_nemu
      • VOCALOID4 Library yumemi nemu
      • VOCALOID4 nemurion set
  • nemurion
    • tone_rion
      • VOCALOID4 Library tone rion
      • VOCALOID4 nemurion set
  • Fukase
    • Fukase_J_Normal
    • Fukase_J_Soft
      • VOCALOID4 Library Fukase
    • ARSLOID_Ext_Soft
    • ARSLOID_Ext_Bright
      • VOCALOID4 Library ARSLOID
  • VY1
    • VY1V4_Power
    • VY1V4_Soft
    • VY1V4_Normal
    • VY1V4_Natural
      • VOCALOID4 Library VY1V4
  • galaco
    • galaco_RED
    • galaco_BLUE
      • VOCALOID™3 Library Galaco
  • VY2
    • VY2V3
    • VY2V3_Falsetto
      • VOCALOID™3 Library VY2V3

  • MIKU_V4X
    • MIKU_V4X_Original_EVEC
    • MIKU_V4X_Soft_EVEC
    • MIKU_V4X_Solid_EVEC
    • MIKU_V4X_Sweet
    • MIKU_V4X_Dark
      • VOCALOID4 Hatsune Miku V4X
      • VOCALOID4 Hatsune Miku V4X Bundle
  • MIKU_V4X
    • MIKU_V3_Original
    • MIKU_V3_Soft
    • MIKU_V3_Solid
    • MIKU_V3_Sweet
    • MIKU_V3_Dark
      • VOCALOID™3 Hatsune Miku V3
      • VOCALOID™3 Hatsune Miku V3 Bundle
  • MIKU_V4X
    • MIKU_V3_Light
      • VOCALOID™3 Hatsune Miku V3 Light
    • MIKU_V3_Vivid
      • VOCALOID™3 Hatsune Miku V3 VIVID
  • MIKU_V4_English
    • MIKU_V4_English
      • VOCALOID4 Hatsune Miku V4 English
      • VOCALOID4 Hatsune Miku V4X Bundle
    • MIKU_V3_English
      • VOCALOID™3 Hatsune Miku V3 English
      • VOCALOID™3 Hatsune Miku V3 Bundle
  • LUKA_V4X
    • LUKA_V4X_Soft_EVEC
    • LUKA_V4X_Hard_EVEC
    • LUKA_V4X_Soft
    • LUKA_V4X_Hard
      • VOCALOID4 Megurine Luka V4X
    • LUKA_V4X_ENG_Soft
    • LUKA_V4X_ENG_Hard
      • VOCALOID4 Megurine Luka V4X
  • RIN_V4X
    • RIN_V4X_Power_EVEC
    • RIN_V4X_Warm
    • RIN_V4X_Sweet
  • LEN_V4X
    • LEN_V4X_Power_EVEC
    • LEN_V4X_Cold
    • LEN_V4X_Serious
    • KAITO_V3_Straight
    • KAITO_V3_Soft
    • KAITO_V3_Whisper
    • MEIKO_V3_Straight
    • MEIKO_V3_Power
    • MEIKO_V3_Whisper
    • MEIKO_V3_Dark

    • Megpoid_V4_Native
    • Megpoid_V4_NativeFat
      • VOCALOID4 Library Megpoid V4 Native
      • VOCALOID4 Library Megpoid V4 Complete
    • Megpoid_V4_Power
    • Megpoid_V4_PowerFat
      • VOCALOID4 Library Megpoid V4 Power
      • VOCALOID4 Library Megpoid V4 Complete
    • Megpoid_V4_Whisper
    • Megpoid_V4_SoftWhisper
      • VOCALOID4 Library Megpoid V4 Whisper
      • VOCALOID4 Library Megpoid V4 Complete
    • Megpoid_V4_Adult
    • Megpoid_V4_MellowAdult
      • VOCALOID4 Library Megpoid V4 Adult
      • VOCALOID4 Library Megpoid V4 Complete
    • Megpoid_V4_Sweet
    • Megpoid_V4_NaturalSweet
      • VOCALOID4 Library Megpoid V4 Sweet
      • VOCALOID4 Library Megpoid V4 Complete
    • Gackpoid_V4_Native
      • VOCALOID4 Library Gackpoid Native
      • VOCALOID4 Library Gackpoid Complete
    • Gackpoid_V4_Power
      • VOCALOID4 Library Gackpoid Power
      • VOCALOID4 Library Gackpoid Complete
    • Gackpoid_V4_Whisper
      • VOCALOID4 Library Gackpoid Whisper
      • VOCALOID4 Library Gackpoid Complete
    • UNAV4_Sugar
    • UNAV4_Spicy
      • VOCALOID4 Library Otomachi Una V4
    • kokone
      • VOCALOID™3 Library kokone
    • Chika
      • VOCALOID™3 Library Chika
      • VOCALOID™3 Library Gachapoid V3
    • Lily_Native
    • Lily_V3
      • VOCALOID™3 Library Lily
    • CUL
      • VOCALOID™3 Library CUL
    • Megpoid_Native
      • VOCALOID™3 Library Megpoid Native
      • VOCALOID™3 Library Megpoid Complete
    • Megpoid_Power
      • VOCALOID™3 Library Megpoid Power
      • VOCALOID™3 Library Megpoid Complete
    • Megpoid_Whisper
      • VOCALOID™3 Library Megpoid Whisper
      • VOCALOID™3 Library Megpoid Complete
    • Megpoid_Adult
      • VOCALOID™3 Library Megpoid Adult
      • VOCALOID™3 Library Megpoid Complete
    • Megpoid_Sweet
      • VOCALOID™3 Library Megpoid Sweet
      • VOCALOID™3 Library Megpoid Complete
    • Gackpoid_Native
      • VOCALOID™3 Library Gackpoid Native
      • VOCALOID™3 Library Gackpoid Complete
    • Gackpoid_Power
      • VOCALOID™3 Library Gackpoid Power
      • VOCALOID™3 Library Gackpoid Complete
    • Gackpoid_Whisper
      • VOCALOID™3 Library Gackpoid Whisper
      • VOCALOID™3 Library Gackpoid Complete

  • AHS
    • Yukari_Jun
      • VOCALOID4 Yuzuki Yukari Jun
    • Yukari_Onn
      • VOCALOID4 Yuzuki Yukari Onn
    • Yukari_Lin
      • VOCALOID4 Yuzuki Yukari Lin
  • AHS
    • Iroha_Natural
      • VOCALOID4 Nekomura Iroha Natural
    • Iroha_Soft
      • VOCALOID4 Nekomura Iroha Soft
  • AHS
    • Kiyoteru_Natural
      • VOCALOID4 Hiyama Kiyoteru Natural
    • Kiyoteru_Rock
      • VOCALOID4 Hiyama Kiyoteru Rock
  • AHS
    • miki_V4_Natural
      • VOCALOID4 miki Natural
  • AHS
    • Zunko_Natural
      • VOCALOID4 Tohoku Zunko Natural
  • AHS
    • MacneNana_V4_Natural
      • VOCALOID4 Macne Nana Natural
    • MacneNana_Petit
      • VOCALOID4 Macne Nana Petit
  • AHS
    • Yukari
      • VOCALOID™3 Yuzuki Yukari
  • AHS
    • Zunko
      • VOCALOID™3 Tohoku Zunko

  • IA
    • IA
    • IA_ROCKS

view • edit


XSY is far from perfect. As with the "GWL" function, this feature may prove very limiting to vocals that are too similar. A common complaint with Megurine Luka V4X English vocals "Straight" and "Soft" is how XSY barely impacts either vocal.

XSY can produce unpredictable or unexpected results when used. This is particularly true when the two vocals used for the feature have significant differences, or when the involved vocals were created without XSY in mind. This occurred with many of the VOCALOID3's voicebanks that gained XSY when they were imported into VOCALOID4.

  • Example: In the Megpoid V4 package, wherein while the respective pairs of vocals (Native and NativeFat for example) offer a moderate XSY result, XSY between the other 8 vocals offers more unpredictable results (Power and Sweet for example). Comparing also to the V3 Megpoid vocal, the V3 Megpoid vocals use of XSY is not so effective, as the voices were never intended for the function. The V3 Megpoid package produces considerably lower quality results when compared to V4.

Common FlawsEdit

Some common issues included;

  • Altered optimum range, either increased or decreased depending on the combination
  • Creation of new noises or the enhancement of known bad ones (such as mild "popping", "crunching/plucking", "static"), resulting in a loss of quality compared to the original two vocals that were used for it or produce undesirable results. [5]
  • tones that change unexpectedly as the vocal goes up and down the octaves (particularly of vocals with large vocal ranges and/or variation between the two vocals), this makes them unstable and even suffer from tonal collapse.
  • Causing vocals to produce a croaky results, a bug which does not impact all vocaloids naturally (see BIG AL as an example of a Vocaloid with a known natural croakiness).

Why do Bugs appear?Edit

These results are not necessarily found in either vocal and vary in strength from subtle to extreme results depending on the variables strength and setting involved with XSY. In addition, while the original two vocals may be HQ, the resulting in XSY may turn out to be LQ or MQ at best.

The reason for these bad results is down to how XSY works itself. XSY's differences are worked out by use of mathematical equations, to work out the differences between the primary and secondary vocals and alter the wavelength of the primary vocal in accordance. The calculations don't work particularly well when the voicebanks have libraries built entirely different to each other as it was not designed to handle this and it is can be impossible to get good quality results.

This is why VOCALOID3 and VOCALOID4 XSY is not always feasible, nor XSY between languages and multiple Vocaloids. This is also why features such as E.V.E.C. may cause issues with XSY.

Many cases, these can be fixed with further editing. However, the editing may be a lot more common or extreme then a non-XSY result will produce.

Loss of Clarity;

XSY can result in loss of clarity because the traits of 1 voice may alter the other significantly enough. In other words, the vocal result produced may not be dedicating itself enough to a single trait of the other vocal to maintain the trait that made it clear originally.

For some vocals, they gain clarity because of a relied upon single or more trait such as a strong attack, powerful/clear tones or high quality recorded samples, all are traits which are common to "power" types. But mixing these vocals with other very different traits can remove the very reason for their clarity.

"Soft" vocals, have been known impact clarity, due to their to looser pronunciations. So mixing with this vocal can cause the sounds on the primarily vocal to loosen to mimic the traits of the soft vocal. This can make the resulting primary vocals results appear to mumble more.

A flaw appearing more noticeable;

One of the more common issues with XSY is how flaws are handled. If the two vocals both have this same flaw contained within their data library. While two vocals with similar traits are often HQ then ones that are not, there is a potential for the result to not be so true.

Often the results are because both vocals were drawn from the same set of (bad) data, or simply both ended up with a similar/same glitch (both in the case of vocals within a same release or different releases).

During XSY the "good" trait can be lessened due to the two vocals differences. However, the share trait is less likely to be altered as there is less variants in the calculations due to them be equal in both vocals, making it more likely to be kept. This makes the flaw appear to be more noticeable, despite the fact that it is the same strength as before, simply because the traits that masked it have been removed.

Exaggeration of a flaw;

When only 1 vocal contains the flaw, the second vocal has been known to mask the issue (and while not true, can appear to "fix" it), by lessening the effect of the flaw of the other vocal due to XSY using the trait of the other vocal in the result.

However, the reverse can occur when a vocal used in secondary has a flaw itself, but its own flaw is even stronger then the primarily vocal being used in the process. In the worst cases, Vocaloid XSY picks up the single flaw and not others that could mask it easily due to its strength. This the primarily vocal is "pulled" towards imitating that flawed trait. Since the flaw didn't exisst in the primarily vocal in the first place, it was not build with masking such an issue at all.

Glitches where there were none;

Sometimes it is a simple case of a glitch exists in the secondary vocal, which when used for XSY causes that glitch to appear in the primarily vocal. So incorrect phonemes, unlinked sounds, random crunches all can be added to a vocal that didn't have them before.

Software AgreementsEdit

Due to the licencing agreements between Vocaloids and studios, Vocaloids generally are not open for XSY between Vocaloids or Vocaloids of studios.



VOCALOID 4 新機能 「クロスシンセシス」 - Cross Synthesis - YouTube
Hiyama Kiyoteru Rock + Nekomura Iroha Soft SoundCloud
Yuzuki Yukari Jun + Tohoku Zunko Natural SoundCloud
Otomachi Una V4 Sugar + Megpoid V4 Sweet SoundCloud
Otomachi Una V4 Spicy + Megpoid V4 Power SoundCloud
Megpoid V4 Adult + Lily V3 SoundCloud
Gackpoid V4 Native + Gachapoid V3 SoundCloud
Tohoku Zunko Natural + Hiyama Kiyoteru Natural SoundCloud
Tohoku Zunko Natural + miki Natural SoundCloud
Tohoku Zunko Natural + Yuzuki Yukari Jun SoundCloud
Macne Nana Natural + Yuzuki Yukari Lin SoundCloud
Macne Nana Natural + Tohoku Zunko Natural SoundCloud
Macne Nana Petit + Nekomura Iroha Soft SoundCloud
Yumemi Nemu + Tone Rion V4 SoundCloud


Please note we are waiting for more information on some languages


Start a Discussion Discussions about Cross-Synthesis

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