LALAL.AI’s Andromeda Gets Guitars and a Cleaner Piano Stem

Two more stems have landed on Andromeda. The model already covers Vocal, Instrumental, Drums, and Bass, and it now adds Piano and Guitars to that lineup, bringing the total to six stems handled by a single network.

Piano is something we have offered for a while. It has now been retrained from scratch on the Andromeda architecture, and the difference is easy to hear. The other, Guitars, is new to LALAL.AI entirely. It pulls every guitar in a track into a single stem, whether that guitar is acoustic, electric, or somewhere in between.

Both instruments sit near the top of our request list, right behind drums and bass. They are also genuinely difficult to separate. A piano spreads across almost the entire frequency range of a mix and rings out long after each note is struck, which means it overlaps with the vocal, the bass, and whatever else is happening at the same moment. Guitars have the opposite problem: there are usually several of them, they are often doubled or layered, and a heavily processed electric can end up sounding closer to a synth pad than to another guitar. Neither instrument gives a model clean edges to work with.

The New Guitars Stem

Guitars does what the name suggests. Select this stem, upload a track, and you get one file containing all of the guitar content the model can find: strummed acoustics, clean electrics, distorted rhythm parts, picked lines, leads, and layered doubles, together in one place.

The Acoustic Guitar and Electric Guitar stems have existed as two separate stems since Orion, and the same split carried over into Perseus. You picked the one you needed, and the model tried to give you only that instrument.

The new approach on Andromeda treats the whole guitar family as a single source, and the payoff shows up as less bleed from other instruments and fewer stretches where a part quietly drops out partway through a section, with the sound holding steady across a whole track instead of wavering in and out. Across a representative set of test material, the failures that bother people most, where a guitar ends up split apart or left behind in the residual channel, occurred roughly 20% less often than before.

There are two reasons for that, and the first one has a failure mode you have probably run into. Sorting guitars by type is finer work than finding them in the first place, and a model doing that job has to make a judgement call on every part it hears. When it gets that call wrong halfway through, a single guitar can end up split across two stems, with some of it landing in Acoustic and the rest in Electric. What comes back is a partial instrument. It sounds thinner than what was actually in the mix, and nothing about it looks obviously broken, so the problem tends to go unnoticed until you are listening for it specifically. Asking only whether something is a guitar removes that decision point, and the whole class of errors that follows from getting it wrong disappears along with it.

The second reason is the training data. Our labelling for guitars as a single class is currently in better shape than our labelling for acoustic and electric separately, and separation quality tracks data quality closely.

The Perseus Guitar Stems Are Here to Stay

Since the new stem cannot do everything the old ones could, we are keeping the old ones. Acoustic Guitar and Electric Guitar stay exactly where they were, and Guitars simply appears alongside them as an additional option.

We recommend to:

● Pick Guitars when quality is what you care about, and having all the guitar parts in one file is fine or even preferable. That covers most backing track work, karaoke-style arrangements, remixing, transcription, and practice sessions where you want the guitars either isolated or gone.

● Pick Acoustic Guitar or Electric Guitar when the instruments need to stay apart, or when the track has one clear guitar type and you want the model looking specifically for it. A folk recording with a single acoustic, or a metal track where the only guitars present are electric, will often do well on the older stems.

Nothing you have already built around the Perseus stems needs to change. Here is where to find them:

1. Open the stem list, the same one Guitars sits in.

2. Select Acoustic Guitar or Electric Guitar directly, they sit right next to it.

3. Upload your file, and separation starts as usual.

Piano, Rebuilt

The Piano model has been retrained on Andromeda from the ground up, and separation comes out noticeably cleaner than on the previous Perseus version, which stays available if you prefer it.

Piano parts hold together better through busy, layered sections, with less bleed from the rest of the mix and a fuller, more natural sound overall. Passages that used to give the older model trouble are handled more reliably now.

If you want to compare separation quality against Andromeda yourself, or you would simply rather work with the older model, here is how to switch to it:

1. Select Piano from the stem list.

2. Click the gear icon in the top right corner of the upload window to open Settings.

3. Under Neural network, choose v4 Orion or v5 Perseus instead of v6 Andromeda.

4. Upload your file once that is set.

Where You Can Use It

Both models are rolling out everywhere LALAL.AI does stem separation:

● On the web, Guitars and Piano are live in Stem Splitter and Vocal Remover. We took the opportunity to rework the stem selection interface as well.

● API users have access to both models, so any platform or product built on LALAL.AI can pass the new stems through to its own users.

● The iOS and Android apps support the new Guitars and the updated Piano.

● In the desktop app, the Andromeda versions of Guitars and Piano run in Cloud mode. 

What People Do With These Stems

Guitar and piano parts are what most people are actually trying to get at when they split a song, and they have been the weakest link in stem separation for a long time.

Guitarists learning a part by ear get the most direct benefit. Pulling the guitars up on their own makes voicings, inversions, and small rhythm details audible in a way that slowing down the full mix never quite manages, and the same stem, inverted, works as a backing track to practice against.

Sample-based producers get something similar out of the piano side. A chord progression or a riff can be lifted clean, without half the arrangement tagging along, and since a stem with the sustain intact holds up under pitching and chopping much better than a thin one, it survives a lot more processing before it starts to fall apart.

The rest is more practical than creative. Teachers and karaoke producers get cleaner minus one tracks to build lessons and backing versions around, and DJs and editors get a harmonic layer they can pull back or push forward in a transition without dragging bleed along for the ride.

Guitars and Piano bring the processing speed and stability that the rest of the Andromeda stems already offer, so none of this comes with a longer wait.

Upload a track and try Guitars or Piano for yourself.

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