What Are Semi-Weighted Keys?

Semi-weighted keys allow digital pianos to be significantly lighter in weight than instruments with a weighted hammer action. Both types of keyboards can be a sensible choice depending on the context and differ mainly in the playing feel.

Due to the lack of a hammer action, semi-weighted keys will not bring an authentic piano touch to an electric piano. However, there are some situations in which semi-weighted keyboards can be very practical. There are also big differences in quality – here are our recommendations.

How do semi-weighted keys work?

Semi-weighted keys provide a completely different playing feel than the keys of a graded hammer action keyboard – even piano beginners will immediately notice this. Semi-weighted or lightly weighted keys are counterbalanced by a spring mechanism when you press the key. In addition, there are small weights inside the keys to assist in the key travel.

How to recognize a good semi-weighted keyboard

Although they all basically work the same, there are big differences in the quality of semi-weighted keyboards. Semi-weighted keys should be easy to press and allow for quick repetition.

If the spring tension is too high, it will not only result in a less authentic “piano feel”, but can also lead to incorrect hand and finger positions. Since inexpensive instruments with semi-weighted keyboards are often recommended for beginners – e.g. as “electric pianos for children” – a little caution is advised when buying one.

Good semi-weighted keyboards do not bounce significantly when you release the keys. If the keys tilt noticeably to the left and right, it is better to stay away from this keyboard.

The difference between weighted and semi-weighted keys

If you are buying an electric piano with semi-weighted keys, you should make sure that you don’t notice any tension while holding down the keys. This is an important difference between semi-weighted keys and a weighted hammer action keyboard:

The hammer action is like a balanced moving counterweight to the key – you can feel in your fingertips how this force accompanies the keystroke. Ideally, the hammer action also supports the rest position of the keys. A spring mechanism behaves completely differently, developing tension by winding the spring. If the spring’s travel is poorly dimensioned, a strong counter-tension builds up in the rest position of the pressed keys.

A special playing technique (also known as piano touch) is required to play the keys of a hammer action in a controlled manner with the desired touch dynamics. With a semi-weighted keyboard, this technique is not possible, or only possible to a limited extent.

Semi-weighted keyboards – Recommendations

Semi-weighted keyboards are used in MIDI keyboards and entry-level electric pianos. However, a low price does not necessarily indicate the quality of the keyboard. For example, Akai’s MPK series master keyboards are among the most popular and expensive models. However, the keyboards here are not convincing because of the immense tension they build up.

If you are looking for the most authentic piano touch possible, we cannot recommend instruments with semi-weighted keyboards. Semi-weighted keyboards are a compromise! Hence the question is: When do they make sense?

• Beginners: Semi-weighted keys are generally suitable for the first few notes on a piano keyboard. Especially if they are easy to play – the Casio CT-S1 is a good example.
• Portability first: If you need a lightweight stage piano that is easy to transport, you should opt for a MIDI keyboard, a portable piano, or a piano keyboard with semi-weighted keys.
• Recording: Authentic piano touch is secondary if you are primarily looking for an 88-note keyboard for home recording.

1. Thomann SP-120 – An absolute no-brainer!

Basically an insider tip – not only for beginners but also for advanced players looking for a lightweight stage piano for rehearsals and small gigs. The SP-120’s 73 semi-weighted keys are easy to play and very responsive. USB MIDI/Audio connectivity allows for easy integration of music computers and mobile devices. The 2×20-watt speaker system sounds clean even at high volumes and is also suitable for unplugged rehearsals with the band. The unit is not only inexpensive but simply top-notch!

2. Casio CT-S1 – Compact and lightweight

The Casio CT-S1 is part of the Casiotone series and is therefore a cross between a keyboard and a beginner’s piano. It has only 61 keys, which also makes the CT-S1 very compact. Additionally, it can be battery operated, so it is ideal for making music on the go: take it to the park, a garden party, the beach, or the city. The sounds are fun, and the optional WU-BT10 adapter allows wireless connection to piano apps. This is also possible via the built-in micro-USB port.

3. Nektar Impact LX88+

If you just want a MIDI keyboard with 88 semi-weighted keys for your home recording setup, we recommend the Nektar Impact LX88+. The keys play well, and there are plenty of knobs, faders, and buttons to control your music software. With its low weight, the LX88+ is perfect for live performances when paired with a piano app.

4. Korg Liano – Semi-Weighted Keys To Go!

Extremely lightweight and compact, but with 88 keys. Professional piano sounds, USB MIDI/Audio for integration of music computers and mobile devices. In combination with music apps like Korg Module Pro or Korg Gadget, the Korg Liano becomes a live workstation.

5. Yamaha Reface CP – Mini-Stagepiano

While it may be the world’s smallest stage piano, you shouldn’t think of it as a toy. The sounds are anything but a gimmick to pass the time. They cover the full 88-note range of a full-size stage piano and using a MIDI keyboard (e.g. Nektar Impact LX88+), you can also play them expressively. Cool vintage effects are also built-in.

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