Hi, everybody, and welcome to another digital piano review video and article here at Merriam Pianos. In today’s review, we’ll be taking a look at Casio PX-870. This is a wonderful instrument in the mid-range home digital piano category with 88 fully weighted keys, great sound, and a nice cabinet.

The PX-870 has been a very popular instrument for us at Merriam Pianos, especially during the lockdowns of 2020 and 2021. The combination of price and class-leading features such as a robust speaker system capable of great sound projection and always reliable Tri-Sensor II action has made the Privia PX-870 a logical choice for many shoppers.

Let’s get into it by starting with a quick overview.

The Newer Casio PX-870 Model | A More Advanced Digital Piano

Casio Privia - Digital Pianos
Casio Privia – Digital Pianos

The PX-870bk sits right at the top of the Casio Privia PX lineup. As such, there are several models below the 870 like the PX-770, the PX-780, and portable units like the PX-S1100 and PX-S3100, but Privia and PX lines have been a staple lineup of Casio’s for quite some time, with newer more advanced models coming out every few years to replace models from the previous generation. It’s been wonderful seeing the line evolve over the years in terms of the fit and finish of the product, as well as the overall musical performance that the various models are capable of.

We had high hope for the PX-870 when it was announced after one quick look at the specs sheet – it’s clear that Casio has equipped the PX-870 with a great tone engine, solid action, and strong internal amplifiers.

In practice and especially for the price point, we’re happy to report that the PX-870 is delivering very nicely. So let’s run down what that means.

Casio PX-870 Piano Sounds and Tone Engine Generators

Multi-Dimensional Morphing AiR Sound Source

Casio has equipped the PX-870 with their Multi-Dimensional Morphing AiR Sound Source tone generator which is delivering an impressive 256-note polyphony count. Polyphony is a less relevant spec these days, especially with home-based digital pianos meant to be a substitute for an acoustic piano because most digital pianos have a sufficient digital piano for solo piano playing.

Up-to-date Polyphony Count

Polyphony used to be a really important spec when computing technology was more expensive as it was a lot more difficult for manufacturers to deliver a decent polyphony count without the cost being through the roof.

These days, it’s almost a given that the polyphony is going to be something pretty decent if it’s an up-to-date product. All of that being said, a count of 256 is very impressive, and that definitely puts the PX-870 among the top of the class in this category. Check out our YouTube channel and our video on polyphony for a detailed breakdown of what it means, but essentially, the spec simply refers to how many notes a tone engine can generate and sustain at one time.

Sound Projection and Speaker System

Moving onto the speakers, we’re looking at a 4-speaker system with a pair of 20-watt amps for 40 watts of power. The speakers are down-facing, however, Casio has incorporated small vents or tone ports on the back of the cabinet to help create a more detailed sound, essentially like a tweeter.

There are 19 onboard sounds in total, and the quality of the sounds that Casio is putting overall has really gotten quite impressive. There are aspects of the tone on the PX-870 here that we think is coming across as successfully as some similar tones that you would get out of comparable Kawai’s, Roland’s, and Yamaha’s. In our showroom, the PX-870 competes primarily against the Kawai KDP-110.

Where would we say the KDP-110 has an edge in terms of sound quality? In our opinion, the acoustic piano tone that the Kawai KDP-110, or similarly priced Roland with their SuperNATURAL engine, is generating is still processing some of the finer details of the piano tone with a little bit more definition and accuracy.

Acoustic Piano Sound with Modeling Technology

That said, this is splitting hairs to some extent here since the PX-870 really is delivering a very impressive acoustic piano sound, and in addition to the sample, they’re using some modeling technology to fill in things like string resonance, damper resonance, lid simulator, and hammer response.

Here are some specific observations regarding the default grand piano tone;

  • There’s Lots of character and warmth which is immediately apparent.
  • There are a few other grand pianos all with different characters, though we do think the default tone is the best of the bunch.
  • Adjustable reverb, hall simulator, and brilliance also give you an extra layer of control over the piano tones.

After moving through the acoustic piano patches we come to a couple of very nice e-piano sounds, along with harpsichord, organs, and strings. There are a few misses among the selection sounds, but overall, it’s a pretty impressive lineup.

Wrap Up

To sum up the highlights of the piano sound of the PX-870, we’re looking at a piano with the most powerful speaker system in the class, with the exception of the Kawai KDP-110 which also has a 40-watt speaker system.

Polyphony also happens to be among the class leaders with a strong 256 notes here, and while the sound engine may not be our favorite in the class, it’s nonetheless a very good sound engine overall. Let’s move on to the action.

Casio PX-870 Digital Piano Keyboard System

Casio has done a few interesting things with its actions over the last few years. Certain things have been very successful, while others we would classify a little bit odd. For the most part, however, their actions have come a very long way and compete very well in the marketplace.

Tri-Sensor Scaled Hammer Action Keyboard II

Casio Tri-Sensor Scaled Hammer Action II

The PX-870 is using Casio’s Tri-Sensor Scaled Hammer Action Keyboard II. This action is using a triple sensor, so it’s very accurate in terms of its dynamic output and touch sensitivity. This is a potentially important consideration if you plan on using the PX-870 as a MIDI controller at any point.

It doesn’t have escapement, which is not unusual for this price range. For example, the Kawai and Yamaha options in the price don’t feature escapement either, with Roland being the only exception courtesy of their PHA-4 action.

Key Texture

An area where Casio is ahead of the curve is with regards to a fairly dramatic simulated ebony and ivory texture on the keytops to imitate the feel of an acoustic piano action. This approach has become common with all the manufacturers, but Casio was a real trailblazer in this regard.

The black keys feel a little bit too slippery right out of the box, but this goes away after playing for a little while as the finger’s natural oils gradually work their way into the keys.

Another thing we like about this current generation of the action is that it feels a lot more solid, and there’s much less unwanted motion in the key action parts than there was with past Casio actions.

Wrap Up

Overall we would suspect that this action will age fairly well, very much in line with Kawai’s RHC action or Yamaha’s GHS action, though we think this action easily outplays Yamaha’s GHS action which is feeling fairly dated at this point.

So, to sum this category up, what we have here with Casio’s Tri-Sensor Scaled Hammer Action Keyboard II is a well-built, enjoyable action to play on, and courtesy of its triple sensor will be accommodating to advanced playing styles.

Features and Connectivity

Music Library

The PX-870 has a fairly standard, but no less impressive set of features available when you consider the price point. For starters, there’s a solid music library of built-in songs that are good for playing along with, or simply sitting back and listening.

Connect with Chordana Play App

Chordana Play App
Chordana Play App

You can isolate specific piano parts for practice purposes, and it’s all easily controllable from the Chordana Play App, which is compatible with both iOS and Android. For a demo of the Chordana app, definitely check out the video review version of this article as Stu Harrison walks us through a nice sample of the app.

From there we have a cool Concert Play feature wherein the player gets to play along with symphony recordings of classic compositions.

Built-in Audio Recorder

There’s also a MIDI recorder as well as built-in Audio Recording and playback capability.

Cabinetry and Pedal System

PX-870 Tripple Pedal and Cabinet Design
PX-870 Tripple Pedal and Cabinet Design

The Casio PX-870 features a nice built-in cabinet and triple pedal system with damper, sostenuto, and soft pedals, though Casio isn’t including a piano bench in the package at this point. Comparable Kawai’s and Yamaha’s do include a bench at no charge, so that’s an area where the PX-870 is a little bit behind.

Dual Headphone Jacks

In terms of connectors, we’ve got two headphone jacks and a designated headphone mode that enhances the sonic experience when playing with headphones. There are no discreet line outputs, so you will need to use the headphone ports and an adapter if you need more power.

The Casio PX-870 also lacks any Bluetooth connectivity which is a little bit disappointing since it is quite common these days at the price point, so you will need to use a cable when connecting to a Smartphone or Tablet.

Of course, the basics are covered such as Layer, Duet mode, a metronome, transpose, and octave shift.

Closing Thoughts

In summary, what do we have? Well, we have an instrument in a sweet spot price-wise that also happens to exist in a very competitive part of the market. Compared to some of the other instruments out on the market, we have an above-average piano tone and action, and an impressive sound projection system courtesy of the 40-watt speaker system.

If you’re looking for an instrument in this price range and you hadn’t yet considered Casio, it’s definitely worthwhile to give the PX-870 a look by getting into a showroom to compare it against a Yamaha YDP-144 for example.

We’ve already mentioned the KDP-110 as Kawai’s comparable model, while the RP-102 on the Roland side of things would be a good match.

It’s definitely fair to say that the PX-870 is a compelling option to consider against anything else in the price point, with Casio’s growth and improvement over the past few years really being something to behold.