Newbie here, so I may use incorrect terms.

From what I've learned you can connect digital piano like, Kawai ES 120 or Korg D1, to a synthesizer like ASM Hydrasynth -- then play on DP using full 88-keys and at the same time be able to alter the sound using knobs, sliders, etc. on the synth and get reverb or other effects (so only control panel is used on synth). So piano here will tell for example that note C4 is played, with volume X, length T, and the actual sound+effects are made by the synth. I hope I got it right :-).

Ok, but what properties are lost from the synth perspective? One thing comes to mind is aftertouch. I assume it is is a property of the actual keybed so when playing on the piano even in this setup, this is lost.

What else is lost?

Clarification 1: I don't want to disable anything by myself. My perspective is like owner of the synth and buyer of the piano -- I want to learn/be aware, what I can potentially lose when playing on the digital piano connected to the synth compared to playing on synth alone.

Clarification 2: "lost" from synth perspective. If a person playing on DP (using DP keys) + synth control panel only is not able to trigger synth feature X, I consider this feature as lost (not available).

3 Answers 3


The ASM Hydrasynth keyboards have one rather uncommon feature: polyphonic aftertouch. Many piano-style keyboards do not have aftertouch at all, and most MIDI keyboards that have aftertouch, send only channel aftertouch but not key-specific aftertouch levels.

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    Thank you very much. With this information I have better understanding how the market is divided. Jan 12 at 20:07

MIDI keyboards sold as such usually supports aftertouch and all the "normal" knob tweaking, so that's rarely a problem. They come with a default and if you need something else, you can do those settings yourself and save them.

Things actually lost are things that can not be expressed in the normal set of MIDI messages. For this there are SysEx (SYstem EXclusive) messages. They are messages that one device can send to another specific device and that only makes sense to that particular receiver. These messages could contain anything that controlls the receiver. It could be samples or other settings for which there is no description in the MIDI protocol.

In order to support that from a generic MIDI keyboard, it needs to be capable of recording and resending and/or producing these SysEx messages. That's not a feature often seen or used (at least not when I was programming these things ~30 years ago). A technique that can be used is to do a "MIDI dump" (using SysEx messages) of the whole syhthesizer's/sampler's settings and have a capable program ready to receive. Cubase 1.0 supported this. It's a bit tedious, but if you are tweaking the sounds in your synth/sampler/drum machine for each song, you need to keep track of the settings, so a MIDI-dump may be an option.

This doesn't often reflect on live capabilities - but it can. Nowadays, MIDI isn't restricted to the 31.25 Kb/s we had in the early days. MIDI over USB3 would allow for samples and other complex settings to be flying over the wire while you're playing. Mapping this to a separate generic MIDI keyboard requires work - and in some cases, you may actually find that someone (rarely the vendor) has made a profile for your keyboard that works.

Disclaimer: I haven't been in this game since the late 90's.

I just remembered what I did to not get a setup where my machinery wasn't capable of communicating all the things I wanted:

I wrote to the vendors I was curious about and asked them for their detailed MIDI implementation specification. Both replied with the full (including SysEx) spec. Roland, who made the drum machine I was using, even sent me a physical EPROM to replace the one inside my machine when they realized what I was up to and they realized that I would stumble on a bug they had in the released version of the firmware.

  • Many thanks. So now I sense, there is DP category which rarely has after touch but have other features like speakers, voice selection and MIDI keyboards (controllers?) which have richer keyboard sensors (like aftertouch) but do not have speakers or voices selection like DPs have. Does my understanding make sense? Jan 12 at 17:50
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    @greenoldman You're welcome! A DP without aftertouch seems odd these days. Even if it's not used on the built-in piano sounds, I would expect it to sense it and send aftertouch. Anyway, if it's not using aftertouch on its own sounds, the aftertouch capability can hardly be called "lost" when transmitted. MIDI keyboards/controllers can have from very few capabilities to an enormous amount. I count DPs as MIDI keyboards - with better keys :-)
    – Ted Lyngmo
    Jan 12 at 17:59
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    I'd like to see a reference to digital pianos having aftertouch. Anyway, the Hydrasynth keyboard has polyphonic aftertouch that is much less common than channel aftertouch.
    – ojs
    Jan 12 at 19:34
  • @ojs Perhaps they've gone out of style since I connected them. Yamaha used to have them. If the Roland DPs don't have it still, I'd be surprised. Since my deep-dive into this territory is a bit old, vendors may have dropped less requested features by now. I still recommend looking into the MIDI implementation chart before buying if this is something you care about. I would personally never buy a keyboard without the capability to sense and send aftertouch, so I'd look for that.
    – Ted Lyngmo
    Jan 12 at 19:41
  • @TedLyngmo, thank you. As for Roland, maybe I miss something, but for example middle class Fantom 0x do not have aftertouch, only top level Fantoms do. But it of course translates to spending a lot of money to get this effect sent to synth from DP :-). Jan 12 at 20:02

A good digital piano should send all the MIDI data out, including things like aftertouch and any control messages. Of course the sounds you are using on your synthesizer need to be programmed to respond to aftertouch.

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    Thank you, but then what does it mean "good digital piano"? From what I read after touch is pressure converter (I simplified) thus it would mean the keybed of the piano would have pressure sensor (per key). Is there any digital piano with pressure sensor with disabled aftertouch? If not, it translates "good digital piano" = "digital piano with aftertouch". If it is not the case I don't know where from DP would get info about the pressure. Jan 12 at 15:22
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    @greenoldman Normally, if a DP has aftertouch, it will be sent via midi. Note that most aftertouch are not by key, but global: if you press harder (after the key is down) on a key than an other one, both have the same aftertouch. Velocity (how fast you press) is different and is nearly always polyphonic.
    – Tom
    Jan 12 at 15:55
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    @Tom, thank you, this is understood -- i.e. piano with aftertouch will send aftertouch. My concern/conclusion from PiedPiper is there DP out there with "hidden" aftertouch, such that you don't get aftertouch when playing DP itself but when you attach a synth to it you will get aftertouch because DP will send this info. For example Kawai MP7SE is either not good DP or it has aftertouch "hidden" because specs does not include this info. And to reverse it -- DP without aftertouch will cripple the setup DP+synth because it does not have such info, and thus won't send it. Jan 12 at 16:43
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    @Tom, no-no, I will clarify this, I am worried in reverse -- what I will loose, not what I will have too much. I want all features from the synth, I am asking what I can potentially miss when connecting DP like the mentioned ones. Jan 12 at 17:44
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    @greenoldman Neither the Kawai ES 120 nor the Korg D1 have aftertouch, so there's nothing to lose.
    – PiedPiper
    Jan 12 at 19:30

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