Welcome to the world of BluetoothMIDI — Wireless MIDI — BLE MIDI

The Truth About Bluetooth MIDI

Wireless MIDI? What about latency?

Thomas Gerbrands
19 min readJan 4, 2020


Many people (including engineers) who did not try Bluetooth MIDI assume a lot of things about latency with MIDI over Bluetooth.

MIDI is a serial based protocol that has been developed in the early 80s. It is not amazingly fast to begin with.

Bluetooth has been rapidly developing over the last decade. It handles a few megabits per seconds easily.

Therewith it is easy to say that MIDI over Bluetooth is capable of offering a professional low latency solution for musicians and producers. Both on stage and in the studio.

Roger Linn, the legendary designer behind the LM-1, MPC and LinnDrum, talks about WIDI Master and his MPE-based in Linnstrument by Roger Linn Design

Let me try to address some main ideas.

Bluetooth MIDI is not Bluetooth Audio and does not experience the same latency issues. They are two completely different technologies.

Latency is normal. It occurs in the human hearing and in the communication between an audio interface, computers, midi controllers, monitor speakers, and so on. Everything has latency.

MIDI only transmits data at a standard speed 31.25 kbit per second via cable. As a comparison, CME’s WIDI Bluetooth MIDI products using Bluetooth 5 go up to 400 kb/sec.

Conversion time is negligible. When is latency really audible by the human hearing? Can your link it directly to a specific part of your system? Or is it a cumulation of parts that are in your system?

WIDI Master + Genki Instruments Wave + Roland Juno-60 + MIDI

A tiny word on MIDI terminology
As you might know, the history of MIDI technology incorporates widely used terms as master and slave. Although the term master is not causing any real issue, the word slave can trigger undesired feelings and emotions to a large group of people.

In this article I’ll try my utmost best to change the terminology to a more modern form of communication.

That is why, with Bluetooth MIDI, we rather speak about central and peripherals when discussing Bluetooth connections. And with USB MIDI, we rather talk about hosts and devices. As the previously used MIDI terminology trivialise something quite horrendous.

Read this article for a better understanding. Let’s return to the fun part. Let’s talk about BLE MIDI and of course…..latency!

WIDI Master Review

Latency is just a number…
There are a lot of claims being made about latency and especially the ability of being able to really notice it as a human. Let alone link it to a specific part of your system. There are musicians who play their instruments based upon the limitations of that device. Latency can be just one of them. Therewith it becomes part of the deal.

Of course, latency is an important metric when it comes to music production and performance. Latency for Bluetooth MIDI does not stand upon itself. It depends on the environment and the connected devices.

One of the early adopters of WIDI Master is the real master: Jean Michel Jarre

Also, when you look at your entire system, it is complex for you as a musician or producer to pinpoint latency to a specific part of the system. What I mean to say is how are you able to say the latency you experience from your monitor speakers are caused by either MIDI communications or audio conversions? Or delays in translation by your operating system?

That is why I chose to keep this simple and not get stuck in a number. From my point of view, that number is not a given in every situation and therefore not something one should make its decision on. That would be a false simplification of the wireless technology (opinion).

In the end a proper musician can play with a stable latency. That is why jitter is also a very important metric. Especially when it comes to real time MIDI clock and sync purposes.

Introduction to WIDI in 1 minute

The difference between a MIDI cable and BLE MIDI
First of all, with Bluetooth MIDI latency is always a bit higher compared to a regular MIDI cable.

That said, you can question yourself if you would be able to distinguish WIDI Master from a standard MIDI cable in a double blind test. We have noticed that this will always lead to the same discussion about latency.

This discussion is quite similar to the one we have had in the start of streaming and the download days involving MP3s and WAV files. Or that one of the supreme quality of vinyl over anything else….it is ongoing, never ending and also very much part of the process of developing innovating technologies.

Bluetooth MIDI and latency on iOS & Mac
When talking about latency of the WIDI technology you’d have to keep in mind we measure latency by using an oscilloscope. It is measured between two WIDI Masters. The lowest outcome is 3ms. The highest is 10ms. We measure an average on 5ms to 6ms.

The latency on iOS and macOS came from the limitation of the Bluetooth connection interval. This is a rule set by Apple. On iOS it is 11.25ms minimum. On macOS it is 7.5ms minimum.

Please note that these are “intervals” and not “latency” metrics. These intervals can cause latency and jitter due to the limitation of that buffer.

WIDI Master + Korg Kronos + Kronos Controller App

The main reason for this limitation is because Apple has no intention to place Bluetooth MIDI at a high priority compared to other more common services. Thus if you connect any Bluetooth MIDI device with iOS or macOS, you cannot get the connection interval lower than above mentioned limitations.

If we break away from the iOS and macOS Bluetooth connection interval, two WIDI Master can set itself with shortest interval that Bluetooth 5 supported. In this way, we can reduce the latency significantly.

To bypass limitations of iOS and macOS an interesting option is WIDI Uhost. It will also allow you to pair automatically, instead of manually setting your BLE MIDI connection every time..

USB MIDI + BLE: https://www.cme-pro.com/widi-uhost/

Make decision based on real life experience..
I consider that you are perfectly capable of making your own decision. If latency is the only metric you make your decision on, and cables work for you, you just stick to your cables. Or at least wait until you and your musician friends can test our Bluetooth MIDI solution in real life at your local dealer. That is fair enough, right?

In the other hand, if you are interested in getting rid of those cables, advanced midi connectivity, app based cable management and wider range plus freedom of movement with midi (like on stage), then Bluetooth MIDI solutions might be of interest for you.

Jordan Rudess & CME WIDI Master

Here are some facts:
With the current BLE MIDI solution as developed with CME’s WIDI it is possible to reduce latency between two WIDI devices using BLE 5 to 3ms. When looking at a stable jitter it is considered that a 4–6ms latency is more accurate.

If you want to find out more about WIDI Master and latency: go read this!

Bluetooth MIDI is the standard as developed by Apple and approved by the MIDI Association already 5 years ago. Many industry icons including engineers from Moog, David Smith, Yamaha, Roland, Korg, Apple, Google, Microsoft etc. worked together to verify this standard.

Learn more: https://www.midi.org/specifications/item/bluetooth-le-midi

There are many professional keyboards and synthesizers already equipped with Bluetooth MIDI features. Tens of thousands professional musicians use it on the stage or in the studio for over several years. If you search on Google, you can find many examples.

For instance: https://www.roland.com/uk/products/ax-edge/specifications/

CME implemented this Bluetooth specific central role MIDI technology in the renowned Xkey Air (2015 www.xkeyair.com) and WIDI BUD (2016 www.widibud.com).

Up until this day CME never received complaints by professional musicians about instability of connections and latency. Therefore MIDI over Bluetooth has already been approved over the time and proven to work by over 4 years of usage.

WIDI Master Review (Reviewer Initiated)

What is the big challenge?
The real challenge is to convince people and allow them accept the innovation. It might be out of their comfort zone and conflict with everything they know and learned. It takes time.

So if you arrive in a discussion about latency, feel free to forward them to this specific blog to get a better understanding: https://www.cme-pro.com/how-to-connect-two-midi-hardware-via-wireless-bluetooth-midi/

Or forward them to this Facebook group to join the discussion and contribute: https://www.facebook.com/groups/cmeprofans

or — if they really know it all and have years of experience as an engineer — welcome them to join the MMA https://www.midi.org/join-the-mma

Here they can contribute their professional knowledge to allow the entire music industry and all musicians to benefit from it by improving the MIDI standard.

Moog, MMA and Roger Linn about WIDI technology

CME WIDI Master VS Yamaha BT-01
Of course CME is not the only company that is into the game of wireless MIDI adapters. Looking more specifically there are others to be found. One of them is the Yamaha BT-01.

The Yamaha BT-01 is a OEM model of the Quicco M1. This means it is exactly the same product, only it carries another brand. When comparing WIDI Master with BT-01 the main difference is that the BT-01 implements Bluetooth 4 (BLE4) compared to WIDI Master implementing BLE 5.

Of course, with the pace consumer technology develops, the difference in performance between BLE 4 and BLE 5 is quite relevant. Leading to lower latency and wider range performance for WIDI Master.

Furthermore BLE 5 will allow the one-to-multiple feature. Something that will be available for WIDI Master after updating the firmware.

Also, Yamaha only implemented Bluetooth Peripheral. Therefore you need a host operating system to function. You would need to use a mobile device or computer to benefit from the wireless capabilities of the MD-BT01

This is one of the unique selling point of WIDI Master. CME’s solution can function fully standalone. Therewith you can pair two vintage synths or your keytar with a keyboard. Without computers.

This is possible because the WIDI Master can fulfil a central role. In Bluetooth terms that means it can switch between the central role and the peripheral role. It can function as a host to any other device.

This means that you now can connect all your MIDI hardware directly to each other. Without a computer. Without cables.

CME WIDI Master VS Roland WM-01
End of September 2020 Roland entered the Bluetooth MIDI adapter world as well when launching its WM-1 and WM-1D. As CME is just a small company, it is great for the wireless MIDI community that industry leaders such as Roland and Yamaha are interested in this niche market.

Looking at the WM-01 compared to the WIDI Master we see the latency performance is quite similar looking at 3ms best case between two adapter devices.

The main difference is that Roland WM-01 has a non-detachable design and is battery powered. Compared to WIDI Master being powered by the MIDI OUT of the device it is attached too and a smart design feature allowing you to detach both connecters. This is especially useful for MIDI devices with only MIDI OUT ports such as many keytars and electronic wind instruments.

Another important difference is the specified range and price. Although Roland is new to the market compared to CME, they report a 10 meters range against 20 meters by CME.

Also, another difference comes in the price where CME’s WIDI Master is US $ 10 to US $20 cheaper than its competitors by Roland.

If you are interested you can find a complete comparison here!

Shook created this retro video ad for WIDI Master! It brings back the fun(k)!

The Power of the Community
The best proof comes from the community itself. If you are interested on how real people use WIDI technology in a wide range of MIDI setups, feel welcome to learn more through these blogs:

Also there are many active community members already making videos of their use case. Watch for instance this one by Defcon Clark taking you into the world of guitar pedals and MIDI. In 3 minutes you see what you can do.

What is next in the world of Bluetooth MIDI?
After the successful introduction of WIDI Master, selling over 15,000 units in the first 6 months, many MIDI enthusiasts requested a more versatile solution for all those neat MIDI devices and the wide variety of MIDI jacks available.

Basically the majority of the request can be divided into two main groups:

  • TRS MIDI solution for guitar pedals, boutique style synths and those slim MIDI controllers.
  • External power option for unpowered MIDI OUT and MIDI IN that are not compatible with WIDI Master 5-PIN MIDI DIN solution.

That is why WIDI Jack was designed. In essence, both WIDI Jack and WIDI Master carry the same WIDI wireless MIDI technology. Therewith the firmware and features are really close related.

WIDI Jack vs WIDI Master
The main difference is that WIDI Jack will allows you to connect TRS 2.5mm (1/10") MIDI , TRS 3.5mm (1/8") MIDI, TRS 6.35mm (1/4") MIDI and 6-PIN MINI DIN MIDI devices to your wireless MIDI network. To cover an even wider range of applications, you can switch between type A and type B when it concerns TRS MIDI.

Furthermore, WIDI Jack offers an external power solution via USB-C. This way you can add an external power bank to connect with unpowered 5-PIN MIDI ports and even devices with only MIDI IN.

In its essence WIDI Master and WIDI Jack are exactly the same products. They carry almost identical firmware. The main difference is its application and your use case.

Upon request, we also added a small magnet. This way you can simply stick WIDI Jack on the casing of your device.

Last but not least, another difference that is noticeable is the form factor. As WIDI Master is really an adapter, WIDI Jack is a tiny interface. Its size is only 40% of the volume of your Apple AirPods in the charger casing.

WIDI Jack comes as a bundle option with 4 different types: www.cme-pro.com/widi-jack

Enter the future of MIDI
The fun part about Bluetooth MIDI is that its development speed goes way beyond what you expect. This is mainly caused by the fact that it is a highly anticipated consumer technology.

Please note that Bluetooth MIDI and Audio over Bluetooth are totally different. The latency is one main point where this difference is made. That said, due to the priority of Audio over Bluetooth for many top tier technology manufacturers, the Bluetooth technology is getting better at a high pace, every day.

As Bluetooth being a technology that is perfectly integrated in today’s mobile devices and operating systems, the fun part is in the user-friendliness from an app or other piece of software you carry around in your pocket.

That is why the firmware of WIDI is constantly improving. This goes hand in hand with an improved app for both Android and iOS.

One Single WIDI device

With WIDI you can pair your MIDI instrument with iOS, MacOS, Win10 (v1909 or higher) and Android (8 or later). With iOS and MacOS Bluetooth MIDI is integrated and you can manually pair with WIDI devices.

With Windows and Android, it will fully depend if your music application runs the Bluetooth MIDI driver. WIDI technology is fully compatible with the latest Windows UWP API.

Unfortunately the specific MIDI driver causes so many issues for software developers, many of them did not implement the latest UWP API as they keep using the old drivers.

That is why it is a bit more challenging to pair with Windows PCs, except if you run Bandlab’s Cakewalk or Steinberg’s latest Nuendo or Cubase. These software programs do implement the UWP API and are natively compatible with Bluetooth MIDI.

If your music application does not support BLE MIDI natively, is strongly recommended to look into (free) MIDI bridge apps such as MIDI BLE Connect (Android) and MIDIMTTR (iOS) when working with mobile devices and operating systems.

These apps bridge traditional MIDI with the onboard Bluetooth technology. Like a virtual MIDI port. This makes any music app that can communicatie via MIDI eligible for Bluetooth MIDI, thus WIDI.

Adding on to this, for Windows 10/11 computers, the latest Korg BLE drivers is compatible with WIDI too. It is freely available and arguably the best solution for software that is not compatible with the latest UWP API on Windows computers.

That said, to optimise your wireless MIDI performance it is recommended to take a look at WIDI Uhost and WIDI Bud Pro.

You simply bypass the onboard Bluetooth MIDI of your operating system. This makes auto-pairing available and the best latency and jitter performance currently possible…

Consider this, if you are on stage and your onboard Bluetooth of your iPad looses connection with your WIDI, you have to manually reconnect.

With two WIDI devices, the changes on disconnecting are seriously smaller. Besides this, in the unlikely event you do loose connection, the WIDI devices will automatically reconnect instantly….

Two WIDI devices: Go DAWless. Without computers. Without cables.

Two WIDI devices will pair automatically with each other. They will function without a host. This means you can simply power them up, and they will find each other and pair. You will be up and running in no-time.

With the latest WIDI firmware (v0098 and up) and WIDI App (v1.2.XX and up), you can set your personal preferences.

For instance you can optimise your setup for latency performance. Or go for optimal jitter performance. It completely depends on your use case.

Furthermore, you can set the power level allowing MIDI instruments that are battery powered or have low power modes, to still deliver the juice for your WIDI device. This is particularly useful for electronic wind instruments and similar portable MIDI devices.

Also, 2 WIDI devices automatically switch between the central and peripheral role. This is Bluetooth wording for the things we used to know in the world of MIDI as master and slave. Also, they transmit MIDI messages bi-directionally. This way 2 WIDI devices that are paired function completely as connecting two MIDI cables.

You can now transmit any kind of MIDI message over air. Including long Sysex and timestamp. You simply power up your WIDI devices, and the rest is fully automated.

Simply enjoy going wireless with ultra low latency performance.

Group Connectivity: MIDI Thru and MIDI Merge Groups

When you go into more complex setups with wireless group connectivity, you need to educate yourself to fully benefit from these features.

For instance, your group always has 1 central. Besides this you can add up to 4 peripherals.

This means you need to manually force the role of your WIDI devices first. Next you create the group in the user-friendly app and save that. When you reboot your devices, all settings are loaded by default.

As communication is duplex, you actually create a MIDI Thru or MIDI Merge functionality. With duplex we mean that communication is bi-directional. You can talk in two ways between your devices.

In short. this means that with this firmware (v0098 and up), you can bypass MIDI interfaces, MIDI merge boxes and MIDI Thru boxes. You now can create the following wirelessly:

  • 1-to-4 MIDI Thru — Group of max. 5 WIDI devices
  • 4-to-1 MIDI Merge — Group of max. 5 WIDI devices
Learn more about group connectivity via BLE MIDI — 1-to-4 MIDI Thru and 4-to-1 MIDI Merge — https://www.cme-pro.com/public-beta-test-ios-widi-app/

Multiple groups simultaneously

You can create groups starting from 2 WIDI devices. You can have multiple WIDI groups to build a complete wireless system with automatic setup. This means, you create the group step-by-step first via the WIDI App. And when it is saved, it connects instantly upon reboot.

This way, you can fully automate your advanced MIDI settings by setting your different connections by default via multiple groups. This goes for instrument to instrument pairing to groups of max. 5 WIDI devices. And they can function besides each other as well. This way, you can manage your virtual cables and set automated connection by default.

Get it. Set it. Enjoy it!

1-to-4 MIDI Thru // 4-to-1 MIDI Merge

Limitations of Bluetooth MIDI groups

When you set a WIDI group, you create 1-to-multiple or multiple-to-1 routings. In other words, all bandwidth will go through one single central device. That is why one group is also limited to 16 MIDI channels.

While in a 1-to-1 connection latency and jitter are not an issue, even in the case of dense realtime clock and control messages, in the groups case you will reach the limits of what you currently can do with Bluetooth MIDI.

Bluetooth is a non-realtime packet based protocol. It uses automatic error corrections. Basically, it will resend data that can interfere with the realtime data transmission of MIDI clock.

In the table below you will find the BPM variation in groups versus direct. As you can see, the variation (jitter) increases as the BPM increases. This is similar to a wired situation.

Also, the jitter (in BPM) is higher in group mode compared to the direct one-to-one connection.

BPM variation: Group vs One-on-0ne

Because MIDI is a serial protocol, if you send more MIDI data on top of this, it will impact the reliability of clock.

Keep in mind, this also happens in wired MIDI and is certainly less of a problem in a 1-on-1 wireless connection. It can become a problem in groups settings.

That is also because in group mode a tiny bit of latency is added to ensure a more stable jitter. In many cases you will not notice the difference. In some cases you certainly can.

Group auto-learn

At the other side the WIDI firmware keeps evolving. The latest addition is group auto-learn.

As WIDI groups can be manually set via WIDI app, with group auto-learn, your central WIDI device can automatically detect up to 4 BLE MIDI peripherals in the same environment.

This means, it can also add non-WIDI devices to your Bluetooth MIDI group. So, Bluetooth MIDI devices from Korg, Roland, Yamaha, and Roli can be part of these groups too.

Group Auto-Learn

What about USB MIDI?
As always, you are right. This question cannot be more valid. The missing link is USB MIDI. That will be delivered by two product named WIDI Uhost and WIDI Bud Pro.

With these 4 first members of the WIDI family, you can seamlessly integrate all your MIDI devices into one wireless network.

What is WIDI Uhost?

WIDI Uhost is is in its essence the wireless MIDI USB host for your all your USB MIDI device. You can use it as a MIDI USB dongle for any PC, tablet or smartphone. With WIDI Uhost you can simply add Bluetooth MIDI to your operating system.

Basically, WIDI Uhost covers three main use cases:

  • Solution 1: Make your USB MIDI controller go wireless by adding WIDI Uhost via USB-C
  • Solution 2: Add Bluetooth MIDI to many MIDI instruments that can operate as a USB host device. Like the Korg Kronos.
  • Solution 3: Add Bluetooth MIDI to any operating system (Windows, Mac, Chrome, Linux) without having to upgrade your PC, tablet or smartphone and even bypass the Bluetooth MIDI limitations of iOS/MacOs.

In other words, WIDI Uhost can be your wireless solution for:

  • USB MIDI to Chrome OS / Linux / Windows / Android
  • USB MIDI to Bluetooth MIDI
  • USB MIDI to iOS/macOS

What is WIDI Bud Pro?

CME released the legacy WIDI Bud that carries Bluetooth 4 technology around 2015. It could operate as a Bluetooth central solution. Basically, it allowed Xkey Air users to communicate with any operating system.

While the new WIDI Uhost is an all-in-one solution for multiple use cases, WIDI Bud Pro is more or less the successor of WIDI Bud. In its essence, it functions as a Bluetooth MIDI super dongle for computers and smart devices (USB hosts).

Looking at WIDI technology, WIDI Bud Pro and WIDI Uhost both offer latency performance as low as 3ms with 20m (65 ft) reach without obstacles. Also you can create wireless MIDI groups and benefit from personalised settings via the WIDI app. Like optimise for jitter performance.

This is different compared to the legacy WIDI Bud. As this solution embedded Bluetooth 4 and could function only as a central device. Today’s WIDI solutions can automatically switch between the central and peripheral Bluetooth connection role.

The main differences are the form factor. While the WIDI Bud Pro has the size of a small USB stick, it is fairly larger compared to the WIDI Bud. This is because the WIDI Bud Pro incorporates a stronger antenna delivering twice the reach.

The main difference between WIDI Bud Pro and WIDI Uhost is the application. Basically, WIDI Bud Pro is a one-case solution for bus powered USB host devices. It simply ads advanced wireless MIDI to your computer or other USB host with a USB A port.

How will WIDI Uhost work with my bus powered USB MIDI device?

Here comes the little trick of WIDI Uhost. Basically, WIDI Uhost offers three ways of operation when it comes to power supply:

  • WIDI Uhost can be powered via USB-C via all familiar and traditional power sources. Think of bus power, USB power supply and USB power banks.
  • When your MIDI device offers a USB-A slot as a USB host, it will also power WIDI Uhost.
  • You can add external power via the secondary USB-C port for MIDI device that solely offer USB device connectors (peripheral, USB-B or micro-B slot).

The external power option will power WIDI Uhost. Plus WIDI Uhost can pass 500mA to power your (bus powered) MIDI device which is connected to WIDI Uhost.

That is how you can make any bus powered USB MIDI device go wireless….

Uhost Cable Solution for Standard MIDI Controllers

In other words, with the right cable(s), WIDI Uhost is the 3-in-1 wireless solution for all USB MIDI devices. Including computers, mobile devices, USB MIDI controllers and USB MIDI hardware.

What can WIDI do for you? Well….

Visit this page!

Bluetooth MIDI & MIDI 2.0

While MIDI 2.0 only exists on paper, you can already find much detailed information about it as shared by the MIDI association publicly.

One thing we do know is that MIDI 2.0 needs bi-directional communication. Like USB MIDI delivers. And Bluetooth MIDI as well.

Although backwards compatibility between MIDI 1.0 and MIDI 2.0 is a major point of attention, it is possible that traditional DIN MIDI and TRS MIDI devices will encounter some issues.

Why? Because those terminals offer solely 1-way communication. Think of it. On your MIDI instrument or MIDI interface you have separate ports for MIDI IN and MIDI OUT.

This does not exist for USB MIDI. It is only one terminal. That terminal offers 2-way communication (and much more).

Here is where Bluetooth MIDI comes in. Because when you add WIDI Master or WIDI Jack to your 5-PIN DIN or TRS MIDI terminals, you create a bi-directional solution.

Consider how useful that will be in the near future…

And then think what it will bring you when you can hook up groups of instruments, and easily add your music apps and software, wirelessly…

No matter if it is USB or TRS or DIN. No matter if it one of the different terminals within that segment.

That will mean the end of those complexities and the beginning of advanced MIDI management via a simple app….

The best is yet to come.

Always. One Step. Ahead.

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This blog is constantly updated with the latest developments. Therewith it is a dynamic documentation for Bluetooth MIDI Enthusiasts.