Are USB hubs any good?

The short answer is you really want a Multi-TT hub for this application, where 2 or more of your USB devices are likely 12 Mbit/sec. Search for "Multi-TT" on Amazon, Newegg or other sites to find these hubs.

Unfortunately, this important technical detail is rarely mentioned. Most hubs use a cheaper Single-TT design. The good Multiple TT ones are rarely advertised as having this feature, not even marked on the package. Sadly, most people have probably never even heard TTs, which is probably why marketers don't bother to tell you which design their hubs use.

You can check if your hub has this feature using the Windows Device Manager. Look for the words "Hub has multiple TTs" in the Advanced tab.

On Linux, the hub type can be checked with "lsusb -v | grep TT". I am not aware of any simple way to check on Macintosh, except the "USB Prober" utility which Apple publishes in their Xcode development tools.

TT stands for Transaction Translator. The details are complex, and fully documented in chapter 11 of the USB specification, which is a free download from www.usb.org. But in a nutshell, the TT converts between 480 MBit/sec from your PC to the slower 12 or 1.5 MBit/sec speeds.

Normally when you play those musical instruments, their controllers generate MIDI messages and pack then into memory buffers, which await the moment your PC requests the data. When your PC connects directly, it sends a message called an IN token to your instrument. Your instrument can respond to the IN token in two ways, either a DATA packet, or a NAK token to indicate no data. Your PC sends those IN tokens very rapidly, so the result is nearly instantaneous delivery of your musical events as MIDI messages.

However, when your 12 MBit/sec MIDI device connects through a USB 2.0 HUB, very different communication occurs, all at 480 MBit/sec. Your PC actually communicates with the Transaction Translator in the hub. It sends 2 messages. First, SSPLIT (Start Split Transaction) message is sent to the TT. If the TT is not busy, it sends an acknowledgement. Then the TT transmits the IN token to your MIDI keyboard at the slower 12 MBit/sec speed. Meanwhile, your PC is able to communicate with other devices at 480 Mbit/sec. Your MIDI keyboard can not tell if the IN token came directly from your PC or from a hub's TT. It does exactly the same thing as if connected to your PC. The TT inside the hub receives either the NAK or DATA response. While this is in progress, your PC begins sending CSPLIT (Complete Split Transaction) messages to the hub's TT. The TT replies with a special NYET token is the TT is still busy communicating at 12 Mbit/sec, or the NAK or DATA from your keyboard.

If you have both a MIDI keyboard and a MIDI drum connected, what happens if your PC wishes to send a SSPLIT message to ask the TT to communicate with the drums, but the TT is already busy communicating with the keyboard? With only a single TT, the hub may reply NYET to a new SSPLIT request, because it is busy performing the IN+DATA at 12 MBit/sec. You definitely don't want that scenario!

Multiple TT hubs have a dedicated TT on every downstream port (which you plug devices in). With multiple TTs, the hub is always able to accept a SSPLIT request, even when the other TTs are busy communicating other downstream devices. With only a single TT, your PC may end up waiting, even through there's plenty of 480 MBit/sec bandwidth, because the hub has limited ability to convert more than 1 message at a time between the different speeds.

This description glossed over many important USB timing issues the TTs handle, but the important point is USB 2.0 hubs can use two distinctly different designs. You really want to avoid the cheaper Single-TT hubs.

USB 3.0 & 3.1 speeds were mentioned elsewhere in these answers. But the TTs in hub never convert between the 5 or 10 gigabit speeds and 480, 12 or 1.5 speeds. Instead, USB 3.0 & 3.1 hubs operate as a pair of hubs. The gigabit signals have their own dedicated pins in the newer USB connectors, which connect to a hub that runs only at 5 or 10 Gbit/sec speed. Simultaneous 480 Mbit/sec communication occurs on the original pins, so 12 and 1.5 MBit/sec devices are converted to 480 Mbit/sec by TTs, but never to 5 or 10 Gbit/sec.

Also mentioned elsewhere is "low speed", which technically means 1.5 Mbit/sec in USB jargon, but may mean 1.5 or 12 Mbit/sec in casual conversation. 12 Mbit/sec is called "full speed" in USB terminology. The USB MIDI protocol, which is technically part of the "Audio Class Specification", uses "bulk" protocol (not the interrupt protocol, as claimed in another answer). The USB spec does not allow bulk transfer protocol for 1.5 Mbit/sec speed. So unless a USB MIDI device very grossly violates the USB speed, it will always be at least 12 Mbit/sec speed. USB MIDI may be 480 Mbit/sec speed, in which case the TTs don't apply. But the vast majority of USB MIDI products today are still 12 Mbit/sec speed.

So you really want to make sure your USB hubs are Multi-TT types, if you plan to maximize performance.

It's often a good idea to get a USB hub to extend one USB port into several other ports. Modern laptops are getting compact and have no more than two USB ports. Such a limited number of USB ports may not be enough if you want to connect multiple IT peripherals over USB. So, in such a situation, you may be wondering, do I need a powered USB hub? If you are thinking of getting a USB hub, then this article is there to help you.

Do I Need a Powered USB Hub?

Let’s learn what is a powered USB hub before deciding whether we need it. There are mainly two types of USB hubs – powered and unpowered. Both these types differ in the way they work. Powered USB hubs have their external power while unpowered USB hubs are bus-powered. Here, bus-powered means that the USB hub takes power from your PC or laptop to operate.

A powered USB hub is not needed when you only need the extension to connect low-power peripherals such as USB flash drives, keyboards, mice, or game controllers. An unpowered USB hub is more than enough for such devices. But, let's say you need to connect multiple external hard drives to your PC at once to perform a lot of data transfer work. Then, in this case, you will need a powered USB hub. External hard drives require more power than keyboards and mice. So, to connect many of them simultaneously, you need something that can keep them powered while reading and writing data.

You should also know that USB hubs are not limited to USB ports only. Modern powered USB hubs provide external connectivity with more ports, including LAN, USB-C, HDMI, card reader, VGA, and audio. Hence, the reasons for choosing the right powered USB hub may be vast. Based on the above information, you can now decide whether or not you want a powered USB hub.

Powered USB Hub vs Unpowered - Where Is The Difference?

Powered and unpowered USB hubs are not the same. There are some solid reasons which differentiate these two types.

1. Power Supply: Powered USB hubs come with their own AC adapters and can run on an external power source. They do not take any power from your laptop. While unpowered USB hubs take all the power from your laptop or PC.
2. Power Output: Every single USB port of a powered USB hub operates at a max power output of 2.5 watts. That means every USB port can deliver a max current of 500mA (0.5 Ampere). That much power is enough to power external hard drives, SSDs, and optical drives. But, in an unpowered USB hub, the power output from a single USB port gets distributed all over the hub. For example, if the unpowered USB hub has four ports, each USB port can provide a max current of 100mA. However, several unpowered USB hubs can provide you with 1 to 2 USB ports capable of delivering 500mA while keeping the rest of the ports capped at 100mA.
3. The number Of Connectivity Ports: Powered USB hubs run on external power and support multiple connectivity ports. See the 7 or 12-port Anker powered USB hubs as an example. So you can have a powered USB hub with more ports, while unpowered USB hubs are mostly limited to 7 ports only.
4. Price: Powered USB hubs cost higher as they provide more abilities to connect different big or small devices. While unpowered ones are cheaper for their limited power supply and connection.

Pros and Cons Of a

Powered USB Hub

Before you can purchase a powered USB hub for yourself, you must know its pros and cons, so that you would not regret it later.

Pros Of a Powered USB Hub

• Runs on their external power without bothering your PC or laptop for power needs.
• It can run most of its USB ports at a load of 2.5 watts max(5V x 0.5A = 2.5 watts).
• They can support power-hungry USB devices.
• They can support up to 12 connectivity options, including ports for display, USB, network, memory cards, audio, etc.

Cons Of a Powered USB Hub

• Powered USB hubs are more expensive than their unpowered counterparts.
• They need a separate mains power socket.

Conclusion

So now you know what they are used for. In this article, we have briefly talked about powered and unpowered USB hubs. USB hubs are a great way to power all your peripherals from the convenience of your desk. And if you plan to get a powered USB hub, you get more freedom while connecting multiple devices. We hope this article will help you to choose the right USB hub.

FAQ about Do I Need a Powered USB Hub

What is the point of a powered USB hub?

A powered USB hub is a device that allows you to connect multiple USB peripherals to your PC or laptop. It helps you to manage and organize them, as well as provides additional power for the devices that need more juice than standard USB ports can provide.

Are USB hubs worth it?

Yes! A USB hub is worth it if you want to keep all your USB devices on your desk. You can plug in multiple USB devices without relying on your laptop's USB port so that enjoy an easy and fast operation. However, avoid cheap off-brand USB hubs because they may damage your PC’s USB port by drawing too much power.

Why are powered USB hubs so expensive?

Powered USB hubs are more expensive than unpowered models because they come with an external power adapter. The power adapter adds to the cost of a powered USB hub, but also makes it more reliable as it can provide up to 2.5 watts per port, as compared to just 500mA from an unpowered hub.

Additionally, powered USB hubs usually have additional features such as over-voltage protection and surge protection like some Anker powered USB hubs which make them well worth the extra expense.