If you're shopping for a new MIDI keyboard controller, you probably have done your research on what to look for in a good model. You also know what type of controller will fit your needs best. Before you head off to make a purchase, though, you should look into the most user unfriendly models out there.

Knowing which models are widely considered unusable will give you a good starting place for things to avoid, as well as an idea of what to look out for in other models. Here are three models to definitely avoid and why you should steer clear of them.

Edirol PCR50

The Edirol PCR50 is a compact, supposedly versatile keyboard controller. However, user reviews speak volumes to the opposite. This inexpensive model has been reported to have a toy-like feeling to it. From the keys to the knobs, the unit offers little in the way of sturdiness or stability.

Aside from the fact that users report the unit feels like it will fall apart at any moment, it doesn't offer any excellent features that make up for its structural deficiencies. Quite to the contrary, the PCR50 has simple components, like an alphanumeric screen, that provide the most basic level of performance.

To add insult to injury, many users have complained that the unit begins to die within months of purchase.

Behringer U-CONTROL UMX25

This entry level controller isn't marketed as anything excellent. Rather, it's offered as a straightforward, inexpensive solution for musicians with mobile needs. Unfortunately, like the PCD50, the UMX25 seems to interpret "mobile" as "flimsy". Users have stated that, while it's light and portable as promised, it is also incredibly ill made. On top of the poor construction, the keys are susceptible to bending (or breakage) by being pushed just a hair too hard.

If the quality of the unit wasn't bad enough, it's apparently nearly impossible to connect to a computer. Once you're successful, though, it works just fine ? aside from the bendy keys. The UMX25 also has a nasty problem of randomly transmitting no signal, which can be a problem if you need to use it.

Korg nanoKEY 25-Key USB MIDI Controller

Like the UMX25 and the PCD50, this controller comes up short on the quality construction department. Users complain about its poor quality, from the shell to the keys to the knobs, although some say it's a fair trade off considering the price. The keys are too small and incredibly easy to jam or pop off. While it's reported to be incredibly easy to set up and use in a pinch, the low quality of the keys make it hard to use accurately.

While the nanoKEY is a marketed as a portable unit, many users have reported a very bizarre propensity for breakage from simple usage. The USB connector is less than stable and prone to disconnecting at best or snapping the connector off inside the unit at worst.

The possibly most devastating problem is the difficulty of the initial installation, especially with Vista. The not-so-computer-savvy may box it up and return it out of pure frustration.