Rdio takes on Spotify with freer free option

Subscription music services aren't all the same, but they're similar enough that it's becoming increasingly important for companies to figure out a way to entice users into trying out a limited version of their service so they can hook them on it and convert them into paying customers. This freemium model has worked well for Spotify and now Rdio is upping the ante with a free streaming offer for PCs that's also ad-free.

We had to read the fine print to figure out just how free this offer is, but here's the basic deal: you get full access to Rdio's catalog for streaming full songs on your Mac or Windows computer. You don't need to supply a credit card to get going; only an e-mail address or a Facebook account. While the Facebook connection is optional, the company says that with Rdio's full integration into Facebook's Open Graph platform, "anyone on Facebook can instantly share and play any song in the News Feed, Ticker, or Timeline."

So what's the catch? Well, the free streaming isn't available on mobile devices, and there is a usage limit. What's the limit exactly? Well, the company wouldn't tell us where it draws the line but apparently it's based on your user habits--or as Rdio's CEO Drew Lerner says, "it's dynamic."

Austin Carr over at Fast Company explains it like this:

The company will track how much usage it takes to convert a free user to a paying customer. That means if a freemium user barely takes advantage of the offer from month to month, Rdio is less likely to limit usage--there's still the opportunity for he or she to get addicted to the service. But if a user continues to max out usage each and every month, it's clear that user is not so likely to become a paying customer.

That all sounds pretty mysterious--and it is--but at least you'll get an idea of how much streaming time you have left by looking at your "customized meter" at the top your profile page.

As for Spotify, it offers 6 months of free ad-supported streaming in your PC, then caps it at 10 hours of use a month after that. Both companies offer very similar pricing structures on their paid plans, though Rdio offers a deal on family plans.

Here are your pay option choices:

• Rdio Web ($4.99 per month): unlimited access to millions of songs from a browser or desktop.
• Rdio Unlimited ($9.99 per month): unlimited Web streaming and unlimited mobile streaming on smartphones, iPad, Sonos, and Roku, as well as wireless syncing to listen offline.
• Unlimited Family: 2 Unlimited subscriptions for $17.99 per month or 3 Unlimited subscriptions for $22.99 per month.

We've been using both Rdio and Spotify and both have their strengths. While Spotify has the bigger catalog with 15 million songs vs. Rdio's 12 million, a lot of people think Rdio makes it easier to discover new music.

As always, let us know in the comments section why you like one service over another (and don't feel limited to Spotify or Rdio).