"We had These jams in Docklands in London that turned into The Russian Album, and Trevor Horn showed up one time. I knew him as a producer, but he told me he used to be a bass player in a ballroom-type show band before [he was in] Buggles. So he showed up, and he had a Wal 5-string bass. I said, 'Oh, that's cool: low B, great.' So I got one too, based on his recommendation, and I really like it. "My favorite thing I've done recently on it was the new Beatles record we've made ["Free as a Bird"], which is really cool." "I played the Wal [on "Free as a Bird"], and what I liked was I played very, very normal bass, really out of the way, because I didn't want to 'feature.' There are one or two moments where I break a little bit loose, but mostly I try to anchor the track. There's one lovely moment when it modulates to C, so I was able to use the low C of the 5-string-and that's it, the only time I use the low one, which I like, rather than just bassing out and being low, low, low. I play normal bass, and then there's this low C and the song takes off. It actually takes off anyway because a lot of harmonies come in and stuff, but it's a real cool moment that I'm proud of. That's my Wal moment." – Paul McCartney [on his Wal 5-String Bass](http://www.macca-central.com/macca-archives/bassplayer.htm) [Here](http://www.poster.net/mccartney-paul/mccartney-paul-photo-paul-mccartney-6206286.jpg) is a still photo from the event in the video.more
There is very little difference in tonal qualities for the Wal basses. They all feature the same circuitry that gives them their signature growl. The differences actually lay in the appearances between the MK 1, 2, and 3 bodies.
The MK 1 features short, stubby horns and a flat back end. They closely resemble a Fender Precision bass that has been squished bridge to neck.
The MK 2 features a much longer top horn but is generally the same shape as a 1.
The MK 3 features the longer horn of the MK 2 but also adds in a slanted back end behind the bridge, running from the strap peg inward and upward towards the players chest. The photo for this entry is accurate as being an MK 3 Wal.