Castiv Guitar Sidekick Hands-On Review

It’s pretty amazing to me how many guitar apps have made their way to the iTunes App Store. Just by searching “guitar” under apps, there are hundreds, if not thousands, of apps related to guitar. These include tuners, tab software, chord charts, metronomes, chord libraries, and much more.

It makes sense then why Castiv decided to create the Guitar Sidekick. This mount attaches to your guitar and mounts your iPhone or any other mobile or portable device to your guitar.

Castiv was so kind to send me one to try out. Here’s what I think.

First Impressions

I really like the idea of this device. I have an iPhone and I use it a lot for my music stuff. This device would work great with my Griffin GuitarConnect cable. Sometimes I don’t always have the convenience of setting my iPhone somewhere safe, like on a table or stand in front of me, so to be able to securely attach it to my guitar is a cool idea.

Mounting the Guitar Sidekick to my Guitar

The Guitar Sidekick comes in three parts: (1) the “Harpo,” which is a metal and rubber piece that clamps onto your strings, (2) the cap, which is a plastic piece that secures the Harpo shut, and (3) the mount which attaches to the ball on the end of the cap piece.

When I first opened up the packaging and got all the parts on the table, the “Harpo,” which I’ll refer from now on to as the clamp, seemed like it was glued shut. I had the most difficult time getting it to unstick itself. I had to use quite a bit of strength to pry it apart. Needless to say, I eventually got it opened up.

The instructions that come with the product are very detailed so I went ahead and mounted it to my acoustic guitar. It took me awhile to figure out the best way to attach the clamp around the strings. In the following picture, you’ll see where I ended up putting it.

Castiv Guitar Sidekick

Unfortunately, it was a bit of a clumsy process to trying to attach the Sidekick. You have to get it right underneath the strings on your headstock and then pinch the clamp together tight enough with your fingers to get the cap on the end of the device. After a few minutes of trial, I was able to get the cap on the clamp although I had to pinch the clamp together pretty hard around the strings. Maybe with practice I’ll be able to get it installed a little faster.

Having the clamp around the strings like that did not effect the tuning of the guitar or the sound of the instrument, which was great.

While the product is advertised to work with acoustic, electric or classical guitars, it’s not guaranteed that this will work on all guitars. I tried used the Guitar Sidekick on my Gretsch Electromatic electric guitar, and the clamp would not fit in the gap between the strings and the headstock. If you have a telecaster or stratocaster electric guitar, it might work okay. Pappy posted a review of the Guitar Sidekick on his blog the Fifth Fret and it looked like he was able to get it attached to his telecaster with no problem.

Using the Guitar Sidekick

Once I was able to get it attached to my guitar, it ended up being a pretty neat device. I was able to pivot and adjust the position of my iPhone with no problem.

The Guitar Sidekick includes a free lite version of the program MP4TABS. I’m not really sure what this program does because there isn’t a very good description on the website about it, and the program download is for Windows only users. I’m a Mac OSX user, so I can’t install it. Bummer. It’s kind of weird to me that the product would be marketed towards Apple iPhone users and not have Mac OSX compatibility. Not a good move there.


Overall, it’s a cool idea, but not as well executed as I would have hoped. I think if the clamp were a bit thinner it might be able to work with nearly every guitar. I wish it was easier to install and didn’t require so much strength to get the cap over the clamp to get it to stay shut. I also wish they had Mac OSX compatibility for their tabs program.

If you have an extra $29.99, it might be a fun toy for you to play around with. Once and if you get it attached, it works as you would expect. If you have a lot of guitar apps on your iPhone, this might be a nice tool for you to have.

About Brett McQueen

Brett McQueen is a musician, songwriter, and the founder and editor of Guitar Friendly and Ukulele Tricks. Learn more about him here and follow him on Twitter at @GuitarFriendly.