Jennings (1978-) was born in Canada, has been based in Paris since 2002 and is well established in Europe for his work with Dhafer Youssef, Nguyên Lê and several of his own groups.
As a child, he played classical guitar and recalls that his parents would often find him playing ‘upside down’ and decided to buy him a left-handed instrument. In junior high school, Jennings played a right-handed electric bass ‘poorly converted’ to be left-handed. Soon after, he attended a specialised music school and began taking lessons on double bass, which he had re-strung straight away.
Jennings recalls that his first double bass teacher wanted him to ‘play right-handed, like everyone else’, but that he and his parents insisted that since he had ‘been playing a guitar-like instrument for five years, [it didn’t] make sense to change’. In hindsight, he has mixed feelings about having made that decision, contrasting the difficulties of travel with the advantages of always having his own instrument.
He notes that, even for right-handed players, it has become the convention to borrow basses on tour, but that there is ‘no standard like there is with classical pianos’. Jennings also observes that what constitutes an appropriately playable instrument is ‘too individual’, and that a ‘setup’ that is ideal for one bassist may be ‘a nightmare for another’.
Jennings has some experience of playing idiodextrously:
“Actually I always play backwards at jam sessions and it’s become like a kind of game. I got tired of going to jam sessions and bringing my bass for one song… so I started… to try to play a couple of songs backwards… And actually I love it because I’m totally enthusiastic to go.”
On the physicality of playing idiodextrously, Jennings’s first observation is that for ‘the fingering hand, the heavy strings are ‘actually in a more convenient location’. He notes that the asymmetry of the bass means you ‘get less sound and less low end than if someone plays the same instrument just standing on the other side’. He acknowledges that ‘to a certain point you can compensate’ and ‘figure out how to pull out the sound of that instrument’, but feels that the structural imbalances are ultimately limiting.
Jennings notes that for someone who only occasionally plays idiodextrouly, ‘you have to change the way you’re playing’ to do it. He suggests that playing up and down one string has increased appeal, since it avoids having to remember the inversion of pitch in the reversed string order.
Jennings likens the conceptual challenge of trying to play idiodextrously to an English-speaker using ‘a computer with a French keyboard’:
“You’d have to look at the keyboard a lot, and then every now and then you kinda take some risks and sometimes it works and sometimes you would type where the English keys are a little bit. It’s exactly like that actually.”
Jennings considers that as a consequence, ‘you find different things’, primarily because the landscape of the double bass ‘presents itself differently’ to the idiodextrous bassist:
“Note choice-wise, it makes you see different things. It’s a balance between playing something you know, which would mean basically transposing something I play on my bass normally… and taking risks and searching stuff that feels good that way, that I wouldn’t normally find.”
 In 2004, luthiers Tom and George Martin built a custom left-handed bass for Jennings, which he named Karla.