Many people think that playing the bass accordion is just like playing accordion, but with lower notes. They also think that in an accordion ensemble you just have to find a volunteer to play the bass accordion and every accordion player should be able to do it and do it well, provided they can read bass clef.
The reality is very different. The bass part sometimes represents a plucked double base or bass guitar and is thus "pizzicato". Sometimes it is like organ. Sometimes it is double base "arco" (played with a bow). The arco works best on the bass accordion: the sound starts slowly, then increases in volume and resonates after the bow leaves the string. On the bass accordion it is the same: sound comes up slowly, and when you release the key or stop pulling or pushing the bellows there is a "growl". So this is easy. Playing "pizzicato" is the most difficult. You need to start early and with force to get the note to sound quickly, and then you reduce force to create a decay. Starting early is hard, and even harder when the notes are played quickly. You need to focus to start each note early without playing too fast. Few bass players can produce a credible pizzicato performance.
But the most difficult part of playing the bass accordion is in predicting how long it will take for a note to sound. A very low note may have a delay of 0,2 or 0,3 seconds (longer if you have registers and play the L reed only), but if you repeat the note it will start almost instantly. And if you try to play "legato" you have to press the each key quite a bit early because notes take longer to start when the previous note is still using air. Often I find that when I for instance have a note that plays for 4/4 and should be followed by another note that plays for some time, the key or button for the second note may have to be pressed 1/8 before its time (and sometimes even more) so that it sounds fully exactly when the previous note ends. Judging the required overlap really take a lot of training to master. Similarly, when you play a long note and a short note should be played while the long note continues, you need to play the short note much earlier than the score indicaes because the long note that's playing robs the short note from air and makes it start later. Such problems all disappear when an accordion plays notes that are two octaves higher... and accordion players can do it those two octaves higher quite well and fail miserably on the bass accordion.
I play the bass accordion in the Dutch Symphonic Accordion Orchestra, and often have quite difficult bass parts, but fast notes are not the biggest challenge. It's the very low notes (in L register) that are the real challenge, and especially getting them to play exactly when the conductor expects them to be played. (With pizzicato that's right on time, and with arco that's with a slight delay, just like it is with a double base.) The most difficult time I had was during Covid, when we were forced to play with 1.5 meters distance between all players. I ended up sitting at about 10 meters from the conductor and had to make sure the sound reached him exactly on time, so everything had to be played a bit earlier than under normal circumstances...
