As we all have mobile phones with us, the necessity of a metronome kind of disappears with metronome applications. However, there are difficulties with metronome apps: (a) it's not always on time (phone lags), (b) the phone output can be quiet (this is mostly not the problem), (c) it's hard to find an app with the same features as DB-90, and (d) your phone battery won't last with metronome always playing.
In my opinion Boss DB-90 is an amazing product. I've been using it for over half a year now. Every day for practice on a pad and on a drumkit. The sound coming out of the metronome's own speakers are loud enough (I don't play metal) to hear it when playing on a drumkit. It's also small enough to fit in a drumsticks case and take it with you on a gig (for warming up or even using it as a click source for a band).
Pros:
- Good quality sturdy housing
- Loud and clear sound (full volume in headphones is even a bit painful)
- It is very-very on time. Also, start/stop button works without any lag. You can synchronize metronome with e.g. loop station from your bass player/guitarist by clicking on a start/stop button.
- Multitudes of options on how to work with metronome: classical counting, speed trainer, couch etc. All are very good things to play with and develop time.
- can be attached to a normal stand (e.g. using a clamp you can attach it to a high hat stand), which is a bit ugly in my opinion, I prefer to throw it on a note stand
Cons:
- No hard case included, only a cover. That's hardly an issue, because it fits inside drumsticks case pocket in my case.
- No charger included for this price. Although any 9V 500mA power supply will work (costs 10 Euros). Note: I would not recommend using power supply, it's not always possible to find a power socket and metronome is required everywhere. I think, that might be why they decided not to include it in the package.
- It eats battery pretty fast. I practice 2-3 hours daily (sometimes 6-7h when the time allows), the battery lasts for around 2 weeks usually. Note: I just bought a pack of 9V chargeable batteries with a charging station. If you have a spare one with you, you are fine (also don't forget to change it before a show)
- When battery is out, the settings are reset
I don't think, it will break ever, but I would buy again if it does.