Flamma FC02 Reverb

I needed a affordable reverb on short notice because the springreverb in my Fender Blues deLuxe died and I had some gigs coming that required a reverb.
This Flamma seemed to do the job and I choose it over the two TC Electroninc pedals that are even cheaper because of it's small size. It just fitted! So I ordered it and it arrived right on time. Well, it did the job (I only used the "plate") and it's nice to have it, just in case. Now I will put it on my "rehearsal pedalboard'. It's not bad at all and with some tweeking it sounds fair, but the pedal makes some strange low "mumbly" sounds for say a second when switched on. Not very loud and nothing you will hear while playing, but still...