I purchased this reverb unit and it does work reasonably well as a spring reverb and also the room effect works reasonably well. The shimmer effect I will probably not use, but the shimmer was not the reason why I went with this unit. While it is reasonable, the unit I have gives out very faint crackles with both high and low volume settings on the guitar, more with chords than single notes when the unit is operating as a spring or room reverb. These crackles are also random and I do not get this with the pedal effect switched off. I tried with more than one power supply. However the build quality and the materials used are both very good. Jack plug sockets very secure and give good connections with the cables. Overall the unit is well made, but the sound quality although it is alright, it is lacking what I would call professional standard. J Maltson.