I am an operator of a C3500, I am not the owner, but I am the only person who has operated it since it was bought in 2017. Back then the firmware version was 1.42
From the beginning I have always taken care of the equipment impeccably, so it should be noted that there has never been any mistreatment or carelessness.
I am very happy with the sound of these mixing machines, but I have to be honest and question the durability of them, especially when compared to other brands on the market.
After about 240 concerts distributed over a period of 3 years and taking care of the material as much as possible, the faders of the C3500 surface began to fail, most of them remaining tremendously inaccurate. I have never had the feeling that there could be a software/hardware fader failure relationship. After requesting a quote from the technical service, it was €800 + VAT (shipping not included) to change all the faders.
My thought is that 240 concerts and taking good care of the material, is not even remotely enough to have to make a change of this magnitude. In any other brand, Digico, Yamaha, this happens, yes, I’m not going to say no, but at least after exceeding the figure of 1000 concerts!
In another order of things, I have also had severe problems with the stage racks, although their operation has been impeccable, they are extremely sensitive to the smoke from the machines that are used to create an atmosphere with the lighting. In the show that I usually operate with the C3500, this type of smoke is used (I clarify that in reasonable quantities and always being of high quality) and also the physical location of the rack is always on one side of the stage and in the back, this way always remains the farthest from the stage. Even so, it seems that the smoke from the show seriously affects the electronics in the racks to the point that it destroys them permanently.
At the end of 2018 a CDM48 was seriously affected by this problem, and all the electronic cards had to be replaced with a high repair cost.
A little later, in 2020, when the pandemic began, the CDM48 system was once again completely unusable due to the same symptom, smoke from the stage that everyone uses for lighting and, consequently, it cost more to repair than to buy a new rack. All of this is tremendously frustrating. The solution was to buy a new CDM64. From then until now, everything seems to work fine.
The point is that in any brand I have worked with, Digico, Yamaha, Roland, Soundcraft, Midas, I have never had this type of problem with smoke from the stage and with much higher numbers of concerts!
My experience may scare other users or potential buyers, and it is not my intention, because both the software and the sound of these tables are excellent, but Allen & Heath, in my humble opinion, should reconsider these weak points, so that in the future nobody will have problems of this type.