I built a pair of M-125 monoblocks in December of 2017. They were to be my weekend amps where I could just sit down and listen. However with 3 kids, weekends are just as busy as weekdays, so they probably have less than 30 hours on them. They both consist of K120 output tubes, Nos Mullard signal tubes, 5ar rectifier, the yellow page rectifier diode mod and the time delay relay board. I check the bias whenever I manage to find time to listen and its always been rock steady and have never had any issues with the amps. They have also never been played at high volumes as it's always been late night listening. I now am retired and plan to listen a lot more. Our line voltage varies here from anywhere between 122-125v so have always been careful to listen when the voltage is on our low end. So here is what I am in the process of:
I have on order a pair of Weber WS1 rectifiers with thyrister.
A gfci installed to shut the amps down permanently when a power interruption occurs.
A 2000 watt peak variable transformer that came today.
I have some questions regarding the variable transformer if I may. I set the output tonight at 118 volts and verified it with my volt meter. So will I need to recheck the transformers output at every listing session as the line in voltage varies to maintain the set 118v out? Or will the variable transformer maintain pretty much 118v on the output regardless of my varying line voltage? Is it safe to leave the VT turned on all the time at my dialed in voltage when not using the amps, or should it be dialed back to zero and then turned off? Can it be shut down safely at the 118v setting without dialing it back to zero and then turned on again at a later date? I have no issue shutting it off but have read that it should be dialed back down to zero beforehand and it seems tedious to to have to dial in 118v every time before using the amps. When using the WS1 is it ok to leave everything as is (diode mod, supply voltage to rectifier socket etc...) in place and just do a swap out for the tube rectifier and re-bias the output tubes? The time delay on my amps is roughly 14 seconds`I am hoping I have all bases covered here to protect these beauties but any input to educate me further would be greatly appreciated.