Internet Noise: A Pest in the Machine

I agree. That has been my approach. I have used my phono stage and have been able to play records with no issue. I do not have a CD player but could borrow one as an experiment. It seems pretty clear that the noise is related to the internet, since I do not have any when it is disconnected. Other than that, I am in the weeds.

Thanks, all. I will follow up on these suggestions and do some investigating.

Thanks for the continued feedback and shared experiences. Just for some added context, I have not had these noise issues with other amps, especially solid state amps. It is not that I think the Synthesis is to blame, not at all. But the tubes appear to be picking up this pollution and it is almost surely related to the internet, since when I disconnect it or unplug it, the noise vanishes.

I will be experimenting more in the days to come and following up on some of the suggestions made so far.

@rolox 

I feel your pain. It has taken me a couple of months to trace the problem down to the relationship between the internet and the amp. I initially thought it had to be faulty tubes or a something going on with the amp, but after much trial and error, it seems the issue is figuring out how to tame the internet noise.

Fiber is not an option where I live unfortunately.

I will try a better switch tomorrow and see if that helps, perhaps a Nighthawk. I appreciate all of the suggestions.

I tried a different switch today. Did not solve the problem. Next will be moving the cables and switches into the next room with the router, and then running a long ethernet cable back into the room and into the Aurender. If that doesn't do it, I will try some tube swapping.

It's almost enough to make me go back to solid state. Almost.

By the way, I do have a dedicated circuit, and a Puritan 156 power conditioner. I have my components plugged into that, but not the ethernet switch. That might be worth a try.

Thanks for the help, folks. You have no idea how much I appreciate it. The cable coming into the house does seem to be pretty shabbily terminated.. There is some exposed wire and the cable can be twisted into an L at the switch, if that makes sense. I am keeping a good thought that maybe this is the issue.

I have contacted the cable company for more information and asked these questions.

I am certainly open to the fiber optic and converter option. I bought a Netgear switch that is certainly sturdier than the cheap, plastic TP-Link switch, though the Netgear is also pretty basic.

You folks have given me a lot of great ideas to explore. Thank you kindly!

I have checked the smaller tubes, but I do not have a substitute KT66 tube to try yet. The amp is new, so the tubes have maybe a hundred hours or so on them. One complication is the KT66 tubes are manual bias, and the design makes is very difficult for the user to do it--difficult and perhaps a little dangerous, which makes swapping out the power tubes somewhat problematic.

For whatever it may be worth to anyone who contributed to this thread or may stumble upon it in the future--especially for anyone who may have a Synthesis amp or be considering one--I seem to have found a solution to the noise problem.

It turns out that the amp did not like being near ANY of the internet gear--router, cables, switches, power supply, none of it. I moved all of it to another room and now have only a single ethernet cable remaining in the music room, which of course is connected to the streamer.

I would have tried this sooner, but with the exception of one person, no one I talked to on either side (amp dealer or importer) or my ISP thought there was much of a chance this was the issue once the router was taken out of the room, which did not solve the problem. 

Prior to moving everything, I tried a new switch, but that also did nothing. For whatever reason, moving all of it was the answer. I will wait at least a couple of weeks before declaring victory, but this is a tremendous relief to say the least!

Thanks so much, guys.. This had become the ultimate conundrum--best amp I've owned, but an annoying problem that was robbing me of enjoying it. Now that the noise issue is gone, I can very highly recommend Synthesis amps to anyone without any reservation. 

The Synthesis uses KT66 tubes, and I do not doubt that the amp was acting as an antenna. If the noise problem recurs now that the system is quiet as a church mouse, I will try tube swapping next. I once had a tube amp that picked up conversations my neighbor was having on his ham radio.

For now, after weeks of tedious trial and error and considerable frustration, I will be enjoying the music for a while. :)