Massdrop x Eddie Current ZDT Jr. (Official Thread)

From memory there have been reports of hum issues persisting even after applying the fix, but the ZDT Jr. that I got to borrow a few years back now I think was basically silent after I shielded the trafo using some tape Zampo very kindly sent over for cheap. Then again, I live in a noisier spot so maybe there was still a significant amount of hum, just at a low enough SPL that it didn't matter to me.

Just out of curiosity, do you have the amp near anything that could be emitting EMI?

 

I'm still using this amp, just used it last night. And I fixed hum myself with the help of Internet and 4 cuts in my hands...

I don't know what the official fix is, maybe it's not enough? It was not hard to open the amp, and do some inspection. And fixing the amp by yourself is not hard neither, as permalloy sheet can be cut by scissors, but that thing is sharp, be careful.

But yes, I suspect it's also caused by EMI, I had experience with a cheap switching PSU of some other device affecting one of my amps. Try to move the amp around, use different sockets and turn off some other devices to see if it helps. It's easier than opening the amp up I guess.

 

Someone could have painted the dot, but SN 375 does seem to be near the end of the run when I think they were all fixed?

Tubes, yes, I have had 3 different set in for the front and rear, and it persists in the left channel. Will try swapping cables (and just listening with nothing hooked up) when I get back to it next weekend (that setup is at my cabin). Thanks!

 

This setup is at my cabin, which is in the woods away from most noise, and when I am listening it is generally in the evening when my wife is reading, so ambient noise will be VERY low. I do have my little test rig that I put together for getting frequency response graphs out of my DIYs, I should take it to the cabin when we go up next weekend and see exactly how loud the hum is.

As for EMI, the only thing is it near is the power supply for the Lokius which is on the floor under the shelf the setup is on, so 3 pieces of wood and the Lokius itself are in between the amp and the power supply (18" maybe), then the router is about 12 feet away. Being that this is at my cabin I am on Starlink, so I'm not sure if that is creating any additional noise.

I can certainly open it if needed and I am handy with tools & soldering iron, so If I need to do some mods, that should not be an issue.

Thanks for everyone's responses!

 

I fixed one myself, again it’s not hard, though some the screws were a pain to get to.
What headphone are you using with it, it’s probably never going to be dead silent, mine was barely detectable on an HD600 after the fix.

 

300ohm Open & Closed DIYs - I'll take my test stand up next weekend and get a level on it to see if it's even worth chasing down.