MHDT Paradesea Repair? New Tube?

The ideal is to find a tube that has been reliably tested. You shouldn't have to spend too much for one of the above tubes.

First thing, replace the tube with another which seems quite likely based on what you are hearing. Tubes can get noisy over time. I do believe the Paradesea uses the same buffer tube as the Havana 5670, 2C51, 396A type.

Streetdaddy

The problem with a noisy tube is that it may test well but still be noisy. I have a Hickock tube tester. While it performs several important tests it doesn't test for noise. Buying from a reliable tube vendor, Andy of Vintage Tube Services immediately comes to mind, is a good way to go if you call him and talk to him and tell him what's going on. In addition to being a tube merchant he is extremely knowledgable in general and can possibly give you greater insight into other possible causes and the MOST probable cause. If you are on a budget and just want to get the unit up and running the FIRST thing I would do is to buy a CHEAP reliably tested tube from a guy like Andy to see if it IS the tube. After the problem is resolved THEN you can consider different tubes which DO make a difference in the MHDT DACs. Hope this helps you going forward.

I am really questioning what he told you. Just because a tube is lighting up doesn't mean it isn't introducing noise. I KNOW this is true because I've experienced this myself, several times. I trust Andy completely but I am at a loss as to why he told you this where in several of my experiences it just ain't so. I would try another tube. It MAY not be the tube but at least you could eliminate the doubt one way or another.

Keep us posted Streetdaddy.