Hum eliminated

[jvmonta]

Here is a picture of how I eliminated hum by clipping between the top of my foil wrapped tube and ground. Wow, did it clean up my sound and add definition to bass too, my wife will even attest. Strange, strange hobby.

[4krow]

Ok, now I gotta try it. I like the looks of Herbies tube ring to keep it in place.

[Grainger49]

It makes sense that a tube shield doesn't do anything till it is grounded.  Although most guys don't need to shield the tubes in the Quickie.  But each of us is in a different EMF/RFI location.  I think I'm in good stead since my house is behind a lot of rock!

[underdawg]

well mapleshade is now selling tube shields with grounds. I have tried the technology and yes it does make a difference in my testing.

[4krow]

I used to have some of those Mapleshade collars. Heavy duty man. I'm gonna look at them now, cuz they quit making them for a few years.

[earwaxxer]

Interesting - I have some hiss now that I'm trying to track down. Of course I suspected the Quickie. No sir. With the uLink off (Gungnir on) the hiss goes away. Dead quiet. I thought it may be the noisy power coming from the laptop, so I bypassed the power to an external supply. Same hiss. It funny that I'm tracking noise like this that isnt the fault of the tube circuit. This Quickie is the shit!

[mortron]

My hum vanished when I ran shielded ICs soldered directly into a shielded passive line level filter. It looks like crap. So quiet.

[4krow]

I looked at the new Mapleshade collars. They are nothing like the old ones. Seems that I could just use copper tape to get the same effect as far as shielding. Then use Herbies dampers over that.

[rif]

So the basic idea is to cover the tubes in some conductive material, then attach that to a ground inside the quickie? Does the material need to actually touch the tube or just envelope it?

I get hum when my hand goes near or worse yet touches a tube, but disappears if I touch an rca ground (any one).

[4krow]

In my experience, it is best to ground the tube damper if it is made of metal. Also, I would think that the damper should be in good contact with the tube. In such cases, it might be able to act as a heat sink for the tube. Unfortunately, there are other cases in which it will hold the heat of the tube in, and that could be a tube killer in time. Then of course, there are tubes such as the 3S4 in the Quickie that seem to produce no heat at all. That wouldn't hurt the tube if you were to get all crazy about damping it with such things as silicone, etc.

[rif]

Ok I'm confused, which is easy. I thought the dampers were the small cylinders attached to an almost complete circle of wire that goes around the tube. That's for microphonics. By necessity it needs to be in strong contact with the glass.

(I am working on a quickie so no heat issues)

[earwaxxer]

rif - I cured that exact hum issue that you describe by 'grounding' the Quickie. I just soldered a wire to ground and connected it to my DAC. Its funny though, that hum is not there for me now, even without the ground wire attached. I guess the Quickie is finding ground through the interconnect(s).

The dampers are more of a voodoo shit affair. You can the the foreskin of a mature Yack. That seems to work well. 

[rif]

Where on the dac? The case? Shouldn't the rca inputs on my amp already attach to the case's safety ground at some point? I'll figure this out, it'll just take some head thumping. Come to think of it, it's gotta be the amp. When I built and tested the quickie in the garage, no hum at all and that was with a cheap lepai 2020 amp.

[Grainger49]

For anything metal to be used as a shield, like a tube damper or tube shield, it needs to be grounded.  This takes the noise/RFI/EMI to ground potential.

[4krow]

Sorry if I wasn't clear here. I was referring to tube dampers that were made of metal or had a significant amount of metal acting as a shield. In the case of 'Herbies' , they are designed only as a vibration control device. Other dampers, such as the ones made by Mapleshade, ARE designed for shielding as well. They will not be effective unless they are grounded to the chassis of the component that they are installed on.