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NEW Vali Schiit AMP!!! - Page 139

post #2071 of 4963

There must be some springiness to the tube leads causing them pop the tubes back up. The adhesive on the foam pad either fails from the heat of the tube, or isn't strong enough to begin with.  It's likely that the tubes will just pop back up after sticking them down. Schiit needs to find a better method of damping the tubes, but in the meantime, it would be nice to find a better adhesive that's permanent.

post #2072 of 4963
Quote:
Originally Posted by Barry S View Post
 

There must be some springiness to the tube leads causing them pop the tubes back up. The adhesive on the foam pad either fails from the heat of the tube, or isn't strong enough to begin with.  It's likely that the tubes will just pop back up after sticking them down. Schiit needs to find a better method of damping the tubes, but in the meantime, it would be nice to find a better adhesive that's permanent.

True, let's hope they will figure a way to dampen them, and offer us a in expenive upgrade service. 

post #2073 of 4963

What's the general consensus on the Vali with HD650 (versus Magni)?

post #2074 of 4963
Quote:
Originally Posted by Mshenay View Post
 

So what exactly did you do? Push the tube straight down, and lay it atop a foam pad. How did you get the Tube to stay on top of the foam pad with out going erect again! 

Yes, I held the tube with a "cautious" amount of pressure to try to adhere the tube to the double-sided adhesive foam. I carefully used the end of the screwdriver to do this and never touched the tube directly.  I also held it for a little bit to try and create a better seal.  If I find the microphonics increase again, I'll take it from there but good so far!

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post #2075 of 4963
Quote:
Originally Posted by CEE TEE View Post
 

Yes, I held the tube with a "cautious" amount of pressure to try to adhere the tube to the double-sided adhesive foam. I carefully used the end of the screwdriver to do this and never touched the tube directly.  I also held it for a little bit to try and create a better seal.  If I find the microphonics increase again, I'll take it from there but good so far!

so a very small screw driver? and double sided adhesive foam ... u put the foam right down onto the PCB board

 

I might try a paper blending pencil I have, just to be extra safe. the things in package so no oil on it, and the paper shouldn't damage teh glass 

 

Thanks! 

post #2076 of 4963
Curious what Schiit has to say about securing the tubes.
post #2077 of 4963
Quote:
Originally Posted by Mshenay View Post
 

so a very small screw driver? and double sided adhesive foam ... u put the foam right down onto the PCB board

 

I might try a paper blending pencil I have, just to be extra safe. the things in package so no oil on it, and the paper shouldn't damage teh glass 

 

Thanks! 


I have not looked in mine yet but I would suspect that the foam is already there, so you don't need to but it in just press the tubes back down onto it.

 

Also, use the handle of the screw driver not the point.  Or get a lint free towel (like a lens cleaning cloth).

The types of adhesives used in application like this are usually called "PSA" (pressure sensitive adhesives). Which, like the name implies, requires pressure of sufficient force to create the lasting bond. I would think they would have used mid or high temp adhesive for this application.  I may replace it with some 3M VHB tape I have use in the past for PCB applications, good and strong stuff and can handle high temps. Mine has some ringing but not too bad, so I may open it up in a week or so to check it out.

 

Oh, and they the Vali is sounding very nice with my HD800 from my uberfrost.

Its sounds even better with the Asgard 2 as pre-amp - lots of bass.  A little sparkle up top but not bad.

 

The Taboo MKIII I compared it too has better balanced sound and is smother, but the Vali is scary close :blink:.

I think the Vali has more weight in the bass area.

 

One more thing: @CEE TEE did you check to see if the tubes were standing so tall that they could have contacted the cover? Front eh pics it looks pretty close, but cant tell for sure.


Edited by bearFNF - 12/8/13 at 6:03pm
post #2078 of 4963
Maybe a tiny cage to secure the tubes would be a idea as it would prevent them from lifting upwards.
post #2079 of 4963
Quote:
Originally Posted by gikigill View Post

Maybe a tiny cage to secure the tubes would be a idea as it would prevent them from lifting upwards.


Except the cage may dampen the tubes and change the sound? dunno???

post #2080 of 4963

Mshenay:  There is already foam in place on the PCB from the factory.  

Using a thin phillips head screwdriver, I removed four screws and "re-secured" both tubes against the sticky foam.

The only tricky part is paying attention to the LED bulb and aligning it to the hole while putting the faceplate/top back on.

 

bearFNF:  I don't think the tubes quite reached the top of the case...but I was not paying close enough attention to know for sure.  

From top view, the one on the left looks pretty close in pics.  

 

I just spent a lot of time doing production today, listening while on the computer and the Vali is MUCH better now! 

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post #2081 of 4963

I can see a toob in a state of arousal through the peep-holes. Not fully erect, but certainly at attention. No squeals when bumped hard. Just a brief, barely audible moan when the knob is turned. No need to screw for now.

post #2082 of 4963
Originally Posted by olor1n View Post
 

I can see a toob in a state of arousal through the peep-holes. Not fully erect, but certainly at attention. No squeals when bumped hard. Just a brief, barely audible moan when the knob is turned. No need to screw for now.

 

brick-lol.gif

post #2083 of 4963

I'm new to tubes, but it appears that the legs of the tubes were not bent enough to begin with. As such the foam/adhesive were trying to hold to tubes in place again the spring back force from the tube's legs. It's going to be a constant tension and with the heat from the tubes, it may be just a matter of time before the adhesive gives up and the tubes would spring back up.

 

[for those not mechanically inclined: when a piece of metal is deformed (bent) it goes through a elastic phase and then plastic. When unloaded, the elastic deformation returns to the initial state, the plastic remains permanent. So once you 'let go', it never really stays that way exactly. If you want it to be in a certain shape, there's a certain amount of over-bending required. I suspect Schiit just pushed the tubes till they lay flat on the board. The remaining 'spring back' is what's working against the adhesive.] 

 

A solution could be just to bend the legs. Would that damage the tubes?

 

Also, I'm a little worried about how the foam would fare being under all that heat for hours and hours. Perhaps some kind of rings made from PTFE, secured to the board might be a solution?

post #2084 of 4963

Peeking through the heat vents on top of my unit I notice that my tubes are also elevated at a 45° angle. I'm going to assume that this is pretty consistent throughout the units that have already shipped. I have unit number 000121. I'm curious to know if this is something Schiit encountered during their R&D and found it to be a non-issue. I had the amp running non-stop for more than a day; plenty of time for the tubes to heat up enough to break the adhesion.

post #2085 of 4963
I was about to order the Vali but will wait until they sort it out. Not too handy with a screwdriver so waiting and watching.
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