Hissing when connected to laptop

[benzxc]

So I went ahead and trimmed some remaining excesses and tightened a few screws here and there. 

The weird very very low volume hiss (I almost have to "look" for it) is still there - although it is not there all the time.  I find that I can get rid of it simply by unplugging the headphone jack and replugging it.  It is a little weird, because it is  independent of the RCA jacks and independent of volume control.  Anyone has similar issues?  Maybe I might have to try a few other tubes?

Apart from this little issue, the crack w/speedball upgrade works beautifully and it has been a great few days working on this.

Thanks,
Ben

[Tom-s]

Have you checked the pointed out resistor by PB?
This could explain your issue and destroy headphones when not properly solved.

Edit: the fact that mechanical influence at the headphone jack changes the sound point to a mechanical problem.
I suspect a solder joint or the resistor mentioned before.
You could try tubes, but that wouldn't explain the influence when fiddling at the headphone jack.

Edit 2: What he says. (points down)

[Paul Birkeland]

Also if you have a noise that changes when you plug and unplug the headphone cable, that is indicative of a loose connection, not a bad tube.

[benzxc]

Thanks, Paul, Tom,

Can you point out again which resistor connection I am missing? I attach a new photo again. I was a little unsure of which one in PBs previous post.

Thanks,
Ben

[oguinn]

That black wire going to the headphone jack looks like it has a good bit that's bare wire (the jacket was stripped kind of far back), and that could be hitting the top plate or interacting with something. Might want to wrap some electrical tape or insulating material around it.

[benzxc]

Thanks, Jameson.  Will do.

[Tom-s]

Thanks, Paul, Tom,

Can you point out again which resistor connection I am missing? I attach a new photo again. I was a little unsure of which one in PBs previous post.

Thanks,
Ben

Look at the more proximal (left) part of the bottom 2.49k resistor, it shows a weird / sharp angle, a possible break.

[benzxc]

Thanks, Tom.

I attach a photo from another angle. It doesn't appear cut to me.

[Tom-s]

I still suspect a bad solder joint somewhere. First, go over all ground connections (trace back all black wires, look for loose or flaky connections) and see that all screws with a ground connection are properly tightened.

When not succesfull.

Get some cheap headphones out. Plug them in. Plug in a source without any sound. Flip crack over on some stands (and put the power switch to on). Plug the powercord in. Get out a wooden (non conductive) chop-stick and start poking at the joints (start around the jack) untill you reproduce the hissing sound, that's your bad joint. Be very careful when doing this.

Edit: forgot to say. Indeed that resistor looks good in this picture (unlike in the one on the previous page)

[benzxc]

Thanks, Tom.  Will do.

Going to get some shut eye now.  It is 3:40 AM in the part of the world where I am located... been the third night I've stayed up this late since I started building the crack.

Thanks for all the help.

Ben

[Paul Birkeland]

That other photo you provided shows that the resistor lead is bent a little bit, not cut.  It looked suspicious at the alternate angle, but not so much now.

[benzxc]

So I went back and resoldered all accessible joints and tightened all screws again to no avail. Then, I did the chopstick test and didn't hear any joints that made the hiss/hum.  The hiss/hum just seemed to be there all the time.
I also noticed the hiss doesn't start immediately after I turn the amp on. Rather, it starts a few minutes after the amp is turned on.

I ordered a set of new tubes just to rule that out as a source of issue. Otherwise, I'm kind of at a loss now and am thinking of maybe sending it back to bottlehead for repair.

[benzxc]

Hi all,

Happy to report that having left the newly built crack w/ speedball upgrade on and playing music for 10 plus hours, the right channel hiss seems to have gone away.  I have checked many times over the past 2 hours and it has not resurfaced.  Needless to say that I am a happy camper now!    Will keep monitoring to see if the hiss comes back. 

Thanks again,
Ben

[benzxc]

Oh no!  It has come back.........

[bernieclub]

Not sure if you've cleaned the tube pins, but I have exorcised various gremlins by doing so.

Bernie