Hissing when connected to laptop

[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

 

[benzxc]

Thanks, Bernie! Will do so right now to see if it makes a difference.

Any suggested/proper way to clean the pins?

 

[Paul Birkeland]

Is this noise still there with nothing plugged into the inputs?

 

[benzxc]

Hi Paul, yes the noise is present when the RCA inputs are not connected.

Thanks,
Ben

 

[Paul Birkeland]

Do you happen to have an ethernet over powerline kit in your home?

 

[benzxc]

Hi Paul, I don't have that, unfortunately.

 

[benzxc]

I just noticed that one of my heatsinks is not entirely in the socket. Attached photo. Could this be the cause of the weird low volume hissing sound, or is this unrelated?

Even if unrelated, is this something that could cause serious issues that I should fix now?  I ask because I am a little hesitant to make any big and unnecessary moves on my crack at this point for fear of messing something else up. Of course, if this is necessary to fix I will do it.

Thanks!
Ben

 

[benzxc]

Oops, photo here.

 

[Paul Birkeland]

That shouldn't cause a problem.

 

[benzxc]

Phew, good to know. Thanks for your help as always, Paul.

The noise occurs sporadically. It is low enough in volume that I can live with it if I can't fix it.

However, once I get those new tubes I will report back to see if anything changes.

Thanks to everyone for all the help so far!
Ben

 

[Paul Birkeland]

I would also suggest doing the modification I posted earlier on this thread, as you may have a polluting device somewhere in your house, and that will give you some extra isolation.