Build Log: A Physician hooked on Crack (My very first DIY project)

[sanadsaad]

After enjoying countless hours of sweet music on Crack, I noticed static in both channels that does two things:

1. Increases when I disconnect source which is my laptop connected via 3.5mm to RCA
2. Increases/decreases when I turn the volume up/down respectively.

I thought I'd post it here rather than start a separate post. Any ideas?

EDIT: It is very faint when I connect RCA to my Mac. It goes away when I play music.

 

[Grainger49]

It could be the source. 

Either make a pair of shorting plugs with some cheap RCA plugs and a pair of resistors, 10k ohms is good, or use a pair of alligator clip jumpers to short the center conductor of each RCA input jack to the ground.  That is a jumper for each channel, center to ground.

If the computer is close to the Crack it can cause all sorts of noise.  Same for a cell phone.

The above will vindicate the computer. 

Also, reseat both tubes multiple times to clean them (I may have suggested this earlier in the previous 4 pages, still a good idea).

If you have a spare set of tubes, always a great trouble shooting technique and way too much fun rolling different tubes, you can eliminate the tubes as the source of static. 

BTW, new tubes need to "form."  If you have put in 100 hours on the tubes, they are formed.  If not keep at it, you don't have to listen.

 

[sanadsaad]

Just finished installing the speedball. All voltages perfect! I was wondering that while I have the "patient" open and on the table, I was thinking if I should ground the headphone jack. The two unused terminals I connected but which terminal should I connect it to to ground?

 

[Grainger49]

Sanad,

Excellent!  I'm glad to hear that everything was good as soon as you converted.  Here we hear of the problems more than the successes. 

I think there is a sticky in the Crack folder concerning a tweak to improve S/N ratio.  I think this is what you want to check out.

 

[Laudanum]

I dont think it specifies where to ground.  Or, I should say, the best point to ground, if there is such a point.  I havent done it yet myself so I have no specifics to add.