Interference in both channels on Crack w/ Speedball

[DenverDude]

Hello all (and Paul)

I've been enjoying my Crack/Speedball, but every once in a while I get a faint "pitter-patter" feedback sound on both channels. As I said, it's faint, but when it happens it's persistent. I have found that when I place my hand near or on the power switch, the pitter-patter noise disappears, but it comes back when I lift my hand.

Any idea what this might be and how I can fix it? Thanks for your help...

 

[JamieMcC]

While waiting a reply from bottlehead try rerouting your external cables away from any power leads, transformers etc andalso  putting a few twists in the rca leads that go from your dac to the Crack. It worked for me.

 

[Grainger49]

If you don't touch the power switch and the noise goes away, that sounds like something induced into the amp.  The most notable offenders are cell phones and computers.

If it goes away when you touch the power switch, that sounds like a bad connection; something mechanical (in an electrical sort of manner). 

A question, is your power system grounded?  Have you tested it to verify you have a good ground?  This causes all sorts of problems and, of course, poses a safety concern as well.

 

[DenverDude]

Thanks Jaime and Granger ... I moved the unit away from my wireless router and plugged it into another electrical socket and that did the trick.

However, I do have a loud feedback hum when I first switch on my Crack. It is only loud when the volume is at its lowest setting, because when I turn up the volume, it disappears, but it will reappear when I turn the volume all the way down again. And it completely disappears after a minute or two (especially if I fiddle with the volume knob).

Any ideas on this on? ... thanks again.

 

[Grainger49]

That sounds like the ground on the pot is not solid.  Retouch the solder joints for the ground on the pot and check the sticky for all ground points in the Crack folder.

 

[Paul Birkeland]

Thanks Jaime and Granger ... I moved the unit away from my wireless router and plugged it into another electrical socket and that did the trick.

However, I do have a loud feedback hum when I first switch on my Crack. It is only loud when the volume is at its lowest setting, because when I turn up the volume, it disappears, but it will reappear when I turn the volume all the way down again. And it completely disappears after a minute or two (especially if I fiddle with the volume knob).

Any ideas on this on? ... thanks again.

We have seen some funkiness in a particular batch of pots. Just leaving the knob up a hair will prevent this.

 

[DenverDude]

Thanks for the feedback, fellas, but I'm not so up on the terminology you are using, so if you could translate for me, that would be much appreciated.

For example... "That sounds like the ground on the pot is not solid.  Retouch the solder joints for the ground on the pot and check the sticky for all ground points in the Crack folder."

I'm assuming the "pot" is potentiameter. What is "checking the sticky"? And what is the Crack "folder"? Sorry, but I was an English major in college 

Another thing ... sometimes I really have to wiggle and play with the headphone jack to get both channels to present properly. Any suggestions on what's up there, or should I upgrade the output jack?

Thanks again for your help and patience with this greenthumb.

 

[Grainger49]

Ok, I have the manual open now.  Looking at page 21 and 22.

If you flip the Crack over, standard orientation for working on it, your plug at the back...

The black wire on the volume pot is the ground.  This comes from the outer conductor of your input RCA jacks.  Then there is a black wire leading from the Pot's grounds to terminal 3 on the front most terminal board.

So touch up the 2 solder joints on the pot and the one at T3.

Here is a link to the sticky:

http://bottlehead.com/smf/index.php/topic,4812.0.html

I can not edit it to change the text color since it is locked.  Maybe a moderator can do that for me?

Paul Birkeland is saying that there were a few pots that didn't work correctly when you turn them all the way down.  He suggests turning it down but not all the way.