Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Tim on January 09, 2016, 01:56:50 AM

Title: light hum on the crack #2 [resolved]
Post by: Tim on January 09, 2016, 01:56:50 AM

I just completed my build, Crack with Speedball, and also have excessive hum and a slight random low level crackle on the right channel.  I have swapped input cables with known good cables, checked and resoldered connections.  I have Sennheiser 650 headphones that sound perfect with other amps.  Looking for solutions.

Title: Re: light hum on the crack #2
Post by: Paul Birkeland on January 09, 2016, 07:39:39 AM

Did you build the Crack stock first?

Title: Re: light hum on the crack #2
Post by: Tim on January 09, 2016, 04:24:51 PM

No, I built the Crack and Speedball simultaneously.  Didn't see the need to complete and disassemble Crack for the Speedball modification.  Additionally, I have rolled all tubes and problem remains.  I suspect the random scratch is due to a component issue on the small "A" circuit board. 

Other than these issues the amp sounds great.  Once I address the annoying right channel issue I'll learn to live with the hum or take additional steps to address it.  Suggestion for reducing hum are welcome.

Title: Re: light hum on the crack #2
Post by: Paul Birkeland on January 09, 2016, 05:25:50 PM

Please remove the Speedball and put the loading resistors in, then repeat your test.  Your assessment is speculation that may be proven incorrect by performing this test.

Title: Re: light hum on the crack #2
Post by: Tim on January 23, 2016, 05:04:22 AM

Grounding issue identified and corrected, no hum or right channel noise.  Thanks for your assistance.