Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: crowleyg on January 21, 2016, 09:19:35 AM

Title: newly built Crack, low hum appears to originate from DAC?
Post by: crowleyg on January 21, 2016, 09:19:35 AM

I recently built my crack, and didn't have any issues building it, all resistances and voltages were inside spec upon completion. I'm using it in conjunction with a fiio e10k dac/amp and hd650 headphones. I've been listening with just the e10k and the Senns before, and never heard a hum like this. However, the hum is only present when I connect the DAC- I have tested the Crack with shorted RCA jacks, and it stays quiet. I have tried two cables for the connection between dac and amp, and the hum remains the same. It does get louder as I turn up the volume knob. Changing tubes also does nothing to quell it. Does anyone have any advice for this? I was thinking either getting some really nice shielded cables, or some sort of noise isolator for the dac. I also have the speedball upgrade ready to install, but I'd rather wait until I track down this hum, unless people think it might help.
Thanks!

Title: Re: newly built Crack, low hum appears to originate from DAC?
Post by: Paul Birkeland on January 21, 2016, 09:36:25 AM

Are you using the DAC on a laptop?  If so, try it with the power brick plugged in, then not plugged in.

Generally noises like this can be eliminated by using an optical cable between computer and DAC.

Title: Re: newly built Crack, low hum appears to originate from DAC?
Post by: crowleyg on January 21, 2016, 10:34:20 AM

I'm using it with a desktop, and I don't think my DAC accepts audio input. Would a usb noise isolator, or rca ground loop filter help?

Title: Re: newly built Crack, low hum appears to originate from DAC?
Post by: Paul Birkeland on January 21, 2016, 02:12:52 PM

A USB noise isolator could be the ticket!

Title: Re: newly built Crack, low hum appears to originate from DAC?
Post by: JoshMorr on January 25, 2016, 02:22:16 PM

I am experiencing a similar problem to yours. Let me know if you track it down.