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Hey Dylan, the problem you had before (right channel not working) is obvisouly caused by the tube was moved during transportation.
Don't worry, let me try to sort out the new issue:
- You mentioned you use the DAC/A1 combo with your laptop. What kind connection did you use between the DAC and your laptop? Did you have the same hum sound when you use the DAC's headphone output with your laptop? Do you hear the hum sound when you connecting your headphone directly to the laptop's headphone output?
- Will you be able to find another wall power socket to connect your laptop? Make sure there is no other electronics using the same power socket. Also, make sure the wall power socket is properly connected to the earth line.
- Make sure you use high quality audio cable to connect the A1 to the DAC. Low quality audio cable will cause interference.
I don't think your unit is a lemon, I personally tested your unit before the shipment. The minimum requirement for the unit to pass my testing is that I can not hear any noise from two headphones(one PX100 and one HD650) in a very quiet room. It has to be dead silence. Your issue, is probably due to bad power source or audio cable. As you did get it working very well in your office environment.
Let me know your testing result and I will help you further. You can leave your feedback here or reply directly on the support ticket.
Cheers,
Ryan
First up, thanks for replying so promptly. I think it's awesome that you take customer service so seriously. This is the reason I chose the A1, that and the beautiful brushed aluminium finish
Let me try and do a better job of summarising the situation and my setup, then I'll try and answer your questions.
Headphones: Sony MDR7506 (63 Ohm)
Speakers: Polk RT-25 bookshelf (8 Ohm)
Sources: Laptop headphone jack, Laptop via AlienDAC, Work Desktop via headphone jack, Work Desktop via AlienDAC, Denon CD Player
At home testing with bookshelf speakers: Sounds great! To hear any buzz/hum I need to press my ear to the speaker. No issues here.
At work and home, no sources connected to A1: headphones have background buzz, not very loud, but loud enough to hear clearly over background noise in office. Adjusting the volume control has little impact on the buzz.
At home, A1 connected to Denon CD player: headphones have background buzz, can be heard during quiet bits in the music or when the music is paused.
At home or work, A1 connected to laptop via DAC or headphone jack: Nasty buzz/noise/interference. Sounds a little like a fax machine. Problem is resolved by disconnecting the laptop from the mains. Another curious thing is that selecting the line-in input, then connecting the DAC to the analog-in still causes the extra noise.
At work, A1 connected via DAC to work PC: same nasty noise as laptop, but not as loud.
At work, A1 connected to headphone jack on work PC: same background noise as when A1 has no source connected.
My gut feeling is that there are two separate issues. At all times there is a background noise when using headphones. The second issue is that connecting a PC via a USB DAC there is a far worse noise issue.
let me try and answer your questions now
- You mentioned you use the DAC/A1 combo with your laptop. What kind connection did you use between the DAC and your laptop? Did you have the same hum sound when you use the DAC's headphone output with your laptop? Do you hear the hum sound when you connecting your headphone directly to the laptop's headphone output?
The DAC is connected to the laptop with a standard USB cable. The DAC is powered from the USB. The DAC doesn't have a headphone amp, it's not powerful enough to directly drive headphones. I will try connecting it to another amp tonight and see if the hum is still present. There is no hum with the headphones directly connected to the laptop headphone jack.
- Will you be able to find another wall power socket to connect your laptop? Make sure there is no other electronics using the same power socket. Also, make sure the wall power socket is properly connected to the earth line.
I tried the laptop on one wall socket and the A1 on another, this didn't seem to make any difference. There was other equipment connected to both sockets. I don't have enough sockets in the house so every plug tends to have multiple devices. I have a "circuit tester thing" I'll connect to both sockets tonight and make sure they pass. The device is supposed to be able to find wiring problems. I also tried connected the A1 to a UPS running on batteries which means no actual connection to the house wiring. Connected to the UPS the background buzz/hum was still present. I don't recall if the additional noise from the laptop was present. If it's helpful I can test it again tonight?
One final comment, when I crank the volume up a little so the background noise is lost, the unit sounds great
Thanks again for you help,
Dylan