Setup: I bought THX 789 for the massive output of idk 6W/32ohms, but whenever I try to use my Sundara/Modhouse Argon/HD600/Arya V2/...whatever, I cannot reach decent listening levels in terms of db without getting this scratching/hissing noise in the background ... I think it's distortion. (DAC I use: Geshelli labs - J2, set to max volume) Settings: With an XLR output, gain setting level at 2/3 and the volume knob set to 2-4 o'clock, hearing distortion from a 250-350$ THX amp shouldn't be a thing, should it? With somewhat hard to drive headphones, I'm not reaching 70db, but I can already hear this godforsaken noise on all tracks without a constant stream of sound. If you dare to up the volume past 4 o'clock, or past 12 on gain setting 3/3, this noise becomes so loud, it might as well be an additional instrument Music: The tracks I usually listen to involve so few instruments, that you don't have a constant stream of sound. (e.g. Creep - Lena Hall) I'd love to get some feedback!...
Jun 5, 2024
When I connect the odac to the computer, turn on the AMP, plug my headphones and increase the volume to the maximum , without playing any sound, I hear a very light electronic noise but really very low, and more clearly when I set the gain to 6.5 db. So I wanted to know if this is normal, because, as far as I understood, the noise should be canceled no matter what volume/gain we are using for getting a totally clean sound.
FYI, I'm using a Sennheiser HD25-1 II .
Thanks
http://www.jdslabs.com/pdf/Instructions_O2-ODAC.pdf
perhaps it's a power issue. How strong is your AC adapter and have you tried a powered USB hub? Also, are you sure you're running the amp on AC power?
http://wiki.diyfaq.org.uk/index.php?title=Wallwart#Rectified_AC
IIUC the point of using AC for the O2 is to avoid the need for "virtual ground", so maybe that means you need to plug the adapter into a grounded wall socket; are you?
Here below are its spécifications:
voltage: 15Vac max. current: 500mA dimensions: 68 x 50 x 80mm input: 230Vac / 50Hz thermal cut-off output: alternating / non-regulated short-circuit protection plug: 5.5mm / 2.1mm cord: 1.85m
It is not having a grounded plug, as the one delivered with the amp.
I think that this is fine, the only thing is that it is a non-regulated, but all the models suggested for this amp are non-regulated, even if I was reading that this could generate ripple and causes hum in some audio equipment.
More details about my problem, When I Just plug the amp to the power adapter and plug my headphones on the audio out; the hum is pretty clear with the volume set anywhere between the middle position to the max. As soon as I plug a input source on the input jack plug (without playing any sound), or if I plug the USB cable to the ODAC, the hum almost disappears and is noticed only if the volume is set to the max or the gain to 6.5 db. When no input source is pluged, and I touch the outside chassis of the O2+ODAC with my hand, the hum becomes stronger and sounds like a static electricity noise.
Do you still think it is the AC Adapter ? or could it be a bad isolation of the O2+ODAC itself ?
Haven't recieved mine yet plus I have grounded wall sockets at my current resident but, in anticipation of school starting again in about a month...
USB port of my desktop to the ODAC mini USB port. The EU power Adapter to the AC input. and my headset, Sennheiser HD25-1 II connected to the Amp output (6.3 mm jack). Just that, turn on the computer, the Amp, and when increasing the volume to the max I'm having that hum problem.
And if I connect my phone to the input 3.5 mm jack, and nothing playing, same problem, and the noise is even amplified if I disconnect the USB from the ODAC.