Don’t know where else to post this so decided on a dedicated thread whereby if people need help with any troubleshooting on their systems this’ll be it.
Anyway, I need some advice/input. I think I’m having a noticeable DC offset problem. I’ve heard my DAC buzzing a few times (heard it happen 3 times) which I assume is the transformer vibrating due to some DC leak. The buzzing doesn’t happen often so should I still be concerned? I’ve read it can damage your equipment. It will be difficult narrowing down what device is causing this since the buzzing noise doesn’t happen often, so doing this is out of the question.
I’m aware there are devices like the iFi DC blocker and the Emotiva CMX-2 that should do the trick. Are there any other products that do this (preferably with more outlets)? Will they affect sound? Can power generators help with this? Are there any other solutions?
There is this myth among audio people that DC on the mains causes transformer hum (transformer hum is caused by loose windings/manufacturing error allowing the windings or core-laminations to physically vibrate).
The mains shouldn’t ever have a DC offset. In case they do, you need to call an electrician.
DC offset on the audio signal means you have a faulty component somewhere.
You can get an isolation transformer like attached.
Justin at Amp and Sound suggested I try one at one point (did not fix my issue). They also float ground.
BUT I’d strongly suggest determining it’s the actual issue before going out and trying something you can’t return. I don’t know if a cheap multi meter will give you enough information, the DC offset only need to be small to cause a transformer to hum.
In the US it very much depends on your local power company, there isn’t supposed to be one, but if there is the odds are if you have a smaller power company they won’t address it unless it’s actually dangerous.
To put it in perspective, my power company is a cooperative that serves less than 10,000 people, it’s not like the national grid in the UK.
Gotcha. How is an isolation transformer different from the iFi and Emotiva one?
It’s going to be tough determining the issue since it doesn’t hum often.
I haven’t looked at the Ifi one inside, it’s probably just a filter, and possibly a pair of Diodes (which is all a HumX is), but I’m guessing.
An isolation transformer is what it says it completely decouples the output from the input, and removes any DC offset. It won’t clean anything though.
They will because it means something on their end is close to a huge fire.
A DC offset means extremely high currents flowing through the substation transformer causing immense heat and a fire.
A friend of mine worked for the major Californian Power Company, you know the one that got sued for not maintaining their equipment and causing the big fires a few years ago, who’s solution to that problem was to shut off all power running through sections they considered risky when it was dry, cutting off power to millions of people.
He told me when they buy transformers they buy the cheapest they can, and assume they can run at 150% of manufacturers rated peak power for hours at a time. When that turned out not to be the case in the 90’s the state had rolling blackouts in the summer, because people turned on their AC.
It really is hard to explain to Europeans how bad a lot of the privately owned infrastructure in the US really is, and most people in the US don’t realize it’s terrible because they have nothing to compare it to.
So to clarify, is the buzzing audible from the actual dac body itself, or can it only be heard in the audio path? Aka is it physical vibration or rattling, or is it something only heard though headphones/speakers
You could try an isolation transformer but they aren’t cheap iirc. The ifi dc blocker looks like a good option for the money, compact too, so I might be more inclined to try that first. Or you could go the conditioner route but not sure on that one, I’d try the more dc targeted things first
There are some with dc offset removal like that emotiva one for example (or a combined isolation transformer + conditioner), but one without won’t remove it that’s correct, I was just suggesting using both a dc offset remover like an isolation transformer or the ifi thing + conditioner in case it was something else as well
Also this is a good option for just dc removal imo
An example of a combined conditioner + isolation transformer
If the actual unit is buzzing, obviously the transformer is bad or unhappy about something else. If the “something else” is not DC on the mains, the unit may have a bad rectifier. Try it at a friend’s house (different power company hopefully). If the buzzing is gone, it’s a problem with your mains. If it’s still there, you have a bad component and the unit needs to be looked at.
I was assured it’s not the DAC itself. I guess Holo Audio prides itself with its QC. Regardless, it’s almost impossible to reliably test out since the buzzing happens rarely, making it hard to troubleshoot.
It might be something in your house causing the offset, but unless you can come up with something that might be turning on when you hear it, tracking down an intermittent issue is going to be hard.
I do second the try it somewhere else point though.
Do you know if DC offset happens constantly or is it only when the buzzing occurs?
So, for example, the light next to me is the cause of the offset.
When that’s off, then no offset is happening?