[Krozzek]

My new FX Audio DAC-X6 is producing background noise (high pitched, steady whine), which seems to be unusual judging by the many reviews that praise its silence. Any help in diagnosing the problem would be much appreciated.

What I know:

It's not my PC. The noise occurs when there is no input source connected.

It's not a ground loop. My plug is only two prong (no ground pin) and the problem occurs when I plug into any outlet in the house.

It's not the power cable because the static occurs even when I swap to a different one.

The static only occurs when the DAC/AMP is powered on, and does not start until after a ~3 second delay from when the power switch is flipped on.

The input source selection switch has no effect on the noise.

The noise gets slightly louder when I increase the volume knob.

The noise is noticeable in my ATH-M50s and a pair of crappy ear buds. However, it is not detectable when I plug in some Samsung ear buds or a pair of 1MORE ear buds.

So, what do you think? Are my MH50s picking up something they shouldn't, or is the amp a lemon and I should return it? Thanks again.

 

[yong_shun]

I guess it is something to do with the amp because when you increase the volume and the hiss increased. I guess you cannot detect it with 1More ear buds is due to the lower sensitivity. Check with other users. If they did not face this issue, most likely it is faulty.

 

[Krozzek]

I guess it is something to do with the amp because when you increase the volume and the hiss increased. I guess you cannot detect it with 1More ear buds is due to the lower sensitivity. Check with other users. If they did not face this issue, most likely it is faulty.

Thanks. I am going to return it and try another one. Hopefully it's just this specific unit that is the issue.

 

[zazex]

I think the return is the right move.
First, it's simpler and faster than attempting to diagnose
the cause of the extraneous noise.
Second, if the "new" amp is quiet - as it's supposed to be -
then the problem is solved; easily and quickly.
And if the "new" amp is faulty in some way, I recommend
crossing the street and looking for a different amp - despite
all the good reviews.

Most likely the amp you receive in exchange will be fine.

 

[Krozzek]

I just got the replacement amp tonight ... and it has the same problem. I am returning both and will look for an alternative. It's a shame because I liked everything about the X6.

The problem can't be my headphones, right? If there is no audio source, then there shouldn't be a signal that could cause the speakers to sound.

 

[zazex]

I'm also disappointed that the new amp failed in the same way.
I don't know the exact percentage, but IME exchanges tend to work OK -
it's just unlikely (see, for example, 'games of chance') that a a customer
will get two defective units in a row from a reputable outfit. Especially today
what with all the automation in the mfg process.

And another thing - the issue you've described is a tricky one to work through.
Mostly because - or, let me put it this way - moons ago, when i was doing
the diagnosis and troubleshooting thing in a very busy lower Manhattan location -
we were taught that we had to make the item at issue "fail". And it had to "fail"
reliably (yes, sounds odd - but makes perfect sense). Because if the unit doesn't
fail, you can't even begin to repair it.

And with your setup, and the problem you experienced, it appeared that the
problem sort of wandered around. Meaning that it was here, it was there,
when you tried different headphones it vanished...I forgot exactly what you
wrote, but it had my alarm bells ringing. Man, I felt > this problem is going
to take some time and effort to figure out. Unless, perhaps, someone has
seen it before. (Always useful in this context.) Anyway, once that's done, the
actual repair might take five minutes.

You might have some weird RF issues in your place, for example.
Such can wreak havoc with unshielded (or improperly shielded) cables
which might be present somewhere in your system.

In the end, unless you have a large surplus of time, I strongly
suggest that you just walk away from this situation. Maybe
introduce the issue on a couple of good forums. (Maybe someone
will have heard of it - or something.) A more solid amp might
be the answer - I can't know at this point, from here. Super-budget
hi-fi can initially sound anazing,, but very often it's done with some cost
cutting that becomes apparent only after some time of actual use.

 

[Krozzek]

Follow-up post for posterity:

I tried my setup with the SMSL M6 and still got the same issue, even when accounting for different headphones, different outlets, etc.

The solution was to just change my headphones to HD650s. I don't know why, but I can't hear any whine on these on the DAC-X6 or the SMSL M6, whereas I can on the M50s and other earbuds. Getting 650s was always the plan, so this works out for me. It's a shame I could not figure out why the M50s didn't work well with both amps.

 

[ProtegeManiac]

The solution was to just change my headphones to HD650s. I don't know why, but I can't hear any whine on these on the DAC-X6 or the SMSL M6, whereas I can on the M50s and other earbuds. Getting 650s was always the plan, so this works out for me. It's a shame I could not figure out why the M50s didn't work well with both amps.

Most likely the combination of low impedance and high sensitivity. An extreme example specs-wise but otherwise more common scenario is how people keep getting noise with their SE530/535, not just on smartphones but also amps.

This is one reason why the O2 is so highly praised. I preferred having a bit more power just in case I use headphones that need it so I got a Meier...which only registered noise when the O2's creator screwed up the wiring for the test bench now knowing it was an active ground amp then railed against active ground as a gimmick.

 

[Pruikki]

Here i have same problem. Also the heck it this jerry rigged thing? fake DAC X6===?

 

[ProtegeManiac]

Here i have same problem.

Probably safe to say that the DAC X6 is as far away as one can get from the ODAC/O2 and Meiers.

Here i have same problem. Also the heck it this jerry rigged thing? fake DAC X6===?

No context so take a guess.

1. DAC X6 boards can be bought off some sites; alternately, manufacturer of DAC X6 could have bought these kits and badged them as DAC X6.

2. Probably some guy trying to see if he can fix a broken DAC X6.