[InsanelyConfused]

Hey people,

just made an account to post here because I am wondering if I got a defective unit or not. My Xduoo TA-26 is running pretty good, no hissing, buzzing, microphonics or anything of that sort that is audible when wearing my headphones. I had some humming from my USB ports that lead to my DAC but resolved that by using the optical input of my DAC. But there is one last issue and it makes me consider returning it or getting a replacement and that is the humming sound the transformer makes when the unit is running. It's not audible while listening to music but I can definitely hear it humming when nothing is being played and it's just bad. Not loud like in some videos of clearly defective units, but still noticeable enough to think about if this is normal or not.

I am wondering if this is a commong thing or normal for the TA-26. Do units exists where there is no humming at all? Is is fixable or can I simply get a replacements and hope that it won't happen again? If this is normal and fixable then I know someone who probably has the know how to do so, so opening it up wouldn't be too much of an issue.

I would appreciate any help! I am so close to having a pretty sweet tube amp on my desk, but this humming is really ruining the experience.

Edit: (btw it's just the unit humming, my headphones are dead silent when nothing is playing)

 

[Bonddam]

Different amp but when my plasma TV is on in the family room it makes my Woo WA5 LE power supply and Flux FS-12 hum. The hum comes directly out of the amp and drove me nuts. My daughter turning off that TV at the right time made the hum disappear. So I had her turn the TV back on and came back.

 

[InsanelyConfused]

Different amp but when my plasma TV is on in the family room it makes my Woo WA5 LE power supply and Flux FS-12 hum. The hum comes directly out of the amp and drove me nuts. My daughter turning off that TV at the right time made the hum disappear. So I had her turn the TV back on and came back.

I checked for that too! I tested multiple outlets and it changes nothing. Even plugged it in somewhere where nothing else was running, same result.. I carried the amp across myt whole place and every outlet created the same result :/

 

[tomb]

When someone mentions "hum" and "transformer" in the same sentence, it's important to be specific:
1. Is the hum over the audio circuit, or
2. Is the hum mechanical and heard outside of the casework and outside of any audio circuit connection?

Every transformer has mechanical hum or buzz (vibration), the question is whether it's audible or not. Most amplifiers, except some of the very top-of-the-line ones, also possess some sort of 60 Hz hum in the audio circuit. Even if it's inaudible, it probably shows up as a 60Hz spike in testing. Again, the question is whether it rises to the level of audibility.

If the mechanical hum or audio circuit hum is audible and it bothers you, a check with the mfr is needed. Transformer mechanical hum, while present in every transformer, should not be audible enough to bother you. If it does, the unit should be replaced. I'm not saying if you put your ear down directly on the transformer casing and hear a buzzing, you should return it. Instead, is the buzzing/hum audible during normal listening sessions and at normal distances such as sitting at a desk, etc.? If so, return it.

For hum in the audio circuit, this can be more difficult to address, depending on the design and the mfr. If it can overwhelm the music signal and you can easily hear it when playing music, then there's no question - return it. That said, most 60Hz hum disappears when the music signal is strong enough, but it still means it's infecting the music and coloring the response - even if your ears can't pick out the hum over the music signal. The problem with many tube amplifiers is that a little bit of 60Hz hum is often "acceptable," depending on the design and the mfr. (I don't agree with that.) There are many very high-level tube amplifiers that sell for $thousands and still exhibit hum, especially when connecting to a low-impedance, high-efficiency headphone. So, it depends on the mfr's point of view and practice to see whether they consider that a defect (I would.).

Hope that helps - good luck!

 

[InsanelyConfused]

When someone mentions "hum" and "transformer" in the same sentence, it's important to be specific:
1. Is the hum over the audio circuit, or
2. Is the hum mechanical and heard outside of the casework and outside of any audio circuit connection?

Every transformer has mechanical hum or buzz (vibration), the question is whether it's audible or not. Most amplifiers, except some of the very top-of-the-line ones, also possess some sort of 60 Hz hum in the audio circuit. Even if it's inaudible, it probably shows up as a 60Hz spike in testing. Again, the question is whether it rises to the level of audibility.

If the mechanical hum or audio circuit hum is audible and it bothers you, a check with the mfr is needed. Transformer mechanical hum, while present in every transformer, should not be audible enough to bother you. If it does, the unit should be replaced. I'm not saying if you put your ear down directly on the transformer casing and hear a buzzing, you should return it. Instead, is the buzzing/hum audible during normal listening sessions and at normal distances such as sitting at a desk, etc.? If so, return it.

For hum in the audio circuit, this can be more difficult to address, depending on the design and the mfr. If it can overwhelm the music signal and you can easily hear it when playing music, then there's no question - return it. That said, most 60Hz hum disappears when the music signal is strong enough, but it still means it's infecting the music and coloring the response - even if your ears can't pick out the hum over the music signal. The problem with many tube amplifiers is that a little bit of 60Hz hum is often "acceptable," depending on the design and the mfr. (I don't agree with that.) There are many very high-level tube amplifiers that sell for $thousands and still exhibit hum, especially when connecting to a low-impedance, high-efficiency headphone. So, it depends on the mfr's point of view and practice to see whether they consider that a defect (I would.).

Hope that helps - good luck!

The hum is audible even one meter away from the unit when sitting at my desk with my HD6XX on, sure it's open back, but I expect to hear absolutely nothing. I'm pretty sure I will get a replacement and if not then I know someone who is probably able to fix this issue

 

[tomb]

The hum is audible even one meter away from the unit when sitting at my desk with my HD6XX on, sure it's open back, but I expect to hear absolutely nothing. I'm pretty sure I will get a replacement and if not then I know someone who is probably able to fix this issue

OK, so now you've confirmed that the "hum" is mechanical buzzing heard outside of the audio circuit.

At least we got that straight. Unfortunately, you're not going to fix it unless the transformer is replaced. Transformer buzzing (better than calling it "hum") is caused by the lacquer coming loose between the plate laminations. The magnetic forces, when energized, cause those plates to vibrate and when there's a loose gap, they touch when vibrating and cause buzzing. You either replace the transformer or shield the noise with sound dampening material.

Buzz can sometimes be caused by a loose mounting, but the magnetic forces in our equipment is usually too small to do that.

Anyway, as I said before, good luck!

 

[InsanelyConfused]

OK, so now you've confirmed that the "hum" is mechanical buzzing heard outside of the audio circuit.

At least we got that straight. Unfortunately, you're not going to fix it unless the transformer is replaced. Transformer buzzing (better than calling it "hum") is caused by the lacquer coming loose between the plate laminations. The magnetic forces, when energized, cause those plates to vibrate and when there's a loose gap, they touch when vibrating and cause buzzing. You either replace the transformer or shield the noise with sound dampening material.

Buzz can sometimes be caused by a loose mounting, but the magnetic forces in our equipment is usually too small to do that.

Anyway, as I said before, good luck!

Yeah it's most likely exactly that, it's difficult to put it into words without being a native speaker lol.. I hope they will give me a replacement, if not then I can see myself opening that thing up and giving it a resin treatment, saw people do it on YouTube and I think this might work as a fix. But before I attempt that I will rather make use of the warranty and get myself a replacement without the hum.

Thanks a lot for your help!

 

[Yoda896]

Hey people,

just made an account to post here because I am wondering if I got a defective unit or not. My Xduoo TA-26 is running pretty good, no hissing, buzzing, microphonics or anything of that sort that is audible when wearing my headphones. I had some humming from my USB ports that lead to my DAC but resolved that by using the optical input of my DAC. But there is one last issue and it makes me consider returning it or getting a replacement and that is the humming sound the transformer makes when the unit is running. It's not audible while listening to music but I can definitely hear it humming when nothing is being played and it's just bad. Not loud like in some videos of clearly defective units, but still noticeable enough to think about if this is normal or not.

I am wondering if this is a commong thing or normal for the TA-26. Do units exists where there is no humming at all? Is is fixable or can I simply get a replacements and hope that it won't happen again? If this is normal and fixable then I know someone who probably has the know how to do so, so opening it up wouldn't be too much of an issue.

I would appreciate any help! I am so close to having a pretty sweet tube amp on my desk, but this humming is really ruining the experience.

Edit: (btw it's just the unit humming, my headphones are dead silent when nothing is playing)

I have two TA-26s which both share the transformer hum described by you. What helped in my case was to put a strong rubber ring around the transformers. This somehow disturbed the resonance of the transformer housing and and made it much more quiet without causing thermal issues.

 

[tomb]

I have two TA-26s which both share the transformer hum described by you. What helped in my case was to put a strong rubber ring around the transformers. This somehow disturbed the resonance of the transformer housing and and made it much more quiet without causing thermal issues.

Great post! That confirms the Xduoo's method of transformer mounting is less than optimum. Of course, the transformer has to vibrate before an insecure housing will make noise. Low-quality control in the transformers themselves has to be a part of this.

 

[InsanelyConfused]

I have two TA-26s which both share the transformer hum described by you. What helped in my case was to put a strong rubber ring around the transformers. This somehow disturbed the resonance of the transformer housing and and made it much more quiet without causing thermal issues.

Then this is probably what I will try first. The humming is very quiet and I barely notice it, but it could definitely be a little less!

 

[mangakaninja2]

hey i have the same issue with my unit,
i did the silicone wristband thingy and it seemed to help a bit,

just contacted xduoo as well, did they offer you a replacement?

 

[InsanelyConfused]

hey i have the same issue with my unit,
i did the silicone wristband thingy and it seemed to help a bit,

just contacted xduoo as well, did they offer you a replacement?

I didn't because it's such a low noise that it's almost not noticeable in use.. How exactly did you do thos wristband mod? If I can lower the humming a little more I will for sure try it

 

[Yoda896]

I didn't because it's such a low noise that it's almost not noticeable in use.. How exactly did you do thos wristband mod? If I can lower the humming a little more I will for sure try it

I am currently travelling so I can't post a picture of my unit with the mod. But, I used a very strong 30mm x 5mm rubber O-ring that I span over the transformer housing. I then moved it up and down to find a position that minimised the hum.

 

[mangakaninja2]

I didn't because it's such a low noise that it's almost not noticeable in use.. How exactly did you do thos wristband mod? If I can lower the humming a little more I will for sure try it

yea same here its barely noticeable too, im just being anal about my brand new toy

just use a 20cm silicone wristband, its tight but it should stretch around that transformer. will look into the O rings one as well to see which is best.
btw when i use the wristband it lowers the pitch of the noise by a significant margin, so its kinda of fix, jut a shame the customer has to do it. will need to stock on those rubberbands cause im guessing they will loose their tension pretty fast ...sigh* tubes and rubber now...

 

[InsanelyConfused]

I am currently travelling so I can't post a picture of my unit with the mod. But, I used a very strong 30mm x 5mm rubber O-ring that I span over the transformer housing. I then moved it up and down to find a position that minimised the hum.

Interesting is it easy to open the TA-26 up to get to the transformer? The only thing I did so far was swapping out a broken potentiometer and I don't want to accidentally shock myself lol.