[xTelepathetic]

I have the same problem. There was a hiss in the left channel. I changed tubes, sometimes it went away, then it came back. I was convinced it was the EL-84 power tubes.
Then I thought of directing the antennas of the Asus router, which unfortunately I have under the table directly under the Cayin, and the noise disappeared and has not been there for many months.
The HA-1A is a great amplifier, unfortunately it is prone to interference.
Much depends on the connected headphones and their impedance. Sensitive, low-impedance headphones will amplify any interference.

Sadly, my router is downstairs so I do not think that is the issue. I am running my RCA cable behind my desktop.. maybe that would do it? The amp is sitting on a desk next to a computer monitor. I am happy you got the noise to go away!

 

[xTelepathetic]

Sadly, my router is downstairs so I do not think that is the issue. I am running my RCA cable behind my desktop.. maybe that would do it? The amp is sitting on a desk next to a computer monitor. I am happy you got the noise to go away!

I want to add that I was just using it and the ringing got so bad I had to stop and turn it off. Completely audible through the music

 

[mbphotox]

Sadly, my router is downstairs so I do not think that is the issue. I am running my RCA cable behind my desktop.. maybe that would do it? The amp is sitting on a desk next to a computer monitor. I am happy you got the noise to go away!

Please try the amp somewhere away from any devices that emit radiation.

Put it on a kitchen table with no other devices nearby to test if it's from interference.

My Yamaha Studio Monitors love to broadcast my smartphone sending/receiving signals too...

 

[xTelepathetic]

Please try the amp somewhere away from any devices that emit radiation.

Put it on a kitchen table with no other devices nearby to test if it's from interference.

My Yamaha Studio Monitors love to broadcast my smartphone sending/receiving signals too...

Hi mbphotox, thank you for the idea! I may try this! The weird thing though is that the distortion is only in the left channel. If this were the case, I would expect it to be present in both, but the right channel is nearly black. I have been talking with the seller and we believe there is a hardware issue with the amp- likely a failure in the left channel circuit. We are trying to find a place to get the amp looked at and repaired if necessary. I emailed Cayin's service department and have yet to hear back.

 

[martas38]

Interestingly. I also had hiss in the left channel. The tubes were burnt, but not old.
I tried redirecting the antennas of the router and since then black, the problem has disappeared.
I hope forever.

 

[Andykong]

Hi mbphotox, thank you for the idea! I may try this! The weird thing though is that the distortion is only in the left channel. If this were the case, I would expect it to be present in both, but the right channel is nearly black. I have been talking with the seller and we believe there is a hardware issue with the amp- likely a failure in the left channel circuit. We are trying to find a place to get the amp looked at and repaired if necessary. I emailed Cayin's service department and have yet to hear back.

I can think of three possibilities:

(1)Tube related. You should eliminate this possibility before move on to other diagnosis. If you have spare set of tube, them you can put on your replacement tubes, or at least swap the left and right channel EL84 and 12AU7.

(2) interference related. Trust me, interference is a very strange happening, it can affect only one channel. This happened in the past so please keep an open mind on this when you try to debug your system.

(3) hardware related. We can't confirm until an engineer examine the amplifier in person. We don't have enough information to even wild guess whats happened inside the amplifier.

 

[xTelepathetic]

I can think of three possibilities:

(1)Tube related. You should eliminate this possibility before move on to other diagnosis. If you have spare set of tube, them you can put on your replacement tubes, or at least swap the left and right channel EL84 and 12AU7.

(2) interference related. Trust me, interference is a very strange happening, it can affect only one channel. This happened in the past so please keep an open mind on this when you try to debug your system.

(3) hardware related. We can't confirm until an engineer examine the amplifier in person. We don't have enough information to even wild guess whats happened inside the amplifier.

Hi Andy, I appreciate the response! I have done a complete tube roll from the stock tubes to a set of PSVANE 12UA7s, Millard EL84s, and a NOS Raytheon 12DT5. The issue persists across all tubes (though worse with the stock tubes), regardless of the side.

For interference, how would you recommend shielding the amp? I have it sitting on a desk next to a computer monitor. No wifi router is in the room with it. In the room, I have my desktop (which my amp and DAC are connected to), my iPhone, and other WiFi connected devices.

With the hardware, I noticed what appeared to be scorch marks on the side of the EL84 holders and other grime on the top of the 12DT5 holder. I was able to wipe the grime away. Nothing looks amiss when viewing the exposed circuitry, although the right channel EL84 LED has now burnt out. The noise is also present when the AMP is disconnected from my DAC (iDac-6 MKII), so its not going to be a source issue.

All the troubleshooting I have done is as follows:
- Add a ground loop noise isolator between my DAC and the HA1A MKII
- complete tube roll
- test with different headphones
- swap HA-1A input from AUX to CD
- change output impedance
- try both of the amp’s headphone putouts
- new power cord
- plug amp directly into an outlet (not a power strip)

How would you recommend troubleshooting?

 

[Andykong]

Hi Andy, I appreciate the response! I have done a complete tube roll from the stock tubes to a set of PSVANE 12UA7s, Millard EL84s, and a NOS Raytheon 12DT5. The issue persists across all tubes (though worse with the stock tubes), regardless of the side.

For interference, how would you recommend shielding the amp? I have it sitting on a desk next to a computer monitor. No wifi router is in the room with it. In the room, I have my desktop (which my amp and DAC are connected to), my iPhone, and other WiFi connected devices.

With the hardware, I noticed what appeared to be scorch marks on the side of the EL84 holders and other grime on the top of the 12DT5 holder. I was able to wipe the grime away. Nothing looks amiss when viewing the exposed circuitry, although the right channel EL84 LED has now burnt out. The noise is also present when the AMP is disconnected from my DAC (iDac-6 MKII), so its not going to be a source issue.

All the troubleshooting I have done is as follows:
- Add a ground loop noise isolator between my DAC and the HA1A MKII
- complete tube roll
- test with different headphones
- swap HA-1A input from AUX to CD
- change output impedance
- try both of the amp’s headphone putouts
- new power cord
- plug amp directly into an outlet (not a power strip)

How would you recommend troubleshooting?

Router is the most obvious source of RF interference but it can be far more subtle than that. I would suggest removing the PC from the chain for testing purposes because USB connection is quite often a hidden problem, I have dealt with hum noise caused by the backlight of the PC keyboard, and the most bizarre case was the graphic card of the PC, when pressing hard to a high utilization rate, will cause interference to the tube amplifier. So if you have another source in your home, please remove the PC from the chain and replace it with a DVD player or a DAP, for testing purpose.

 

[mbphotox]

You swapped all the tubes but never thought about trying it in a different room?
It's a headphone amp, you can basically bring it out to your garage and just try it with a simple DAP and leave the phone in the house

 

[Lubak]

I had a similar problem although not so one-chanelled, in so that I would get a really high noise floor, like a hiss that was audible on quiet music also. The way I fixed it was by insulating the rca outs for the preamp function of the Cayin. I did move it about the house to no real effect, but when i plugged an rca cable to the preamp out and then into my Atom amp, the Cayin went completely silent. I discovered it by accident, as I was using it as a preamp with my Atom and just wanted to see how different the sound is - plugged the headphones in the Cayin with the Atom connected to it and there was zero hiss. Silent. So that's how I use it now, just keep an rca cable from the preamp out of the Cayin plugged into any input on my stereo amp that I don't use. So I don't know, that may be worth a try also.

 

[Andykong]

Hi Andy, I appreciate the response! I have done a complete tube roll from the stock tubes to a set of PSVANE 12UA7s, Millard EL84s, and a NOS Raytheon 12DT5. The issue persists across all tubes (though worse with the stock tubes), regardless of the side.

For interference, how would you recommend shielding the amp? I have it sitting on a desk next to a computer monitor. No wifi router is in the room with it. In the room, I have my desktop (which my amp and DAC are connected to), my iPhone, and other WiFi connected devices.

With the hardware, I noticed what appeared to be scorch marks on the side of the EL84 holders and other grime on the top of the 12DT5 holder. I was able to wipe the grime away. Nothing looks amiss when viewing the exposed circuitry, although the right channel EL84 LED has now burnt out. The noise is also present when the AMP is disconnected from my DAC (iDac-6 MKII), so its not going to be a source issue.

All the troubleshooting I have done is as follows:
- Add a ground loop noise isolator between my DAC and the HA1A MKII
- complete tube roll
- test with different headphones
- swap HA-1A input from AUX to CD
- change output impedance
- try both of the amp’s headphone putouts
- new power cord
- plug amp directly into an outlet (not a power strip)

How would you recommend troubleshooting?

You did a complete tube rolling, which probably will eliminate the tube as a source of your noise problem. However, I'll ask for one more test so that we can compare your test result with ours - since we don't have the PSVANE/Millard combination in our factory.

Let's go back to your stock tubes. Install them randomly into your HA-1AMK2, and after hearing the noise, swap the left and right 12UA7 first, and then swap it back again, and finally swap the left and right EL84, and tell us whether the noise level changed during these swapping. Maybe this can give us some clues in diagnosis.

 

[covgyw]

Just got this amp a few days ago. I had to troubleshoot two things:
1. Ground Loop Issue (loud hissing): Some one mentioned that to connect the RCA out (so the HA1A can act as a pre-amp) to something. I connected the HA1A to my solid state amp RCA in and it solved the ground loop issue
2. Humming Noise (Noise floor of the tubes): I bought ifi iematch and it fixed the issue.

Shout out to @r343 for walking through it with me!

 

[jokervn91]

Thinking about getting this since it fits my need quite well but curious how bad is the interference problem since I have to have my PC and routers, etc around the amp

 

[Bostonears]

Thinking about getting this since it fits my need quite well but curious how bad is the interference problem since I have to have my PC and routers, etc around the amp

No interference problem for me with the Cayin about 2 feet from my PC and 4 feet from my router.

 

[Chodi]

No interference problem for me with the Cayin about 2 feet from my PC and 4 feet from my router.

Same, I'm listening to mine as I type this. Totally black background. PC 3 feet away. Router 5 feet away. If I move the router closer it injects RF into everything. I love this amp. I have others including the Cayin SS amp so I switch around but this HA-1A MK2 is a keeper.