[Andykong]

I have had a similar experience, static noise mostly in the left side. Swapped tubes around but same problem. I noticed strong micophonics in the power tubes. I eventually purchased new power tubes and so far no reoccurring issues. Not sure why the power tubes failed. I may have left the amp on for a while with no phones connected, can’t truly remember, apparently this can cause potential problems including tube failure. Bit new to tube amps so not really sure what has caused this problem, hopefully your problem is just tube related & can be easily solved, good luck

For Cayin tube amplifier products, theoretically, this will only age the components gradually. For the record, we have added extra preventive protection measures to the output of our tube amplifier products to prevent any damage to the tubes and output transformers when our user power on the amplifier without any loading (i.e, no headphones connected in case of HA-3A, HA-6A, and HA-300MK2).

Having said that, when the tube headphone amplifier is turned on without plugging in the headphones, the transformer and components in the machine are still operating. All electronic components, including vacuum tubes, have a limited lifetime, if you keep the amplifier running like this, it is equivalent to consuming the life of the components, so we do recommend our users to turn off their amplifier when not in use.

 

[Andykong]

I've had a couple strange instances with the HA-3A today, seemingly out of nowhere. This morning I booted it up and all sounded good but as I was listening I was noticing some feedback and static noise creeping in. Shut off the music and the noise continued, probably 30-40db. I gently tapped a pencil on the tubes and all except the rectifier gave major microphonics through left-side of my headphone. I shut it off, gave it 10 minutes, booted it back up and it was quiet and normal again.

Later I booted it up when I started work at 9. I worked with it running fine for 3 hours and left it on while I went to get lunch. When I got back in 20 minutes the static and crackling was back, even more noticeable than in the morning. Tried the gentle tapping again, same results. Shut it off, waited, turned back on and normal again.

Any ideas? I'm assuming one (or more?) of my tubes is on the fritz. Hopefully nothing internal, and I don't think it's external interference based on my basic troubleshooting.

We can't draw any conclusion based on your observation. This can be a hardware problem (including tube-related) or something caused by external interference. Random interference is wild and difficult to catch, it can be caused by, for example, the lighting in your room and there is a dimmer in your lighting circuit.

 

[mudguardiain]

For Cayin tube amplifier products, theoretically, this will only age the components gradually. For the record, we have added extra preventive protection measures to the output of our tube amplifier products to prevent any damage to the tubes and output transformers when our user power on the amplifier without any loading (i.e, no headphones connected in case of HA-3A, HA-6A, and HA-300MK2).

Having said that, when the tube headphone amplifier is turned on without plugging in the headphones, the transformer and components in the machine are still operating. All electronic components, including vacuum tubes, have a limited lifetime, if you keep the amplifier running like this, it is equivalent to consuming the life of the components, so we do recommend our users to turn off their amplifier when not in use.

I only leave the amp on when I know that I will be using again relatively soon. If I know I won’t be using for several hours I do switch it off, I try not to switch it on & off unnecessarily. The new Gold Lion tubes seem to be working a treat & no noise issues, must have been unlucky with the original 6v6 tubes, only had them running for a couple of months.

 

[fullbass]

I connected both inputs to the same DAC.

Thanks for the detailed response. But my question was not about input, but about output. Should I connect the headphone cable to the output when the amplifier is on for safety? Or I can connect the cable without headphones (e.g. I don't want accidental clicks or crackles in the headphones in case the tube fails)?

 

[Andykong]

Thanks for the detailed response. But my question was not about input, but about output. Should I connect the headphone cable to the output when the amplifier is on for safety? Or I can connect the cable without headphones (e.g. I don't want accidental clicks or crackles in the headphones in case the tube fails)?

https://www.head-fi.org/threads/cay...-tube-amplifier.963983/page-113#post-17951224

 

[DrDen]

Thanks for the detailed response. But my question was not about input, but about output. Should I connect the headphone cable to the output when the amplifier is on for safety? Or I can connect the cable without headphones (e.g. I don't want accidental clicks or crackles in the headphones in case the tube fails)?

IMO connecting headphone cable without headphone makes no sense. There is no load in this case.

 

[AnyDave]

I would only add my 2 cents from a DAC point of view. Some DACs do not like if both the RCA and XLR output is connected at the same time as it can affect volume and sound quality. So, it is recommended to do some research regarding one's chosen DAC if the intention is to use both outputs.

Yeah, my Denafrips and Chord DACs both specifically state not to connect both RCA and XLR. Other DACs I have aren't picky. It's definitely smart to check that first with the DAC manufacturer.

 

[DrDen]

Yeah, my Denafrips and Chord DACs both specifically state not to connect both RCA and XLR.

 

[betula]

Yeah, my Denafrips and Chord DACs both specifically state not to connect both RCA and XLR. Other DACs I have aren't picky. It's definitely smart to check that first with the DAC manufacturer.

Yes, Denafrips, Chord, Musician are definitely like this. For most users it is not an issue, but if you want to use the same DAC with two different amps with RCA and XLR out, that won't work. (Also have to avoid using both RCA and XLR interconnects to the same amp at the same time, but that doesn't make much sense anyway.)

 

[NJoyzAudio]

Yes, Denafrips, Chord, Musician are definitely like this. For most users it is not an issue, but if you want to use the same DAC with two different amps with RCA and XLR out, that won't work. (Also have to avoid using both RCA and XLR interconnects to the same amp at the same time, but that doesn't make much sense anyway.)

Betula
Thanks for the post above and the previous one.
I believe you and I are using the same DAC and when I wrote earlier, I might have mistakenly quoted the DAC manufacturer specifically that both Ety Dave and Dr.Den have identified and posted also

Also as noted by several on this forum, and Andy confirmed, for output Andy has previously posted information about what he called "open loop" and has discouraged that practice
With ANY audio device, I've always made it a practive to turn the volume to min, after at shows, or after lending my HW to a friend to test, I get to it and the volume is at a much higher level than I want or tollerate. Just a personal preference and something I've done with both Tube and Solid State home gear years ago after damaging some speakers by not doing this.

Thanks all for your input and posts!

 

[betula]

With ANY audio device, I've always made it a practice to turn the volume to min, after at shows...

That is a good practice, something that perhaps could be advertised at shows. If there was a little note next to the amps to turn it down once finished, that could save some headache for vendors.

 

[skeeb23]

On the other hand, one of the biggest differences between Solid-state and Vacuum tube amplifiers is that you should not listen to your tube amplifier at an unconnected input setting. I don't know the exact technical term but I have described this as an “Open-loop” condition in other Cayin tube amplifier threads, and I have advised users NOT TO listen to an unconnected input and use that as your reference for a silent background test, you can check out my previous explanation HERE.

To be honest, I never would have even thought about doing this...or why you would till you mentioned the black background check. Good to know and learn so I never would make that mistake in the future. Thank you!

 

[Andykong]

I would only add my 2 cents from a DAC point of view. Some DACs do not like if both the RCA and XLR output is connected at the same time as it can affect volume and sound quality. So, it is recommended to do some research regarding one's chosen DAC if the intention is to use both outputs.

When I picked up HeadFi hobby many years ago, I planned a very simple headphone system that would allow me to explore as many headphones as possible, and my first headphone system comprised of 1 DAC with two headphone amplifiers (one Solid State and one vacuum Tube), My System was installed on a wall-mount rack with very limited space behind the gears, so connecting and disconnecting is a very difficult task, I have no choice but to connect everything in advance. I used YULONG DAC at that time and I have checked with the brand owner, he confirmed that both RCA and XLR outputs are active and I can connect them all up as planned. He explained that the DAC will perform better when connected to one amplifier only, but in my case, when I need to use two amplifiers, asking me to connect and disconnect equipment every time is not practical. At the end of the discussion, I connected both amplifiers to the DAC and minimized the performance loss by keeping one amplifier power off.

I think we need to differentiate between two arguments:

• Is it technically safe to connect both outputs of DAC at the same time? If the supplier said this is not safe and might cause damage to the DAC, then I'll urge you to follow their advice strictly.
• It is technically safe to do that but will affect the performance, then it is up to the users to evaluate the options within their own practical needs.

Maybe we can perform a simple performance check? Connect to one amplifier only, use it for a week, and then connect to two amplifiers and use it for another week, and revise back to one amplifier again. (ABA test method but with extended periods instead of 2-minute intervals)

This is a methodology that can be applied to many scenarios. For example, I always advise users to start with the impedance setting according to headphone specification, but once they are familiar with the sound signature of the default impedance setting, they can be free to explore other impedance settings. This is another form of ABA test over an extended period.

 

[Andykong]

Yes, Denafrips, Chord, Musician are definitely like this. For most users it is not an issue, but if you want to use the same DAC with two different amps with RCA and XLR out, that won't work. (Also have to avoid using both RCA and XLR interconnects to the same amp at the same time, but that doesn't make much sense anyway.)

For users who primarily use XLR as their audio source, an RCA connection can be used as a grounding connection between DAC and Amplifier to solve the ground hum problem. Yes, you only need one RCA cable to achieve ground connection, but a lot of users feel uncomfortable to connect only one RCA cable.

 

[betula]

When I picked up HeadFi hobby many years ago, I planned a very simple headphone system that would allow me to explore as many headphones as possible, and my first headphone system comprised of 1 DAC with two headphone amplifiers (one Solid State and one vacuum Tube), My System was installed on a wall-mount rack with very limited space behind the gears, so connecting and disconnecting is a very difficult task, I have no choice but to connect everything in advance. I used YULONG DAC at that time and I have checked with the brand owner, he confirmed that both RCA and XLR outputs are active and I can connect them all up as planned. He explained that the DAC will perform better when connected to one amplifier only, but in my case, when I need to use two amplifiers, asking me to connect and disconnect equipment every time is not practical. At the end of the discussion, I connected both amplifiers to the DAC and minimized the performance loss by keeping one amplifier power off.

I think we need to differentiate between two arguments:

• Is it technically safe to connect both outputs of DAC at the same time? If the supplier said this is not safe and might cause damage to the DAC, then I'll urge you to follow their advice strictly.
• It is technically safe to do that but will affect the performance, then it is up to the users to evaluate the options within their own practical needs.

Maybe we can perform a simple performance check? Connect to one amplifier only, use it for a week, and then connect to two amplifiers and use it for another week, and revise back to one amplifier again. (ABA test method but with extended periods instead of 2-minute intervals)

This is a methodology that can be applied to many scenarios. For example, I always advise users to start with the impedance setting according to headphone specification, but once they are familiar with the sound signature of the default impedance setting, they can be free to explore other impedance settings. This is another form of ABA test over an extended period.

For users who primarily use XLR as their audio source, an RCA connection can be used as a grounding connection between DAC and Amplifier to solve the ground hum problem. Yes, you only need one RCA cable to achieve ground connection, but a lot of users feel uncomfortable to connect only one RCA cable.

Yes, this is all very logical and makes sense. With the DACs I tried where the manufacturer did not recommend using both RCA and XLR out at the same time, the sound degradation was immediately obvious, did not have to give it much listening.