Cayin HA-6A Tube Headphone Amplifier (KT88 and EL34) with XLR4 and 4.4mm Impedance Matched Output
Sep 19, 2021 at 2:19 AM Post #841 of 894

kimdeug

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Its a new one it come with 12au7 JJ tube. first I got hiss when I use my PC as a source then I try with streamer all hiss disappear with my hifiman he1000se but Verite I hear hiss only volume at 3Oclock or more.
It is normal (acceptable for me) hiss. After replacement of my unit, it arrived with JJ 12AU7 tubes. And it was exactly like you said with my ZMF Auteur hiss was after 3 oclock, but in my situation on only in XLR output and high impedance position. 1/4 was quiet in all impedance position. I have done some tube rolling 12AU7, switched to RCA input (XLR -too much gain), as a source switched from PC to laptop Apple MB Pro15 (less USB ground interference), used Ifi USB signal cleaner, DAC Cambridge Audio 851D and now it is dead silent.
BTW: I am using now Tesla ECC802S and KT88 Gold Lion UK made
 
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Sep 20, 2021 at 2:15 AM Post #842 of 894

tinariwen

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It is normal (acceptable for me) hiss. After replacement of my unit, it arrived with JJ 12AU7 tubes. And it was exactly like you said with my ZMF Auteur hiss was after 3 oclock, but in my situation on only in XLR output and high impedance position. 1/4 was quiet in all impedance position. I have done some tube rolling 12AU7, switched to RCA input (XLR -too much gain), as a source switched from PC to laptop Apple MB Pro15 (less USB ground interference), used Ifi USB signal cleaner, DAC Cambridge Audio 851D and now it is dead silent.
BTW: I am using now Tesla ECC802S and KT88 Gold Lion UK made
When you say 'acceptable hiss' and '1/4 was quiet in all impedance position', do you mean you can still hear hiss, but it's quiet enough to be acceptable? I'm trying to understand if your amp is actually dead silent, or that it's quiet enough for you to accept the typical tube hiss
 
Sep 20, 2021 at 4:37 AM Post #843 of 894

kimdeug

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When you say 'acceptable hiss' and '1/4 was quiet in all impedance position', do you mean you can still hear hiss, but it's quiet enough to be acceptable? I'm trying to understand if your amp is actually dead silent, or that it's quiet enough for you to accept the typical tube hiss
We are talking about replaced unit which came with JJ12AU7 tube. The first unit was with very loud hiss and humm, so I have returned it and have got a replacement (6months after :))). The replaced unit came with no any hiss/humm on 1/4 out at all impedance position. In XLR output hiss only starts on high impedance and volume 3 o'clock. I have used ZMF Auteur and HD800s balanced XLR and 4.4 balanced cables. After tube rolling, switched to laptop, USB signal filtering and better DAC, even this hiss (after 3 o'clock on high impedance and XLR output ) is gone. Now it is very quiet, even I turn my volume on max without any music. Regards, Kim
PS, doing all this different setups I have found that Cayin HA-6A is very sensitive to USB quality signal, wi fi and some other interferences when you place it close to computer case, or near wi fi station, or even when mouse or keyboards cable cross the DAC USB cable.
 
Sep 20, 2021 at 5:03 AM Post #844 of 894

kimdeug

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When you say 'acceptable hiss' and '1/4 was quiet in all impedance position', do you mean you can still hear hiss, but it's quiet enough to be acceptable? I'm trying to understand if your amp is actually dead silent, or that it's quiet enough for you to accept the typical tube hiss
Small life hack. To understand in my case, where the hiss was coming from I made a simple experiment. Took a paper box. Big enough to cover all HA 6A and tall enough to give a space to remove the heat from tubes. After I have covered this box from inside and outside by aluminium food foil. Simply say: made a double shielded box cover. And after listen music covering with box and without. That is how I found that external factors are giving me a hiss after 3 o'clock. On balanced output ,high impedance setting. Not sure what was exactly, but this double shielded box test helps me a lot. So, sharing my trick here. Regards, Kim
 
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Sep 25, 2021 at 10:53 AM Post #845 of 894

tinariwen

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Small life hack. To understand in my case, where the hiss was coming from I made a simple experiment. Took a paper box. Big enough to cover all HA 6A and tall enough to give a space to remove the heat from tubes. After I have covered this box from inside and outside by aluminium food foil. Simply say: made a double shielded box cover. And after listen music covering with box and without. That is how I found that external factors are giving me a hiss after 3 o'clock. On balanced output ,high impedance setting. Not sure what was exactly, but this double shielded box test helps me a lot. So, sharing my trick here. Regards, Kim
I think mine is one of the first batch, as there is some hum / hiss when in high impedance, but nothing that I can hear over music.

The worst part is there is random, intermittent 'static' that appears in the right channel. It doesn't seem to be tube dependant as I've changed tubes and swapped them left to right, and it's always on the right side. It sounds like muffled static.

Do you have any ideas what could cause it? I've moved the amp to a different room and it still has the same problem. I've tried different sources and even tried different RCA cables, too.
 
Sep 26, 2021 at 9:41 AM Post #846 of 894

tinariwen

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Hey all,

I posted yesterday about an odd static noise coming from the right channel of my Cayin ha-6a amp. Oddly enough, I managed to reduce the problem quite a bit by trying some different NOS tubes, but then things went downhill pretty quickly. Now I've got no sound coming through my headphones apart from a low hum. D'oh!

I wanted to try a couple of 'accessories' I thought might help reduce some of the background hiss when no music is playing. First, I changed the power cable to an Audioquest NRG Y3, which made no noticeable difference, regardless of whether music was playing or not. I then added two Audiocrast XLR Noise Stopper Caps to the XLR inputs on the rear of the amp, and again, no noticeable difference.

I then decided to switch back to the original power cable and remove the XLR Noise Stopper Caps (for a comparison). When I turned the amp on, no noise was coming from my headphones except for a low hum. I've removed and reinserted the tubes, changed the tubes entirely for different ones, changed the RCA source cable, and tried a different power cable. I've also tried a different source, tried different headphones, and tried a different headphone cable. The amp will power on, the tubes will heat up, but there is nothing but a low hum coming from the headphones.

I then noticed that the VU meters weren't registering any sound, despite music being played. Could the XLR Noise Stoppers or the power cable somehow damaged the input section of the amp? If so, what is likely to be the fault, and is it something that a local repair shop could fix? Unfortunately I have no warranty, so I'm looking to repair the amp locally.

Any advice or suggestions would be really appreciated.
 
Sep 27, 2021 at 10:28 AM Post #847 of 894
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Hey all,

I posted yesterday about an odd static noise coming from the right channel of my Cayin ha-6a amp. Oddly enough, I managed to reduce the problem quite a bit by trying some different NOS tubes, but then things went downhill pretty quickly. Now I've got no sound coming through my headphones apart from a low hum. D'oh!

I wanted to try a couple of 'accessories' I thought might help reduce some of the background hiss when no music is playing. First, I changed the power cable to an Audioquest NRG Y3, which made no noticeable difference, regardless of whether music was playing or not. I then added two Audiocrast XLR Noise Stopper Caps to the XLR inputs on the rear of the amp, and again, no noticeable difference.

I then decided to switch back to the original power cable and remove the XLR Noise Stopper Caps (for a comparison). When I turned the amp on, no noise was coming from my headphones except for a low hum. I've removed and reinserted the tubes, changed the tubes entirely for different ones, changed the RCA source cable, and tried a different power cable. I've also tried a different source, tried different headphones, and tried a different headphone cable. The amp will power on, the tubes will heat up, but there is nothing but a low hum coming from the headphones.

I then noticed that the VU meters weren't registering any sound, despite music being played. Could the XLR Noise Stoppers or the power cable somehow damaged the input section of the amp? If so, what is likely to be the fault, and is it something that a local repair shop could fix? Unfortunately I have no warranty, so I'm looking to repair the amp locally.

Any advice or suggestions would be really appreciated.

Please check PM, I have send you some questions, hopefully that will help us to shortlist your problem.

By the way, coming Friday is the National Day of the People's Republic of China and the country will celebrate over a one week period. The 7-day holiday begins from October 1st and runs until the 7th. I'll check the forum regularly but I won't have any support from our Engineer during this period.
 
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Sep 28, 2021 at 3:12 PM Post #849 of 894

kimdeug

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Sep 28, 2021 at 3:18 PM Post #850 of 894

robyzfi

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Same reason as yours. I have one from the first batch. Perfect with the Empyrean, too much noise floor with the Verite Open (I didn't try to use the high impedance setting).

Cayin Germany offered me to apply the same modifications done in newer units. I'm evaluating if I can get something else.
 
Sep 30, 2021 at 1:09 PM Post #851 of 894

tinariwen

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So I managed to fix the problem - somehow the fuse had blown inside (t160 I think).

The really interesting thing is that, after replacing that fuse, the noise floor has dropped dramatically (same tubes). It's practically inaudible, except for perhaps a ground loop hum as it's near my work desk and shares the plugs with a lot of other devices.

So, for anyone having a problem with the noise floor, try replacing the fuse. It's a 2min job, and the spares come in the box. It might not fix anything for you, but it's a very cheap and easy fix if it does.
 
Sep 30, 2021 at 1:19 PM Post #852 of 894

kimdeug

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So I managed to fix the problem - somehow the fuse had blown inside (t160 I think).

The really interesting thing is that, after replacing that fuse, the noise floor has dropped dramatically (same tubes). It's practically inaudible, except for perhaps a ground loop hum as it's near my work desk and shares the plugs with a lot of other devices.

So, for anyone having a problem with the noise floor, try replacing the fuse. It's a 2min job, and the spares come in the box. It might not fix anything for you, but it's a very cheap and easy fix if it does.
Thanks for sharing. Good to know. Will do experiments with some very high quality audio fuses.
 
Oct 7, 2021 at 5:15 AM Post #854 of 894

ThanatosVI

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Screenshot_20211007-105422_Chrome.jpg

Andy shared this picture in the Ha300 thread.

Thought I'd post it here since there is also a Black Ha-6A on the horizon.

Not sure if it's just the color or a Mk2 Kind of deal.

If it's Mk2 I'd really hope for Support up to KT170
 
Oct 7, 2021 at 5:23 AM Post #855 of 894
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So I managed to fix the problem - somehow the fuse had blown inside (t160 I think).

The really interesting thing is that, after replacing that fuse, the noise floor has dropped dramatically (same tubes). It's practically inaudible, except for perhaps a ground loop hum as it's near my work desk and shares the plugs with a lot of other devices.

So, for anyone having a problem with the noise floor, try replacing the fuse. It's a 2min job, and the spares come in the box. It might not fix anything for you, but it's a very cheap and easy fix if it does.

Thank you for your update. Glad you fixed the problem, so its the 300B High voltage fuse after all. Interesting part is, if the fuse had blown, you should have a defeated channel , instead of noise or lower volume output in a particular channel. This sure has gone beyond my previous observations and I'll definitely recommend users to check the internal fuse whenever they run into similar problem.
 
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