[dpump]

Regarding the noise issues being discussed here. When you want to test any amp to see if the amp is generating noise itself, you cannot, repeat cannot, unplug all inputs, connect headphones, and then turn up the volume. You need to have shorting plugs in the inputs you are testing. An open or unloaded input will always cause you to hear more noise than the amp is generating by itself. I'm very surprised Andy Kong and Cayin haven't mentioned this. You need RCA shorting plugs and XLR shorting plugs to do the noise tests you are performing to be sure hiss is coming just from the amp.

Another thing is the impedance and sensitivity of the headphones you are using. Unfortunately, in my view, there has been a race by manufacturers in recent years to make their headphones or iems more and more efficient so they can claim that any source from a computer, phone, dap, portable amp, etc, can properly drive their phones. When you connect higher sensitivity and/or low impedance phones you will hear more noise. Connect a 93dB headphone and you have little to no noise. Connect a 100dB headphone and, no surprise, you hear more noise. Iems often go up to 110dB sensitivity or more so can be unusable on many amps due to noise. You have to take into consideration the specifications of the phones you are using when you are testing any amp for noise.

High and higher output power from headphone amps. There also seems to be the expectation now that amps should have as much output power as possible. We're up to 3 watts, 5 watts, 8 watts and more. There are almost no headphones that need this kind of power. The more power you have from an amp, especially tube amps, the more noise you can have. To some extent, you can't have a lot of power on a tube amp and expect to hear no noise of any kind. Tube amps will almost have more noise than solid state amps, although lower power tube amps can often be very quiet.

Bottom line, you should expect to hear some noise from Cayin amps using KT88, EL34, 300B, and EL84 power tubes when they have been designed to output multiple watts of power. These output tubes were originally designed and used to power speakers before headphones were even in use the way we are using them. All of these can be great sounding tubes, but in some sense are being used outside of the use they were designed for. I own a number of tube headphone amps, including the Cayin HA-1A MK2. My Cayin does have some hiss and noise with high impedance/high sensitivity headphones, but almost none with lower impedance phones. Other amps I have with less than 1 watt output have little noise. So don't expect to have no noise on a higher power tube amp. Tubes are inherently noisier than solid state and designing a tube headphone amp with a high output level, no matter what power tubes are being used, will pretty much guarantee you will have some audible noise depending on the headphones you are using.

I'm not saying that there might not be something in the design of the Cayin amps that is causing some of the noise. That may be the case. A possible fix could be to lower the gain somewhere in the amp, but I tend to think the Cayin is designed for the best possible sound and some noise is a result of their design choices. It will be interesting to see if Cayin makes any design changes and then discusses them here so owners can decide if they want to make any changes themselves.

 

[kimdeug]

Regarding the noise issues being discussed here. When you want to test any amp to see if the amp is generating noise itself, you cannot, repeat cannot, unplug all inputs, connect headphones, and then turn up the volume. You need to have shorting plugs in the inputs you are testing. An open or unloaded input will always cause you to hear more noise than the amp is generating by itself. I'm very surprised Andy Kong and Cayin haven't mentioned this. You need RCA shorting plugs and XLR shorting plugs to do the noise tests you are performing to be sure hiss is coming just from the amp.

Another thing is the impedance and sensitivity of the headphones you are using. Unfortunately, in my view, there has been a race by manufacturers in recent years to make their headphones or iems more and more efficient so they can claim that any source from a computer, phone, dap, portable amp, etc, can properly drive their phones. When you connect higher sensitivity and/or low impedance phones you will hear more noise. Connect a 93dB headphone and you have little to no noise. Connect a 100dB headphone and, no surprise, you hear more noise. Iems often go up to 110dB sensitivity or more so can be unusable on many amps due to noise. You have to take into consideration the specifications of the phones you are using when you are testing any amp for noise.

High and higher output power from headphone amps. There also seems to be the expectation now that amps should have as much output power as possible. We're up to 3 watts, 5 watts, 8 watts and more. There are almost no headphones that need this kind of power. The more power you have from an amp, especially tube amps, the more noise you can have. To some extent, you can't have a lot of power on a tube amp and expect to hear no noise of any kind. Tube amps will almost have more noise than solid state amps, although lower power tube amps can often be very quiet.

Bottom line, you should expect to hear some noise from Cayin amps using KT88, EL34, 300B, and EL84 power tubes when they have been designed to output multiple watts of power. These output tubes were originally designed and used to power speakers before headphones were even in use the way we are using them. All of these can be great sounding tubes, but in some sense are being used outside of the use they were designed for. I own a number of tube headphone amps, including the Cayin HA-1A MK2. My Cayin does have some hiss and noise with high impedance/high sensitivity headphones, but almost none with lower impedance phones. Other amps I have with less than 1 watt output have little noise. So don't expect to have no noise on a higher power tube amp. Tubes are inherently noisier than solid state and designing a tube headphone amp with a high output level, no matter what power tubes are being used, will pretty much guarantee you will have some audible noise depending on the headphones you are using.

I'm not saying that there might not be something in the design of the Cayin amps that is causing some of the noise. That may be the case. A possible fix could be to lower the gain somewhere in the amp, but I tend to think the Cayin is designed for the best possible sound and some noise is a result of their design choices. It will be interesting to see if Cayin makes any design changes and then discusses them here so owners can decide if they want to make any changes themselves.

Hi, Thanks for reply.
I have done this test with no signals to avoid any discussion about noise which is generated outside of amplifier. This method has been chosen because, after connecting any DAC via XLR and RCA cables, the initial noise has been multiplied almost double in XLR and roughly triple at RCA connection at Zero Volume position.
Regarding to different impedance and sensitivity for each headphones: for this purpose I have deliberately listed the headphones used, and choice of each was specifically chosen because of different impedance and sensitivity. Also I have connected HA-6A via XLR to the X Grace design balanced DAC, which was powered via USB from laptop working on Battery only, with the same noise effect.
30% of Humm noise reminds me situation when I had WA-6SE Humm issue, but solution was very easy: you need to remove the power block away from amplifier block. Here it is not possible.
70% Hiss was hard to define why. First, I was thinking due to loud tubes, but after burning them around 70 hours all the same. Going further I have rolled them to used GEC88 tubes from my friend (just have took from his daily working amplifier) -with the same Hiss effect. Also rolled the driver with Lorenz E82CC tubes, and hiss is still there.
From early discussions the original ElectroHarmonics 12AU7 are the quietest. It is obvious that more sensitive headphones are prone to pick up more noise, but early Andykong mentioned that with 300 Ohms headphones (Sennheiser HD800S and 6XX) Ha-6a suppose to be dead silent.
This is a not my first tube amplifier. I have Darkvoice, LaFigaro339 and Bottleneck Crack Speedball around, but all of them do not produce this amount of hiss/humming noise at any Volume level. At this stage I can not justify my self why I should pay 5 times more for the worse sound quality?
Apart, I really like the design and presentation. More refined than WA22.
Regards,
Kim

 

[Fatdoi]

White Noise Test

Hello Cayin HA-6A lovers.

Finally have got little bit time, so have conducted some tests to investigate the hissing issue on HA-6A.
To eliminate all speculations about dirty signal coming IN, this test has been conducted without any audio inputs XLR or RCA connected. Means: No any input cables has been plugged to HA-6A, except power cable to operate. In this situation, I tried to create the most convenient for HA-6A operation room environment, with attention to Clean power supply. OK, Lets do the White Noise Test......

Equipments: Ha-6A, Power Filter Belkin PureAV PF40, Heavily Shielded Power Cables KRELL 20A, DC Blocker Supra MD Mk3
Headphones: Sennh HD800S, 6XX, ZMF Auteur, Focal Elex, Sony MDR Z-7

Room environment: All electronics are plugged OFF (except the lighting), Wi Fi is off, Mobile phone in the next room.

DC Block >> Power Filter >> HA-6A >> Headphones

Results: In my situation, adding or removing the power filter and DC blocker from the power chain has not changed the noise coming out from HA-6A. It means no any changes in tonality, loudness, and character of noise - all was the same. The same about Heavy shielded power cables.
The noise can be described as combination of Humm and Hiss in proportion (Humm/Hiss) as 20/80 or 30/70 at Volume position Zero/Minimum.
The noise becomes louder with increasing the Volume.
The noise was present at all impedances and all outputs.
The noise was more noticeable/louder on high impedance and XLR output selection,while on 1/4 and Low impedance was the lowest.
Switching from Triode to Ultra-linear mod, made the noise more louder.
Low sensitivity headphones made the noise less noticeable.
Only one Volume step from Zero made 6XX loud. Next 3 steps - already too loud. Other 21 actuator steps are not usable on Hi Impedance for 6XX, HD800S and ZMF Auteur.

Conclusion: At this stage it is clear that the source of Hissing noise is coming out from Ha-6A and not related to the power supplied. Very high gain does not benefit hi impedance headphones to shine. In opposite, it brings distortion on the last Volume actuator steps. By the character of noise, I can assume, it relates to Transformer power filtering and impedance matching issues, probably before amplifying stage.
The presents of noise is very audible and unacceptable for this price range equipment. Looks like you are listening music via old radio with all existing interferences.
In this stage I will pack the unit and will send it back to the dealer tomorrow.

Regards,
Kim

That's a bit of a bummer isn't it..... so you getting your money back or try another unit?

 

[Gr3g277]

Hello my Friend.

Really appreciate your efforts to replicate my tests and share your findings.
At this moment I have canceled order of 6L6 and KT66 tubes, until the hiss issue will be solved.
But I am very curious how 6L6 tubes sounds like, compare to stock KT88 or EL34?
Also, please, look my previous post with Terminology.
I was in the same boat and was thinking: "OK, I am only using 6XX at 9 o'clock volume maximum, and the hiss is not so noticeable. May be I will keep like this?"
But, when I have done Initial Noise Test (6XX, 4 pin XLR out, High Impedance, Music on PAUSE) and compared to Zero Point, I have found that this Hiss/Humm noise was so loud!!! It was on all outputs: 1/4, Penta, 4pin XLR (slightly less on 1/4, but still very audible). At Volume position 9 o'clock (for normal volume listening), we are talking about this amount of hiss noise coming to your headphone on top of the sound from music track. And this is unacceptable for me.
So, doing further investigation, while waiting response from Andykong.

Regards,
Kim

PS: Also you can do Initial Noise Test for White Noise, to see how much exactly noise your amplifier produces by itself.

Hello kim,

I did your zero Point test, initial noise test, and background noise test, with similiar findings with my high sensitivity headphones.

especially so with the hd650 on high impedance. Background noise is clearly audible, I can hear It as well on quiet moments in acoustic music or classical pieces.

Results: In my situation, adding or removing the power filter and DC blocker from the power chain has not changed the noise coming out from HA-6A. It means no any changes in tonality, loudness, and character of noise - all was the same. The same about Heavy shielded power cables.
The noise can be described as combination of Humm and Hiss in proportion (Humm/Hiss) as 20/80 or 30/70 at Volume position Zero/Minimum.
The noise becomes louder with increasing the Volume.
The noise was present at all impedances and all outputs.
The noise was more noticeable/louder on high impedance and XLR output selection,while on 1/4 and Low impedance was the lowest.
Switching from Triode to Ultra-linear mod, made the noise more louder.
Low sensitivity headphones made the noise less noticeable.
Only one Volume step from Zero made 6XX loud. Next 3 steps - already too loud. Other 21 actuator steps are not usable on Hi Impedance for 6XX, HD800S and ZMF Auteur.

I think this is a great resume of the symptoms we are getting with the HA-6A.

That said let's not forget, this is a very HIGH power tube amp, and tube amps, especially class A, single ended, low negative feedback are much more noisy than your average SS amp... and making a very silent one is very hard as well.

I think we choose this amp for that reason, the purest amplification form, but it comes with the cost of elevated noise floor.

On the other hand, the selling point of this amp, is the versatility it has, with the loading options, and here it is clearly lacking an acceptable noise floor tu use it with a big majority of todays headphones...

Now It fits perfectly with my arya, but cannot use it properly with with my hd650.
But my I can also use my aryas on the 8 ohms speaker taps of my primaluna kt88 40w speaker amp with no noise...
I also tested different rectifier tubes, with no changes, as well as power tubes, with no changes in Initial noise or background noise.
IMO the noise issue is in the preamp section, I can clearly hear changes in noise floor, when swapping preamp tubes. I even had crazy microphonics with some tubes that worked fine in my speaker amp.

I think a mk2 version with maybe a gain switch ? or maybe more steps attenuator ?

@kimdeug what is the voltage of your unit ? 230 or 110V ? mine is a 230V , I wonder if 110V/60hz versions are quieter ?

@Andykong I would like to apply as well, to any running changes that will be rolled out

 

[kimdeug]

That's a bit of a bummer isn't it..... so you getting your money back or try another unit?

Not sure yet.

It is 04:30 morning in Auckland now.
Will see at day time.
Actually I really like the built quality and presentation.
Much better, compare to WA22.
But this Hiss/ Humm noise makes this amplifier almost unusable for my headphones collection.
Except AKG 7XX, Q701 (both 62 Ohms, 105 dB), Fostex T50, 60, Argon (all 50 Ohms 92 dB).
AKG and Fostex are "swallowing" this hiss/humm sound.
Looks like Low Impedance and sensitivity is more beneficial at this case.
What is bother me more that the humming noise does not increase with hissing noise.
While Hissing noise increases linearly with volume increase (but much slower), humm noise is remaining the same and at the end (around 3 o'clock) suddenly becomes more loud and creates distortion.
We will see today, But I really want to fix this issue and keep this amplifier as end game unit.

Regards,
Kim

 

[kimdeug]

Hello kim,

I did your zero Point test, initial noise test, and background noise test, with similiar findings with my high sensitivity headphones.

especially so with the hd650 on high impedance. Background noise is clearly audible, I can hear It as well on quiet moments in acoustic music or classical pieces.




I think this is a great resume of the symptoms we are getting with the HA-6A.

That said let's not forget, this is a very HIGH power tube amp, and tube amps, especially class A, single ended, low negative feedback are much more noisy than your average SS amp... and making a very silent one is very hard as well.

I think we choose this amp for that reason, the purest amplification form, but it comes with the cost of elevated noise floor.

On the other hand, the selling point of this amp, is the versatility it has, with the loading options, and here it is clearly lacking an acceptable noise floor tu use it with a big majority of todays headphones...

Now It fits perfectly with my arya, but cannot use it properly with with my hd650.
But my I can also use my aryas on the 8 ohms speaker taps of my primaluna kt88 40w speaker amp with no noise...
I also tested different rectifier tubes, with no changes, as well as power tubes, with no changes in Initial noise or background noise.
IMO the noise issue is in the preamp section, I can clearly hear changes in noise floor, when swapping preamp tubes. I even had crazy microphonics with some tubes that worked fine in my speaker amp.

I think a mk2 version with maybe a gain switch ? or maybe more steps attenuator ?

@kimdeug what is the voltage of your unit ? 230 or 110V ? mine is a 230V , I wonder if 110V/60hz versions are quieter ?

@Andykong I would like to apply as well, to any running changes that will be rolled out

Waaw, Thank you for reply and following my tests. Highly appreciated. You are real Headphone enthusiast)

I have bought this amp to run HD800S and ZMF Auteur, mostly for Jazz/blues female vocal listening. Also very like HD6XX for low female vocals. All of this headphones 300 Ohms, Sennheisers 102-103 dB sensitivity and ZMF -97dB
My normal listening Volume actually only 1 step from the minimun/zero Volume and this hissing noise made all my headphones unusable.
My unit is 230V
Interesting finding: that AKG 7XX and Q701 (62 Ohms, 105 dB) are very quiet at medium impedance.
I do not mind to send and wait 2-3 months to fix all issues.

Regards,
Kim

 

[Gr3g277]

Yeah,

I bought mine mainly for my aryas, but still love my hd650 for vocals, and my kennerton for the fun bass...
I also dropped 2.5K€ on the unit , as an end game amp, and was eyeing on the focal utopia to pair with it, ( we can get good prices used here in france ) but I will wait a bit.

It's a bummer, that noise issue, because it is the best sounding amp that I have ever heard, and the looks is simply awesome.
for the moment I'll use it with my planar, and stick to my asgard3 for the dynamics.

It is really interesting that your AKG's are silent ! cannot understand why really ( maybe the rated sensitivity is overrated ? )

I do not mind waiting for a fix as well.

i'll wait for @Relaxasaurus to receive his unit back, and hope that it will be fixed.

 

[kimdeug]

Yeah,

I bought mine mainly for my aryas, but still love my hd650 for vocals, and my kennerton for the fun bass...
I also dropped 2.5K€ on the unit , as an end game amp, and was eyeing on the focal utopia to pair with it, ( we can get good prices used here in france ) but I will wait a bit.

It's a bummer, that noise issue, because it is the best sounding amp that I have ever heard, and the looks is simply awesome.
for the moment I'll use it with my planar, and stick to my asgard3 for the dynamics.

It is really interesting that your AKG's are silent ! cannot understand why really ( maybe the rated sensitivity is overrated ? )

I do not mind waiting for a fix as well.

i'll wait for @Relaxasaurus to receive his unit back, and hope that it will be fixed.

Agree, the tube sounds so beautiful and from my experience it is the best match for HD800S and all Sennheiser series.
Apart of pauses between the songs I really immersed in jazz band (listening a lot of acoustic instrumental music too).
But when song is over the hiss is puling me back to reality.
Fostex T50, 60, Argon also sound quieter due to low sensitivity (50 ohms, 92 dB)
I have found interesting feeling that all my planars sound on HA-6A little bit artificially, Like may be lucking some juiciness of the sound, sounds more like hollow sound.
Everything is coming back when I connect all planars to Topping A90, Oppo HA-1 or hybrid Pathos Aurium.

It is quite interesting feeling, that is why planning to use HA-6A mostly with dynamic headphones.

 

[kimdeug]

If this is power related background noise, then the determining factor should be impedance and sensitivity of the headphones: you won't hear background noise with high impedance or low sensitivity headphones. For instance, the headphone amplifier should be silent with 300Ohm HD6xx and HD800S. This doesn't seems to be the case here, so I don't think this is background noise related to high output power.

Hi Andy

I have exactly hiss/humm noise on High impedance from all 1/4. Penta, 4 pin XLR outputs.
Headphones used: Sennh HD800S, HD6XX (300 ohms 103dB), ZMF Auteur 300 Ohms 97dB
Please response.

Regards,
Kim

 

[Fatdoi]

such a pity i've been on the lookout for OT tube amp for last few years... HA300 came along but has hum/hiss issue.... now HA6a has similar issue....

 

[kimdeug]

such a pity i've been on the lookout for OT tube amp for last few years... HA300 came along but has hum/hiss issue.... now HA6a has similar issue....

Don't worry my friend.
I will fight for it. Have done by myself few mods (Film capacitors, Chokers, matching impedance etc on my Bottleneck Crack Speedball, Have upgraded my LaFigaro 339 too).
I am very serious to keep it for my joy, as the sound produced by HA-6A is amazing, the best ever synergy I have heard with HD800S. And I almost have tried all tube headphone amplifiers available on the market.
From my experience the Humming noise is coming due to luck of isolation/shielding from output transformer, may be something on rectification stage or power filtering. While the hiss is more related to the pre-amplifier stage. Try to contact with Cayin engineers to discuss. I can install a bigger resistor on Balanced output, but I think this solution will only "hide" the existing noise, but not eliminate the problem.
Any idea from electrical point will be very helpful.
Regards,
Kim

 

[kimdeug]

Hi All Cayin HA-6A lovers.

Finally, I have GOOD NEWS!!!!! to share with you, or at least cheap solution for Hiss solving.
Obviously, it was noticed that low sensitivity headphones Ariya, Fostex T-50, 60 etc with sensitivity 90 dB do much cleaner sound on HA-6A.
Suddenly , I have remembered one video from youtube Resolve Reviews about Cayin iHA-6.
Where he has mentioned about custom made sensitivity reducer ( 06:45 -on video).

Link:

I don't have the XLR one, but I had iFi iEMatch adapter for my IEMs around.
So, I have plugged into 1/4 output with HD6XX, and OMG!!!
It was the first time, since I have got HA-6A, when I had 100% satisfaction without any interruption of hiss and humms.
Pure liquid tube magic was flowing to my ears via HD800S and ZMF Auteur too.
Small test has been turned into 3 hours listening session with joy somewhere out of this world.
I think, until Cayin will fix the hiss/humm issue. This is the best and cheapest solution.
Will try to find on web who can make it as Penta, XLR and 1/4 jack and may be will order as permanent accessories specifically dedicated to HA-6A.
I think Cayin should provide these adapters for free to all HA-6A owners witch serial number has been sold before noise fixing upgrade.
If anyone will find this type of adapters, please post link here.


Yes!!!!!, at this stage I will keep my unit until Relaxasarus and GU1DO will post their feedbacks after repairing.

Regards,
Kim

Photo of iFi iEMatch

 

[Relaxasaurus]

Hi All Cayin HA-6A lovers.

Finally, I have GOOD NEWS!!!!! to share with you, or at list cheap solution for Hiss solving.
Obviously, it was noticed that low sensitivity headphones Ariya, Fostex T-50, 60 etc with sensitivity 90 dB do much cleaner sound on HA-6A.
Suddenly , I have remembered one video from youtube Resolve Reviews about Cayin iHA-6.
Where he has mentioned about custom made sensitivity reducer ( 06:45 -on video).

Link:

I don't have the XLR one, but I had iFi iEMatch adapter for my IEMs around.
So, I have plugged into 1/4 output with HD6XX, and OMG!!! It was the first time, since I have got HA-6A, when I had 100% satisfaction without any interruption of hiss and humms. Pure liquid tube magic was flowing to my ears via HD800S and ZMF Auteur too. Small test has been turned into 3 hours listening joy out of this world.
I think, until Cayin will fix the hiss/humm issue. This is the best and cheap solution.
Will try to find on web who can make it as Penta, XLR and 1/4 jack and may be will order as permanent adapters specifically dedicated to HA-6A.
I think Cayin should provide these three free adapters for HA-6A owners witch serial number unit has been sold before noise fixing upgrade.
If anyone will find this type of adapters, please post link here.


Yes!!!!!, at this stage I will keep my unit until Relaxasarus and GU1DO will post their feedbacks after repairing.

Regards,
Kim

Photo of iFi iEMatch

This sounds promising, thanks tons for the post! I'm glad you were able to get rid of the hiss but personally I'd rather not deal with an adapter. Hoping the repair is a success but will keep this in my back pocket just in case

Edit- here's the adapter Resolve is talking about at Garage 1217's site:

http://www.garage1217.com/garage1217_diy_tube_headphone_amplifiers_012.htm

$45 USD for the 4-pin XLR balanced version, not bad

 

[kimdeug]

oops

 

[kimdeug]

This sounds promising, thanks tons for the post! I'm glad you were able to get rid of the hiss but personally I'd rather not deal with an adapter. Hoping the repair is a success but will keep this in my back pocket just in case

Edit- here's the adapter Resolve is talking about at Garage 1217's site:

http://www.garage1217.com/garage1217_diy_tube_headphone_amplifiers_012.htm

$45 USD for the 4-pin XLR balanced version, not bad

Thank you my half asian brother with the same headphone taste and the same watch ) Yes, I am a full asian headphone enthusiast, if you remember my comment on youtube) "HP Battle! Arya vs LCD-X vs HD800S vs Aeolus"
I am still listening HA-6A non stop with adapter now. And the joy of the sound, I am getting, is absolutely amazing!
Even, I agree to accept adapters as part of HA-6A equipment.

Big props for adapter link.
Life is much better now.

Regards,
Kim