[Andykong]

@GU1DO @kimdeug

Sorry for the problem you have encountered with our HA-6A. If the repair turns out to be unsuccessful, you can also contact your seller or agent and ask for refund. We hope you can grant us this opportunity to at least give it a try to solve the problem.

 

[Gr3g277]

@GU1DO @kimdeug

Sorry for the problem you have encountered with our HA-6A. If the repair turns out to be unsuccessful, you can also contact your seller or agent and ask for refund. We hope you can grant us this opportunity to at least give it a try to solve the problem.

Hi andykong !

Please do not forget me

Do you think it would be possible to have details on what the fix is ?

 

[kimdeug]

Hi andykong !

Please do not forget me

Do you think it would be possible to have details on what the fix is ?

Thats why I have asked my friend: one for you in France, one for me in New Zealand and one for GI1DO in Germany.
Relaxasaurus has already contacted in NY. Only three of us left. But I wanna fixed amp instead of refund, as I really like it.
Regards, Kim

 

[Relaxasaurus]

But I wanna fixed amp instead of refund, as I really like it.

Same page as you.

 

[GU1DO]

@GU1DO @kimdeug

Sorry for the problem you have encountered with our HA-6A. If the repair turns out to be unsuccessful, you can also contact your seller or agent and ask for refund. We hope you can grant us this opportunity to at least give it a try to solve the problem.

I bought it directly from Cayin

 

[Andykong]

Hi andykong !

Please do not forget me

Do you think it would be possible to have details on what the fix is ?

I tried to, that's why I want to wait till I receive the report from New Zealand dealer initially.

 

[Andykong]

Yes I have hiss too.It is more like combination of Hiss and Humm together. In proportion Hiss/Humm as 70/30. Hiss is gradually increases with increase of Volume, but much slower (not like sound increases), while the Humm noise almost reminds on the same level and with Volume increase, suddenly start to distort (depends of RCA or XLR input selected) at 1 or 3 o'clock respectively. Right now I am using Sennheiser HD800S. Hiss/Humm on 4 pin XLR output in all L, M, H impedance positions. Hiss/humm starts to distorted when Volume at 3 o'clock (assuming that the Volume knob traveling from min 7 o'clock to max 5 o'clock position). I am using XLR input from DAC with max volume for me no more than at 9 o'clock position).
In my situation hiss/humm comes from all 1/4, pentagone, and 4pin XLR outputs. Looks like loud valves, but very noticeable when switching between headphone's outputs on minimal volume.
Control test: Unplug everything. No any inputs. Only Power cable. Sennheiser HD800S plugged in into 4 pin XLR output. Hiss starts on the last 2-3 actuators steps on each L,M, H impedances.
Next test: RCA input from DAC. Music on pause. Hiss starts from 1 o'clock volume position, very loud on maximum volume on each L, M, H impedances.
Next test: XLR input from DAC. Music on Pause. Hiss starts from 3 o'clock volume position, noticeable hiss when volume on maximum on each L, M, H impedances again.
RCA input gives the most loud hiss. Usually I am using XLR input and at volume at 9 o'clocks it is inaudible. Will play with better shielded RCA and XLR cables tomorrow.

Also will play tomorrow with Power filtering, DC blocker, Power filter conditioner, good shielded power cable and will do very short run/cable from DAC. may be 3.0inch XLR and RCA with extra shielding.
Also will do more tube burning may be 100 hours.
Will post my results here.
At this moment try to exclude any other reason of hiss.

kimdeug PMed me and asked me to take on his case starting from page 15. I did, but I was hoping that I can receive the report from New Zealand dealer and find out what happened to kimdeug’s HA-6A before I explain his situation. Unfortunately there wasn’t any update till now, so I'll try to clarify some questions first and come back to that later.

Regarding the noise test that kimdeug has conducted, some of them are truly valid, otherwise I won't wait for the inspection report from his dealer. However, tube amplifier has a very different electrical characteristic from solid state amplifier, so some of the test that is applicable to Solid-State but not to tube amplifier. One of the biggest different is that you must not listen to the tube amplifier with unconnected input. I described this as “Open-loop” condition. This is very similar to the condition that @dpump has explained in #211. Alternatively when you connected a DAC or CD player as your music source to the tube amplifier properly, you are listening to your amplifier in Closed-loop condition. I have mentioned, previously in other Cayin tube amplifier thread that you’ll hear excessive noise when you hear the amplifier at open loop condition. I know this sound crazy because we always assume that when we didn’t connect anything to the amplifier, we’ll reduce interference from other equipment and listen to the amplifier only, but the input impedance of tube amplifier makes it a totally different story.

External interference in open-loop condition applied to both Solid State and Vacuum tube amplifier, but the components of Solid State amplifier will typically make the input impedance at fairly low rating, something between several KΩ to 10KΩ, and the low input impedance makes them almost immune to interference. On the other hands, the input impedance of tube amplifier will raise to 40~100+ KΩ. The high input impedance will amplify the interference and spoiled your test. Theoretically, if we determined, we can lower the input impedance to a much lower value (but still higher than the input impedance of Solid State amplifier) but that will compress the dynamic and music will lost its liveliness.

So what was the hissing noise from interference related to volume control setting? That’s because the each volume control position of HA-6A has its own resistor, and the value of resistor are part of the sound turning process. So as you turn up the volume control, the input impedance will increase. It doesn't increase linearly but last few steps in the volume control have the biggest change. For the record, at maximum volume the input impedance raise all the way to 100KΩ. Therefore at certain volume position, the high impedance will make the external interference audible, and that’s why some volume position is higher then other and the impedance of your headphone will contribute to that as well.

That explained why you won’t hear any noise with Solid State amp in open-loop condition but you hear relatively loud noise with tube amp in open-loop condition and the noise varied according to volume position and headphone loading. Even in closed-loop condition, interference can still enter the system, but at a much lower level. Interconnect with good shielding will help to reduce the interference from entering your audio system through.

Last but not least, because of the nature of amplification in tube amplifier, tube amplifier are more prone to RF interference and ground noise, and the overall noise floor is indeed higher then solid state amplifier, especially high power headphone amplifier that can drive the most demanding headphones such as HE6, Susvara and AB1266. Our concern is to control the noise to the level that it won't get into your way when you listen to music practically. However, if you turn off the music and deliberately "look for" noise, you'll find it very easily. This is like deliberately reduce the signal to noise ratio of your amplifier in order to make the noise audible. This reminded us a case that an oversee customer complained he can hear hum noise from the output transformers of his Cayin speaker amplifier. We tested his unit again and we found it clean and meeting our standard, after a lengthy communication, we found out that he use a pair of stethoscope to test whether the transformer is silent.

I am not trying to falsify kimdeug's test, I want to find out whether there is anything wrong with his HA-6A, and that implies I suspect something is not right with his unit, but I hope we can appreciate the musicality and the constraints of high power tube headphone amp at the same time.

 

[GU1DO]

Now i am in the hunt for the amp LOL
Cayin accepted to refund me once they have the amp which look like it is lost by now. they asked me to ship it once i have it hehehe , wtfff they should look for the shipment not me but i will try my best to find it ,, pray for me guys
Fingers crossed

 

[GU1DO]

kimdeug PMed me and asked me to take on his case starting from page 15. I did, but I was hoping that I can receive the report from New Zealand dealer and find out what happened to kimdeug’s HA-6A before I explain his situation. Unfortunately there wasn’t any update till now, so I'll try to clarify some questions first and come back to that later.

Regarding the noise test that kimdeug has conducted, some of them are truly valid, otherwise I won't wait for the inspection report from his dealer. However, tube amplifier has a very different electrical characteristic from solid state amplifier, so some of the test that is applicable to Solid-State but not to tube amplifier. One of the biggest different is that you must not listen to the tube amplifier with unconnected input. I described this as “Open-loop” condition. This is very similar to the condition that @dpump has explained in #211. Alternatively when you connected a DAC or CD player as your music source to the tube amplifier properly, you are listening to your amplifier in Closed-loop condition. I have mentioned, previously in other Cayin tube amplifier thread that you’ll hear excessive noise when you hear the amplifier at open loop condition. I know this sound crazy because we always assume that when we didn’t connect anything to the amplifier, we’ll reduce interference from other equipment and listen to the amplifier only, but the input impedance of tube amplifier makes it a totally different story.

External interference in open-loop condition applied to both Solid State and Vacuum tube amplifier, but the components of Solid State amplifier will typically make the input impedance at fairly low rating, something between several KΩ to 10KΩ, and the low input impedance makes them almost immune to interference. On the other hands, the input impedance of tube amplifier will raise to 40~100+ KΩ. The high input impedance will amplify the interference and spoiled your test. Theoretically, if we determined, we can lower the input impedance to a much lower value (but still higher than the input impedance of Solid State amplifier) but that will compress the dynamic and music will lost its liveliness.

So what was the hissing noise from interference related to volume control setting? That’s because the each volume control position of HA-6A has its own resistor, and the value of resistor are part of the sound turning process. So as you turn up the volume control, the input impedance will increase. It doesn't increase linearly but last few steps in the volume control have the biggest change. For the record, at maximum volume the input impedance raise all the way to 100KΩ. Therefore at certain volume position, the high impedance will make the external interference audible, and that’s why some volume position is higher then other and the impedance of your headphone will contribute to that as well.

That explained why you won’t hear any noise with Solid State amp in open-loop condition but you hear relatively loud noise with tube amp in open-loop condition and the noise varied according to volume position and headphone loading. Even in closed-loop condition, interference can still enter the system, but at a much lower level. Interconnect with good shielding will help to reduce the interference from entering your audio system through.

Last but not least, because of the nature of amplification in tube amplifier, tube amplifier are more prone to RF interference and ground noise, and the overall noise floor is indeed higher then solid state amplifier, especially high power headphone amplifier that can drive the most demanding headphones such as HE6, Susvara and AB1266. Our concern is to control the noise to the level that it won't get into your way when you listen to music practically. However, if you turn off the music and deliberately "look for" noise, you'll find it very easily. This is like deliberately reduce the signal to noise ratio of your amplifier in order to make the noise audible. This reminded us a case that an oversee customer complained he can hear hum noise from the output transformers of his Cayin speaker amplifier. We tested his unit again and we found it clean and meeting our standard, after a lengthy communication, we found out that he use a pair of stethoscope to test whether the transformer is silent.

I am not trying to falsify kimdeug's test, I want to find out whether there is anything wrong with his HA-6A, and that implies I suspect something is not right with his unit, but I hope we can appreciate the musicality and the constraints of high power tube headphone amp at the same time.

i didnt read the whole post because i dont understand technical things , but for the record ,my Bottlehead Crack amp which is a home mad amp , doesnt hiss

 

[Slim1970]

Now i am in the hunt for the amp LOL
Cayin accepted to refund me once they have the amp which look like it is lost by now. they asked me to ship it once i have it hehehe , wtfff they should look for the shipment not me but i will try my best to find it ,, pray for me guys
Fingers crossed

This is bad, I really had high hopes for this amp. It has all the features you needed to be a potential endgame all in one amp solution. I wish you luck

 

[kimdeug]

kimdeug PMed me and asked me to take on his case starting from page 15. I did, but I was hoping that I can receive the report from New Zealand dealer and find out what happened to kimdeug’s HA-6A before I explain his situation. Unfortunately there wasn’t any update till now, so I'll try to clarify some questions first and come back to that later.

Regarding the noise test that kimdeug has conducted, some of them are truly valid, otherwise I won't wait for the inspection report from his dealer. However, tube amplifier has a very different electrical characteristic from solid state amplifier, so some of the test that is applicable to Solid-State but not to tube amplifier. One of the biggest different is that you must not listen to the tube amplifier with unconnected input. I described this as “Open-loop” condition. This is very similar to the condition that @dpump has explained in #211. Alternatively when you connected a DAC or CD player as your music source to the tube amplifier properly, you are listening to your amplifier in Closed-loop condition. I have mentioned, previously in other Cayin tube amplifier thread that you’ll hear excessive noise when you hear the amplifier at open loop condition. I know this sound crazy because we always assume that when we didn’t connect anything to the amplifier, we’ll reduce interference from other equipment and listen to the amplifier only, but the input impedance of tube amplifier makes it a totally different story.

External interference in open-loop condition applied to both Solid State and Vacuum tube amplifier, but the components of Solid State amplifier will typically make the input impedance at fairly low rating, something between several KΩ to 10KΩ, and the low input impedance makes them almost immune to interference. On the other hands, the input impedance of tube amplifier will raise to 40~100+ KΩ. The high input impedance will amplify the interference and spoiled your test. Theoretically, if we determined, we can lower the input impedance to a much lower value (but still higher than the input impedance of Solid State amplifier) but that will compress the dynamic and music will lost its liveliness.

So what was the hissing noise from interference related to volume control setting? That’s because the each volume control position of HA-6A has its own resistor, and the value of resistor are part of the sound turning process. So as you turn up the volume control, the input impedance will increase. It doesn't increase linearly but last few steps in the volume control have the biggest change. For the record, at maximum volume the input impedance raise all the way to 100KΩ. Therefore at certain volume position, the high impedance will make the external interference audible, and that’s why some volume position is higher then other and the impedance of your headphone will contribute to that as well.

That explained why you won’t hear any noise with Solid State amp in open-loop condition but you hear relatively loud noise with tube amp in open-loop condition and the noise varied according to volume position and headphone loading. Even in closed-loop condition, interference can still enter the system, but at a much lower level. Interconnect with good shielding will help to reduce the interference from entering your audio system through.

Last but not least, because of the nature of amplification in tube amplifier, tube amplifier are more prone to RF interference and ground noise, and the overall noise floor is indeed higher then solid state amplifier, especially high power headphone amplifier that can drive the most demanding headphones such as HE6, Susvara and AB1266. Our concern is to control the noise to the level that it won't get into your way when you listen to music practically. However, if you turn off the music and deliberately "look for" noise, you'll find it very easily. This is like deliberately reduce the signal to noise ratio of your amplifier in order to make the noise audible. This reminded us a case that an oversee customer complained he can hear hum noise from the output transformers of his Cayin speaker amplifier. We tested his unit again and we found it clean and meeting our standard, after a lengthy communication, we found out that he use a pair of stethoscope to test whether the transformer is silent.

I am not trying to falsify kimdeug's test, I want to find out whether there is anything wrong with his HA-6A, and that implies I suspect something is not right with his unit, but I hope we can appreciate the musicality and the constraints of high power tube headphone amp at the same time.

Hi Andykong

Thank you for reply and clarifications.
Regarding to my tests: Of cause, I have conducted the same tests with all my DAC sources (look my DACs). And you will not like the results. Because, the Humm/hiss noise was on close loop too. The quietest result was at no any sources plugged to HA-6A - around 20dB at Zerro Volume, around 25dB with XLR input and 30dB at RCA input. So, I have published the results with the minimal noise scenario with no source plugged. Was used hi-End triple shielded XLR and RCA cables.

From my research I prone to think that the humm noise (non volume dependent) produced due to alternative current 60Hz still comes to the driver 12AU7 tube.

HUMM noise can be due to:

• not enough shielding, and as result secondary EM inductance in the circuit.
• loose ground tightening
• Power filtering (the capacitors are not smoothing the rips enough)

What usually using to find hum issues is a tape head Demagnetizer. A Demagnetizer uses an electromagnet to produce an AC field around its probe tip. I'd use a scope to monitor the background noise then probe around the circuitry wiring to find wires and/or components that are most susceptible to hum and then move them around, usually closer to the chassis to minimize the amount of noise they can generate.


Common sources of HISS noise are cathode biasing resistors, coupling capacitors (between gain stages) or reverb/trem. cct.'s. After eliminating the obvious (tubes, AC power source, etc.), depends of the guilty of internal component(s).
Some amps hiss brand new (by design) and some develop hiss over time (as components like carbon composite resistors deteriorate). Sometimes, due to using some noisy carbon-film or carbon-comp instead of metal-film resistors in the amp. Could have some non-polarized caps wired backwards (yes that CAN make a difference especially with Orange Drops) or low-quality/wrong type of coupling caps. There are quite a few design issues in an amp that contribute to noise. If several of these reasons are built into the amp, then they multiply quickly and the amp gets noisy.

Hiss noise could be due to:

• noisy tubes
• Noisy plate resistors. The carbon composition resistors used on the plates of preamp tubes often go very noisy, especially in older Fenders. If swapping tubes does not fix the trouble, locate the circuit that seems noisiest by tube swapping, and then replace the plate resistors in that circuit with equal-value metal film or metal oxide resistors. You can use carbon comp if you can find them, but the problem is likely to recur.
• Noisy resistors in the B+ decoupling string, often around 10K in value
• Unusual: An ultrasonic oscillation can cause an intense insect-like hissing that sounds very much unlike normal hiss.
• Rare: leaky coupling capacitors or faulty controls
• Rare: a slight ongoing arc on the output tube socket(s)
• Rare: a bad solder joint somewhere in the signal chain
• Rare: internal arcing or noise in almost any part in the preamp section

A good way to divide and conquer is to turn the volume control(s). If the hiss changes levels as you do this, then the source of the hiss is something that affects the stages of the amp before the volume control (this is a note regarding to your (Andykong) comment about resistor step Volume attenuator above). A faulty, hissing preamp tube will be turned up this way very quickly. Conversely, if the volume control does not affect the hiss, the cause is somewhere after the volume control. In general, the volume level of the hiss is an indicator of where the hiss is occurring - the louder the hiss, the more likely its source is near the input of the amp where the gain applied to it will be the greatest

The procedure of locating by removing one tube at at time working from the phase inverter/driver back towards the input until removing a tube no longer stops the hiss should then localise the problem to one tube's worth of circuitry.


For hiss better to monitor the noise levels with a scope and try different tubes to find ones that produced minimal background noise. You can do the same for resistors and caps in key areas like coupling caps and bias resistors if needed. All this can be time consuming but it is what's needed sometimes when an amp misbehaves. Small tweaks that cant be heard clearly with the ears are cumulative so finding several may help to improve things.

This is my small extract from research finding.
Also suggest to look Fitz mod on Darkvoice thread, which helps me a lot to reduce humm on driver tube.
Hope it will help to bring HA-6A back to desired amplifier.

Regards, Kim

 

[IPMano]

Hi all,
I'm glad I didn't buy the HA-6A, I'm very happy with my Feliks Euforia which doesn't make any noise, hiss, etc ... just music. My Cayin HA-1A MKII had a faulty power tube, but it still does a little zzzz which changes depending on the position of the impedance selector, I think I will sell it soon.

 

[Gr3g277]

Hi guys,

Yes all the testing I did was in a close loop condition ( with dac connected to input with xlr or RCA ).
I think we all understand that making a powerful AND quiet tube headphone amp is no easy task.... and that tube amps do not respond the same way as solid state amps, for power delivery, or noise levels.

In my opinion, there is an easy fix, reduce the gain of the amp. We already know that it works ,because the IEM adapter @kimdeug tried worked to reduce the noise level of the amp.
The problem is that it is a resistor network attached to output transformers, the amp sees a 30 something Ohm load, and the headphone sees a 3 something ohm output resistance.the result is a reduction of Gain of 10db ( or more depending on the maths done, when calculating the resistors values ). And you lose the benefit of impedance matching , and maybe ,compressed dynamics. ( Should be ok if the amp is left with L impedance mode though, I wonder ).

So the easy fix should be adding a simple -10db "Low Gain" switch, on the preamp side of the amplifier, instead of on the output.
That would make the amp usable with high sensitivity headphones, balanced or not. reduce the preamp sensitivity to noise, microphonics etc...

When you need all the horsepower, just flip it to "normal" mode, and boom here you can go deaf with your susvara's, as it was designed. ( Still not going past 12 o'clock with my aryas XD )

When using utopia's or anything more than 100db sensitive , use Low gain mode.

Hell, my 200€ Schiit asgard3 has exactly that.... and sounds good in both mode with no noise to heard.

that is just my two cents.

Now I will do my homework, so I can keep up with @kimdeug great technical ideas.

 

[Fatdoi]

Hi all,
I'm glad I didn't buy the HA-6A, I'm very happy with my Feliks Euforia which doesn't make any noise, hiss, etc ... just music. My Cayin HA-1A MKII had a faulty power tube, but it still does a little zzzz which changes depending on the position of the impedance selector, I think I will sell it soon.

oh well I'm not so glad that I'm still hunting for a OT tube amp... still resisting on Woo stuffs and so far Cayin has not shown they upped the game since their HA300 issue.... to invest such money for a product that seems they haven't done their beta testing is kinda disappointing.... and to use their initial customers as their testing subjects is very cruel to say the least...

 

[IPMano]

oh well I'm not so glad that I'm still hunting for a OT tube amp... still resisting on Woo stuffs and so far Cayin has not shown they upped the game since their HA300 issue.... to invest such money for a product that seems they haven't done their beta testing is kinda disappointing.... and to use their initial customers as their testing subjects is very cruel to say the least...

are you looking for an OTL amp? I recommend the feliks euforia.