[Andykong]

preamp tubes helped significantly! Stock JJ were so noisy because my computer is very close and next to power conditioner. Moving around the HA-6A amp plug (upgraded power cable) I noticed the scrolling signal noises stopped but still had loud hiss even with 4.4mm. Swapped out to another old 12au7 I had and it got better. Ordered green label baldwins for $45 per zmf recommendation and now I can barely hear the hissing. Hiss is still obvious with xlr but with 4.4mm its almost all gone. You have to really pay attention with ZMF to hear the hiss but with HD800S I really can't tell because it's open back and I prob have other louder sounds in my room. Got some preamp siemens E82CC and SE KT88's after reading some reviews in this thread. Preamp tubes like Telefunken NOS smooth or ribbed you can't go wrong with either. Also look for the tesla E802CC as they are suppose to be very close to the expensive TeleFunken E802CC. Just watch out for fakes! But as far as what ZMF recommended to me which is the GEC KT8C w/ adapters and sylvania green baldwins anyone would say this is a great amp. I just ordered the other set of tubes to rotate monthly or so and also to keep the wear and tear down. I even got a small case with foam to store my tubes thanks to @ThanatosVI for the inspiration! BTW, I have iphone, bluetooth lamp, and mesh wifi all near my HA-6A and even with cage off no noises. Just ittybittytiny hiss with 4.4mm @hung031086 edit** forgot to mention I'm using A26 dac and use the volume attenuator with HA-6A volume staying put at one tick past 12 o'clock most of time unless I'm listening to Jazz / Orchestral.

If we are comparing the tubes that are currently mass-produced, JJ is actually one of the lowest ones in terms of tube noise. For unknown reasons, the vintage tubes are indeed quieter than the current production tube, but we can only use vacuum tubes that can guarantee a steady supply during the 5+ years of production time of the amplifier.

 

[Andykong]

I find the 300MKII to have a little more noise compared to the 6A.

Really? thats dissapointing, I was hoping the MKII model with its stated improvements would be superior in this regard.

You have to understand the difference between 300B and KT88/EL34 vacuum tubes before you know the loophole in your assumption.

Most triode vacuum tubes are designed on or before 1940s and they are directly heated (hence referred to as DHT) There are some indirectly-heated triode vacuum tubes developed after the 40s. The 300B is a directly-heated triode vacuum tube introduced in 1938 by Western Electric

The EL34 is a thermionic pentode vacuum tube introduced in 1955 by Mullard (owned by Philips). The KT88 is a beam tetrode vacuum tube introduced by GEC in 1956. Both types of vacuum tubes were relatively modernized when compare to the 300B and they are indirectly heated.

DHT tends to generate more noise or hum than indirectly heated vacuum tubes because of their construction. In a directly heated vacuum tube, the filament or heater that generates the electrons is also used as the cathode. This can lead to fluctuations in the current running through the filament, which can generate noise or hum. Indirectly heated vacuum tubes, on the other hand, have a separate cathode that is heated by a filament that is isolated from the cathode. This isolation reduces the likelihood of fluctuations in current and therefore reduces noise or hum. Additionally, noise or hum in directly heated vacuum tubes can also be caused by the varying magnetic fields around the filament, which again, does not exist in indirectly heated vacuum tubes.

While the indirectly heated vacuum tubes are less noisy and their circuit are more linear, they don't offer the same signature as the DHTs. For more detail, please refer to the SETA discussion in the HA-300MK2 thread. In addition, the DHT tube amplifiers are in general more expensive than indirectly heated tube amplifiers because we need to put extra attention, from design to construction, to minimizing the Hum and noise of the DHT tubes.

Let's go back to the original question.

Yes, the HA-300MK2 is quieter than the original HA-300, but the HA-300MKII still produces a little more noise compared to the HA-6A despite the fact that the HA-300MK2 is more expensive than the HA-6A.

 

[jamato8]

You have to understand the difference between 300B and KT88/EL34 vacuum tubes before you know the loophole in your assumption.

Most triode vacuum tubes are designed on or before 1940s and they are directly heated (hence referred to as DHT) There are some indirectly-heated triode vacuum tubes developed after the 40s. The 300B is a directly-heated triode vacuum tube introduced in 1938 by Western Electric

The EL34 is a thermionic pentode vacuum tube introduced in 1955 by Mullard (owned by Philips). The KT88 is a beam tetrode vacuum tube introduced by GEC in 1956. Both types of vacuum tubes were relatively modernized when compare to the 300B and they are indirectly heated.

DHT tends to generate more noise or hum than indirectly heated vacuum tubes because of their construction. In a directly heated vacuum tube, the filament or heater that generates the electrons is also used as the cathode. This can lead to fluctuations in the current running through the filament, which can generate noise or hum. Indirectly heated vacuum tubes, on the other hand, have a separate cathode that is heated by a filament that is isolated from the cathode. This isolation reduces the likelihood of fluctuations in current and therefore reduces noise or hum. Additionally, noise or hum in directly heated vacuum tubes can also be caused by the varying magnetic fields around the filament, which again, does not exist in indirectly heated vacuum tubes.

While the indirectly heated vacuum tubes are less noisy and their circuit are more linear, they don't offer the same signature as the DHTs. For more detail, please refer to the SETA discussion in the HA-300MK2 thread. In addition, the DHT tube amplifiers are in general more expensive than indirectly heated tube amplifiers because we need to put extra attention, from design to construction, to minimizing the Hum and noise of the DHT tubes.

Let's go back to the original question.

Yes, the HA-300MK2 is quieter than the original HA-300, but the HA-300MKII still produces a little more noise compared to the HA-6A despite the fact that the HA-300MK2 is more expensive than the HA-6A.

Worked with tubes before going into the military and used them there as well (so this dates me as to age). I have been using tubes for around 55 years, and to what you have said, I would agree. And it is part of the fun of working on tube equipment and the challenge when designing it. And to the loading of the tubes, what I don't see used and is exceptional for the sound is inductor loading rather than resistive loading. Inexpensive and another step in sound quality.

 

[Andykong]

I'm still waiting for the refund so I can get the 300mk2 from them. Actually the noises are much better after I changed the outlet and burned in the amp a bit. I used Ifi Nova and Power Quest 2. They helped a little bit too. It was really quiet with HD800s and almost the same with Diana TC. For ZMF Aeolus, I only heard tiny noises if nothing played. But its different story if I uncaged. It was very loud. I even could hear when music was playing.

Cage attenuates interference, so you have interference in your room. You need quiet driver tubes like Telefunken or Sylvania 3 mica. For lush sound try GL KT77 (these run as EL34) and Mullard EL34.

It will drive both Diana and Susvara but it will have more headroom with Diana.

Give it at least 100h burn in and also new tubes need about 50h to burn in and settle.

Also consider power conditioning if you have noise issues.

Have fun

I just received the HA-6A today. Its really nice amp and heavy. It sounds really nice too. But I heard some noises when I listened to my HD800s and Aeolus.
With HD800s its kinda quiet. But with the Aeolus, its different story. Noises with the XLR output is louder than the 4.4mm output. And noises is much louder when i open the cage. I could easily hear noises when I listen to music with no cage. With cage on, i couldn't hear any noises. Is this normal ?
Any recommendations for tubes rolling for a reasonable price ? I'm looking for a lush sounding.
And can this amp drive Susvara or Diana TC easily? I'm thinking to get one of those soon.

As @krude has put it, the cage attenuates interference, so proven you have interference in your room. If you couldn't find out the source of the interference, handle that effectively, and reduce the interference level, exchanging the HA-6A for HA-300MK2 will most likely put you and your sound system into a tough battle against interference.

As you had briefly experienced, integrating a tube amplifier into your home audio system requires a lot of patience and devotion, and you probably won't feel the upgrade until you solved these problems.

 

[AnyDave]

They are now using a different rectifier for the 6A.

Not aware of that though. Only know Cayin has changed the 3A to using the 25AX4GT instead of 22DE4.

My HA-6A came with 17AX4-GTB rectifiers. Based on the manual, I assume both the 17AX7-GTA and 17AX4-GTB rectifiers will work, but I haven't been able to find datasheets for both to confirm.

 

[Newbman123]

My HA-6A came with 17AX4-GTB rectifiers. Based on the manual, I assume both the 17AX7-GTA and 17AX4-GTB rectifiers will work, but I haven't been able to find datasheets for both to confirm.

Does this mean the rectifier tubes aare interchangeable or does it mean that the circuit has been redesigned?

 

[AnyDave]

Does this mean the rectifier tubes aare interchangeable or does it mean that the circuit has been redesigned?

The heater voltages are different, so I assume that there was a tweak to the circuit, but Cayin would have the definitive answer.

 

[Newbman123]

So my final configuration for now after trying a lot of stuff, and my favourite. Svetlana winged c el34 and brimar cv4003. My got the layering and warmth from the winged c and nature tamber what i seem to get from the brimar cv3004. I'm smitten. This i feel is the best combination for me after trying the following albeit not trying all permutations and combinations yet.
El 34: stock eh ele4, Svetlana winged c, tungsol nos 5881
Kt88: goldlion stock(sadly haven't been able to get a hold of nos kt88)
12au7: stock jj, rca clear top, brimar cv4003, rca 5814a black plates(my pick after brimar), ge 5814a black plates

The list is probably not all that long, but i think these tubes are quite decent. All the apparently better tubes would probably burn a big hole in my pocket .

Chain : kann alpha (source) - holo spring 1 lvl2 - cayin ha6a(brimar, Svetlana) - he6se/atrium

 

[AnyDave]

So my final configuration for now after trying a lot of stuff, and my favourite. Svetlana winged c el34 and brimar cv4003. My got the layering and warmth from the winged c and nature tamber what i seem to get from the brimar cv3004. I'm smitten. This i feel is the best combination for me after trying the following albeit not trying all permutations and combinations yet.
El 34: stock eh ele4, Svetlana winged c, tungsol nos 5881
Kt88: goldlion stock(sadly haven't been able to get a hold of nos kt88)
12au7: stock jj, rca clear top, brimar cv4003, rca 5814a black plates(my pick after brimar), ge 5814a black plates

The list is probably not all that long, but i think these tubes are quite decent. All the apparently better tubes would probably burn a big hole in my pocket .

Chain : kann alpha (source) - holo spring 1 lvl2 - cayin ha6a(brimar, Svetlana) - he6se/atrium

I'll have to track down a pair of Brimars. I've got Telefunkens, RCA Cleartops, and just received a set of shield logo Mullards. I love Brimar 12ax7s, but haven't heard them here. Plus, I use the 12ax7s in my old Marshall guitar amps, so it's a completely different application. I'll be curious to see what they are like.

I haven't tried the Svetlana Winged C EL34s, but I've got a set of those (not market Winged C, but have the dual UFO style getters), so I need to give those a shot. I also have a pair of old Mullard XF4, but those are currently in a guitar amp and I don't think I can be bothered to pull those out and rebias that amp.

 

[AudioPowerHead]

My HA-6A came with 17AX4-GTB rectifiers. Based on the manual, I assume both the 17AX7-GTA and 17AX4-GTB rectifiers will work, but I haven't been able to find datasheets for both to confirm.

Interesting to see Cayin moving away from 22de4 for rectifier tubes on both 3A and 6A. This being the case, I think it will be a question of time before they do the same for the HA-300 mk2. This may make sense if the supply of 22de4 tubes are uncertain or limited.

 

[AnyDave]

Interesting to see Cayin moving away from 22de4 for rectifier tubes on both 3A and 6A. This being the case, I think it will be a question of time before they do the same for the HA-300 mk2. This may make sense if the supply of 22de4 tubes are uncertain or limited.

It could be argued that it's better for existing customers as well as they are switching over before depleting the NOS supply of an out of production rectifier tube. 22DE4 tubes can still be had for a reasonable price and there is likely a decent stock of them out there still.

Complete conjecture on my part, of course.

 

[Newbman123]

It could be argued that it's better for existing customers as well as they are switching over before depleting the NOS supply of an out of production rectifier tube. 22DE4 tubes can still be had for a reasonable price and there is likely a decent stock of them out there still.

Complete conjecture on my part, of course.

Can it be replaced by a ss rectifier if one wants and stock dies out?

 

[AnyDave]

Can it be replaced by a ss rectifier if one wants and stock dies out?

I don't know of a SS rectifier equivalent, but that's not to say one couldn't/doesn't exist.

 

[AudioPowerHead]

It could be argued that it's better for existing customers as well as they are switching over before depleting the NOS supply of an out of production rectifier tube. 22DE4 tubes can still be had for a reasonable price and there is likely a decent stock of them out there still.

Complete conjecture on my part, of course.

Just saw @Andykong ’s reply over at HA-300 mk2 thread that Cayin has no current plan to change out the 22de4. So I reckon they still have a good supply of it in-house at least for foreseeable near-future. These tubes last long approx 10,000 hours(5-10 years). If one has 2-3 sets as back-up, it is unlikely to be an issue on longevity.

That said, for some of us that has tried rolling 22de4s, it is actually a lot of fun as it alters the sound in interesting ways.

 

[jamato8]

Just saw @Andykong ’s reply over at HA-300 mk2 thread that Cayin has no current plan to change out the 22de4. So I reckon they still have a good supply of it in-house at least for foreseeable near-future. These tubes last long approx 10,000 hours(5-10 years). If one has 2-3 sets as back-up, it is unlikely to be an issue on longevity.

That said, for some of us that has tried rolling 22de4s, it is actually a lot of fun as it alters the sound in interesting ways.

There are still a lot of them around, if you know where to get them but you don't really need many, as you point out.