[dpump]

I don't think the 6A still uses the 22DE4. I seem to remember Cayin changed it to 25AX4 at some point. Cayin's website still says 22DE4, but Moon Audio says their 6A has 17AX4 rectifiers. And I believe the 3A and 2A also use the 17AX4. The 300 is the only amp that still uses the 22DE4. So if you are shopping for a 3A or 6A, I would confirm with the seller which rectifiers it has to be sure you get what you want. It's a little confusing since I think at one point the 300, 6A, and 3A all came with 22DE4. Maybe Andy Kong can clear this up.

 

[LXMc]

And I believe the 3A and 2A also use the 17AX4

3A currently uses the 25AX4GT for rectifier (got mine in Feb and it uses this).

On an unrelated note, had an Apos Ray 12AU7, less than a month old, go bad on me today. Had been hearing some very slight background noise the past day and then all of a sudden this afternoon some loud crackling and popping out of the left side of my Caldera. Got those unplugged and the amp turned off quick as I could, then went through trouble shooting to check it and narrowed it down to one of the Rays. Thankfully Apos has a solid warranty on them, but between this and the stock power tube going bad within a month, I'm really not having good luck with these new production tubes so far..

 

[Andykong]

So people often mistake tube sound with thick and warm due to the OTL nature of cheap tube amps like dark voice or xduoo ta26. Cayin's amps are otc and these sound more smooth and natural. If you want a thicker sound there are options like brimars or rca backplate 12au7. Ultimately if you wanted to you can get a thicker sound out of the ha6a vs 3a, but the differences between these 2 amps are more nuanced with different tube configurations. The 6a requires 2 rectifier 22de4 tubes, so if sourcing them or the kt88/el34 is a problem for you or you prefer the sound of 6v6gt/12au7 then the 3a would be the way to go. Stock tubes, the 6a and 3a are more or less similar since stock tubes are just not that good.

I don't think the 6A still uses the 22DE4. I seem to remember Cayin changed it to 25AX4 at some point. Cayin's website still says 22DE4, but Moon Audio says their 6A has 17AX4 rectifiers. And I believe the 3A and 2A also use the 17AX4. The 300 is the only amp that still uses the 22DE4. So if you are shopping for a 3A or 6A, I would confirm with the seller which rectifiers it has to be sure you get what you want. It's a little confusing since I think at one point the 300, 6A, and 3A all came with 22DE4. Maybe Andy Kong can clear this up.

We issued a Minor Revision on Cayin HA-6A back on July 13, 2023. The rectifier tube of HA-6A had been changed from RCA 22DE4 to RCA 17AX4GT

 

[DrDen]

Does it mean that former rectifiers are not anymore so easily available as many tried to say? I see no other reason for such redesigning. After all, it seems to cost really much.

 

[betula]

Does it mean that former rectifiers are not anymore so easily available as many tried to say? I see no other reason for such redesigning. After all, it seems to cost really much.

Not as easily available in large quantities for production. For the odd user it is still relatively easy and cheap to find the old rectifiers. Plus, if you buy a handful of them, that will keep you going for a lifetime.

 

[DrDen]

Not as easily available in large quantities for production. For the odd user it is still relatively easy and cheap to find the old rectifiers. Plus, if you buy a handful of them, that will keep you going for a lifetime.

I think they have decided to save the rest of their 22DE4 rectifiers for HA-300 production only.
But there are already two amp models that were redesigned and now use different rectifiers — HA-3A and HA-6A. From new users point of view it’s a bit confusing.
IMHO using some unique NOS tubes for mass production gear is dead end strategy. Initially these tubes are cheap because no one needs them, but soon they disappear from market because many want to make an excessive supply. It’s easy to spend a little money for a lot of cheap tubes. As a result fewer people want to purchase the new gear using unobtainable consumables. For the small audiophile segment it’s okay, but not for mass market.
Maybe it’s not my business, but I like Cayin products and wish them success.

 

[Andykong]

Redesign is a big word, for those who can compare the RCA 22DE4 and RCA 17AX4GT, it is obvious that the two tubes are very similar, to the level that we didn't need to change our circuit design, merely adjust the voltage setting of the HA-3A circuit when we perform the switch.

From a user or tube rolling point of view, you want to keep as much variety as possible, but from a manufacturing point of view, changing from RCA 22DE4 to another brand 22DE4 or even the same brand but another shape (different period), we need to go through the same amount of documentation and logistic changes. So @betula is correct, it is still relatively easy and cheap to find the 22DE4 to keep your amplifier going, but Cayin needs to move away from 22DE4 in headphone amplifiers because we can't find the same version of 22DE4 in large quantities.

 

[DrDen]

Redesign is a big word, for those who can compare the RCA 22DE4 and RCA 17AX4GT, it is obvious that the two tubes are very similar, to the level that we didn't need to change our circuit design, merely adjust the voltage setting of the HA-3A circuit when we perform the switch.

From a user or tube rolling point of view, you want to keep as much variety as possible, but from a manufacturing point of view, changing from RCA 22DE4 to another brand 22DE4 or even the same brand but another shape (different period), we need to go through the same amount of documentation and logistic changes. So @betula is correct, it is still relatively easy and cheap to find the 22DE4 to keep your amplifier going, but Cayin needs to move away from 22DE4 in headphone amplifiers because we can't find the same version of 22DE4 in large quantities.

I always thought that changing voltage from 22 to 17V means rearranging secondary windings of the power transformer. At least I read it was done when switching from 22DE4 to 25AX4GT. Not that small change imho (unless each Cayin’s transformer already has windings 17,22 and 25V)
Please correct me someone, but I consider transformers as core of tube amplifier. The rest is easily upgradeable.

 

[calypsocat]

Hi. Do you think it would make sense to use 4pin XLR-to-2xRCA cable to occasionally connect HA-3A to a set of active speakers (Triangle Borea Active BR03 BT) ? Would that work?

 

[WailingBanshee]

Anyone know how far the tubes should be seated into their sockets?

Got my first set of NOS tubes yesterday and something I noticed when installing both the 6v6 and 12au7 tubes is that some of them are not quite firmly touching the base of the sockets. Pins are exposed with the 12au7s (and have a bit of play) and to a lesser extent for one of the 6v6. Only the other 6v6 and rectifier are firmly touching the base.

Should I be concerned? Are there ways to know if they're installed correctly? Amp is operational and I don't notice any anomalies after the installation.

 

[MacMan31]

Would this amp be considered an upgrade from my Feliks Audio Echo Mk2?

 

[Renexx]

Would this amp be considered an upgrade from my Feliks Audio Echo Mk2?

Definitely. It's in the same league like a Feliks Euphoria AE. Tubes are plenty full available and relatively affordable.

a cool sounding combination: RCA 12au7 1950s long black plates, Cossor 6V6G and Sicte 22DE4

Except the RCA, both tubes are quite bright sounding tubes. Great synergy of these unobtanium tubes in my system. It took me long to find those RCA 12au7 long black plates as well.

 

[Gagalactyca]

Anyone know how far the tubes should be seated into their sockets?

Got my first set of NOS tubes yesterday and something I noticed when installing both the 6v6 and 12au7 tubes is that some of them are not quite firmly touching the base of the sockets. Pins are exposed with the 12au7s (and have a bit of play) and to a lesser extent for one of the 6v6. Only the other 6v6 and rectifier are firmly touching the base.

Should I be concerned? Are there ways to know if they're installed correctly? Amp is operational and I don't notice any anomalies after the installation.

Hello. Since I have the same USSR 6P6S (I have a production year of 1964, but it should be exactly the same)... and they fit exactly without being 1 mm apart. I also think the quality of the sockets for inserting into the Cayin is very good
I had the problem once with an amp, but it was only 1 tube and the distance between the pins was even smaller.

This concerns several things for you: please remove all 4 tubes again. Please make light circular movements, grasp one at the top and one at the bottom of the tube with both hands, circle and pull lightly.
Please insert all 4 tubes again like this: carefully thread the pins into the holes, and then circle, calmly at the beginning in large circles and slowly circle with both hands and press at the same time without too much force. that should be fine.
I don't think that hifi in the living room has any negative consequences if the amp isn't moving.
As I said, I find it strange that they don't quite fit, but of course it's not bad at first.
I would have a bad feeling and they shouldn't stick out that far!
Otherwise, of course, it could be the case and you're unlucky that all the tubes don't fit.
This could happen in 1% of cases even with non-NOS tubes but rather completely new tubes, I see it as very rare (I probably have 100 NOS tubes here and different amps and this has only happened to me with 1 tube so far...).
Good luck. And please tell us about your results.

 

[DrDen]

Anyone know how far the tubes should be seated into their sockets?

Got my first set of NOS tubes yesterday and something I noticed when installing both the 6v6 and 12au7 tubes is that some of them are not quite firmly touching the base of the sockets. Pins are exposed with the 12au7s (and have a bit of play) and to a lesser extent for one of the 6v6. Only the other 6v6 and rectifier are firmly touching the base.

Should I be concerned? Are there ways to know if they're installed correctly? Amp is operational and I don't notice any anomalies after the installation.

I’m sure it’s nothing to worry about.
Just push the tubes firmly in place.

 

[WailingBanshee]

Hello. Since I have the same USSR 6P6S (I have a production year of 1964, but it should be exactly the same)... and they fit exactly without being 1 mm apart. I also think the quality of the sockets for inserting into the Cayin is very good
I had the problem once with an amp, but it was only 1 tube and the distance between the pins was even smaller.

This concerns several things for you: please remove all 4 tubes again. Please make light circular movements, grasp one at the top and one at the bottom of the tube with both hands, circle and pull lightly.
Please insert all 4 tubes again like this: carefully thread the pins into the holes, and then circle, calmly at the beginning in large circles and slowly circle with both hands and press at the same time without too much force. that should be fine.
I don't think that hifi in the living room has any negative consequences if the amp isn't moving.
As I said, I find it strange that they don't quite fit, but of course it's not bad at first.
I would have a bad feeling and they shouldn't stick out that far!
Otherwise, of course, it could be the case and you're unlucky that all the tubes don't fit.
This could happen in 1% of cases even with non-NOS tubes but rather completely new tubes, I see it as very rare (I probably have 100 NOS tubes here and different amps and this has only happened to me with 1 tube so far...).
Good luck. And please tell us about your results.

The wiggling did help with seating the tubes perfectly. I avoided it at first because I was concerned about wearing out the sockets, but the pins sticking out really bugged me lol.

This also happened to solve a minor noise issue I had with the preamp tubes. Very happy with the result. Thank you!