[ArkNerevar]

Thats a tough one to answer as people report different things, for myself despite very heavy modifications to my system, I still have background noise that varies a great deal based on the pre-amp tubes, some sets are virtually silent and some sets are most definately not, the fact it can still apparently randomly occur can sometimes drive me nuts to be perfectly honest.

As I said, you get a lot of variance with this amp and it should be mentioned that your headphone has a massive difference to this problem as well, I use ZMF Atrium & Verite, which are considred to be the single worst headphones for this, every slight twinge of the tube is picked up and comes through the drivers as some crackle or hissing, many headphones and in particular all planars it seems, dont pick up these noises (to the point where I am very seriously considering a planar just for this reason (being driven nuts by your daily driver isnt a good thing in my book)) so you should take these things into account as well as that some people also with dynamic driver headphones simply dont have these problems (lucky buggers), hope this helps.

 

[krude]

Hi,

Is the background noise still there on this amp? I would like to buy one, but pay for noise, no thanks.

Amp itself has no noise issues, but it also does not attenuate the noise of the tubes and your environment. If you have good power, interference free environment and good tubes slotted in you get virtually zero noise. The more sensitive the headphone you want to drive, the more you need to sort those things out, but also the better it sounds.

 

[suno23]

As the M1 fuse continues to burn in and opens up, I am starting to realize just how wonderful the Ha6a really is. I have never heard such holographic sound out of my HeKse as well as my Caldera. The M1 fuse has indeed cleared up the last remaining congestion/veil I was hearing in the sound. The sound is clean, crisp and airy. THe bass is deep and tight and not as bloomy as before. I am still being impressed each time i turn on this amp and noticing subtle improvement in the overall sound. Cant wait till I hit atleast 300 hours and comparing it to stock.

if you had to pick HeKse or Caldera which one would it be? I love my zmf AC I just got and just saw a video comparing Susvara to Caldera and he had a lot of good things to say about the Caldera.

 

[krude]

if you had to pick HeKse or Caldera which one would it be? I love my zmf AC I just got and just saw a video comparing Susvara to Caldera and he had a lot of good things to say about the Caldera.

I haven't heard Caldera but had HEKse ... which is not a bad set by any means, but if Caldera trades blows with Susvara and TC then HEKse is not in the same league.

 

[shafat777]

if you had to pick HeKse or Caldera which one would it be? I love my zmf AC I just got and just saw a video comparing Susvara to Caldera and he had a lot of good things to say about the Caldera.

Since i own both, I am gonna be very unbiased with my opinion. If you want a jack of all trades, go with the Caldera. IMO, its the better headphone, period. However, the Hekse is no slouch either. The caldera does everything extremely well. The Hekse does a few things a little better/different than the caldera. IF you want the absolute cleanest, detailed, airy, trebley sound, then go for the hifiman. It has a treble thats sweet with lots and lots of micro details with soundstage thats taller than most headphones. Also it sounds more open than the caldera. However, for just about everything else, its caldera hands down.

 

[shafat777]

@suno23
Also, since this is the HA6A tread, I would like to state that HA6A plays both of these headphones perfectly. I prefer my Caldera with my Bliss KTE for critical listening, however, for casual listening as well as for the HEKSE, i will pick the HA6A hands down.

 

[gallionetech]

Does anyone know how the HA-6A pairs with the Abyss Diana TC? I have the Cayin HA-6A & Chord Hugo 2. I’m running SE KT88s & Telefunken 12AU7s.

I run Utopia 2022s with this setup now. However I do get some hiss. I wanted to try a Diana TC again but just not sure how the pairing would sound.

 

[shafat777]

Does anyone know how the HA-6A pairs with the Abyss Diana TC? I have the Cayin HA-6A & Chord Hugo 2. I’m running SE KT88s & Telefunken 12AU7s.

I run Utopia 2022s with this setup now. However I do get some hiss. I wanted to try a Diana TC again but just not sure how the pairing would sound.

I wil be able to tell you tomorrow, I m getting my TC tomorrow and will do some A/B ing between the HA6A and my Bliss KTE

 

[jamato8]

I have never cared a great deal for the 12AU7 in the audio circuit, good for current but I don't care for the sound, ultimately. I got some adapters to change over to 6SN7, which electrically is about the same but they draw .6 amps more for the heater. I can't imagine the 6A would not be engineered enough to handle this modest extra current draw.

The sound, has better separation and for my ears, better "air". I am using some 6SN7W NOS in the non metal base. Same basic tube but the metal base are all too often noisy and IMO, too expensive for the roll of the dice. I have a box full of NOS 6SN7s but enjoy the W in this iteration and I have a few sets. Also using some Japanese 22DE4 rectifiers and old NOS Mullard EL34 tubes.

 

[BiscuitHammer]

Does anyone know how the HA-6A pairs with the Abyss Diana TC? I have the Cayin HA-6A & Chord Hugo 2. I’m running SE KT88s & Telefunken 12AU7s.

I run Utopia 2022s with this setup now. However I do get some hiss. I wanted to try a Diana TC again but just not sure how the pairing would sound.

I’m planning to run similar tube setup like you (SE KT88 and Telefunken 12au7) with Utopia.

Besides the hiss, how does it sound compared to the original tube that came with the amp?

 

[krude]

I’m planning to run similar tube setup like you (SE KT88 and Telefunken 12au7) with Utopia.

Besides the hiss, how does it sound compared to the original tube that came with the amp?

I get great synergy with 1266 TC so Diana should also work well.

SE KT88 and Telefunken 12au7 are totl tubes for this amp. Sound great, fully detailed, smooth, great bass. Totl sound.

On low impedance with same tubes I get practically zero noise with OG Utopia could be power and or electromagnetic interference.

 

[gallionetech]

I’m planning to run similar tube setup like you (SE KT88 and Telefunken 12au7) with Utopia.

Besides the hiss, how does it sound compared to the original tube that came with the amp?

I’ll say basically what Krude said however on 2022 I do get hiss

 

[ARCXENOS]

I have never cared a great deal for the 12AU7 in the audio circuit, good for current but I don't care for the sound, ultimately. I got some adapters to change over to 6SN7, which electrically is about the same but they draw .6 amps more for the heater. I can't imagine the 6A would not be engineered enough to handle this modest extra current draw.

The sound, has better separation and for my ears, better "air". I am using some 6SN7W NOS in the non metal base. Same basic tube but the metal base are all too often noisy and IMO, too expensive for the roll of the dice. I have a box full of NOS 6SN7s but enjoy the W in this iteration and I have a few sets. Also using some Japanese 22DE4 rectifiers and old NOS Mullard EL34 tubes.

were there any internal mods involved, because if someone tells me the 6SN7 adapter is functionally safe with EL34 and KT88, I am gonna need to buy another rack

I recently got an EL34-KT88 custom amp for cheap, its goddam fantastic with the utopia, but pales when used with HEK and Susvara, if there is a 6SN7 + EL34 possibility.....

 

[ArkNerevar]

Quite a while back in this thread we had someone who did the same thing, using adaptors to run 6SN7 in his amp, he calculated based on the maximum output of the rectification stage that this could be done when using 6L6GC tubes, based on his calculations he didn’t believe it was safe to do it with any other power tube as they would draw more current, something to consider.

 

[ArkNerevar]

I found it

Hello guys,

I wanted to share a little tube experiment I am doing at the moment with my ha-6a.

disclaimer:
First please, this my personal experience with my amp, please do not try to reproduce what I am doing here unless you know what you are doing, and then you are doing it at your own risk
What I verified in my amp, may not hold true for yours.

SOME MORE TUBE ROLLING MADNESS :

I have some 6sn7 lying around from my Freya preamp, and knowing that the 6sn7 is one , if not the best preamp tube available, I wanted to experiment a bit....

The 6sn7 have the same electrical parameters as a 12au7. BUT, it is octal based, and draws twice the heater current, and the heaters runs only in parallel.
So... not quite the drop in replacement right ?

Right, but not too complicated either !

To use a 6sn7 in place of a 12au7, one must first know if the 12au7 are used with heater in series (12.6V) or in parallel (6.3V).
the 12au 7 is a double triode, that means, two triodes in the same tube. The 12a7 family has the heater center tap on pin 9, and heaters on pins 4&5.



To Know if the tube is used with triodes in parallel or in series, you have to look inside the amp: if pins 4 and 5 are connected and pin 9 left unconnected, that means it is wired in series so 12.6v is applied.
If pin 4&5 are wired together, and pin 9 connected as well ( center tap ) that means a parallel connection is made and the heater voltage is therefore 6.3 V.

On inspection , I have noted that MY HA-6A is wired in 6.3V !!! so that means even more tube rolling possibilities are opening !!

second disclaimer : the correct adapter (6.3V) must be used, never ever do this with a 12.6V adapter or fire will happen !
be absolutely sure you are using the correct adapter on the correct socket !

with this out of my chest :

12bh7,6sn7,6cg7,6fq7..... are possible candidates !

so just put in an adapter and all is good right ?

wait my friend not so fast !

second we have to know if the power transformer can give us enough power without burning itself trying...
the 6SN7,12bh7,6cg7,6fq7... wants 0.6A of current for it's heater.
the 12au7 wants 0.3A.

that is twice the current ! and the power and rectifier tubes still needs to be powered as well...

So how one can do this safely ?

ask the manufacturer of the amp if the power transformer is overbuilt enough to withstand the load ?

I am therefore asking Mr @Andykong : Does the power transformer of the ha6a has enough current capacity to withstand the added total load of 0.6A when used with compatible tubes ? Even better would be to know exactly what is the rated amperage on the power transformer used in the ha 6a ?


lets do some calculation here on what is the amperage consumed from the stock tubes : based on the tubes datasheets.

12au7*2 : 0.6A
kt88*2 : 3.2A
22de4*2 : 0.9A

total is 4.7 A.

putting 6sn7 in place of the 12au7 would take us to 5.3 A.
Problem is, we don't know if that is safe , as we don't know the rating from the power tranny.

But, what if we use a less current hungry power tube ? the el34 draw 1.5A per tube, so the problem is the same...
Here comes the 6l6 tube, with it's current draw of 0.9A only !

Those of you who read that thread since last year, knows that it is one of my favorite tubes in this amp
so with the 6l6 installed we have :
12au7*2 : 0.6A
6l6*2 : 1.8A
22de4*2 : 0.9A
Total : 3.3A

so know adding 0.6 A to the total for the 6sn7 tubes will get us to 3.9A only... even less than stock with the kt88 !

so here you go : ( I know It looks kinda silly.... )



I had to put an extra socket saver between the adapter and the socket, as the adapter would not fit in the small recessed cutout in the amp chassis.


So this looks like crap right... but let me tell you, Holy mama ! the sound is know nothing short than amazing !!!
The noise floor is lower, less microphonic, hiss is almost completely gone and the music is just superb.
With my utopia, which is very sensitive , the hiss can only be heard a tiny bit with the highest impedance setting.
The bass is tighter, more full bodied, soundstage is wider, highs are super smooth, music flows freely with an added sense of fluidity.

The tubes here are nothing really special, new production Tung sols 6sn7 GTB pulled from my main system Freya preamp.

I am now eager to try it with kt88 also, And waiting eagerly for @Andykong to respond

The tube preamp hierarchy is respected the 6sn7 are far better than any 12au7 Nos or new production.

Now this opens even more possibilities with that .6A heater :

the 6cg7 : a 9pin 6.3V tube ( adapter still needed ) that is basically a 6sn7 in smaller envelope. with an internal shield that reduce noise and increase separation.
the 6fq7 : Same as 6Cg7, only without the shield. A lot of great NOS options available for cheap
the 12bh7 : direct drop in replacement ! no adapter needed, only the heater at .6A as the on above.


I have some of those coming on the way.... will be reporting here

Yes I know I am crazy, In France we call it not an audiophile, but an audiopath....

see you next time fellas !