Cayin HA-6A Class A KT88/EL34 Tube Headphone Amplifier
Sep 26, 2022 at 1:12 PM Post #1,081 of 1,921
gkt77mpxx-p.jpg


Evaluating the Gold Lion KT77 with JJ 12AU7 compared to Electro-Harmonix EL34 with JJ 12AU7.

Price paid for matched pair: $109.99 USD

Headphones used: Arya V2 and HE1000se

Right off the bat I noticed two things.
  • Decrease in bass quantity by 2 dB
  • Different tube harmonics
The Gold Lion KT77, in Ultra-Linear mode, sounds like a true solid-state Class-A amp (much better rendition than the Mullard KT88), it brought back a lot of familiarity I have with my Soloist GT with upgraded op-amps. The romantic sound of the EL34, where the notes have longer sustain and lush mid-range, is no longer present with the KT77 on board.

What we have is greatly improved:
  • Clarity
  • Transient response
  • Shorter sustain of musical notes
The KT77 have an extended presence that makes enthusiastic open hi-hat and crash cymbal hits have a piercing ring. EL34 suffer from this as well but not as much as the KT77. A good remedy is equalizing down 2.5 dB at 12 kHz.

Clarity quality is well throughout the whole frequency range with just a tad more tube harmonics than the Mullard KT88.

The transient response is excellent, it gives the listener better discernment of notes and improved sense of note imaging within the headstage. At one point in my evaluation using the Arya V2, I thought I had the HE1000se on. I was very surprised to be hearing such good imaging depth with the Arya V2. In contrast, with the EL34, melodic notes tend to be smeared and blends in with the other layers of musical notes within the song track. And as a result, the EL34 have a two-dimensional soundstage.

Personally, I prefer this sound signature because of the transient response, but I do miss the EL34 bass and lushness. Hopefully I can bring that back by rolling different 12AU7.
TYSM for your evaluation

Btw, glad you got the good impression of EL34. I would say it’s not really 2D, but rather put yourself into audience seat instead of the standing at maestro stand. In this audience seat the sound project at you with the reverberation beside and behind you. It might just be my imagination though

You make me want to make purchase of the KT77 now, really do.
I had it on my cart last year, but I was settled after rolled the Amperex 12au7. It’s time for me to trigger it now😂
 
Sep 27, 2022 at 6:19 PM Post #1,082 of 1,921
TYSM for your evaluation

Btw, glad you got the good impression of EL34. I would say it’s not really 2D, but rather put yourself into audience seat instead of the standing at maestro stand. In this audience seat the sound project at you with the reverberation beside and behind you. It might just be my imagination though

You make me want to make purchase of the KT77 now, really do.
I had it on my cart last year, but I was settled after rolled the Amperex 12au7. It’s time for me to trigger it now😂
It must be the JJ 12AU7 that's holding back the EH EL34, because I just got a pair of RCA 12AU7 clear top and the sound has much more resolution with the GL KT77. I have to try them with the EH EL34 later.
 
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Sep 27, 2022 at 7:50 PM Post #1,083 of 1,921
It must be the JJ 12AU7 that's holding back the EH EL34, because I just got a pair of RCA 12AU7 clear top** and the sound has much more resolution with the GL KT77. I have to try them with the EH EL34 later.
** that is a wonderful 12AU7 and not an ‘arm / leg’ price !!
 
Sep 28, 2022 at 3:30 AM Post #1,084 of 1,921
Is the HA-6A available in all black like the HA-3A?
 
Sep 28, 2022 at 3:48 AM Post #1,085 of 1,921
Sep 28, 2022 at 4:11 AM Post #1,086 of 1,921
Sep 28, 2022 at 4:19 AM Post #1,087 of 1,921
Shame... the HA-3A looks very smart all in black but liked the extra feature here.
Yeah they should make a black Ha-6a just like the HA-300.

@Cayin are there any plans for that in the future?
 
Sep 28, 2022 at 5:48 AM Post #1,088 of 1,921
12au7 rolling with GL KT88, testing with Susvara :
- Sylvania (circa '64) - detailed tube with a softer more romantic top end and midrange but still strong bass. It's not a dark sounding tube, maybe slightly warm off neutral signature.
- RCA black plate - also really detailed tube, softer and warmer than Sylvania with good bass. This is something that I would call a warmer tube but it still has ample air for separation and details up top.

I settled on RCA black plate -> GL KT88 at the moment, running mostly in triode mode and lowest impedance with the Susvara. Probably the most relaxed and full bodied I've heard Susvara sounding to date.
 
Sep 29, 2022 at 3:40 PM Post #1,089 of 1,921
The GL KT77 finally starting to settle into its optimum sound after 100 hours. Used in conjunction with RCA 12AU7 clear top and sound is very similar to Class-A with tube harmonics (thick bass, thumping kick drums and bold forward mid-range frequencies).

GL KT77 after 100 hours:
  • -2 dB Bass is back to normal level
  • High brilliance rolled off
  • Holography opened up (used LCD-4z and HE1000se. HE1000se does a better job, my listening was done at 70 dB)
 
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Oct 5, 2022 at 1:58 PM Post #1,090 of 1,921
After a brief email exchange with Zach from ZMF I ordered the HA-6A today. Excited to try it out and will be looking for some good KT88 tubes. Mostly, will be running the ZMF Verite Closed but also the Atrium, HiFiMan Arya Stealth, and Audeze LCD-X (2nd gen). I may add Susvara so the power was a selling point. Considered the other two Cayin amps especially the 300B. Not sure there is a wrong answer but at least the HA-6A seems more versatile. While remaining diplomatic Zach essentially recommended the HA-6A over the others for my use case.
 
Oct 5, 2022 at 2:20 PM Post #1,091 of 1,921
After a brief email exchange with Zach from ZMF I ordered the HA-6A today. Excited to try it out and will be looking for some good KT88 tubes. Mostly, will be running the ZMF Verite Closed but also the Atrium, HiFiMan Arya Stealth, and Audeze LCD-X (2nd gen). I may add Susvara so the power was a selling point. Considered the other two Cayin amps especially the 300B. Not sure there is a wrong answer but at least the HA-6A seems more versatile. While remaining diplomatic Zach essentially recommended the HA-6A over the others for my use case.
Mullard and Gold Lion KT88 are the same, Mullard is cheaper, keep that in mind. I recommend replacing the JJ 12AU7 as soon as you can, unless you like a warm sound and flat soundstage.
 
Oct 5, 2022 at 2:46 PM Post #1,092 of 1,921
Mullard and Gold Lion KT88 are the same, Mullard is cheaper, keep that in mind. I recommend replacing the JJ 12AU7 as soon as you can, unless you like a warm sound and flat soundstage.
Any suggestions for the jj12au7?
 
Oct 5, 2022 at 3:02 PM Post #1,093 of 1,921
After a brief email exchange with Zach from ZMF I ordered the HA-6A today. Excited to try it out and will be looking for some good KT88 tubes. Mostly, will be running the ZMF Verite Closed but also the Atrium, HiFiMan Arya Stealth, and Audeze LCD-X (2nd gen). I may add Susvara so the power was a selling point. Considered the other two Cayin amps especially the 300B. Not sure there is a wrong answer but at least the HA-6A seems more versatile. While remaining diplomatic Zach essentially recommended the HA-6A over the others for my use case.
This is the route I went as well - even after hearing the 300B in Chicago. I've been thrilled with the HA-6A and my VC. Best tubes I've found are the Tesla Vrsovice KT88 and Telefunken ECC802S. Both are quite expensive but they are truly amazing. Tesla ECC802S yellow label (from the '60s and early '70s) are a great option to and much cheaper.
 
Oct 5, 2022 at 4:12 PM Post #1,094 of 1,921
This is the route I went as well - even after hearing the 300B in Chicago. I've been thrilled with the HA-6A and my VC. Best tubes I've found are the Tesla Vrsovice KT88 and Telefunken ECC802S. Both are quite expensive but they are truly amazing. Tesla ECC802S yellow label (from the '60s and early '70s) are a great option to and much cheaper.
Cool, thanks for the tube recommendations. There are soooooo many possible tubes I'll see how I like it out of the box first then try to decide where to go. I was poised to get the 300B but the universe had other plans.
 
Oct 6, 2022 at 1:38 PM Post #1,095 of 1,921
Has anyone tried using 17DE4 rectifier tubes instead of 22DE4? There's a brand I would like to try but it's impossible to find the 22DE4. I'm wondering if it's ok to use it in the HA-6A?
 

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