[UntilThen]

The magic continues with Tung Sol 6550 and Shuguang Treasures KT88. I discovered that my Brimar 12au7 long plates are the culprit for the static, hissing sound I get on the left channel. Which is a shame as the pair of Brimar is NOS NIB. When I switched to Psvane 12au7, it is quiet.

I'm prepping the tubes for Odyssey.

 

[OctavianH]

Found a pair of Sylvania 6CA7 matched 5%. This is rebranded MESA STR416.

It is also quite strong, stronger than my EL34 pairs which are around -15.5-16.5V:

At first I thought this is an american EL34 equivalent and has to sound the same, BUT I was wrong. 6CA7 does not sound the same, it has a very special and refined sound combining KT66 + EL34. I like this:

I am quite impressed about these. 6CA7 has a chance to become one of my favourite types.

And in the end, I finished my stash of Tesla EL34, which I found very cheap compared to what they provide, in years these will go up a lot, the double angled getters:

Now all I have to do is measure and match and enjoy.

 

[UntilThen]

Sylvania 6CA7 fat boy are different from Philips Miniwatt 6CA7/EL34. Fat boy can also be branded GE or RCA. I will get a pair of Fat Boy to try for myself.

Meanwhile once I've selected a pair of quiet Psvane 12au7 drivers, all power tubes I roll in now are just so quiet. That makes me very happy. It's the Philips Miniwatt 6CA7 in the power slot now.

 

[OctavianH]

Sylvania 6CA7 fat boy are different from Philips Miniwatt 6CA7/EL34. Fat boy can also be branded GE or RCA. I will get a pair of Fat Boy to try for myself.

It is my first time I hear 6CA7. I like these a lot. I'll get another pair at a cheap price, Shuguang Black Treasure Z 6CA7 and compare them.

Later edit: While reading several guitar amp forums I saw an interesting comparison for Sylvania "fat bottle" 6CA7: a combination of 6550A + 6L6GC.

 

[UntilThen]

Tested 3 more pair of power tubes. They are all quiet and sound incredible. I can't wait to try them in Odyssey. As I said before, Elekit TU-8200 is the test bed for my tubes.

GEC KT66


Shuguang Treasures KT88 Z


Tung Sol 6550 1960s

 

[OctavianH]

Shuguang Treasures KT88 Z

How are those Shuguang Tresures Z? The 6CA7 I'm receiving are similar.

In the meantime I start to burn in my perfect pair of Tesla EL34 double angled getter. I made measurements today and made 2 perfect pairs (less than 1mA between) and one decent pair (2mA). 2 are unmatched, candidates for future pairing. These Tesla EL34 are incredible, for me are better than the Mullard xf2. I am glad that I made my stash, now I do not care anymore about the prices.

The angled getters:

These tubes are selling rebranded as Edicron EL34 for less than 50 EUR/piece and for me are absolutely incredible. The Mullard xf2 are laid back and refined, but these have better treble and almost the same bass, with a little bit of harshness in the mids, however, for me and T1.2 these are perfect. For the price, absolute winners.

 

[UntilThen]

How are those Shuguang Tresures Z? The 6CA7 I'm receiving are similar.

Might be what you're after. More laid back than Gold Lion or Psvane KT88. The term laid back is only use here to compare with the other KT88 types because you can never accuse the KT88 of being laid back.

EL34 is more relaxed than KT88. Relax is a term I rather use than laid back because even EL34 is not laid back. It's just more relaxed and comforting.

I'm still listening with GEC KT66. This is a beautiful tube in Elekit TU-8200 with He1000se but so are the other power tubes. With the 6as7 / 6080 types, I know straight away what the different variants sound like but with KT88 / EL34 / KT66 / KT77, I'm still coming to grips with it but I certainly prefer the latter group of tubes (KT88 / EL34) for their dynamics, punch and bigger and more powerful sound signatures.

 

[triod750]

Might be what you're after. More laid back than Gold Lion or Psvane KT88. The term laid back is only use here to compare with the other KT88 types because you can never accuse the KT88 of being laid back.

EL34 is more relaxed than KT88. Relax is a term I rather use than laid back because even EL34 is not laid back. It's just more relaxed and comforting.

I'm still listening with GEC KT66. This is a beautiful tube in Elekit TU-8200 with He1000se but so are the other power tubes. With the 6as7 / 6080 types, I know straight away what the different variants sound like but with KT88 / EL34 / KT66 / KT77, I'm still coming to grips with it but I certainly prefer the latter group of tubes (KT88 / EL34) for their dynamics, punch and bigger and more powerful sound signatures.

But you are comparing OTL with output transformers now, aren't you? Not only the tubes?

 

[UntilThen]

But you are comparing OTL with output transformers now, aren't you? Not only the tubes?

Nope. I use 6as7 / 6080 in Wa22 and that's transformer coupled not OTL.

 

[UntilThen]

The only 2 OTL that I feel have enough grunt and power are the La Figaro 339i and GOTL with 6 x 6bx7gt configuration.

 

[OctavianH]

Might be what you're after. More laid back than Gold Lion or Psvane KT88. The term laid back is only use here to compare with the other KT88 types because you can never accuse the KT88 of being laid back.

I have a feeling those are similar with Ayon KT88. Here is an old picture, in 2019 when I last tried them. As far as I know those were manufactured by Shuguang for Ayon to sell with their amplifiers and your sound description matches what I remember.

 

[UntilThen]

It’s probably the same except my pair has a silver metal base whereas yours is gold.

 

[OctavianH]

Yes, I bought them from someone who owned an Ayon speaker amplifier and upgraded to KT120. So he sold these at a basic price to get rid of them. There is an article about these on a polish website here. I will put here an excerpt:

Maybe it was meant to be so, although I am not a fatalist. Just a few days before our guest’s visit I received tubes from Ayon, the KT88sx – a brand new product of Gerhard Hirt. I knew something was cooking because I reviewed the Orion II amplifier which used the KT88s, a Chinese product modified by Gerhard, sold with his company logo. I asked about his plans and it turned out that the KT88s will only be used in the basic Ayon amplifier; the more expensive ones will use completely new KT88sx tubes instead of the KT88 Shuguang Black Treasure. The KT88sx is a development version of the Black Treasure, designed according to Gerhard’s plans and manufactured by Shuguang. And the Austrian has vast experience in making vacuum tubes.
And here they are, beautiful, brilliantly made KT88sx Ayon Audio. Their sockets are made from gold plated metal, just like the pins. The glass is covered with carbon particles (Shuguang talks about a polymer alloy) to help with focusing the electrons in the anode. Another material used in their construction and called Super Alloy helps maintaining the tubes electrical parameters for prolonged period of time. It took three years to develop this technology and Shuguang is probably the biggest company in the world manufacturing vacuum tubes. You can find 65 differences between their tubes and KT88 from other companies. Gerhard made sure that there are even more of them…

 

[UntilThen]

Sound impressive. I almost bought the Shuguang 300b tubes.

Rolling in the RFT EL34 tonight. Another quiet pair. When it's quiet in the tube amp, it's like heaven. There's a sweetness and euphony from the EL34 and variants.

A little about RFT ...

RFT stands for Rundfunk- und Fernmelde-Technik - a group of state-owned technology companies in the former German Democratic Republic (East Germany). This company produced valves for Telefunken and Siemens and made the famous Siemens EL34. These valves are of very good quality and have excellent consistency.

 

[OctavianH]

Shuguang 6CA7 Black treasure, wam, full, forgiving but still soemhow similar with the other pair of 6CA7 I tried. I like these for a warm forgiving signature, with more neutral inputs. But the bass is not as tight like on EL34, they compensate somehow on mids which are sweeter, if you prefer that kind of sound (reminding on KT66). Another disadvantage for me would be a little bit of recession in the high frequencies area, I always liked clean detailed highs.

I found these used in Germany, matched by Tube Amp Doctor. I have to say are perfectly matched (less that 0.5mA). The build quality is not as impressive as on the Psvanes KT88 which are heavier and have that ceramic base dressed in aluminium, these look cheaper, but glow nice and are light as a feather.