[Isaacc7]

Indeed, these GEC KT61 pair very well with 6J5. For example with GEC CV1067 L63.



This was an important milestone in Eternity's life, the KT61. I was not expecting that I would be so pleased about these, and soon I'll try them on input. I am curious about the gain in that case, I guess I'll pair them with some EL34 or higher gain outputs.

Would you use an adapter to triode strap them for input Duty?

 

[OctavianH]

Would you use an adapter to triode strap them for input Duty?

Yes, I asked Deyan to make me some 6V6 -> 6J5 adapters. The plan was to dwell more into KT61/KT63 area because 6V6 exceeds my bias trimmer. But these work well with grid bias under -13V and I can use them. I am unsure if these will sound fine on input, but on output they surely are better than 6V6 which sounded weak on this amp.

 

[OctavianH]

Deciphering more from these marvelous GEC KT61, I realized that GEC always works with RCA for me, regardless of the type. I mentioned this when I played with ATS25 and also later with 12E1 or KT66. So I had to try my RCA 6SN7GT and voila! Great result. As expected, I might say.

RCA knows how to tame that excessive mid forward tone of GEC and adds a little bit of bass to the overall signature. In the end this tube rolling game is very simple when you start to realize how these house sounds work and then what adds each tube type. In the end you'll be the perfect cook adding this and that to match your perfect recipe and taste.

Today was a very rewarding day for me, discovering some new stuff which is excellent. Now, I guess, I should start listening to music instead of my equipment. In the last days I was quite absorbed by the latest Fleshgod Apocalypse album, Veleno, and today I went more on the extreme side listening to some Rotten Sound. Grindcore was always special to me, starting from my Napalm Death days. But for this evening I guess I'll return so some more "classical stuff" like Udo. I'll stop here because the purpose of the thread is tube rolling in the context of UltraSonic amplifiers and not about my personal music tastes. However, I mention them from time to time to remind people that my assumptions and assessments are quite biased by some personal preferences.

 

[OctavianH]

Exactly after I complained about 6SN7, I had the idea to try the Raytheon VT-231. Wow, this one has a strong and controlled bass, I never heard something like this from a 6SN7. Incredibly fast and powerful sounding tube, dynamics close to what I hear on 6SL7. More than this, this one biases around -7.2V while the average 6SN7 goes around -6.5V.

I do not know much about this one, but I'll try to find out more. There are some things mentioned on the dedicated thread, but unfortunately the pictures are not available anymore to see the construction details of each type mentioned there.

It has a vertical square getter. I'll try to find out what "I3" means because it is most probably the date code.

 

[Isaacc7]

Exactly after I complained about 6SN7, I had the idea to try the Raytheon VT-231. Wow, this one has a strong and controlled bass, I never heard something like this from a 6SN7. Incredibly fast and powerful sounding tube, dynamics close to what I hear on 6SL7. More than this, this one biases around -7.2V while the average 6SN7 goes around -6.5V.



I do not know much about this one, but I'll try to find out more. There are some things mentioned on the dedicated thread, but unfortunately the pictures are not available anymore to see the construction details of each type mentioned there.



It has a vertical square getter. I'll try to find out what "I3" means because it is most probably the date code.

I really like the Raytheon 6f8g with the same plate structure although I think they are black plates. I also love the Raytheon 12j5wgt with the flat ladder plates. Keep meaning to try some of the regular 6/12sn7 tubes.

 

[triod750]

Surprises usually come from where you don't expect them .

 

[OctavianH]

Surprises usually come from where you don't expect them .

It is true that I was surprised and usually when something like this happens I wait for another day to check again. But today the same impression. These are in another league in terms of bass and the overall signature is very nice. I'll continue to listen to this one.

 

[OctavianH]

Friday beerday! But first I had to make some order in my tube collection which decreased a lot lately. Eternity was for me a source of economy. I sold mostly all my 6SN7 or 6AS7 and newer production tubes and kept many used NOS I got here and there which are sounding a level better than the famous ones even if they do not measure as good as others. No problem for me.

But honestly all I need is this drawer. This is my stash I'll never leave and which gives me everything. And here we have mostly 6SL7, 6N7, a few 6SN7 and in rest, KT66/77/88, E3375 and 807/ATS25. That's all folks. Ah, I forgot about the GEC 12E1. Life is simple with Eternity, you do not need so many to be happy.

Ok, now we have time for a beer.

 

[Thaddy]

All of those tubes bumping against each other

 

[OctavianH]

All of those tubes bumping against each other

Do not worry nobody is hitting them, they just sit there. And this is my used stash where I keep stuff I daily use. I never had a problem with these in years. The others sit in boxes, vertically, and so on... those I'll most probably never use. LOL

 

[OctavianH]

I circled around these 6SN7 trying to understand more about their nature but they were not able to impress me. Of course, except the Raytheon VT-231 I mentioned a few posts back. Today, while preparing to give up, I wanted to try the Haltron I identified with your help as Brimar made. And what a surprise!

This is a very special tube, exceptional, I would say.

It has incredible detail and a very large soundstage. I started to dig about it and I found very close to what I hear the remark of tubemaze from here. He describes better than me what I am hearing. Of course, it needs to be paired with outputs with good bass, but in rest it is not missing anything.

I guess I can put all the rest of the 6SN7 to storage, I was never a fan of them anyway. But Raytheon VT-231 and Brimar 6SN7GT will definitely remain close.

 

[Isaacc7]

The first set of output tubes I put in were some Sylvania JAN 7c5 tubes. They are supposed to be identical to a 6v6. First set of input tubes were tall 7n7. In triode they were... fine. Kind of round and warmish sounding but also blah. Then I switched to Ultralinear and was shocked at the transformation. It was much cleaner and more detailed. After a while I found it a bit fatiguing. If you're familiar with the stereotypical sound of Sylvania 6sn7 tubes, extended top end, solid bass, open sound then you'll know how this sounded but x2. Sylvania on the input and output were just too much. Too forward and an emphasis on the upper mids/lower treble. MOV cv1102 sweetened up the sound considerably but after a while still noticed the fatiguing sound. Switched my preamp to Tungsol BGRP from Raytheon 12j5wgt and that helped but still wasn't enough.

Finally tried a tube that I have never really had a lot of luck with, the RCA 6sn7. They always sounded thicker, more opaque, and a bit dry to me whenever I used them in my other amp. Turned out they are a good match with the 7c5. It really toned down the aggressiveness. In the end though, the 7c5 was still a bit much for me. This is completely different than what I got out of them in my SEP amp. In that they were very well balanced and a tad warm.

And then I started to wonder, maybe that's what the amp's character is. That wouldn't be good. Dove into my tube stash looking for some more 6v6. I have a slew of pairs and triplets but finally found a quad of Sylvania grey glass 6v6gt to try. As I got ready to put them in I realized they weren't all the same tribes. I had two pairs of slightly different 6v6. Well, I wanted to know if the amp's character was going to override the tube's character so I put them in. I hope the audiophile police don't arrest me!

These sound completely different! Whew! The sonic presentation got much bigger and super rich/warm. Total chocolate cake kind of vibes. That was a welcome relief. but in a short while I heard what I had always disliked with the RCA 6sn7. The sound had flattened out, the dryness was there, and the bass was a bit wild. Switched back to the 7n7 tall bottle inputs and Raytheon 12j5wgt in the preamp. The Sylvania 6v6gt tubes are more laid back than the 7c5 and a bit warmer. This is closer to what I was getting with my SEP amp with the 7c5.

Listening more I felt like there was a subtle crunchiness to the sound. It reminded me of the distortion you get when you overdrive a mic preamp. So I backed off the voltage a little and that cleaned it up. So it looks like I will need to continue to experiment with operating points to get the best sound. I will try this tube in triode tomorrow probably and may try to find a better tube combo for the 7c5 in triode as well.

My current plan is to stick with lower voltage tubes right now. After I've satisfied my initial curiosity with the 6v6 I will probably try the 6f6, 6k6gt, and 6aq5. I reserve the option to deviate from that though!

 

[OctavianH]

These sound completely different! Whew! The sonic presentation got much bigger and super rich/warm. Total chocolate cake kind of vibes. That was a welcome relief. but in a short while I heard what I had always disliked with the RCA 6sn7.

I hear the same about RCA. On Elise I never liked them but on Eternity they became my favourite american type.

Can you tell me a little bit more about the Triode/Ultralinear modes and differences? You said triode is rounded while ultralinear is clean. It goes towards Solid State sound or? What is the situation with the bass on ultralinear compared with triode mode?

 

[triod750]

I hear the same about RCA. On Elise I never liked them but on Eternity they became my favourite american type.

Can you tell me a little bit more about the Triode/Ultralinear modes and differences? You said triode is rounded while ultralinear is clean. It goes towards Solid State sound or? What is the situation with the bass on ultralinear compared with triode mode?

Good questions!

 

[Isaacc7]

I hear the same about RCA. On Elise I never liked them but on Eternity they became my favourite american type.

Can you tell me a little bit more about the Triode/Ultralinear modes and differences? You said triode is rounded while ultralinear is clean. It goes towards Solid State sound or? What is the situation with the bass on ultralinear compared with triode mode?

I’m still in the process of figuring it out. I have mostly been using ultralinear so far, haven’t even tried triode yet with the Sylvania 6v6gt. When I think of a “solid state” sound the first thing that comes to mind is a homogenization of timbres. One of the classic symptoms of schizophrenia is “dull affect.” It’s a dulling of emotional emote leading to a kind of sameness for all of their reactions. That’s the best way I can describe how most solid state amps sound to me. So in that context, no, ultralinear does not sound solid state to me. The short comparison I did with the one tube between ultralinear and triode made me think that ultralinear is cleaner and had more jump. On the other hand I also found that particular tube rather fatiguing to listen to. Not having that problem with these tubes. Once I get in the proper cables I will eagerly try the 14c5 tubes I have. They have the same grey glass appearance as these 6v6gt but the micas are different so they’re bound to be different tubes.

In regards to the RCA 6sn7. These are clear glass with the silver logo. I have an older, grey glass pair of 12sn7 that I will try once I can run 12v tubes. So many people like them I can’t help but think I just haven’t found the right combo yet.