Some additional info here from AK about 6C4C which talks about the difference in sound based on the year the 6C4C was manufactured.
https://audiokarma.org/forums/index.php?threads/replacement-6b4g-tubes-for-gsg-set.490012/
See text from Prelius.
https://audiokarma.org/forums/index.php?threads/replacement-6b4g-tubes-for-gsg-set.490012/
See text from Prelius.
I will have to take a look at my 6C4Cs to see what date codes are involved. Having said that, I may just go the trioded sweep tube route anyway. I have plenty more LL500s than I do 6C4Cs. I may set up a differential folded cascode driver using a couple of 12SN7s, to see if nasty sand can give rise to nice sounds.
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I have no idea what the rating is for my Electra-Print P-P transformers - I may try running them at the upper limit for a 6C4C. First off, though, I'll try dragging them into work to ply them with a variable frequency sine power source (convenient to have that on hand) to see what the turns ratio and primary inductance are.
I think I'm getting a clearer idea from recent builds. I have 4 working amps as follows
1. My main 2a3 amp with NP Acoustic 3.5K OPTs. 2a3s are EH.
2. A 6C4C amp with Lundahl LL1682 OPTs, 5K into 5 ohms. Less power, though sounds nice. 6C4C are Svetlana.
3. My "other" 2a3 amp with O-Netics 3.5K OPTs. 2a3s are EH.
4. A 6C4C amp with Techno 5K OPTs. 6C4C are Svetlana.
I've given all four an extended listen. My impressions are:
So given the similarities in the sound of the last 3 amps, my impression is that the Svetlana 6C4C can hold its own against the EH 2a3. I couldn't hear any strong difference. I was getting very nice sound from all three. The extra detail in the NP amp I attribute to the amorphous cores not the output tubes.
1. My main 2a3 amp with NP Acoustic 3.5K OPTs. 2a3s are EH.
2. A 6C4C amp with Lundahl LL1682 OPTs, 5K into 5 ohms. Less power, though sounds nice. 6C4C are Svetlana.
3. My "other" 2a3 amp with O-Netics 3.5K OPTs. 2a3s are EH.
4. A 6C4C amp with Techno 5K OPTs. 6C4C are Svetlana.
I've given all four an extended listen. My impressions are:
- Both the 2a3 and the 6C4C valves can sound very good. Very little in it. Hard to tell much difference.
- My main NP Acoustics amp sounds different from the other three - some more micro detail from the amorphous cores.
- The other three sound very similar indeed. I like all of them very much, and could listen to any of them. They all do justice to the 10Y input stage I use. Given that the Lundahl and O-Netics are expensive and well regarded OPTs the Techno is up there with the same kind of quality. Techno AFAIK make the transformers for the Radford Revival amps.
So given the similarities in the sound of the last 3 amps, my impression is that the Svetlana 6C4C can hold its own against the EH 2a3. I couldn't hear any strong difference. I was getting very nice sound from all three. The extra detail in the NP amp I attribute to the amorphous cores not the output tubes.
Of course. Because the bigger envelope allows the sound to expand better. So the soundstage necessarily must be wider. Any doubts on this???
Best regards!
My post is pointless, as it is fully subjective (compounded by the the belief that memory of a sound has merit!), but I started my diy hobby about 15 years ago with a SET amp based on some diytube.com boards that I sampled a huge amount of tubes in -- 45, 2A3 and 6A3 while listening to a variety of new full range and vintage speakers. I used off board DC supplies from Broskie for the filaments. Most 2A3 were RCA and rebrands. 6A3 were mostly RCA and Sylvania. In the end, I became totally convinced that the old green box Sylvanias with the etched leaf emblems were the cat's meow -- and better than all the 2A3. Probably because they were all strong NOS, but it is what it is. I even tried some of the single-plate whatever they are (VT52?).