So my tubes arrived, now I have 6 of them (listed left to right)
- Mullard M8136 (CV4003)
- Amperex Bugle Boy
- JJ Electronic
- Fivre
- La Radiotechnique
- Mullard CV491
Worth repeating that I listen to 75% EDM, and 25% is a mix of nu metal, indie rock and synth pop. This means that my ears/brain will prioritise different things to you all, who listen to classical or jazz. Also, my source is dCS Bartok, which differs to most of you using mDave. What I value in EDM is coldness (recessed mids, airy treble) and spaciousness (3D holographic soundstage). Very few of my EDM tracks will have some vocals, where mids recession would be a problem, and that's why Abyss 1266 TC with dCS Bartok is such an elegant solution to me, kinda all in one device and punchy, resolving headphone.
Those familiar with my journey may remember, that I tried other headphones like Spirit Torino Valkyria (piano perfection) and Hifiman Susvara (good balance), with an intention to own one of them, but in the end, when I got Riviera AIC-10, I realised that (even with the stock tube) 1266 sounds better than these two, as AIC-10 simply changes the mids to my liking (for the 25% of my listening). When I was told that Riviera tube rolling is an inexpensive experiment, I got myself 5 more tubes, thinking that they won't change it much, but the differences are there, between some tubes more than others, but I will get to that.
There are many ways how to compare these headphones, but what matters to me the most, is how they work on EDM and "the rest". For me, the benchmark would be Bartok itself, which is really good at spacial cues, presenting the soundstage in very 3D fashion, making it seem holographic. The closest tube that does this with Riviera would be
Amperex Bugle Boy, essentially disappearing and making the music sound exactly like it did with Bartok. To me, this tube is a keeper, as I can imagine owning Rossini in the future, which (currently) does not have a headphone amp. Having a tube that does not alter connected DAC, is a big plus for me. Then there is
Mullard M1836, which to my surprise does like 90% transparency (measured as resolution + holographic soundstage). Now, what I did not expect is that this tube also works for "the rest" of my music, presenting mids in forward way, making them sweet and relaxed, while keeping the resolution/layering. This is a big difference from the
stock tube, which was sweet and relaxed, vocals were right in front of you, BUT resolution was significantly lacking and the soundstage was very intimate. This worked well for demo purposes (as if I had tested Riviera with Amperex, I would consider it transparent and not worth it over Bartok), so I am glad Riviera folks selected it as default.
But what about
Fivre and
Mullard CV491? To my ear, they are very similar and both work well for "the rest" of my music. Where they differ is how much they work for EDM, but that was never my goal (just an added bonus). Fivre is a bit more punchy, or bass is better resolved/defined, where as Mullard CV491 feels more relaxed/balanced. At the high level, this would be a difference between "V" and "--" shape, but VERY subtle (not like 1266 vs Susvara).
Now,
La Radiotechnique tube is a bit of an oddity in my opinion, it works quite well for EDM (like Amperex and Mullard M1836), but not as much. And it does not work that well for "the rest", where Fivre and Mullard CV491 are much better, and Mullard M1836 being universal as well. I think it has to do with the fact that this tube is very spacious (like Amperex), but changes tonality a bit, and unlike Mullard M1836 it does not work for EDM, neither for "the rest". I am finding it hard to describe what the tonal shift is, but I don't think it work well. Don't take me wrong, the tube is very resolving and technically impressive, so it is worth the cost and it is not "another stock tube".
If I was to rank them, in order how they fare, it would be something like this
For EDM:
- Amperex Bugle Boy / dCS Bartok
- Mullard M1836
- La Radiotechnique / Fivre
- Mullard CV491
- Stock tube
For "the rest" (nu metal, indie rock, synth pop):
- Mullard M1836
- Fivre
- Mullard CV491
- La Radiotechnique
- Stock tube
- Amperex Bugle Boy / dCS Bartok
As you can see, Mullard M1836 is the best for "the rest", while being close second for EDM. This makes it, in my opinion the absolute best tube to use, so much so, that for majority of my listening, I don't bother using dCS Bartok direct out, and happily keep 1266 connected to Riviera AIC-10. The second closest tube would be Fivre, and I understand why everyone was saying it is a good "all rounder". As for Mullard CV491, I had higher expectations, but that comes to the tonality, I guess. And, technically speaking La Radiotechnique is an excellent tube, very resolving and spacious, BUT it does something to the sound which I cannot put my finger on it, maybe I need more hours listening to it. And as you can see, even though Amperex Bugle Boy is a fantastic transparent tube, I simply do not have a use case for it (it sounds like Bartok, so I well as may plug 1266 to Bartok), but has potential in the future.
If I were to keep only 3 tubes, it would definitely be Mullard M1836 and Fivre. You say, these are just 2 tubes, and you are right, but I would keep Amperex Bugle Boy in reserves, for future DAC upgrades. As far as which tube I am going to be using the most, it is definitely Mullard M1836, and Fivre will stay as a backup. I may roll in La Radiotechnique occasionally, just to figure out what is bothering me with this tube!
Thanks for reading.
