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PRIMA LUNA owners, what power tube are you using?

To all Prima Luna owners, specifically those with a DiaLogue One integrated amp (although owners of the new Premium amps and the ProLogue series are more than welcome to chime in with opinions and feedback), which power tube are you currently using? Which others have you tried in the same amp, and what made you prefer the ones you ended up going with? And, of course, please specify what speakers you are using the amp with.

I own a DiaLogue One myself. Happy owner for close to 4 years now. It comes standard with EL-34's, and it's, in fact, designed for that specific tube. But Prima Luna amps are a tube-roller's delight, and the manufacturers encourage trying other types.

Personally, and after experimenting with the Gold Lion KT-88's and Tung Sol KT-120's, I ended up going full circle and back to where I started: the stock EL-34 tubes. These are labeled as "Prima Luna", but are actually made by Shuguang in China and, supposedly, only the best rated ones end up being used for the Prima Luna amps.

My system consist of the DiaLogue One, Sonus Faber Toy Towers, and Oppo 95 for CD's, SACD's and digital files (mostly hi-res and FLAC files sourced from an external drive), Pro-Ject RPM 5.1 SE with a Dynavector 10X5 for analog, and Nordost cables all around (Brahma PC, Heimdall and Red Dawn LS interconnects, etc).

My journey could basically be described like this: I started with EL-34's, loved the sweetness, transparency and midrange magic but needed a little more grip on the low-end (and also detected a hint of harshness in the upper highs from time to time), so I switched to the re-issued Gold Lion KT-88's. The Prima Luna auto-bias feature took care of the rest. I LOVED that combination (and loved the way the Gold Lions LOOK, as inconsequential as that sounds), but reliability was an issue. One exploded while in use, and the rest would loose their sparkle and life in less than a year, with moderate to low use on the amp. At $200+ per quad for tubes that don't even last a year, things get expensive really quickly, so I needed an alternative.

I then tried the KT-120's that everybody was raving about and that were actually cheaper than the Gold Lions. Originally, they were not my cup of tea. Too aggressive and bright on the one hand, but not that much different than the Gold Lions when it came to added bass grip and control. I actually gave them a second chance, burned them in for at least 200 extra hours and they definitely got better (less harsh on the top, rounder in the mids, but, again, with no extra "grip" gained on the bottom). Still, the magic was just not there and my amp was never designed with that tube in mind anyway, so why even bother?

I then went back to the stock EL-34's that I still had sitting in the closet. These were not as "sweet" and "magical" as I originally remembered them, ironically, offering bass aplenty (albeit looser, slightly sloppier bass, a quality that for some reason I tend to like on most material since it seems to allow the music to feel more tangible, less sterile and artificial), and an incredibly more open, extended and detailed soundstage, which definitely got "wider" and more STABLE when compared to the KT-120's. With the emphasis being on the mids, there's a lot of details to be gained that were perhaps a little obscured by the more linear characteristics of the KT-88's and KT-120's. Notes in the upper-lows are now considerably more clear and I'm simply hearing a ton more music in the bass and low end. Yes, the KT-120's were sturdier and allowed my Sonus Faber Toy Towers to go a little lower, no question, but at the expense of detail and finesse, I believe. This translates into a significantly more "crystalline" presentation, with the well-known musicality and ripeness of the EL-34 in place, and one that I am finding myself preferring. It all works wonders with jazz and classical, particularly with strings, but rock albums actually sound more vibrant as well. Certain passages tend to break up a little bit, but oddly enough this only happens with very few instances of highly distorted guitars and/or very, very complex passages on extreme metal albums (a genre I also love). Overall, though, I think the EL-34's are back and staying, at least for now. Next experiment: the Gold Lion KT-77's. Anybody have any experience with them?

Would love to hear about your own experiences.
beyondarkness

Showing 2 responses by beyondarkness

beyondarkness OP
24 posts
 
Well, the quest for the perfect output tube for my Prima Luna DiaLogue One and Sonus Faber Toy Towers combo, as futile as it may seem, continues. You can read more about my experiences with different tube types and brands in the previous posts in this thread.

I am now burning in a new matched quad of Electro Harmonix 6CA7s, the consensus about this particular tube being that it is basically an EL-34 on steroids. Almost all of the midrange magic of a traditional EL-34, but with more bass. That was certainly the case when I first installed them, and while I listened for the first few hours. In fact, I was astounded at the amount of bass energy. Tight, deep, extended, sometimes more so than with my Gold Lions KT-88s! I was in heaven for an hour or two and thought these were keepers. I thought I had found the perfect tube type for my amp and tastes.

BUT, after about 20 hours or so, the bass is weak, not as extended, nor tight, etc. Just like with the Shuguang EL-34s. And the midrange not as sweet, so it's kind of a "worst of both worlds" scenario. I now remember going through a similar experience with the factory-installed Prima Luna EL-34's. They seem to sound INCREDIBLE at first, but loose their grip and "slam" factor shortly after. Don't ask me why. I am puzzled. Could it be a voltage issue? I live in a condo, so I'm sure the quality of our electricity here is not optimal, yet every power conditioner I have tried made things worse. Highs can be harsh and piercing sometimes as well.

Could it be the Prima Luna auto-bias circuit acting up? Or the tubes going through some sort of phase as they break in? Or could it be me? Those days where the stars align and the system sounds JUST RIGHT seem less and less frequent now.

Any ideas about why a quad of power tubes (brand new) would offer plenty of bass extension and midrange sweetness when first installed, and loose some of that tightness, grip and beautiful tone shortly thereafter?
beyondarkness OP
24 posts
 
Thank you all for the feedback. I'm happy to read that I'm not the only one preferring the EL-34 sound, nor the stock Prima Luna tubes, which seem to be a lot better than folks give them credit for.

I did run into a little bit of a dilemma, though. When I switched from the KT-120's back to the amp's stock EL-34 tubes (and after I collected my jaw from the floor and kicked myself in the head for having sacrificed all that sweetness, midrange magic, openness and transparency for so long), most of my listening was done using the digital side of my system (an Oppo 95 playing mostly FLAC and hi-res files from an external drive, and SACDs via Nordost Heimdall interconnects). This combination sounded simply glorious. All the usual attributes of the EL-34 sound were there, but bass was also abundant and tuneful. It wasn't as tight as with the KT-120's, but nor was it excessive or bloated. In my room and with my speakers, it was simply JUST RIGHT. My digital "front end" never sounded better! In fact, it never sounded this smooth and analog-like. I could listen to this combination for hours and hours, and that is precisely what I have been doing lately.

BUT, when I finally decided to listen to some vinyl (Pro-Ject RM 5.1 SE table with Dynavector 10X5), the synergy was not as magical. In short, for whatever reason, unknown to me, the bass is considerably weaker now. Tight, ripe and alive using digital, and yet VERY limited in extension when switching to analog. Low bass is almost NON-EXISTENT. My Sonus faber Toy Towers now sound like terrific monitors instead of 3-way (almost) full range towers. The midrange magic is there more than ever, but I'm missing the foundation. Phono pre-amp is a Pro-Ject Phono Box S. I triple-checked all the settings and nothing had changed since the last time. I have to say that the KT-120 and KT-88s were a better match in this case, particularly since I listen to a lot of 70's rock on vinyl.

So, now, of course, I miss my Gold Lion KT-88's. I know the 120's are NOT for me (too harsh and bright, too "solid-state" for digital), and if anything these last few days serve as confirmation and reminder that I am more of an "EL-34 type of guy". But I listen to vinyl a lot and now there's something not quite right with this tube and my table/cartridge combination. Digital sounds like analog and analog sounds TOO soft and with no real "bite". I REALLY, REALLY love the Prima Luna with EL-34's and my digital front-end, but I am torn as to what to do to aid bass extension when listening to vinyl. I might have to give the Gold Lion KT-88s another try, hoping NOT to loose much of the beauty of the EL-34's in the process.

Could any of you folks with similar experiences share your thoughts, try to explain to me WHY such a huge discrepancy in overall presentation is apparent between digital and analog, or recommend an EL-34 that that has a little more of a pronounced and ballsier low-end? Thanks in advance.
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