Here is a the summary of the TRP tube rolling session we did at my place with David, Fabio and myself mid summer this year. I think it should also be in this Thread.
Setup: We tested a variety of output tubes to see which ones are working best in the TRP. We kept the setup simple with the SuperKomputer feeding the TRP DAC. Amp was the Ayon Crossfire. Speakers the hORNS. So no pre-amp and no subwoofer was used.
The first round we did with the KR Ann Recti. Second round we compared our favorite tubes with the Takatsuki.
Music: Stevie Ray Vaughan - Tin Pal Alley (2.30 min. & 5:00 min.); Yosi Horikawa - Bubbles (from start 1-2 min); Jose Carrera - Misa Criolla (from start 1-2min); Keith Jarret - Köln Concert Part I (1-2 min from start & 6:00 min); Blues Company - Dark Day (1:30 min); Jon Hopkins - Abandon Window (start 1-2 min & 3:40 min)
KR / Tung Sol EL34: clear over full spectrum, well defined bass (one of the better we heard)
KR / Philips EL24 Blackburn Code (NOS): warmer than the Tung Sol, pronounced mid-range, lacks treble extension
KR / RFT EL 34 (NOS): most dynamic and defined of the EL 34, clean over the full specturm, more details, good flow, clearly the winner of the EL34s
KR / Brimar 6L6G (NOS): less dynamic than EL 34s, soundstage moves slightly further back, beautiful organic tonality, very smooth, less treble then the RFT but nothing to worry about, good bass quantity which is softer than with the EL 34s, most emotional and touching of the bunch
KR / TAD KT66: most bass quantity, missing snap, polished and glossed over, a clear pass from all of us
KR / Genalex KT 77 Gold Lion: massive soundstage, cleanest of the all, quite background, has the fullness of the EL 34s but is more precise adn more transparent, good treble extension, tonality is spot on, involving and physical, fantastic intradynamics, most complete tube of the bunch and in all disciplines ahead except from emotionality wher the Brimar is slightly better
Elextro Harmonix 6CA7 EH: a lot of details, most powerful, good punch and dynamics, missing body in the lower midrange/upper bass, does not transport the chest voice as the KT77 and the Brimar.
Our favorite tubes were the Genalex KT77 and the Brimar 6L6G. The Brimar is mor emotional but the KT77 more involving. Tonality of the Brimar is beautiful but not as correct as with the KT77. We switched the rectifier to the Takatsuki to find out how these two favoites would do with the Japanese rectifier.
Takatsuki / Brimar 6L6G: Depth, focus and imaging improved a lot. Also the soundstage increased. The Takatsuki completes the Brimar. Very detailed but never losing the flow and the focus on the complete picture. The step up from the KR to the Takatsuki is impressive.
Takatsuki / KT 77: Also here, the soundstage increases slightly. There's more air and better separation than with the KR. But the difference to the KR is much smaller than with the Brimar. We all could very well live with the KR.
Overall, the Takatsuki and KT77 was the winner of the day. If you own a TRP it makes sense to own a Brimar and the KT77 as they are quite different in their presentation. The KR is doing a great job overall. If you got the spare money, go for the Takatsuki”
Later Fabio tried NOS GEC KT66 and wrote the following:
“Did some further comparison between the GEC KT66 and Genalex KT77. After having had the KT66 in the system for several weeks I changed back to the KT77 and was first impressed by the presence, slam and details I got. The soundstage moves much closer to the listener. Dynamics and microdetails are great. At times I almost had a heartattack when an unexpected impulse hit my body. It reaches slightly deeper in the bass than the KT66. However, bass control is inferior to the KT66 with more focus on the very low end and a slight dip in the upper mid bass. The high gain, dynamics and details come at the cost of being less musical. Some music can sound a bit forced and nervous at times. The KT66 is more relaxed with lower noisefloor. Music just flows better. Details are presented in a more natural manner. Both tubes have excellent treble extension and reach deep down (the KT77 a bit deeper). Think of the GEC KT66 as a better version of the Brimar 6L6G.
If your system is a bit sleepy, you’re looking for more dynamics and punch or your pre-amp has a low input gain I would chose the KT77. If you want to calm down things and you are rather into long-term relaxed listening go for the KT66. Both tubes are exceptional in their own ways. I compared them in the TRP with the RK Ann. Rectifier.”
BTW would you somehow have a feeling it kind of blends well with more output tubes types then RK one or let me change the question is it more for forgiving somehow then RK as i have this feeling about it...
I never thought the RK 5u4g needs to be more forgiving.
I don't experience the RK 5u4g as shouty as you (and others?) obviously do.
I love the RK 5u4g for what this recti brings to the table and it is still my No. 3 favorite recti for Lampi DACs and I have tried dozens.
At the moment I'm only listening to the ACME 274B and am enjoying it.
Will compare more combinations another time in the new year.
After a few months of listening to the Acme 274B, it is now my favorite rectifier paired with the KR RK PX25. At first I had a nagging feeling I was missing some of the music, but I attribute that to its significantly deeper soundstage compared to any other rectifier I have tried. Tonally, it is almost perfect as well. It also appears to have less gain than most of the other rectifiers I have tried, which really gels with my downstream components.
Many thanks to @Golum for taking a punt on this tube an enlightening us on its virtues. I'll soon be borrowing a pair of the Acme 300Bs to try in the DAC. I'll be sure to report here what my findings are. I'll be comparing it to the RK PX25, Elrog 300Bs, KR 242.
My Acme 274 b has around 100h so probably fully burn-in and it is my no 1 , no 2 being NOS Fivre from late 50's and no 3 RK 5U4G.
I have not tried Tak though.
As by Adamaley my Acme is paired with KR PX 25 but regular version ,not RK.
Very curious about his findings for Acme 300 B .
Moving outside to 211 valves, of which I have the most of any type of valve, then GE, RCA, Shuguang all measure remarkably constantly, almost exactly the same over all the quads I have.
Amperex, the ones I use and that I have put many, many hours on, measure stronger by about 15% and again consistently so.
All good here then. Excellent valve, the 211, and obviously well made by all the above brands. Surprised with Shuguang TBH, but hey, they have done good with their cheap 211 spec wise. And they sound great considering the cost.