Few more details about the synergy between el51 amd diff rectifiers from Fabio:
“Spent more time with the EL51 and rolled some rectifiers. Results are very consistent and in line with what these tubes deliver in other settings.
Kron RK 5U4G: linear, good bass, flatter than others but good detail retrieval. Most ss-sounding of the bunch
PSVANE Acme 274B: great treble extension. More forward and more pulpable than the Kron. Leanest sounding of the bunch: suited for systems which are a bit heavy in bass and lower midrange.
Philco 1948 5U4G: Darkest sounding rectifier. Beautiful lower midrange and full bass. The perfect tube for male voices. It really shines with singer/songwriter anf folk music.
Takatsuki 274B: similar to Philco but slightly faster bass and better treble extension. Great inner tension. Full and forward midrange and great weight.
Shuguang GZ480: great upper midrange and treble. Airiness is comparable to Acme but with more midrange and bass. Hence, fuller sound. Great soundstage with voices hanging slightly higher in the air compared to others. Moves a lot of air and produces a direct, involving and dynamic sound.
So most of this doesn’t sound new to you if you heard these rectifier tubes. I couldn’t say that the EL51 is a perfect match with just one or two of them. It works with all. The choice is very dependent on system match and hearing preferences. I prefer the Shuguang GZ480 for the scale, treble extension and dynamics. It is a very complete tube.
Compared to my initial assessment the bass has improved with additional burn-in time. It reaches deeper now while still being very controlled and hard hitting. Also, the tubes got slightly more musical compared to the first few hours. It has to be said though that the changes - while being clearly audible - are not like day and night as for example with the PSVANE 6CA7, wich opened up massively in the upper midrange and treble after approx. 30 hours. My EL51 sounded good right from the start.
Also, I want to share again my enthusiasm. In my opinion, these play in a different league than all other output tubes I heard to date. Definition, presence, tone, details and imaging are head and shoulders above the rest. There’s not even a comparison. Also soundstage is massive and on par with the PSVANES. The background is pitch black and there‘s a calmness, superiority and sublimity I have not yet experienced.
The EL51 produce a present, euphonic, organic and pulpable sound. You can almost touch the music or the artist in the room. You’ll suddenly hear things which were rather grayish and flat in the background before. Now these elements are rendered precise and clear with contrast and detail. This overload of detail and presence may seem a little analytical initial but once you get used to it and with more burn-in time the music speaks as one. These tubes generate the most realistic and emotional sound I heard to date.
My system is on a whole new level (not exaggerating here). The EL51 brought way more than just a little tonal change. Even after a few weeks I constantly sit in front of my speakers with a big grin on my face experiencing old, familiar music in a completely new way.
If you have a TRP you should get these tubes and I sincerely hope they will transform your system in the same way as they did mine.”
Happy rolling guys...
