So when it arrived, the first thing I checked was the provenance of the tubes supplied. To my pleasant surprise, it came with Russian 6n14p OTK (military equivalents)! The 12ax7 were Chinese. In this configuration, it sounded great. I kept the Chinese tubes in for several weeks to see if the character would change over time–it did not.

My first switch was to put in the Sovtek LPS. This made a little difference, but mostly very subtle, and mostly in the high end, which was ever so slightly better defined.

After another few weeks with these, I had in the meantime purchased brand new JJ/Tesla ECC803S and two NOS RCA. I next rolled in the NOS RCA (from the codes on them, they appeared to be from the ’70s). I couldn’t really tell much of a difference with the Sovteks. I left them in for a few days and thought that some of that high-end “shimmer” was missing from the sound now.

I next put in the JJ/Tesla ECC803S. These were my new favorite, although again, the sound was still more or less like the original Chinese Tubes, though closer to the Sovtek LPS, but a very slight subtly better high-end. I left these in for a couple of months and enjoyed listening to music.

The last change and current preamp section tubes is with used Telefunkens. I had in my tube stock from my previous amp a single Telefunken ECC83. I finally got a “good” deal on another single on eBay ($20 w/shipping), so now I had a match. Again, there was no amazing difference, but there is definitely a very subtle improvement in overall definition of music. I’ll probably keep these in until they burn out, but I won’t miss them terribly when they do: none of my backups are bad, and the worst are merely good.

As for the power tubes, I tried the Russian NOS 6p14p, brand new JJ/Tesla EL84, and brand new TAD EL84. I could discern no noticeable difference. They were all uniformly excellent and the music sounded the same: same bit of warmth, detail, bass, mids and high end. Of all the tubes rolled, only with the preamp tubes did I get any difference at all, and even that was minimal.

For reference purposes, my sources were: Music Sever > V-DAC; Rega Planar 3 w/Super Elys 2 > Bellari Rolls VP29. My speakers are Klipsch KG2 (91db horn-loaded and passive radiator, 4ohm taps on amp used).

Dan

What a good news !!!!!!! Many thanks for the info. The tubes I will received are Russian NOS 6P14P. I will try Mullard later when i get money Thanks again. Regards. Chris.

Using el84 unmatched tubes will be ok because the yaqin amplifier, has auto bias for the el84 tubes, so it will automatically match the tubes bias and match them. Just be careful with chinese tubes, they are not very good quality. Try these following tubes MULLARD EL84,JJ ELECTRONICS, TELEFUNKEN. ALSO OTHER TUBES WHICH I FIND VERY GOOD AND CHEAP RUSSIAN 6P14P WORK GREAT IN THE YAQIN AMPLIFIER. sorry the tubes are 6P14P not 6n14p

Using el84 unmatched tubes will be ok because the yaqin amplifier, has auto bias for the el84 tubes, so it will automatically match the tubes bias and match them. Just be careful with chinese tubes, they are not very good quality. Try these following tubes MULLARD EL84,JJ ELECTRONICS, TELEFUNKEN. ALSO OTHER TUBES WHICH I FIND VERY GOOD AND CHEAP RUSSIAN 6N14P WORK GREAT IN THE YQIN AMPLIFIER.

Does anybody knows if i can use 4 El84 if not matched what will happen ???
What about the bias for thos amp?
Many thanks….

He is located in belmore here is info below

KIMIL ELECTRONICS
ELCTRONICS REPAIR AND SERVICES
220 GEORGES RIVER ROAD
CROYDON PARK NSW 2133
PH:9799 3019 FAX:9799 3688

HIS NAME IS Kimil HE IS THE MOST HONEST AND KINDEST PERSON.

Thank you Corrado