I was writing as of few ago there was a new tube type on horizon to be evaluated for the TRP owners. Quest for new options never cease so this was a legit attempt to de-throne el51. What I found on the web for el156 was quite impressive in terms of tube and specifically what I liked is that it was developed for audio usage which set the hopes quite high. Hence I asked Yoda to approve it for TRP and with his blessing we come to two reports from Urs and Fabio who are always, but always willing to engage in this type of "experiments". I can't recall if I mentioned but they are great buddies living across each other with cumulatively maybe one of the biggest stashes of different tubes for TRP so their experience and possibilities to swap and compare is just enormous. With this small intro here is Fabios report on this particular tube:
"Telefunken EL156
I bought these Telefunken 156 NOS/NIB here in Switzerland for around 240 bucks a pair. This tube delivers an impressive 50 Watt. Yoda confirmed that they are save to be used in the TRP.
Once the tubes arrived a few weeks ago I had to be patient and wait another week or two for the adapters to arrive. Once they, did I initially struggled to insert the tube into the adapter. So I pushed down the metal connectors on the adapter to make more room for the pins to enter. Finally, still applying a lot of force, I managed to insert the tube into the adapter and I was ready to burn them in.
They have been in use now for 50-70 hours and haven’t changed much the last 20 hours or so. During the burn-in phase these were volatile: treble was glassy and bass was instable. In the meantime, I have used them with a variety of rectifiers (gz480, taka, acme, Usaf 596, rk 5u4g, Marconi 5u4g, Fivre 5u4g and a few more) and their distinctive character comes through with all of them.
In terms of output tubes I have directly compared them against the PSVanes 6Ca7 and mostly against the Teslas EL51 as these are probably the two tubes which perform best in most systems including mine: the Teslas by the way much more so than the PSVanes. There‘s not even a comparison which I realized again during this test.
So how about the Telefunkens? First thing that you‘ll notice is the extreme power. These tubes are full throttle and produce the most muscular sound I have heard to date from any tube in the TRP by quite a margin. The bass reaches a felt octave lower and punches so hard that you sometimes get a clubbing- or amplified live concert impression.
Second thing that pops to mind is the extreme presence and focus of how instruments and sounds are portrayed in the room. Imaging and separation are excellent. This is on the level of the Teslas although the stage is further back in the room. Also, images don‘t have the same 3D body as with the Teslas but they equally grab your attention by their strong attack and presence. The PSVanes in comparison are rather sleepy.
Marco dynamics are phenomenal and the stage is impressive. Especially width. Stage height and depth are less compared to EL51.
Treble is extended and clear. Despite the massive bass these tubes feel fairly neutral as they are very extended on the top end too without any midrange bloom. Negatively spoken this neutrality somewhat reminds me of a KT88 (but with way more tension and elements that keep it interesting). If this was a rectifier then it’s closest sibling would probably be the RK 5U4G.
Considering the neutrality, voices are not rendered with this intimacy as the Teslas would do. Also voices are not as holographic. The soundstage is more 2D and mostly behind the speakers. There’s not the same depth and layering as with the Teslas.
Details are excellent. Especially in the bass department plenty of nuances can be picked up. Despite this massive bass, the tube is clean and bass is well separated from mids. Thus plenty of details can be retrieved with this tube.
The biggest problem I had with it is timbre. I don‘t know whether it has to do with the massive weight and muscle that overshadows things and causes a slightly veiled sound. In my setup it somehow sounded rounded-off in the midrange. Initially, I did not mind but the longer I listened the more I was missing this organic, direct, open and intimate sound that the Teslas would produce. Switching back to the EL51s confirmed this impression. Timbre is on a different level in my setup.
So where does it leave this tube? Well - unlike many other output tubes I tried - this one is worth writing about. The attack, presence, focus, imaging and macrodynamic are as good as it gets. The sound is alive and grabs your intention: only the Tesla can do that to the same degree. The bass is impressive, reaches deeper than with all other output tubes I tried and has massive impact. If a system lacks muscle/weight, this is definitely the tube to go for. In my system and to my liking it produces slightly too much low end power. I would use this tube for rock and electronic music, playing loud and bringing the live-concert or techno club home.
Concluding it can be said that el156 is a really good tube and worth having it in the collection because in certain disciplines it plays champions league. Due to the slightly coated timbre (in my system), the lack of depth and 3D as well as the massive bass (not for me in the long run) it will not displace the EL51."
With this written/said - quest to de-throne el51 is still ON.
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