I’ve been listening for over a week the Elrog ER801a prototypes. I can say that I’m very please with them. Before I make any further impressions about their sound, let me start from the beginning.
I purchased last year from ELROG (now Deutsche Elektronenröhren Manufaktur GmbH.) a pair of these valves to be used on my VT25/10Y preamp. I do not own any 801a, but have a good stash of NOS VT25 and 10Y valves. I love this preamp, probably my favourite with the 01a.
Thomas Mayer offered me to send me a preliminary set of prototype valves in advance so I can submit them to the mercy of my tests. That sounded like really good fun and also I thought that the folks out there would be very keen to see the results.
When I received the valves, I was impressed with the quality of the manufacturing as well as the size of these valves. What a piece of german engineering precision!
My first test was to trace the curves and see how linear these prototypes are.
Thomas advised me that the prototypes had a lower mu. I confirmed their 7.5 mu, instead of the 8 expected. Either way, the curves show how linear this valve is. Elrog made a great work in replicating the 801a and delivering a really linear valve.
My next step was to test the distortion and harmonic profile. I replicated on the bench my preamp operating point with the exception that I did fixed bias instead of filament bias:
As you can see, I’m running the 801a rather cool due to the HT power supply limitation on 230V. I biased the valve on 200V and 14mA. The output distortion of the stage is really low at 0.02% for 10Vrms output. The harmonic profile is dominated by H2 and also a nice decay of H3 and H4.
The valve performs consistently across the entire band:
Solid response as expected.
Listening impressions
This is a very subjective point, but I’d try to share some impressions regardless.
So far, this valve is outstanding. I love the sound of it. Very detailed and with a strong bass. No microphonic noise and dead quiet. Congratulations for the device ELROG!
i am afraid to say that i not interested in any of those new old replica tubes. Although the nice measurements you did i don’t see any benefit for the e55l, ec8010 or the many russian triode mode tubes you mentioned on your side. For the power tubes there are lovely tubes as gm70m or even better the sv811 or sv572 tubes available “everywhere”.
What i would like to see is a new tube, not old replica’s which are almost
extremely expensive.
Martin
I tried 10Y, VT-25 and 801A tubes in a line preamp with autoformer volume at output (based on Thomas Mayer design found in Audio Asylum). Original 10Y and 801A are in the same “sonic league” in that case.
Hi Ale,
thanks for testing these prototypes and I am glad you like them.
There is another tube in development which never existed before, so a real new development and I hope to have it ready for the Munich High End show in May. You can also have those for some initial tests when first prototypes are ready.
Thomas
Thanks Thomas! I’d be very interested in testing new prototypes!
I hope for new tube: a indirectly heated tube, super lineair (triode or triodemode) high S and low Rp
I believe these tubes look astomishing high quality, I really like their look…but I believe for 1000Euro/pair they must do stuff at least significantly better than the Hytron 801A, otherwise the business case is really difficult. Just as good would not be good enough as the 801A is still very well available.
Hi, After many years watching, I just completed a pair of RCA Radiotron 801s with ceramic bases and graphite plates for under US$200. Inspires me to build a preamp! Much as I admire Thomas Mayer’s efforts in so many directions, it won’t be with ELROGs.
Best, Happy New Year! RC
Hi Robert
Happy New Year! I’m pleased to hear you secured a pair of nice 801a valves. You won’t be disappointed with them at all and I’d suggest you build the preamp I made with them.
Good luck
Ale