Handmade in Japan LCR RIAA Phono Tube Pre Amplifier & 12AT7 Kind of Valves

[kurorin]

 

[kurorin]

Another high-mu tube similar to the 6SQ7 is the single-triode 6SF5. I have quite a few NOS of the 12V glass version. Thomas Mayer has the curves for the 12SF5GT displayed on his VinylSavor site. If you can use mu=100, it doesn't get much better than this!

Jack

Thank you Jack.
I already received the new valves 6SF5 (together with 6SQ7, so two new options).
Now I´m waiting for the adapters.

 

[kurorin]

Talking about Thomas Mayer from Germany (he recommend very well the 6SF5 valve for Phono Stage), I left a video with the sound of one of his SET amplifiers (801A), 3.5 watts, in this Thread: audiokarma.org/forums/index.php?threads/visit-to-valves-fever-diy-hifi-meeting-at-schlierbach-austria-july-2022

 

[kurorin]

When I was breadboarding my most recent build here . . .

https://www.audiokarma.org/forums/index.php?threads/the-nuance-my-inverted-set-diy-project.990205/

. . . I tried numerous DHT input tubes including the 12A but I've never seen anyone use it as an output tube. It sounded OK in my circuit but there were others I preferred. Different circuit / different use, though. I have no experience with the 71A.

I ended up using the 26 but I suppose any similar DHT could be used as an output. I imagine that most people would find such low power to be of limited use unless they listen at low volume. Maybe with very efficient speakers in a small room, perhaps even a near field setup, but even then.

What speakers do you use and how efficient are they? How far do you sit from them?

Your video sounds nice but, as with all such YouTube videos, the viewer can never really experience the same sound quality as they would if they were in the room. I know it is meant to feature the preamp but it would have been nice to also see the amp and speakers that you're using instead of static shots of album covers.

Please do take some pics of your amps and post them in the Flea Power thread here:

https://www.audiokarma.org/forums/index.php?threads/show-us-your-flea-watts-amps.545147/

The rule is 10w or less, so I think your's qualify. They may actually set the record for the lowest powered amps on there!

I've seen, but not heard, a couple of under 1w amps, including the well known Darling, which uses the 1626 and puts out .75w. I used the 1626 in my Boogie Factor preamp. I saw another amp that puts out .5w a while back but I don't recall what tube it used. I'll update this post if I find it.

For anyone who's interested in Japanese amps, there's a long running thread on DIY Audio which contains numerous designs. It gets updated with new designs sporadically.
https://www.diyaudio.com/community/threads/gold-mine-of-di-audio-tubes-schematics-from-japan.311212/

I´m presenting my flea watts amplifiers there with the tubes: 45, 46, 71A and 12A. From 1.6 watts until 0.2 watts power.
I never talk about them like "flea watts". For me they are just my amplifiers.

 

[kurorin]

I left the video to 12A (0.2 watts) amplifier in that Thread.

 

[kurorin]

Now I´m adding the valve 47 to the power amplifier, instead of 46 or 45 tubes. And I´m still waiting for the adapters for the 6FS5 tube.