Included is also Power Supply schematic, with many details. In schematic one 100 kohm potentiometer used for output. Is a clever idea and should be able to drive normal loads. Recomended cathode follower circuit - audio-talk. The output stage, using cathode follower into a constant current source, He uses 3 stages and Two ECC83/12AX7 Tubes per channel! Yet, they can be regarded very high quality. His published amplifiers are still built by many, and after many years, Hiraga died not long ago and is one of the Great Legends of early audio amplifier designs. I judge this one as the most serious and possible best performer: There are many interesting and old tubes amplifiers of all sorts. I went to have a look at website in your link. This is why we need at least 2-3 triode stages per channel. RIAA, even Moving Magnet pickups, needs plenty of voltage gain. You should be able to find quite simple RIAA, using 2 Triode Halves per channel (=1 tube/ch).ĭo not expect to find a really good RIAA using only 1 triode.īecause if they do, you most surely will have some else preamplifier to feed your power amp input. cathodyne) phase inverter and a fixed-bias output stage with a negative feedback loop to tighten up the response. You have MM cartridge or you have MC, which requires a level more of gain? Central elements of the design included a cathode-follower tone stack with independent bass and treble controls that were effectively driven by a 12AY7 preamp tube (a lower-gain relative of the 12AX7), a split-load (a.k.a. Note that the single tube version has an output impedance around 60K and the two tube version around 10K. (A single 7812 regulator with a diode in series with the ground lead, and properly heat sunk is all that is required to get the 12.6V 600mA this design requires.) Filaments should be well regulated 12.6Vdc particularly as the cathodes are unbypassed. Power supply could be a well filtered unregulated 300V. I recommend the 5751 as being somewhat quieter than the typical 12AX7. It'll drive lower impedance loads better as well. I'd recommend the two tube per channel version, it's much quieter than the single tube implementation, more transparent and a lot more dynamic. There are several circuits shown, one should suit your needs quite well. It was originally published in Positive Feedback longer ago than I would like to admit. The simplest requires a single 12AX7 per channel, but does have pretty high output impedance. IF you check out my site you will find some very simple phono stages that work well and have been built by lots of people over the years.
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