created a template. If there are enough interested, I can have a few circuit boards made.
This old thread seem to be report the latest version for both phono and power supply : https://www.diyaudio.com/community/threads/gb-merlin-riaa-pcb.338606/ , may be snapper have used as reference. I there anyone than can give transformer characteristics ( power and seconday voltage/current ) ?
It is a pity they do not have an equivalent of the Wiki functionality that the old site had. Very useful for parking the definitive picture.
Some very good projects get destroyed over time due to vary long discussions, with the odd revision and PCB update along the way. Ultimately it gets to the point where it is hard to get the proper overview of the project status without a lot of effort, so the interest in the project wanes, and it gets sidelined.
Maybe that is meant to be the way of the tube jungle?
Some very good projects get destroyed over time due to vary long discussions, with the odd revision and PCB update along the way. Ultimately it gets to the point where it is hard to get the proper overview of the project status without a lot of effort, so the interest in the project wanes, and it gets sidelined.
Maybe that is meant to be the way of the tube jungle?
yes, too bad, the wiki was probably shut down at the end of 2021 because there have only been 4 entries since 2016 !
https://www.diyaudio.com/community/threads/el34-baby-huey-amplifier.326920/post-6679194
https://www.diyaudio.com/community/threads/el34-baby-huey-amplifier.326920/post-6679194
From the original design in Merlin Blencowe's book (Designing High-Fidelity Valve Preamps) each channel has a PC97 and one 12AU7/ECC82.
The version being discussed here can use either a 6N1P or a 12AU7.
The current version specifies a 230Vac winding for the plate supply and a 9Vac winding for the heater supply.
PC97 plate current is about 3mA.
6N1P plate current is about 5mA per triode.
The MOSFET draws about 5mA, I believe.
That's 13mA plate current per channel, so 26mA plate current for the preamp. I'd choose a 230Vac winding rated for 40mA or 50mA, so about 10VA to 12VA.
PC97 heater is 4.5V 300mA. There are two per preamp, so 600mA heater current.
6N1P heater is 6.3V 600mA. There is one per preamp, so another 600mA heater current.
That equals 1.2A heater current for the preamp.
I'd choose a 9V winding rated for 2A, so about 20VA.
For Old World folks, a 230V:230V isolation transformer could be used for the plate supply. It doesn't need to be a big one. 230Vac 20VA would be plenty. A 230V:9V 25VA toroid will work for the heaters.
For those in the Americas, Antek sells a 9V 25VA toroid and a 240V 50VA toroid. Triad Magnetics makes a 230V:115V 50VA isolation transformer that can be turned around to step up from 115Vac to 230Vac.