Hi!
I know EL503 tubes are quite rare nowadays and maybe it is stupid to base a new project on them. But some years I got some old guitar amps for free, they were named Faylon P200 and they were not really good sounding amps.
But the amount of power (200watts on 4 tubes!) and pretty special specs in the 4 (!) EL503s in the power stage made me interested to test them out in a diy hifi amp.
They seem to be like one of the last new tube designs before solid state took over!
I got two guitar amps working well and sold those, sold another set of 4 EL503s (I got good money for the last 4...) and I’m now left with remnants from two amps, minus one set of tubes. So 4 EL503s, two PTs and two OPT (IIRC 1.7kohm push pull). Stock they were configured as parallel push pull.
I can’t restore another amp, enclosure and all is so rotten and I’ve already brought two back to life. So I would like to design a hifi stereo amp around these four tubes regardless, just for fun/for teaching myself.
I’m learning designing tube stages based on load lines etc, but I am a rookie right now. I have constructed one ef86+el34 se amp and one el84 push pull just from others schematic. This is my first own design. I’ve heard it described as the last evolution of the EL34, which sounds good if there is any truth to that...
I’d like to hear simple SE amp with these, just one per channel. Maybe hard to get suitable OPT for that? If I understand correctly they do seem to be pretty easy to drive. I have two e80cc that i could use as drivers, maybe need more gain?
I was thinking if anyone else have had this idea before and maybe have a schematic or an opinion on whether or not it could make a good amp or not?
All critisisms are welcome!
Best regards,
Lars
I know EL503 tubes are quite rare nowadays and maybe it is stupid to base a new project on them. But some years I got some old guitar amps for free, they were named Faylon P200 and they were not really good sounding amps.
But the amount of power (200watts on 4 tubes!) and pretty special specs in the 4 (!) EL503s in the power stage made me interested to test them out in a diy hifi amp.
They seem to be like one of the last new tube designs before solid state took over!
I got two guitar amps working well and sold those, sold another set of 4 EL503s (I got good money for the last 4...) and I’m now left with remnants from two amps, minus one set of tubes. So 4 EL503s, two PTs and two OPT (IIRC 1.7kohm push pull). Stock they were configured as parallel push pull.
I can’t restore another amp, enclosure and all is so rotten and I’ve already brought two back to life. So I would like to design a hifi stereo amp around these four tubes regardless, just for fun/for teaching myself.
I’m learning designing tube stages based on load lines etc, but I am a rookie right now. I have constructed one ef86+el34 se amp and one el84 push pull just from others schematic. This is my first own design. I’ve heard it described as the last evolution of the EL34, which sounds good if there is any truth to that...
I’d like to hear simple SE amp with these, just one per channel. Maybe hard to get suitable OPT for that? If I understand correctly they do seem to be pretty easy to drive. I have two e80cc that i could use as drivers, maybe need more gain?
I was thinking if anyone else have had this idea before and maybe have a schematic or an opinion on whether or not it could make a good amp or not?
All critisisms are welcome!
Best regards,
Lars
The P200 is a class B push pull amp by the looks of the schematic. You'd need both different power and output transformers to build a SE amp.
The datasheet of the EL503 doesn't even list SE operation, but for the EL520 SE is given as 250V HT into a 2k load.
The datasheet of the EL503 doesn't even list SE operation, but for the EL520 SE is given as 250V HT into a 2k load.