A new amplifier build has begun. The 4P1L PSE is coming to life. First top plate developed and arrived this morning. A succesful layout for being the first one. Need to submit for machining the other 2 panels. It will be modular so I can make changes and experiment with different output transformers I have at hand (Monolith Magnetics, Lundahls, etc.). The HT power supply is ready and I’ve been fitting the filament supplies in child-proof boxes over the Christmas holidays. It will take me some time though to get this one up and running. Not much time to work on it am afraid.
Tag: PSE
Russian PSE in steroids (4P1L into 4P1L)
Introduction: DHT madness
I’m not going to dwell on DHT sound. I’d rather say that if you’re looking for a stellar DHT candidate, the 4P1L beats them all. It’s dirty cheap, reliable and sounds amazing. You can go any route you like, it’s your own decision of course. However if you’re looking for a 100% DHT amp to build, here is an interesting example for your consideration.
I’ve tried 4P1L in many topologies. The advantage of its low filament requirements is that you can implement it in filament bias and simplify the circuit significantly.
The gyrator driver using the PCB I designed recently, can be used to avoid iron and have an excellent first stage and make this Russian Amp in steroids: 4P1L driving 4P1L.
One minor caveat around 4P1L in excess. I have found (as well as many others) that if you use too many 4P1L stages (e.g. 4P1L line stage driving a 4P1L-4P1L amp) then it will sound a bit harsh in the treble. i suspect this may be explained due to the H3 component level when triode-strapped. I’d rather limit the number of 4P1L stages to two. You’ve been warned.
The other great thing about the 4P1L is that is quite consistent between samples and easy to match pairs. Also in PSE mode you can drive it to full tilt with only 20Vrms and achieve up to 5W in class A1 with a pair of valves.