All about electronic valves and hi-fi
A very interesting Russian directly-heated pentode related to 4P1L is the 2P29L. It has a similar mu (μ=9), much higher anode resistance 2.8-3KΩ and transconductance of 3mA/V when triode-strapped. The filament requirements are much lower at 120mA. I picked one valve from my collection to submit it to the mercy of the curve tracer: The … Continue reading “2P29L – Preamp and driver for 4P1L PSE Amp”
It’s always great to come back and revisit a great design. The 4P1L preamp performs flawlessly so I tweaked the gyrator board to see how it worked with the BF862 FET. The result is great, it sounds as good as it measures: The 4P1L is biased to 150V/25mA which is the maximum current that the … Continue reading “Gyrator Test Mule: 4P1L Preamp”
More power Our previous west meets east circuit can be improve further. In fact, a compromise made with the filament bias design is that coupling between driver (FET follower) and the output stage wasn’t DC. We want DC coupling to get best performance, to ensure we can drive well the output stage and provide sufficient … Continue reading “Russian PSE in Steroids (01a into 4P1L) – Part IV”
From Russia with Love The interesting combination to explore from our previous designs is to mix some western valves like 01a into the Russian parade. The result would be quite interesting, as the sound of the 01a has proven to be amazing. Therefore 01a driving 4P1L is possible as the 4P1L doesn’t need a lot … Continue reading “Russian PSE in Steroids (01a into 4P1L) – Part III”
Well, it was obvious I couldn’t leave last post as it was. There is an option to change the driver for a different valve. You can use a C3m (low gain in triode mode which is ideal here), a C3g, E180F/E280F. 6S45P or my loved 6E5P (or 6E6P) as the driver. Not longer a 100% … Continue reading “Russian PSE in Steroids (6E5P into 4P1L) – Part II”
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% … Continue reading “Russian PSE in steroids (4P1L into 4P1L)”
A monster DHT amp Lately I haven’t had any time for audio work unfortunately. Changing nappies to a 4 week old baby whilst working long hours is tough. I can get the odd 30 minute here and there and every time I try to get upstairs to the workshop something pops up. Never mind, hopefully … Continue reading “813 triode SE with 4P1L Pentode”
Some of the DIYAudio fans have built this version of the 4P1L with great success. There are several upgrades that can be easily implemented to improve this. I haven’t tried this myself, but my recent experience with the Gen3 and the 01 preamp gen2, I think are worth trying: Replace the gyrator FET for a … Continue reading “4P1L Siberian Gen1 upgrade”
Introduction Building a new version of the venerable 4P1L “Siberian” was very encouraging. This belated project finally came to life after some recent work on a new set of power supplies. So why 4P1L again? I always found the 4P1L sound to be unique. Great detail, overall tone and fantastic treble. What it makes it well suited … Continue reading “Siberian Gen 3 (4P1L pre-amplifier)”
A friend in DIYAudio came up with a great idea of using the 4P1L in a different way for a pre-amp/line stage. Given availability of IT and its gapped current, he suggested connecting the 4P1L differently. Instead of using the anode as the anode element, the screen is used as anode. The 4P1L screen has … Continue reading “4P1L with screen as anode”