ECC85 have a nasty reputation for not lasting long and their gain falling. Usually the first thing to go is the ability of oscillators to start.
On the other hand, the number of double triodes suited for cascode use because of heater-cathode insulation for the running voltages of the upper triode, and also the need to keep cathode-heater capacitance down to prevent horrible coupling problems, is rather limited.
I stopped using valves for any new work a long time ago. The only valves being made revolve around hifi people and guitarists with fat wallets. Radio-type valves aren't being made and I see them as a dwindling resource, so I choose not to use any of them up and leave the remaining ones for servicing period equipment.
Sometimes transistors
are the right answer.
They aren't products of the devil, they aren't harder to use. They're just different. You need more of them than you'd need valves to do the same job, but they're small, cheap and light on power so you can use as many as it takes. Like valves, they have limitations, so you have to design ways of evading them. The limitations are different to the limitations of valves, so there is culture-shock involved, but once you see the patterns in the different limitations of different devices it all suddenly becomes easier to undertand and easier to handle. It's all a lot simpler than it looks, once you get up the learning curve.y
As a piece of, um, shall we say micturition-artistry, I designed an audio power amplifier
using as many transistors as possible but subject to the requirement that I could show that each and every one of them was doing something useful. It worked rather well and was a good joke with a friend who was designing a minimalist one. Bill's amp turned into a product at Linn (of Sondek fame) after he moved there. A small run of mine were built at HP. My prototype has been sitting in the corner of my lounge for 40 years. It's the size of a good picnic hamper.
David
Oh, should have said, I have two FM tuners I'm playing with, one is one of the last Sony 'ES' series, the other is more interesting, a Revox B261, the manual is available on-line. This takes very different approaches. LC filtering and no ceramic filters. separate stages of limiting in the IF. An analogue pulse-count discriminator, and stereo decoding using several general-purpose ICs, not the usual one-chip wonders.