What would be a good sounding low Rp triode for a line stage? Requirements - Rp under 2K and low gain, like under mu=10.
Possibilities include:
7233 - 230 ohms
A2293 - 380 ohms
6S19 - 420 ohms
12B4 - 1K
6CK4 - 1.2K
6AH4 - 1.8K
6BX7 - 1.3K (double triode)
4P1L - 1.5K (in triode) DHT (needs 25mA or more)
71A - 1.7K DHT (getting rarer and more expensive)
There are also all the 6AS7/6080 type tubes and bigger DHTs like 2a3/6B4G/6C4C but that would be overkill.
Possibilities include:
7233 - 230 ohms
A2293 - 380 ohms
6S19 - 420 ohms
12B4 - 1K
6CK4 - 1.2K
6AH4 - 1.8K
6BX7 - 1.3K (double triode)
4P1L - 1.5K (in triode) DHT (needs 25mA or more)
71A - 1.7K DHT (getting rarer and more expensive)
There are also all the 6AS7/6080 type tubes and bigger DHTs like 2a3/6B4G/6C4C but that would be overkill.
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Good call - all the dissimilar triodes...
6EM7 double triode. Section 2 = 750 ohms. Mu=5
6EA7 double triode. Section 2 = 750 ohms. Mu=5
6EG7 double triode. Section 2 = 800 ohms. Mu=6
6EW7 double triode. Section 2 = 800 ohms. Mu=6
6DR7 double triode. Section 2 = 930 ohms. Mu=6
6DE7 double triode. Section 2 = 930 ohms. Mu=6
6EM7 double triode. Section 2 = 750 ohms. Mu=5
6EA7 double triode. Section 2 = 750 ohms. Mu=5
6EG7 double triode. Section 2 = 800 ohms. Mu=6
6EW7 double triode. Section 2 = 800 ohms. Mu=6
6DR7 double triode. Section 2 = 930 ohms. Mu=6
6DE7 double triode. Section 2 = 930 ohms. Mu=6
<< This is probably not news but ime a dht+mosfet follower kills both objectively and subjectively any of the low Rp triodes.
Good call! I've only really used DHT line stage tubes myself for the last 20 years or so, though I've never used a mosfet follower. I really should try that. I don't need a low Rp myself since my DHT stage drives the output stage directly. I just need low Rp for any builds I do for other people who may be using solid state amps. Hence the thread.
Good call! I've only really used DHT line stage tubes myself for the last 20 years or so, though I've never used a mosfet follower. I really should try that. I don't need a low Rp myself since my DHT stage drives the output stage directly. I just need low Rp for any builds I do for other people who may be using solid state amps. Hence the thread.
I've used the 6AH4 which I like a lot for an indirectly heated tube. Similar to a 6V6 in triode, but I suspect a little better. Both work.
The 12B4 is liked by some but I prefer the 6AH4. 12B4s test all over the place and used ones might have come out of computers.
The tube I'm curious about is the A2293 because there's a decent used selection in the UK.
There isn’t a lot of difference between a 6Y6 and a 6W6.
And the reason you can push a lot of current through it is the hungry heater. It’s just a nice tube to experiment around with in the 3 watt range, 10 ish push pull. And push to 20 (out of a pair) when you’re channeling your inner Tubelab.
And the reason you can push a lot of current through it is the hungry heater. It’s just a nice tube to experiment around with in the 3 watt range, 10 ish push pull. And push to 20 (out of a pair) when you’re channeling your inner Tubelab.
I suspected. Ran into a brick wall using a mu follower in standard config to drive a UL 828. Slewed at high levels and frequencies like crazy but simple remedies appear achievable. Still tuning a pentode mode 12gn7 biased under 4 ma currently swinging 150 Vp-p into 47k+1nF at ~ 0.6% thd predominantly 2nd.
