Here is a quick test I did today that the 6e6p-dr is a promising valve as a driver. I’ve used 6e5p and made several tests with these fantastic valves. Anyway, looking at a single sample from my stock:
The 6e6p-dr can do well and provide a nice 0.17% @ 200Vpp. Not many valves can do this in triode-mode.
Now, let’s look at the harmonic composition:
Edit (28th July 2014): The harmonics should be read: K1=H2, K2=H3, K3=H4 and so on.
Harmonic level is very low and dominated by H2 with raising H4 above 120-130Vpp. An interesting dip takes place in H3 closer to maximum swing level. This may be due to CCS FET load interaction and harmonic cancellation I guess. Beyond 205Vpp my CCS is limited by its HT supply. It can be boosted, but for a quick test, here is were it ends 🙂
This will be another valve to try as a driver in my next 300B project.
Hi Ale,
Interesting results.
I used this tube as driver for a quad 4p1l in class A2 and I was pleased with the sound. I am using an interstage LL1671 in 4:1 config at 30mA. I was actually impressed by the driving capability in this configuration. The amp got to 10W in A2 without problems( higher order harmonics are starting to show on the FFT beginning at 7W, but clipping beyond 11 W is not harsh and can get about 12.5W before hard clipping… Didn’t expect that )
I think this tube could be sleeper…
Radu
Hi Radu,
More interesting is to read that you have tried it and liked the sound of it. It’s definitely not a sleeper. I have some 6e6p, 6e6p-i and now these 6e6p-dr. The latter are not cheap though as it has a gold grid. There are some many comments out there about the sound of these valves. They all have superbly high linearity in triode-mode and will work perfectly fine as drivers. Even a pair of them in PP would be quite interesting to try.
Ale
Wit this gain, what is the expected input voltage for it to be able to drive a 300B to clipping? I suspect you need one more stage in front of it.