Excellent.
The DR version has become quite expensive though but as a driver, run not too hot, the "e" version is just as good.
Read here www.bartola.co.uk/valves/2012/06/17/thd-benchmark/
And here www.bartola.co.uk/valves/tag/6e5p/
Oh dear I see 45's done so already......my apologies
And here www.bartola.co.uk/valves/tag/6e5p/
Oh dear I see 45's done so already......my apologies
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That is service life guarantee by the manufacturer.
The best linearity on benchmark for the driver does not guarantee the best linearity on the output, especially with the 300B, sometimes you must consider distortion cancellation, mostly for the third harmonic.
I am obtaining good results in simulations with more pedestrian valves like the ECC81/12AT7, belly curves seems to help more than exotic valves.
The best linearity on benchmark for the driver does not guarantee the best linearity on the output, especially with the 300B, sometimes you must consider distortion cancellation, mostly for the third harmonic.
I am obtaining good results in simulations with more pedestrian valves like the ECC81/12AT7, belly curves seems to help more than exotic valves.
It would be nice to be able to use a plate (anode) choke on your driver triode, to make use of the choke's energy storage for brief bursts of voltage peaks. However that would mean the driver triode should have low rp (ra), so that the driver stage will have good low frequency response using a plate choke capable of >20mA standing current and with achievable inductance (50 to 60 H). That disqualifies ECC81/12AT7, even with two triodes paralleled (rp = >8k under real-world conditions).
That's where something like a triode-strapped small power pentode might be good. Perhaps a triode-wired 6P14P or 6P15P with a plate choke?
But will that yield enough input sensitivity for a 2-stage power amp? I don't think so.
That's when we get to Wavebourn's suggested 6J52P. Or 6S45P? (Both tend to be really microphonic, but maybe okay for a driver stage.)
If trying to fulfill popilin's suggestion, you'd need to find a triode with so-so linearity, high mu, and high gm. Hmmm... triode-wired 6JD6A? (Semi-remote-cutoff RF frame grid triode with 14mA/V gm -- https://frank.pocnet.net/sheets/127/6/6JD6.pdf)
Oh well. I guess that's why there are so many 3-stage SE 300B amps, and why WE designed the original 300B amps with a pentode driver.
That's where something like a triode-strapped small power pentode might be good. Perhaps a triode-wired 6P14P or 6P15P with a plate choke?
But will that yield enough input sensitivity for a 2-stage power amp? I don't think so.
That's when we get to Wavebourn's suggested 6J52P. Or 6S45P? (Both tend to be really microphonic, but maybe okay for a driver stage.)
If trying to fulfill popilin's suggestion, you'd need to find a triode with so-so linearity, high mu, and high gm. Hmmm... triode-wired 6JD6A? (Semi-remote-cutoff RF frame grid triode with 14mA/V gm -- https://frank.pocnet.net/sheets/127/6/6JD6.pdf)
Oh well. I guess that's why there are so many 3-stage SE 300B amps, and why WE designed the original 300B amps with a pentode driver.
That's the idea, a mu follower and a source follower DC coupled to 300B.
6GK5 also works very well in simulations, but was discarded for aesthetic reasons and the difficulties to obtain 7 pin sockets here in my country.
Yes, they can work well.. I like ASC motor runs. In addition to the 100uF cathode bypass motor run you can add a 20uF film cap from the cathode cap (filament end) to the B+, this will provide some canceling of ripple on the power supply.
Don't confuse motor run and motor start caps, you want run caps.. The start caps are usually short lived electrolytics.
Don't confuse motor run and motor start caps, you want run caps.. The start caps are usually short lived electrolytics.
Cap for cathode 300B must be best quality /it define quality of sound/ like Black Gate, Rubycon, Elna, Nichikon. Every regular cap is not suitable....but You can try...
I am doing ultrapath with DC Link film capacitors. Not so expensive, and better IMHO than electrolytics such as Elna cerafine or Nichicon muse. I prefer them to the crazy expensive black gates too... 
To cancel any residual PSU ripple, CR couple power cathode to input/driver cathode (like original loftin-white circuit).
Ian
To cancel any residual PSU ripple, CR couple power cathode to input/driver cathode (like original loftin-white circuit).
Ian
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