Andrew knows more about where we are with the higher-current (3A?) ones, but I've used one for a decent period to test GK-71 ( ie. same as GM70 ) so 3A and 20V - sounded really good ( better than KR300B with Guido's ) . Now, this was fed from a 24V 5A Sony laptop SMPS - just didn't fit the rectifiers or smoothing caps to the board & patched in the 23.8V to feed the voltage reg & current-reg. I think however Nick and Andrew had more developments in the pipeline for higher current. Maybe other Nick can comment too and my apologies for using his thread to continue a bit off-topic.ed wrote: ↑Tue Apr 18, 2017 2:59 pm
I must have been away when all this occurred but I would ask the same question as Simon at first. I too had no visibility of the top octave not working......so, two questions
1. are the Mark/Andrew solutions readily available and can they cope with high currents, and
2. How does this all compare with Guido's solution?
yes, I know, that makes three questions really
I did most of my testing with a 4P1L driver valve for 300B, and the Guido ones were on the output stage 300B. So.... I think Andrew's ones are better than Guidos ( but bear in mind these are the original Guido type so about 13 or more years old ) but this is based on KR300B+Guido vs. GK71 triode+Lehane ; both with Bud Purvine output trannies.
We know the Lehane ones match Rod Colemans in the bass and mids, and improve on them in the treble. Also they beat Thorsten's DIY ones with coils, caps and CMC, that he used on the 'Ladyday' mods - had those to hand during testing.
It's worth saying that AC heating and the Thorsten ones ( passive, low output impedance ) both beat the Coleman ones in treble, so you can understand why there are lengthy debates on DHT threads about DC vs. AC. It's all about implementation with DC DHT heating.
( also worth mentioning Rod's ones have gone up one more version now - v5? - but I don't know what the changes are )