I will do if you agree or not....my next punch with F6 .. Poor bulls eye!
On Monday I will fetch four Edcor 600:600 from the German customs and implement them on a perfboard in the wonderful flexible F6 pcb from Tea-bag. Yes two separated 600:600 transformers for one channel.
Any advices, opinions.....what could happen, will the bull die.....?
On Monday I will fetch four Edcor 600:600 from the German customs and implement them on a perfboard in the wonderful flexible F6 pcb from Tea-bag. Yes two separated 600:600 transformers for one channel.
Any advices, opinions.....what could happen, will the bull die.....?
Is Mr. Ebaen a diyaudio member? Maybe mutually benefical if he eavesdrops on the chatter and participates; e.g. like semisouthfan. Are there female "critics" of audio gear like him?Srajan Ebaen Really knows how to write again and again in a very clever way about the everlasting problem "how sounds the amp".
It was a pleasure to read his F6 article.
Would be niece when Papa Nelson would explain a bit how he trimmed this "final" F6.
I can't follow Srajan in one point. For my ears the M2 does a kind of detail and presence and directness, despite his warm characte that is unique. And I do not find the sound "retro" oriented.
With the M2, I had always the feeling to sit in the first row, the sax blowing me away!
And indeed I find the sound of the F6 a bit damped.
So for me Nelson succeeded with the M2 also to hit the eye of the bull!
But maybe I did not yet find the right punch for the F6....
Thanks generg and Zen Mod. It may be possible to ask Mr. Ebaen to clarify generg's "issues" in the earlier post.
Yup. I have a similar cascoded version of the F5 undergoing bench testing which uses one or more 0.015F caps across the source resistors. Preliminary tests show similar results. It is not yet clear that the pot adjustments for nulling H2 are stable. Also, some the Spice waveforms (particularly Vds across the MOSFETs) look really ratty. I am trying to understand the implications of that on the sound quality.
Per Mr. Pass, harmonic distortion emanates from gain variations of transistors in action. These changes in their gain [HFE, Gm] are due to the variation in the current passing through the device [Idss], and the variation in the voltage across the device [Vds]. Lock Vds to a constant value [cascode], to cause a tight value of gain or its increased linearity in operation. Thus, THD decreases.
I agree with all of that. Also, by minimizing the AC degeneration of the output FETs, that also reduces H3.
A very good question. EUVL has in the past commented on issues regarding the cascoding of the output FETs. Until I actually finish the engineering and construction of this design I cannot evaluate its sonic characteristics.
I am doing simulations of the F6 using 2 x bifiler transformers. I think the P3 hack might be used to tune H2.
US 4,107,619 [inventor Pass] gave us STASIS [R] technology, and its THRESHOLD power amps. Gain devices are both cascoded and the fluctuation of current flowing through them is minimized. The gain of the [amplifying] device is now almost constant, and this transistor is highly linear in action. There is a schematic which will add more transistors to your application. Nothing is really free.
I find it interesting that your work is minimizing THD which has sonic benefits in Pass diy amps. The ultimate in THD reduction is/maybe SuSy. There is a patent and schematic for it too.