Thank you Mr. Pass for the schematic. Both F6 [B; transient name if I may], and notably F6 [UB; transient name; you buffer it from our {we} perspective] are continuing examples of the Pass Discipline for creating the simplest, most effective, and most elegant designs.
F6UB [if I may give it this transient nomenclature] appears to have a gain of 15 dB and the performance attributes of F6B. Most interesting is that error correction happens in the primary winding of its transformer. We now have a universal, new and improved Classic.
F6UB [if I may give it this transient nomenclature] appears to have a gain of 15 dB and the performance attributes of F6B. Most interesting is that error correction happens in the primary winding of its transformer. We now have a universal, new and improved Classic.
baaad Pa .......
? ?
Would you rather prefer him to build 10 for the out-house ?
(for some reason, I almost feel proud for still having experienced those in my early years)
Now that the cat's out of the bag via BAF, here is the official F6 schematic.
Thanks !
However, I know from DIY attempts of cloning J2 (I have the original here), that schematics and same parts isn't enough to reproduce the sound of the original. My J2-clone with same schematics and same parts sounded very noticeably different from the original.
I learned from that, that it's very important to select transistor values and/or adjust resistors to get into the sweet spot. It is also important to have possibility to measure THD and 2nd/3rd harmonic - to see where one is going when modifying values.
As a consequence, any F6 clone build only according to schematics can sound different from another F6 attempt, unless Nelson gives us advice on how to fine-tune it. Or you fine-tune it to your personal liking....
I hope and wish that Nelson will give us some advice on how to get at least a bit close, on how to select transistors and what THD%-value and 2nd/3rd harmonic-% we should be designing and building for ?
Last edited:
Hopefully I understand the F6 schematic ( thanks Nelson ) well enough to ask the following question but there are no guarantees. When P2 is adjusted to give the 1.2V bias what is the corresponding current draw?
I am asking because I have transformers that are just asking for a choke filter. To get the minimum inductor size for the power supply I need the expected current and voltage. Minimum inductance = .9 x (Voltage/ current)
Thanks
Bob
I am asking because I have transformers that are just asking for a choke filter. To get the minimum inductor size for the power supply I need the expected current and voltage. Minimum inductance = .9 x (Voltage/ current)
Thanks
Bob
let's just say that Iq was in 1A55 ballpark
somewhere earlier I gave little table of SJEP tempco at 2A (or something like that ) , so I'm expecting that , on value what I think I heard in Pa's Lecture , it's spot on dead ..... or dead spot on
so , let's Iq be a pulsar , not ookin' Ugs
btw. guys - flocchini didn't asked for Iq measuring procedure , but for expected Iq , for PSU calculus purposes
somewhere earlier I gave little table of SJEP tempco at 2A (or something like that ) , so I'm expecting that , on value what I think I heard in Pa's Lecture , it's spot on dead ..... or dead spot on
so , let's Iq be a pulsar , not ookin' Ugs
btw. guys - flocchini didn't asked for Iq measuring procedure , but for expected Iq , for PSU calculus purposes
Last edited:
And you could put it series with either source pin with the capacitor connected to the source pin. That way the resistor is NOT performing degeneration. I suspect that Nelson will eventually show a schematic with source resistors of around 0R1 and one or more pots to adjust the 2nd harmonic similar to what I show in post http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-222.html#post3188855.
You could put it in the drain of the top xister with probably no effect at all
I am considering a new stock market strategy based on what components Papa uses in his amplifiers.
Do it, it is one of the easiest PTP I made, only thing is to check twice the polarity of the windings to be correct.
@ ZM ISKRA adventure continues tomorrow, my wife has a cold and I have to do the household and some more....
Yes i did so, even with the smaller Jensens....
As to the sonics I am still divided some things are perfect others I miss.
Of course I am positively impressed that Nelson installed ten in his house, he would not do this if he wasn't enchanted.
Or is it the way he is always checking his First Watt Amps?
Putting a 1k pot over the upper secondary winding changed in my circuit only the k2! it got bigger and bigger, but not smaller.
As to the sonics I am still divided some things are perfect others I miss.
Of course I am positively impressed that Nelson installed ten in his house, he would not do this if he wasn't enchanted.
Or is it the way he is always checking his First Watt Amps?
Putting a 1k pot over the upper secondary winding changed in my circuit only the k2! it got bigger and bigger, but not smaller.