Nice work lhquam - my vote goes to typpe 2
My vote also goes to type 2.
But I have something interesting up my sleeves to reveal once I have a more thorough understanding of the circuit. Here is a teaser: Consider the feedback possibilities if you also have the negatives of the various signals.
I'm dumb ...... and I know I'm dumb ..... and that's certainly why there is a fact that I know exact schm of F7 ........ but am I wrong in thinking that exploring this circuit in tiniest possible detail in public is somewhat before it's time ?
wasn't it possible to keep it private at least 6 months , a year ........ whether Papa decide to seize production of F7 , or not ?
we have enough written info , pictures , enclosed articles from Yore ....... it is not hard to guess it , at least for those equipped with more than (mine) two cells ...
this way , slabbing another iteration after iteration , it seems that all we are waiting for is just Papa's nod - "that's Real McCay!"
I'm pretty sure that everyone would get confirmation from Papa , in private correspondence .....
to be frank , all what world cloners/IP stealers need to do is simply to buy F7 , and draw schmtc from it ....... as the case is with 95% of amps on market
but , I don't think that our guessing/deciphering joy needs to be there to help them ..... even if I'm not sure in NP's intentions , as generg already put ...
at least babelfish it , making it 50% more complicated , say that you cracked it ...... then nobody on ebay will sell Fx knockouts , be it exact or almost exact thing ....
wasn't it possible to keep it private at least 6 months , a year ........ whether Papa decide to seize production of F7 , or not ?
we have enough written info , pictures , enclosed articles from Yore ....... it is not hard to guess it , at least for those equipped with more than (mine) two cells ...
this way , slabbing another iteration after iteration , it seems that all we are waiting for is just Papa's nod - "that's Real McCay!"
I'm pretty sure that everyone would get confirmation from Papa , in private correspondence .....
to be frank , all what world cloners/IP stealers need to do is simply to buy F7 , and draw schmtc from it ....... as the case is with 95% of amps on market
but , I don't think that our guessing/deciphering joy needs to be there to help them ..... even if I'm not sure in NP's intentions , as generg already put ...
at least babelfish it , making it 50% more complicated , say that you cracked it ...... then nobody on ebay will sell Fx knockouts , be it exact or almost exact thing ....
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My intention was not to offend anyone,however it seems that I may have. I've removed the post and offer my apologies to Mr.Pass.
I'd rather buy a Firstwatt amp than clone one verbatim.
For me there is far more pleasure in trying to create something from my own mind based on my understanding of music and what Papa has taught me about electronics. It's virtually impossible to be truly original but at the very least we can design something that is custom made to meet some personal crireria which in the end often leads to a better outcome.
I tried to build a positive feedback amp many years ago but failed miserably. I thank Papa for constantly exposing us to new ideas of how to skin the cat. There's always something new to learn or think about, that is what gives me joy.
We don't need to clone Papa's latest project when there is already so many pearls he has given us. I prefer to rejoice in Papa's success and sit back and admire the show from a distance, no need to jump on stage with the actors to enjoy the show.
For me there is far more pleasure in trying to create something from my own mind based on my understanding of music and what Papa has taught me about electronics. It's virtually impossible to be truly original but at the very least we can design something that is custom made to meet some personal crireria which in the end often leads to a better outcome.
I tried to build a positive feedback amp many years ago but failed miserably. I thank Papa for constantly exposing us to new ideas of how to skin the cat. There's always something new to learn or think about, that is what gives me joy.
We don't need to clone Papa's latest project when there is already so many pearls he has given us. I prefer to rejoice in Papa's success and sit back and admire the show from a distance, no need to jump on stage with the actors to enjoy the show.
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Get on board the happy band wagon.I've yet to build a Pass amp, but 7 is my lucky number so perhaps I had better keep an eye on this one
First off, I am not releasing the official schematic at this time, and none of
the circuits here match the F7, except to the extent I have described it.
Also, keep in mind that the notion of positive feedback is reasonably old -
even I have played with it in the past. It is a general concept, and it so
happens that I have found a cute reason and way to apply it.
Of course I could have kept my mouth shut and just released product, but it
is too cool to not share, and I knew it would create a usual wave of speculation.
So you have, mostly thanks to lhquam, a selection of potential topologies,
even some nice equations for them. Probably more than you asked for.
This being DIY, I suggest that you pick one and build an amplifier.
the circuits here match the F7, except to the extent I have described it.
Also, keep in mind that the notion of positive feedback is reasonably old -
even I have played with it in the past. It is a general concept, and it so
happens that I have found a cute reason and way to apply it.
Of course I could have kept my mouth shut and just released product, but it
is too cool to not share, and I knew it would create a usual wave of speculation.
So you have, mostly thanks to lhquam, a selection of potential topologies,
even some nice equations for them. Probably more than you asked for.
This being DIY, I suggest that you pick one and build an amplifier.
F7 Balanced
Here is a hybrid of the Type 1 and Type 3 topologies.
How to generate the -Y signal will be shown in a later post.
Here is a hybrid of the Type 1 and Type 3 topologies.
- Speaker negative terminal at ground
- Sense resistor above load
- Negative feedback as in Type 1
- Positive feedback as in Type 3 computing the feedback signal as Z-Y
How to generate the -Y signal will be shown in a later post.
Attachments
Now the THD still puzzle me. Bottom right figure at 6moons audioreviews: FirstWatt F7, p4 as attached, unlike THD posted on the F7.pdf, shows increasing THD > 3kHz on the 8 ohm graph (not the wavy ones).
Attachments
Th wavy one is for the "tough load", whose impedance goes down below
3 ohms at a couple of places (where the distortion peaks are) and is
inductive at the top (where the distortion goes down accordingly.
The flat one where the distortion rises at the top is with a resistive 8 ohms,
and shows the non-linearity of the Fet capacitances.
Thank you for the explanation. So it seems that compared to the F5, the F7 has a bit higher THD vs Freq, probably due to lower transconductance of the output Fets, but started to rise several octaves higher, most likely due to lower input and miller capacitances of the Allfets. I'm guessing a bit less edge on the transients, smoother top end and tighter bass control with perhaps a somewhat more depth to the soundstage presentation. I'm with Generg here, waiting for Srajan's review.