Thanks for the idea of the power supply. I would like to use it to power another Push-Pull amplifier (M2 Firstwatt clone) from 40V AC single coil transformer. Is it safe? What are the advantages and disadvantages of this solution?
Attachments
Hi sts9
I think that by continuing this PSU type discussion will be more way of-topic from original F7 thread , which I don`t want to abuse on the first place ,
but if you want you can always start new thread , let`s say in `Power Supplies ` DIY A. sub-forum , I`m sure that there can be answered and revealed all advantages and disadvantages of that PSU type applied for your M2 -FW amp clone.
Best Regards !
I agree.
I'd rather build my own dumb amp than try and clone one of Papa's new amps that hasn't even made it to the store yet.
I feel sorry for Papa, too much greed happening amongst greedy boys.
Hi, what I went after by starting to write about the power supply and especially the grounding was Papa's "found a clever way to further reduce the effect of high frequency DAC noise and environmental RF".
It is of course of much greater interest also for me to learn more about the actual amplification part.
Still, immunity to the more and more RF polluted world should be of great interest. (I do not want to open this can of worms, but I must mention that I happen to believe much of the "audible differences" between cables of all sorts can be addressed to RF. But you do not need to arrest me here in this thread because it is off-topic from what really matters here. The F7 topology itself.)
Thanks.
Could be worse. You could be spending your time speculating about Hansen
or D'Agostino.
Nelson: How do you estimate the open-loop gain and negative feedback factor of the F7? Both look quite high to me. See post #316 http://www.diyaudio.com/forums/pass-labs/275921-first-watt-f7-review-32.html#post4567310.
F7.pdf shows the input impedance as 10K. Is that correct?
F7.pdf shows the input impedance as 10K. Is that correct?
Could be worse. You could be spending your time speculating about Hansen or D'Agostino.
The 10K figure is correct.
Your open loop figure is higher than mine, which was derived from looking at
the damping factor of about 5 into 8 ohms without positive feedback.
Probably your output transistors.
The 10K figure is correct.
Your open loop figure is higher than mine, which was derived from looking at
the damping factor of about 5 into 8 ohms without positive feedback.
Probably your output transistors.
With a closed-loop gain to 14dB, without positive feedback, and no sense resistor I see a damping factor of about 7. With a 0R33 sense resistor I see a damping factor of 5.4. I guess I am not estimating open-loop gain correctly.
In the case of the F7 it seems to be the bottom side of the amp.....
Joking!
This time it was an unusual mix of announcement very much enriched by diyaudio contributions and pictures even appearing earlier than the review.
So all was a bit fast! like pushing fever...
Maybe this is all wanted..... But I have to get accustomed to acceleration and mix of information.
THX
Joking!
This time it was an unusual mix of announcement very much enriched by diyaudio contributions and pictures even appearing earlier than the review.
So all was a bit fast! like pushing fever...
Maybe this is all wanted..... But I have to get accustomed to acceleration and mix of information.
THX
I removed the negative feedback resistor keeping the feedback shunt resistor and recalculated the openloop gain as 48 (33.6dB), which implies about 20dB of negative feedback. Is that in the right ballpark?Your figures make sense, but I don't see them coming from a 42 dB open
loop gain.
Since I only understand about 1% of what's been covered in these posts, it makes my head swim, but I just can't stop reading!
)
Yes, but that figure applies to your version of the circuit. I'm running more
like 10 dB feedback (depending on load).
Could be worse. You could be spending your time speculating about Hansen
or D'Agostino.
Hahaha.
Could always be worse