Leave P3 empty. Or populate it with the pot.
Bridging it will short the source resistance to ground.
Bridging it will short the source resistance to ground.
Thanks Kpsthakur, sorry I didn't see this post until today. I actually got rid of my hum by turning the transfo, moving wires and reducing loops but turning the transfo was the biggest improvement, see post 15472. Thanks.
As the dcb1 is an evolution of the pass b1 buffer and is very evident that the buffer had benefited greatly by improved power supply and as the front end of the f5 isnt overly dissimilar (assuming it is as sensitive to ps) was curious if anyone has tested using a separate cleaner supply to the k170/j74
I'm not sure anyone has tried, but I think it's worth doing! Give it a go and report back with your findings. 😀
not good idea
modulation from JFets (to output mosfets ) is referenced to rails , so messing with them (rails) is no-no
modulation from JFets (to output mosfets ) is referenced to rails , so messing with them (rails) is no-no
Yes, that is one of the results of the cascodes in the F5T. The ground-referenced base reduces the amount of ripple seen by the JFET, without affecting the ability of the JFETs to look into the gates of the output devices.
The DCB1/B1 have absolutely nothing in common with the F5 front end. They are about as similar in topology as a turntable and a CD player. A few minutes with the F5 manual will illustrate this quite nicely.
b1 buffer based on two 2sk170's
f5 front end based on 2sk170 and its complement 2sj74
thought it was a similar enough comparison/analogy
to question effect of power supply on same or similar jfets even though used as a common source rather than a common drain
so if a +/-18 vdc shunt is used for the jfets and their biasing
and a standard ps for the output mosfets
all reference to gnd whats the worst that can happen?
just the concept i'm interested in really, not suggesting it should be the way
looking at positive side : you can't break/disturb solid line between top of JFet drain resistors (practically JFet PSU rail ) and top of Mosfet's source resistor (practically Mosfet PSU rail)
in fact , you can do exactly that with some level shifter ( as made in BAF FE -resistor in parallel with capacitor)) , but there is important difference between function of level shifter and function of regulator
same applies for negative side , just use bottom instead of top
in fact , you can do exactly that with some level shifter ( as made in BAF FE -resistor in parallel with capacitor)) , but there is important difference between function of level shifter and function of regulator
same applies for negative side , just use bottom instead of top
well its just that the signal going into mosfet gate is referenced to mosfet v rails (connected through resistor) in and whatever noise is on those rails
i was thinking more like this
i was thinking more like this
well , I wrote ...... and you feel free to try
not even to mention puzzle what could happen if those two voltage rails (main and shunt) aren't arriving exactly in same time
not even to mention puzzle what could happen if those two voltage rails (main and shunt) aren't arriving exactly in same time
You are 74th guy in this thread with the same bad idea and people are tired of explaining the same thing over and over again.
The why not: voltage drop across JFETs' drain resistors will determine the Vgs i.e. Id for output MOSFETs. So if you apply fixed voltage on JFETs' drain resistors and unregulated voltage on MOSFETs' sources the Id of the output stage will be moving up and down, potentially dangerously.
So if you still think that it's a great idea go ahead and do it but please have fire extinguisher ready.
Let them try and they will find out for themselves.
No pain no gain.
Reminds me of some other smart guy who put a 10R // IN4148 as Gnd lifter between the Amp Gnd and the PSU Gnd in a F5 Headamp.
The best bit was of course that the PSU caps were before the 10R, i.e. on the PSU side.
Still amuses me today.
🙂
Patrick
No pain no gain.
Reminds me of some other smart guy who put a 10R // IN4148 as Gnd lifter between the Amp Gnd and the PSU Gnd in a F5 Headamp.
The best bit was of course that the PSU caps were before the 10R, i.e. on the PSU side.
Still amuses me today.
🙂
Patrick
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thanks for highlighting the potential hazards guys
I really appreciate that and thats just what i was looking for
however i can't understand on a forum entitled diyaudio
why its necessary to add condescending comments in a reply to non audio professionals wanting to learn and explore a particular circuit
i sure can understand its annoying if the same questions pop up often
i did search for it
i didn't find the topic been brought up before
in fairness the thread is almost 9 years old and 15500 odd posts long
a sad day you get shot down for asking questions and sharing ideas suspect or otherwise, if people stop doing that they are just building kits and learning nothing
I really appreciate that and thats just what i was looking for
however i can't understand on a forum entitled diyaudio
why its necessary to add condescending comments in a reply to non audio professionals wanting to learn and explore a particular circuit
i sure can understand its annoying if the same questions pop up often
i did search for it
i didn't find the topic been brought up before
in fairness the thread is almost 9 years old and 15500 odd posts long
a sad day you get shot down for asking questions and sharing ideas suspect or otherwise, if people stop doing that they are just building kits and learning nothing
not a problem at all, we all had friendly slap here and there (even if you really wasn't slapped in any way)
however - you neither did your homework after first reply to your question nor you simply asked for clarification
I seldom didn't got proper reply when I asked "why" , if I didn't got it from first
however - you neither did your homework after first reply to your question nor you simply asked for clarification
I seldom didn't got proper reply when I asked "why" , if I didn't got it from first