Been following along on this thread and see that a CCS version of a simple 085 jfet amp has been built. Is the most recent schematic on page 61?
Haven't finished the Z9 yet and dying to build this one!
Thx,
Vin
Haven't finished the Z9 yet and dying to build this one!
Thx,
Vin
The most recent schematic with R085 is here : http://www.diyaudio.com/forums/pass-labs/153832-pass-delite-amp-baf-67.html#post2619650But I have
a new one , mainly becouse of the way the negative voltage has been apply from the original power supply, thank you Mr Pass for the ciruit . With lightbulb , with ccs of page 61 , or also a ccs with fixed current ( to be tested more ) where the -V at the gate decide just the Voltage operation of the circuit ( typical half -the rail ) and the current through the Jfet remains the same .
New Schematic with R085 Power Jfet
Here it is , that is how I built it , for the ligth bulb version there are obviously some modifications in the Power Supply .
I left to the current source to be drawn since there are various permutations for it .
Enjoy .
s
Here it is , that is how I built it , for the ligth bulb version there are obviously some modifications in the Power Supply .
I left to the current source to be drawn since there are various permutations for it .
Enjoy .
s
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Cool, I am dumb - this version allows you to tap off the PS to get a negative voltage I presume, without another bench supply?
What have you settled on roughly for negative gate supply voltage?
What have you settled on roughly for negative gate supply voltage?
Tea-Bag, Nelson posted this in one of my threads. It may help as well.
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Yes it does that .
The negative gate voltages varies , depending on the current source implementation , the voltages of VDD , and the current throug the Jfet .
Now with fixed CCS of 1,4 amps for example , VDD = 30 , Drain of the Jfet at 16 volts , the gate to ground voltage is - 3,5 volt
As Mr Burns would say, "Excellent!"
BTW- The negative supply doesn't need to be high current, correct? It only needs to be a fraction of the Drain current, yes, no, maybe so?
Vin
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Stefanobilini and All,
It's been discussed elsewhere that the IRFP9240 can cause distortion or is a bad choice for a CCS mosfet? Is this a concern in this design? Would a Fairchild P channel mosfet be a better choice?
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-887.html#post2300838
Mr Pass goes on to say that some people actually pefer the IRF9240 to the Fairchild FET.
It's been discussed elsewhere that the IRFP9240 can cause distortion or is a bad choice for a CCS mosfet? Is this a concern in this design? Would a Fairchild P channel mosfet be a better choice?
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-887.html#post2300838
Mr Pass goes on to say that some people actually pefer the IRF9240 to the Fairchild FET.
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That's correct . For a current source the IRFP9240 should be pretty good , and afaik it is the device implemented for the F2 current source ( but also F1 ) . Actually that is the current source arrangement I am listening from a week or so , and imo it is ok .
Got the 085s from Tea-bag the other day. Great price, nicely packed and quick delivery!
Thanks Tea-bag! Looking forward to using them soon on the Delite-CCS!
Vince
Thanks Tea-bag! Looking forward to using them soon on the Delite-CCS!
Vince
Just finished to set up one channel with the SJEP120R100 from the previous schematic with just one more resistor . Works well and good sound also .
I am just wondering what a marvelleous amp will this come with feedback and also the aleph current source 🙂
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