I don't quite understand why you would use this modified version compared to the simple complementary JFET follower from John Curl (Just 2SK170 / 2SJ74). Are you trying to drive more current with the BJTs than the JFETs can cope?
For the Pass F5, (or maybe even the original JLH circuit), the situation is different, as the first stage is just not capable of driving the intended load.
Maybe you care to explain ?
Patrick
For the Pass F5, (or maybe even the original JLH circuit), the situation is different, as the first stage is just not capable of driving the intended load.
Maybe you care to explain ?
Patrick
Hi
The 5457/5460 just doesn't have the transconductance required to supply enough current as source follower output. I like them and use them a lot, they are nice linear transistors with a small input capacitance but only good around the 100uA range, plenty of current to drive the base of a small signal BJT.
The 5457/5460 just doesn't have the transconductance required to supply enough current as source follower output. I like them and use them a lot, they are nice linear transistors with a small input capacitance but only good around the 100uA range, plenty of current to drive the base of a small signal BJT.
hi
i use this circuit as a volume control buffer, it alows me to tack more or less anything on the output that i may have or be playing around with at the time, universal buffer is how i would describe it. good old JLH.
i was wondering if an improvment could be made by replacing the transistors with better types, and as i had the original made up, i did some sims, and replaced the transistors and altered the values around them, sounds nice.
i suppose losing the preset would would have some advantage, but it trims the offset nicely.
i think it is good that the buffer has a low impedance output makes it versitile. (drive capability etc)
in my non expert simulations the distortion is very low, mayby someone who is more expert could do the sims and compare with a simple compementary jfet follower, because in my world of fumbling around with sims it comes out better?? surely this cant be correct. this would be educational and give people a chance to understand a simple circuit. (including me)
ps thanks guys for the comments
i use this circuit as a volume control buffer, it alows me to tack more or less anything on the output that i may have or be playing around with at the time, universal buffer is how i would describe it. good old JLH.
i was wondering if an improvment could be made by replacing the transistors with better types, and as i had the original made up, i did some sims, and replaced the transistors and altered the values around them, sounds nice.
i suppose losing the preset would would have some advantage, but it trims the offset nicely.
i think it is good that the buffer has a low impedance output makes it versitile. (drive capability etc)
in my non expert simulations the distortion is very low, mayby someone who is more expert could do the sims and compare with a simple compementary jfet follower, because in my world of fumbling around with sims it comes out better?? surely this cant be correct. this would be educational and give people a chance to understand a simple circuit. (including me)
ps thanks guys for the comments
I think you going to be dissapointed in the sound. Its a buffer, and this one what comes in comes out. I use this circuit between a cd player and amp because of long interconnect run to my monoblocks. When testing, with low impedance headphones I cannot distinguish any difference between the input signal and after the buffer. It has virtually no sonic imprint, a wire with gain, Exactly what it should be. Yep, I lost the caps too.
Having never simmed this buffer before, this buffer has most excellent performance. Like BJT their is a optimum drain resistance acording to device IDss. Can drive heavier loads like headphones easily.
Thanks burbeck for starting up this thread, I buit this circuit ages ago and had about forgotten about it. Modern Jfets brings its performance to another level. My sims show that it outperforms the simple complementary Jfet easily especially given any kind of load. Very nice spectrum too.
BTW this buffer is also used in some Krell amps.
Good old JLH.
Thanks burbeck for starting up this thread, I buit this circuit ages ago and had about forgotten about it. Modern Jfets brings its performance to another level. My sims show that it outperforms the simple complementary Jfet easily especially given any kind of load. Very nice spectrum too.
BTW this buffer is also used in some Krell amps.
Good old JLH.
Bob I dont know if Im smoking my socks, but it seems that this buffer actually likes some loading.
I used your values in ltspice and up to a certain load the buffer actually performs better than no load or light load. Do you find this as well?? The original JLH does this too, as does different operating curents.
I used your values in ltspice and up to a certain load the buffer actually performs better than no load or light load. Do you find this as well?? The original JLH does this too, as does different operating curents.
Yes to the first question. Increase the current for better performance.
Itll perform very well, the jfets provide very high input impedance causing very little loading on the opamp.
Complementary Jfets are hard to come by these days and is only hiccup for this circuit but even with common parts like 2n series Jfets one can get below 100 db distortion at 20Khz. Better can be achieved with toshiba jfets.
Itll perform very well, the jfets provide very high input impedance causing very little loading on the opamp.
Complementary Jfets are hard to come by these days and is only hiccup for this circuit but even with common parts like 2n series Jfets one can get below 100 db distortion at 20Khz. Better can be achieved with toshiba jfets.
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