I also have J231 and K246. Could i use them? Here where I am now the internet is very bad and I can hardly look for information on the internet, that's why I'm asking here instead of looking for it myself.
I don’t know the answer to you last question, I am afraid. But no matter which JFET you use, ensure not to exceed half the max wattage rating, and if possible subtract 20-25 additional percent. Example: K170/J74: 400mW max (?), try not exceeding 150mW over time, etc.
So it makes sense that being on the same die they would always be matched pairs. Would that be true?
I don't think that is necessarily the case, but of course you have perfect thermal tracking (where that matters).
yes, that was exact reason for production - same die - pretty good matching, same temperature
Looking good. I would be prepared to tweak the input series gate resistor depending on how you like the final sound result. 50R pot is OK, but you can probably get away with less if matching is good. I use neither pot/resistors there or on the output (I see you to have omitted that 🙂 ).
At the output I want to mount a bipolar 10uF and then play with the position of the 50 ohm potentiometer to see how the sound changes, because it will change.
Naaah, MZM can never be lost. But I now see some stuff I didn’t notice earlier in his schem: it needs correction, no?
So, either I am completely lost and confused by use of other devices than I used, or the schem is off. Here is what I see wrong, in all humility:
The two gates need to be tied together, this connection is missing. Also, source to drain is wrong: the two sources are to be tied together, and both drains to v+ and v- respectively.
That 470R input resistor may work fine, but is lowrr than the stock 1K. Though higher than in the IP.
Tweaking the halves with a pot affecting level of defen, will affect the residual waveform, but also lead to unsymmetrical clipping/loss of effective swing, no? But that is perhaps not much of an issue in this circumstance. He may perhaps need a pot with more R in order to achieve significant changes in the residual, but I don’t have equip to see the waveform of this low distortion circuit, so I am not able to speculate on exact value. Plus matching level of JFETs will affect his need anyways.
So, either I am completely lost and confused by use of other devices than I used, or the schem is off. Here is what I see wrong, in all humility:
The two gates need to be tied together, this connection is missing. Also, source to drain is wrong: the two sources are to be tied together, and both drains to v+ and v- respectively.
That 470R input resistor may work fine, but is lowrr than the stock 1K. Though higher than in the IP.
Tweaking the halves with a pot affecting level of defen, will affect the residual waveform, but also lead to unsymmetrical clipping/loss of effective swing, no? But that is perhaps not much of an issue in this circumstance. He may perhaps need a pot with more R in order to achieve significant changes in the residual, but I don’t have equip to see the waveform of this low distortion circuit, so I am not able to speculate on exact value. Plus matching level of JFETs will affect his need anyways.
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Andinor, It is the B1 R1 but with symmetrical supply, it is not the B1 R2.
if speaking of this (linked from cucu70's post), then everything is OK as drawn
trimpot value can be lowered to 20R, covering most cases
input gate stopper can be anything from 100R-1K
you can introduce 1K gate stopper for lower JFet
no need for output cap, with stable dual rails
trimpot value can be lowered to 20R, covering most cases
input gate stopper can be anything from 100R-1K
you can introduce 1K gate stopper for lower JFet
no need for output cap, with stable dual rails