I have recently found this thread and have read it through from first post to last. I have even extracted the relevant posts and copied them into a Word doc (Phew! what a job. I don't think I've ever seen so many OT posts in a single thread before. I think there just might be a new record set here).
I am about to build the basic version, but am also interested in trying out various enhancements (as long as they are really improving the sound, not just the measurements.)
Some where along the line, Mr Pass, you commented that it looked like time for something a bit more complex, but haven't mentioned yet what you were thinking about. Is that going on in a different thread or is there something else you had in mind which hasn't come to light yet?
I am about to build the basic version, but am also interested in trying out various enhancements (as long as they are really improving the sound, not just the measurements.)
Some where along the line, Mr Pass, you commented that it looked like time for something a bit more complex, but haven't mentioned yet what you were thinking about. Is that going on in a different thread or is there something else you had in mind which hasn't come to light yet?
Just looked at some pages of pumpkin thread. Nice moderator removed OT comments. Looks like excellent preamp, but I don't have bucks for that level of equipment right now. I gotta start small and develop gradually, which is why this simple "building block" caught my eye.
I have soldered one up on perfboard yesterday, but haven't had a chance to try it yet. I have quite a few ideas I want to try out and that is why I wondered if anyone was still interested in this thread.
I have soldered one up on perfboard yesterday, but haven't had a chance to try it yet. I have quite a few ideas I want to try out and that is why I wondered if anyone was still interested in this thread.
Sorry, digging up an oldish thread like I did a few pages back. I have been playing with the JFET BoZ just to have some fun while I wait for some parts to get here for my new/soon-to-be 2A3 mono's. I am not sure if anyone has tried this, I have been in and out of the Pass forum as of late...tube addiction. Anyways I pulled my 22R resistor (in place of the 10R on the source) and popped in a red LED. Anyone dropped and LED onto the source of the JFET? Something that some of the tubies play with, 417A seems to really like a LED on the cathode. I attribute the difference in sound to the obvious, the voltage difference. With a V+ of 18v I am getting:
22R- 2.1v at the drain and 0.159v at the source
LED (RED)- 11.4v at the drain and 1.575v at the source
I am not sure yet if I like the sound 100% yet, I am going to have to play with some values a little bit still since I am radically changing the voltages here. It seems a bit more open, but it just seems to sound...muffled maybe, I don't know. There also seems to be a bit more of a hummmm in it, very quiet, but it means the music isn't coming from inky blackness like I like. I think I may have to play with a CCS on this one, if nothing else it will improve the PSRR. Which leads me to my other question...
Why do I see some people sticking a current sink on the source? I could be overlooking the obvious here while I was off in tube land...that and college. It seems to me though and my knowledge about triodes (JFET's are very similar...just sand) points that you would want a CCS on the Drain. In theory this should maximize linearity, greatly improve PSRR a lot, and in theory improve dynamics, detail, etc... I could see maybe a sink with a choke as a load, that would be an interesting experiment, looks like I have something else to try tonight. Yes though I have seen a choke loaded JFET BoZ (Carpenter I believe(?))
I can see a shunt reg in the near future too!
Cheers
James
22R- 2.1v at the drain and 0.159v at the source
LED (RED)- 11.4v at the drain and 1.575v at the source
I am not sure yet if I like the sound 100% yet, I am going to have to play with some values a little bit still since I am radically changing the voltages here. It seems a bit more open, but it just seems to sound...muffled maybe, I don't know. There also seems to be a bit more of a hummmm in it, very quiet, but it means the music isn't coming from inky blackness like I like. I think I may have to play with a CCS on this one, if nothing else it will improve the PSRR. Which leads me to my other question...
Why do I see some people sticking a current sink on the source? I could be overlooking the obvious here while I was off in tube land...that and college. It seems to me though and my knowledge about triodes (JFET's are very similar...just sand) points that you would want a CCS on the Drain. In theory this should maximize linearity, greatly improve PSRR a lot, and in theory improve dynamics, detail, etc... I could see maybe a sink with a choke as a load, that would be an interesting experiment, looks like I have something else to try tonight. Yes though I have seen a choke loaded JFET BoZ (Carpenter I believe(?))
I can see a shunt reg in the near future too!
Cheers
James
OK sorry to double post but I just hooked up a "choke". Well, it is actually the primary side of a stray transformer I had close at hand. I have been diddling with the V+ in the past few min, since it is on an adjustable power supply. The highs got HHHIIIGGGHHH and detail abounds, but my bass has all but disappeared! Not enough H? I am going back to the resistor for now even though the resistor sounds dark in comparison. I will have to throw a CCS together here soon, I have the bread board out so this weekend if I can find time. My girlfriend is home and we see each other like once every couple weeks, she might be upset if we spend the whole weekend watching me tinker 
Cheers
James
Cheers
James
Re: Lineup Audio, 2SK170GR jfet-boz version 1.0
Do not forget this High Fidelity Hi-fi JFET Boz
that I contributed in the beginning of this topic.
That is, if you want one whole Level lower distortions.
Which is maybe NOT what all will like.
Not in this forum of Pass Labs
hehe, hehe, haha
Regards
Lineup
-------------------
See Post #93
for additional setup instructions
to Jfet BOZ modificated version
lineup said:
Well, for myself speaking: I do not do much anything else
Comment to my attached SCHEMATIC
Lineup 2SK170GR Jfet BOZ - beta version 1.0a
---------------
Regards
Lineup Audio Labs, the design division
/lineup
Do not forget this High Fidelity Hi-fi JFET Boz
that I contributed in the beginning of this topic.
That is, if you want one whole Level lower distortions.
Which is maybe NOT what all will like.
Not in this forum of Pass Labs
hehe, hehe, haha
Regards
Lineup
-------------------
See Post #93
for additional setup instructions
to Jfet BOZ modificated version
Attachments
So my girlfriend is out shopping with her mom this morning so I go some time to tinker with a CCS. I basically closed my eyes and reached into my parts collection and pulled out some random resistors and passives. It is a very basic CCS, red LED to the base of a BC560, 10k from there to ground. There is a 22R from the V+ rail to emitter, lastly and obviously, the collector to the drain. I hooked the whole thing up across a Fluke and more or less the current varies very nicely as I turn the voltage on the power supply up or down. In other words nothing is optimized.
From there I hooked the whole thing up to the JFET BoZ, my one with the LED in the source. I then proceeded to turn the voltage and consequently current up and down until I hit a sweet spot...see very very not optimized. I will say, what a sweet spot. Almost no noise at all, very close to inky blackness in the background. Dynamic, detailed, yet still very sweet sounding. It will really take some more tinkering but right now I am impressed with even this basic CCS.
Time to listen
Cheers
James
From there I hooked the whole thing up to the JFET BoZ, my one with the LED in the source. I then proceeded to turn the voltage and consequently current up and down until I hit a sweet spot...see very very not optimized. I will say, what a sweet spot. Almost no noise at all, very close to inky blackness in the background. Dynamic, detailed, yet still very sweet sounding. It will really take some more tinkering but right now I am impressed with even this basic CCS.
Time to listen
Cheers
James
Re: Re: Lineup Audio, 2SK170GR jfet-boz version 1.0
Hello Lineup,
What tools are you using for the simulation in this post #93 and #97?
Thank you,
-David
lineup said:
Do not forget this High Fidelity Hi-fi JFET Boz
that I contributed in the beginning of this topic.
That is, if you want one whole Level lower distortions.
Which is maybe NOT what all will like.
Not in this forum of Pass Labs
hehe, hehe, haha
Regards
Lineup
-------------------
See Post #93
for additional setup instructions
to Jfet BOZ modificated version
Hello Lineup,
What tools are you using for the simulation in this post #93 and #97?
Thank you,
-David
jameshillj said:
Way off topic:
House is coming along... I'm painting the wainscoting in the stairwell. Will be for some time as I'm using a brush, not spray.
Shoulder's good enough to work. I'm still useful...
Hope all is well in your neck of the woods.
Here's a pic taken last winter:
Attachments
