I'd be more worried about power dissipation than Idss. 35V is approaching the voltage limit of most JFETs and by the time you put a few mA through it the Pd is going to get annoying.
Grey
Grey
True. The Vds limit is 40 V for SK170 if I remember correctly. However, the Pd limit is 400 mW, so unless using the rare and very high Idss units, there is probably nothing to worry about. We don't drop the whole rail voltage over a single JFET.
It raises an interesting question, though, that have myself wondered about regarding another design: Should the Pd figure be treated as an instantaneous maximum or an average maximum? For average maximum, it is usually sufficient to check the Q conditions, while for transient power, we have to check what happens when feeding a signal into a load. (Yes, I am aware that my question implies the follow-up question of how to interpret 'average' here 🙂 ).
It raises an interesting question, though, that have myself wondered about regarding another design: Should the Pd figure be treated as an instantaneous maximum or an average maximum? For average maximum, it is usually sufficient to check the Q conditions, while for transient power, we have to check what happens when feeding a signal into a load. (Yes, I am aware that my question implies the follow-up question of how to interpret 'average' here 🙂 ).
Re: Re: Re:Constant Current Source
That is called SRPP in tube circuit. Would it give lower output Z also? I still want to use normal 12V SLA battery, easy to get and I have the charger.🙄
Cheers
Nelson Pass said:
That is called SRPP in tube circuit. Would it give lower output Z also? I still want to use normal 12V SLA battery, easy to get and I have the charger.🙄
Cheers
Hi,
Yesterday, i had the opportunity to go to a Baroque Musicke concert, (with my test equipment
). Authentic string instruments like Viola da gamba uses strings made of guts wich give them a very special, appealling, specific sonic signature, difficult to describe : precise, very clear but rich, bloomy and very tasty, and with, thats important, a slight overall mattity, an incredible mix which makes them very easy to listen to.
Back at home I could confirm my impressions : the BOZ JFET ist the first/only pre I've ever heard really capable of reproducing this very nice sonic signature. Superb.
(Steen : was that OT enough?)
-Steen : thank you, I've got the urge to finish to build a F4 as a partner for BOJZ.
Pic of the chassis enclosed. It too big for just one stereo but could be usefull if I need a // config later
- Zen Mod, I didn't yet manage to find the value of the possible input protection zener
.But thats no problemo, I will stay here waiting, maybe some good samaritain will come along...
Manu
Yesterday, i had the opportunity to go to a Baroque Musicke concert, (with my test equipment
). Authentic string instruments like Viola da gamba uses strings made of guts wich give them a very special, appealling, specific sonic signature, difficult to describe : precise, very clear but rich, bloomy and very tasty, and with, thats important, a slight overall mattity, an incredible mix which makes them very easy to listen to.Back at home I could confirm my impressions : the BOZ JFET ist the first/only pre I've ever heard really capable of reproducing this very nice sonic signature. Superb.
(Steen : was that OT enough?)
-Steen : thank you, I've got the urge to finish to build a F4 as a partner for BOJZ.
Pic of the chassis enclosed. It too big for just one stereo but could be usefull if I need a // config later
- Zen Mod, I didn't yet manage to find the value of the possible input protection zener
.But thats no problemo, I will stay here waiting, maybe some good samaritain will come along...Manu
Attachments
Manu said:Hi,
Yesterday, i had the opportunity to go to a Baroque Musicke concert, (with my test equipment
Back at home I could confirm my impressions : the BOZ JFET ist the first/only pre I've ever heard really capable of reproducing this very nice sonic signature. Superb.
(Steen : was that OT enough?)
-Steen : thank you, I've got the urge to finish to build a F4 as a partner for BOJZ.
Pic of the chassis enclosed. It too big for just one stereo but could be usefull if I need a // config later
- Zen Mod, I didn't yet manage to find the value of the possible input protection zener
Manu
Thanks for the excellent description. If you like going to classic concerts and experience how the real thing sounds, I think its a very good thing for you to build the F4. It has the best soundstage that I ever heard. Both width and depth is tremendous. I build mine as dualmono all the way, and I suggest you do the same. To my ears a dualmono layout adds to the soundstage.
Manu, turn on your mail or send me one.
Steen🙂
I see, you exactly know what I mean, nice. 🙂
Dual mono, I agree, will be a must (but is one trafo for both channel still Ok?)
Manu
You've got a mail.
Dual mono, I agree, will be a must (but is one trafo for both channel still Ok?)
Manu
You've got a mail.
Manu said:never
That monkey could be a nice avatar 😀
You can do it with one trafo. If each channel is running from seperate cap-banks the crosstalk will be minimal🙂
Steen🙂
BTW I send you a mail, not sure if I used the correct email though.
Thank you. Saviour. I was already thinking about connecting my house to two separate power plants...
A good avatar. I don't know. Because, for myself, I'm happy most of the time. (It's not really me on this picture)
🙂
manu
A good avatar. I don't know. Because, for myself, I'm happy most of the time. (It's not really me on this picture)
🙂
manu
Manu said:I didn't yet manage to find the value of the possible input protection zener
Manu
I think ourselves are the best protectors.
When we change interconnection lines, we should not forget "power-off" before doing it ^^.
Done!
I just finished it, works excellent! It draws around 6 mA per channel. I divided the supply by putting 220 ohm resistors and then 1000 uF+100 nF capacitors. Voltage drop across these resistors is
1, 333 V. Source resistors are 2x27 ohm in parallel (somewhat bigger-I just had them in a box), other values are just as in the original schematic. I strongly encourage everyone to build this one. Looks like a toy, but...
Regards,
Vix
I just finished it, works excellent! It draws around 6 mA per channel. I divided the supply by putting 220 ohm resistors and then 1000 uF+100 nF capacitors. Voltage drop across these resistors is
1, 333 V. Source resistors are 2x27 ohm in parallel (somewhat bigger-I just had them in a box), other values are just as in the original schematic. I strongly encourage everyone to build this one. Looks like a toy, but...
Regards,
Vix
Attachments
Zen Mod said:
The volume knob doesn't have a proper odour, gotta replace it 😀 That one is just temporary...
Vix
Hi,
Those pics are done improperly (via phone camera). I'll borrow a decent one those days, and make shots again. I get upset when I see blurry pics. They should be at par with Jfet Boz sound: Crystal clear!
Thank you very much,
Vix
Those pics are done improperly (via phone camera). I'll borrow a decent one those days, and make shots again. I get upset when I see blurry pics. They should be at par with Jfet Boz sound: Crystal clear!
Thank you very much,
Vix
Babowana said:
I think ourselves are the best protectors.
When we change interconnection lines, we should not forget "power-off" before doing it ^^.
Forgive me master, I'll never do it again.
BTW : a good samaritain came along.
Vix : Very nice work. The sound is great isn't it ?
I see, I'am the only one who's happy with Rs at 22R...
manu