Aleph J Schematic

Jump to Latest
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
EUVL said:
Choky,

I am a bit tied up this week. Maybe earliest next week before I have time to look in detail.

Why not do some simulations of the 3 main proposals in the meantime (J511, 4V Zener below LU1014 source resistor, and yours) ?

:)


Patrick
Click to expand...


there is slight problem or two ......... this week I'm also not tied , but grounded :clown:

second one is that I don't do sims ...............never enough time for quick adjusting to proggies ..........

we'll see .........
 
EUVL

EUVL

Member
Joined 2003
xen-audio.com
So, while driving home tonight, I have the following idea.
Actually so simple that I should have thought of it before.

Take the schematics from :

http://www.diyaudio.com/forums/attachment.php?s=&postid=1343785&stamp=1194303063

Replace Q7,8 by LU1014, then R18,19 to 0R66, then instead of driving the gate of Q7,8 with R7, add a high pass filter of 22uF / 10k in between.

If you do the maths, I don't think the open loop bandwidth would suffer much because of the high Yfs of the LU1014, and the cascode.

No rail voltage change necessary.
Now, this is really difficult to beat in terms of simplicity.

;)


Patrick
 
G

GRollins

Member
Joined 2001
Sadly, the Lovoltechs won't take that much voltage/power dissipation. You could cascode it, at which point you'd have a Zen #9 with a front end. The idea is seductive...however, the JFET front end will run out of juice if the amp is driven hard; the LU1014D draws a significant amount of Gate current if pushed. The ticket would be to add a strong follower after the first stage to ensure that the LU1014Ds get all the current they can eat.

Grey
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
EUVL said:
So, while driving home tonight, I have the following idea.
Actually so simple that I should have thought of it before.

Take the schematics from :

http://www.diyaudio.com/forums/attachment.php?s=&postid=1343785&stamp=1194303063

Replace Q7,8 by LU1014, then R18,19 to 0R66, then instead of driving the gate of Q7,8 with R7, add a high pass filter of 22uF / 10k in between.

If you do the maths, I don't think the open loop bandwidth would suffer much because of the high Yfs of the LU1014, and the cascode.

No rail voltage change necessary.
Now, this is really difficult to beat in terms of simplicity.

;)


Patrick
Click to expand...


EUVL said:
> Replace Q7,8 by LU1014

Sorry. My mistake.
I meant of course Lu1014 cascoded by IRFP240, a la ZV9.

PS My understanding is that the LU1014 will draw current at the gate IF the Vds is high. I suspect that it is not the case for the Vds level as in ZV9.


Patrick
Click to expand...


one little birdie , with gray beard and gray haired , with mucho funny hat on top of everything , told me that my idea is ......... full of drek :clown:



anyway - if I understood you correctly - ya mean that drain of input jfet will be connected via 22uF to gates of lovoltechs , and that 10K is for ground referencing of LU gates?

if you think like this - that's boiled water ........ triode LTP with totem pole output ....... and then you need servo for offset maintenance .

once I have clever idea .......... with 1:1+1 xformer ........... my friend Oly couldn't stop laughing 3 days ....... after that I remembered importance of DC feedback
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
this schmtc :
http://www.diyaudio.com/forums/attachment.php?s=&postid=1357915&stamp=1195754369

from post 250 is still fave of mine

I don't think that implementing another , more negative , rail is so evil thing.......

especially ifwe implement another - current mirror from drains of 2SJ, but with lowered load resistor.......... so dreky little stage can drive that (sometimes ??) hungry LU gate......
 
Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
EUVL said:
Replace Q7,8 by LU1014, then R18,19 to 0R66, then instead of driving the gate of Q7,8 with R7, add a high pass filter of 22uF / 10k in between.
Click to expand...

This will work, but of course you will need to deal with the DC.
The same is true of transformer coupling. Of course on the ZV9
the DC is adjusted via the cascode voltage.

Zen Mod said:
one little birdie , with gray beard and gray haired , with mucho funny hat on top of everything , told me that my idea is ......... full of drek :clown:
Click to expand...

I thought the word was "merde". The problem was that the
Source current of the JFET was passed through the Mosfet that
you used as the level shifter. An alternative here is a separate
supply for the load resistor off the input JFETs, regulated to the
AC value of the main negative rail, but minus a few DC volts.

:cool:
 
Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
Try this one.

:cool:
 

Attachments

  • lvlshft.jpg
    lvlshft.jpg
    42.7 KB · Views: 2,230
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
EUVL said:
> It would be if I was paying attention, but since I wasn't, I take full credit for it.

I was expecting more ingenious solutions from the Master himself.
But I guess we at least agree on what the best solution is.

;)


Patrick
Click to expand...


ya can't beat engineer , even if he 'Claus is ......... ;)

all my credit for your solution,but we mustn't forget who made our playground , in this case ......... :clown:
 
Vix

Vix

Member
Joined 2003
Zen Mod said:



ya can't beat engineer , even if he 'Claus is ......... ;)

all my credit for your solution,but we mustn't forget who made our playground , in this case ......... :clown:
Click to expand...

Yeah...We must not forget who gave us a ball to play with (no pun intended) :D

Papa is the coach, and we are just players...

Good if someone scores a goal....

At the moment I'm just watching..:clown: :)
 
EUVL

EUVL

Member
Joined 2003
xen-audio.com
Gentlemen,

If Nelson would really want the credit (which I doubt; it was just his humour I guess), it's fine with me.
I don't need to claim first idea to massage my ego.

I DO sincerely wish to see a more ingenious solution from Nelson or whoever else.
Otherwise I would have never bothered with this discussion at all, because I have already built the thing 6 months ago.
And I know how it works.

So please don't stop the mental challenge (me including)......


Patrick
 
J

jupiterjune

Member
Joined 2006
Patrick-

Since you asked:

So please don't stop the mental challenge (me including)......
Click to expand...

I'll will whine again about somehow getting rid of that distortion in the active current source at high output level and high frequency? Any ideas???

What causes it, anyway?

is it voltage dependent?
is it current dependent?
or is it due to some characteristic of the source vs. the drain???

JJ
 
You must log in or register to reply here.
Top Bottom