JfetBOZ mods

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#102
Implementing Nelson's suggestions:
 

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#103
Hi,

Isn't a 1000 uF for C3 too much? 100 uF should be enough. Other than that, it looks fine.

By the way, besides using transformers from the scrapped microwave ovens for L1 and L2, what would be the minimum acceptable mains transformer size that could be used as a choke? Will a 220v/12v 1 A one be sufficient?

Somehow, I get an impression that choke loaded amps and preamps sound better than resistor loaded ones? Or, is it just a delusion?

If you were to replace the 1 kohm drain resistor on the original BoZ with the choke, will it sound better?

Sorry for OT

Vix
 
#104
Quest for ZEN MOD

Hi all,
I wonder about Zen Mod prescriptions about the "tail voltage " of the CCS, and especially concerning the zener value,:
should we understand that for a given voltage of say 27volt tail(the neg psu)
the zener used has to set greater than 5v on the source resistor, Nelson set about 10V in his schematic...but if the current that has to be set by the CCS is fixed, as well as the neg voltage PSU then this means that the CCS transistor will have less VDS than it would be with a lower voltage zener and then what could be taken as a rule in that matter? I mean give 2/3 of tail voltage to the CCS transistor VDS and 1/3 to the source res?
zen stated it has already been discussed maybe someone has a link for that topic?about dinamic resistance of CCS ..., this sounds very interesting to learn about🙂
Vince
 
#105
Re: Quest for ZEN MOD

bobsinclar said:
Hi all,
I wonder about Zen Mod prescriptions about the "tail voltage " of the CCS, and especially concerning the zener value,:
should we understand that for a given voltage of say 27volt tail(the neg psu)
the zener used has to set greater than 5v on the source resistor, Nelson set about 10V in his schematic...but if the current that has to be set by the CCS is fixed, as well as the neg voltage PSU then this means that the CCS transistor will have less VDS than it would be with a lower voltage zener and then what could be taken as a rule in that matter? I mean give 2/3 of tail voltage to the CCS transistor VDS and 1/3 to the source res?
zen stated it has already been discussed maybe someone has a link for that topic?about dinamic resistance of CCS ..., this sounds very interesting to learn about🙂
Vince
Click to expand...


http://www.diyaudio.com/forums/showthread.php?postid=951277#post951277

not exactly covered entire issue , but few rules of thumb ......

download these files and read , can be handy

edit :

word-game .......... :
resistance ........multiple.........xconductance.........dynamic impedance........... etc :clown:
 
#106
Vix said:
Hi,

Isn't a 1000 uF for C3 too much? 100 uF should be enough. Other than that, it looks fine.

By the way, besides using transformers from the scrapped microwave ovens for L1 and L2, what would be the minimum acceptable mains transformer size that could be used as a choke? Will a 220v/12v 1 A one be sufficient?

Somehow, I get an impression that choke loaded amps and preamps sound better than resistor loaded ones? Or, is it just a delusion?

If you were to replace the 1 kohm drain resistor on the original BoZ with the choke, will it sound better?

Sorry for OT

Vix
Click to expand...

1000uF is an interesting idea that I will try. Babowana is pretty sharp, and if he thinks something sounds good, it's worth a try.

Nelson mentions using a 1H spool of wire in his prior experiments with excellent results. He was flowing several amps and we're only using 5 to 10 uA per side, which means to me that there's little chance for saturation. I'm going to surplus sales of Nebraska for some of their light-duty chokes--very reasonably priced, I might add.

I like the sound of a choke loaded transistor--it seems more dynamic to my ears. Of course, I'm hard of hearing in the upper register--to someone with normal hearing, it may sound all wrong. 😀
 
#112
paulb said:
This is great. Just ordered some 2SK170s. Got lots of transformers to play with.
Thanks John.
Still, it would be nice to use those Lovoltech FETs somewhere...
Click to expand...

I can't wait to hear what you think.

Regarding the Lovoltech Fets:
I know what you mean! I ordered several hundred from Grey thinking they would be more revered than the "second-coming". I wanted plenty, just in case they quit manufacturing the darn things.

On the bright side, they do sound wonderful in my cascoded version of the ZV7-T. The down side is that they don't resolve the high frequencies nearly as well as the arrangement on this thread: JfetBOZ, or Balanced JfetBOZ plus F4.

Maybe they can cascode with the 2SK170! But then again, they don't do high voltage and the current is controlled by the 2SK170... I wonder if they can do the P channel as well as the N? I heard that Jfets can be swapped, I just can't remember where I read that. I wonder if they can do complementary circuits? Perhaps F4 duty? A simple experiment may tell the tale.😀
 
#113
Wow. I followed the latest schematic. The sound is very very nice!🙂 😀

I left C3 alone (22uF) but proceeded with all the other changes.

Wow. I'm so sold on this design. I'm also sold on batteries. Talk about a quiet power supply!😀
 

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#115
Look's very good carpenter!

What's the size of torrid you use here ?
Bigger is better, i mean high mH / (H) with low resistance right ?
I am having a 230v - 15v - 0 - 15v Torrid with ~0,8ohm on each secundary winding. donno the mH(H) through...

Did you place them 2sk170, face to face ?
Have you meassured how much voltage it can swing before clipping ?

I am considering trying to setup this circuit, just for fun(at first), but having a hard time finding zvn3310 here in DK/Europe through. , Anyone know where to purchase ?

BTW: Happy new year...

Jesper.
 
#117
lykkedk said:
Look's very good carpenter!

What's the size of torrid you use here ?
Bigger is better, i mean high mH / (H) with low resistance right ?
I am having a 230v - 15v - 0 - 15v Torrid with ~0,8ohm on each secundary winding. donno the mH(H) through...

Did you place them 2sk170, face to face ?
Have you meassured how much voltage it can swing before clipping ?

I am considering trying to setup this circuit, just for fun(at first), but having a hard time finding zvn3310 here in DK/Europe through. , Anyone know where to purchase ?

BTW: Happy new year...

Jesper.
Click to expand...


ask Magura ; he can maybe have some new schematic 😉
 
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