BAF 2015 Coverage

[Zen Mod]

well , with that kind of SE power , I'm used to see a blower and a chimney ........... and 3CX1500A7 ...........

good work !

 

[cwtim01]

Wow Jama, you're fearless

Congratulations.

 

[kasey197]

wow nice!!! Jama your schematic looks like its missing something around the input buffer (Q4,Q5 DC path to earth)? Or maybe its just me who'se missing something 🙂))

 

[flocchini]

Jama and Steve

Very nice !!!!!

 

[ci11]

wow nice!!! Jama your schematic looks like its missing something around the input buffer (Q4,Q5 DC path to earth)? Or maybe its just me who'se missing something 🙂))

Hi kasey - chalk that one up to me as the scribe. The buffer earth path is "implied" and left off as it was getting crowded in there. It is needed and should be there. My bad.

 

[Chul]

Contratulations Jama~!

I wonder how you like the sound from that monster. What is your power supply? I got 65V SMPS ready but no time to go ahead...

 

[jama]

Thanks all. Last schematic as here (thanks Steve). It is as ever, only that with two vfets. I have not mount buffer yet, but sure that I need do it.

 

[jama]

When I started this project I was searching go out output capacitor. And it works. But I measure one dc offset of +-200mV at load. This is my last target. Using one servo controller I suppose that it works. I am thinking how..

 

[jama]

This is the ltspice simulation of the idea.

 

[jama]

@Chul
Power supply is one trafo of 60Vac and 450VA and one enormous cap of 100k 100V. But this is only for checking.

 

[jama]

I have a question for all. With one tokin alone, I found that frequency response is a lot better with one THF51 than one 2SK180. I have not graphics, but I measured it. With thf51 I found that is flat until, more or less 70 or 80 Khz, and with 2sk180 (one of mounted) this response is a lot worse, flat until 25 or 30 khz. Well.
Now I mount two 2sk180 in parallel. Frequency response is a lot better. Look square wave at 10Khz and (really 6.8/2 ohm).
I am using 50ohm output of generator all time.

 

[jama]

Both square wave at 10Khz

 

[Zen Mod]

This is the ltspice simulation of the idea.

look at post #644

 

[jama]

Thanks ZM. I will try.

 

[Soundhappy]

Thanks all. Last schematic as here (thanks Steve).
It is as ever, only that with two vfets.
I have not mount buffer yet, but sure that I need do it.

Big thanks Jama for amazing work and schematics. Always fantastic sit's topology explorations.
Audio input transformer option are interesting or 2SK79 ?
Have a nice day 🙂

 

[jama]

Hi Christophe. How are you?. Use of 2sk79 it is not necessary. You can use what you like.
For full output, always in function of transconductance of vfet pairs, you need a little of voltage gain at input, and sure the buffer.
I simulate for buffer position 2sk79 as cathode follower and 2sk170 and 2sj74. The best results were with the last, being transparent in simulation. And 2sk79 introduce a lot of harmonics.
Other possibility is use the fantastic jboz pre with one 2sk170. I used when I tried csx1 and I liked a lot.
But these ideas are only subjetives.

Best

 

[jama]

For reference, with this ixys mosfet and using one nice power pot of 10ohm 100w, i could get values for current of ccs, so

3.1 ohm -> 0.45 A -> 1.39V
1.25 ohm -> 1.09 A -> 1.37V
0.85 ohm -> 1.58 A -> 1.35V
0.56 ohm -> 2.34 A -> 1.32V
and .22//1 ohm -> 6A -> 1.08V

 

[dady]

Fantastic work friend, you are a builder without rest.
And your findings are usefully for me.
Congratulations!!!!!!!

 

[Soundhappy]

Hi Christophe. How are you?. Use of 2sk79 it is not necessary. You can use what you like.
For full output, always in function of transconductance of vfet pairs, you need a little of voltage gain at input, and sure the buffer.
I simulate for buffer position 2sk79 as cathode follower and 2sk170 and 2sj74. The best results were with the last, being transparent in simulation. And 2sk79 introduce a lot of harmonics.
Other possibility is use the fantastic jboz pre with one 2sk170. I used when I tried csx1 and I liked a lot.
But these ideas are only subjetives.

Best

Thanks Juan Antonio i am fine after i see your diy work i guess you are fine too
Yes i agree if simple jfet buffer give you satisfaction keep it !
Some very apreciated by audiophiles 300B SET's amplifiers have pentode tubes drivers some others are all triodes
i was curious if new all vfet's signal path are possible today.
Remember Papa speak with passion and entusiasm about Yamaha B-1:

https://www.youtube.com/watch?v=cyfdm4zsPx0

My hats off for Dady great amigo 😀

 

[Michael Rothacher]

Beautiful, Juan 🙂

You're a maker extraordinaire.