F5 meets Buzquito

[prakit]

Hi Juma,
Greetings. I was searching for a power amp to build. I like JFET input stage and I want to use Lateral Mosfet for output. I found Zenquito then this one using K2013/J313 as VAS. Everything fits the bill. This seems like another gem of yours. 🙂 Hard to believe this thread was buried this deep.

My diy buddy helps draw a pcb for this version of F5 as the attachment. Do you think it worth using regulated ps for input and VAS stages?

 

[juma]

... Do you think it worth using regulated ps for input and VAS stages?

Of course - as every gain stage does, this front end will also appreciate clean and Low Z power supply.

 

[tinitus]

Hard to believe this thread was buried this deep.

digging deep 😀 any progress ?

 

[prakit]

Built the amp. Worked very well, sounded very nice I've asked my friend to rework the pcb layout for 3 pr of output devices, cascode the input stage, balanced operation, and etc. 😀

digging deep 😀 any progress ?

 

[prakit]

Sorry, forgot the attachment

 

[tinitus]

Sorry, forgot the attachment

is that a cascoded input for higher voltage/output ?

 

[tinitus]

while you're fresh with it - will you try it in B class ?

...... with small bias current the amp sounds a bit "thin". With 0.5A it's really good and marginally better with 1A per MOSFET.

if lower bias current, maybe it would help with higher voltage

 

[prakit]

Yes, it's so that I can use higher voltage supply for higher output with 1.2A~1.5A bias.

is that a cascoded input for higher voltage/output ?

 

[tinitus]

would it work in high biased class AB

(Juma's original schematic from post 1)

 

[Zen Mod]

it will

remember original Hitachi schematics , and all other derivatives .......

 

[tinitus]

great, thanks

I fear my Renesas will get moldy 😛

 

[tinitus]

would it work in high biased class AB

it will

remember original Hitachi schematics , and all other derivatives .......

would it make sense to try classAB with Toshiba 2sk1530/2sj201 ?

 

[Zen Mod]

The World is your Oyster ........

😉

 

[tinitus]

it was just a thought i got after i decided to invest in some of those lovely 'leftovers' from the big F5X project

nice jfet input, the finest drivers, and the great Toshiba outputs

 

[tinitus]

at least i got me F5 Oyster Toshiba mosfets

 

[tinitus]

maybe I will be electricuted now 😱😀

 

[Zen Mod]

you're dead



beware of output mosfets polarity !

(sources to out )

 

[tinitus]

beware of output mosfets polarity !

(sources to out )

noted, thanks

 

[tinitus]

ahh, completely forgot the higher +/-40V means cascoded jfets
but lots of info available on that

 

[tinitus]

hope its ok to post juma's reg supply here
'borrowed' from his other F5 version with 2sk2013/2sj313

just got the idea to try and make it a 40V reg
(I happen to have two monster trafo with 2x38V)

would that be ok ?