Hello,
I saw that Ura1012 realised a VFET N-Channel Build and he replaced the 2sk82 by a THF51 :
https://www.diyaudio.com/community/threads/diy-sony-vfet-pt-2-n-channel-build.375437/post-6859881
Do you think I can get more power from this amp ?
Many thanks,
Guillaume
I saw that Ura1012 realised a VFET N-Channel Build and he replaced the 2sk82 by a THF51 :
https://www.diyaudio.com/community/threads/diy-sony-vfet-pt-2-n-channel-build.375437/post-6859881
Do you think I can get more power from this amp ?
Many thanks,
Guillaume
Last edited:
Yes. The VFET is quite robust, but you will need lots of heat sink and a
big power Mosfet current source and power supply to get there.
big power Mosfet current source and power supply to get there.
Many thanks for your answer Mr Pass.
If I want to use it as is - ie just by replacing the 2SK82 by a THF51 - can I use all the current values of the components in the BOM ?
Regards
If I want to use it as is - ie just by replacing the 2SK82 by a THF51 - can I use all the current values of the components in the BOM ?
Regards
generally , Ugs** of 2SK180, 2SK182, THF51 "family" is different of Ugs of smaller ones , so that demanding some change in circuit
then, optimisation of circuit for bigger parts demands higher Iq, than is the case with Little Sony VFet amp
with those changes - better to look at some other amps already made by Greedy Boyz, originally with Biguns
there are at least 2 or 3 made as followers, be it with big IXYS mosfet puck as Mu load, or with choke
**voltage at gate needed to set SIT to desired Iq
then, optimisation of circuit for bigger parts demands higher Iq, than is the case with Little Sony VFet amp
with those changes - better to look at some other amps already made by Greedy Boyz, originally with Biguns
there are at least 2 or 3 made as followers, be it with big IXYS mosfet puck as Mu load, or with choke
**voltage at gate needed to set SIT to desired Iq
Last edited:
I will have a nice simple circuit for this fairly soon, something to let the SIT's personality come through.
👍I will have a nice simple circuit for this fairly soon, something to let the SIT's personality come through.
This sounds wonderful! I already have a pair of matched 2SK180 devices and appropriate aluminum bracket material. The CCS can be done with an IXFN140N20P or perhaps an IXTH64NL2?
I would lean hard towards 50V to 60V rail and an OPA552 or OPA445 based front end. Lots of fun possibilities..
I would lean hard towards 50V to 60V rail and an OPA552 or OPA445 based front end. Lots of fun possibilities..
I think this depends a lot on the power supply voltage used by the output stage. A higher voltage, say 48V to 60V could make good use of the big SIT transistors' capabilities. That higher supply voltage would also require some rework to the circuit design of the various front end cards. I think the answer is a qualified 'yes', particularly for the Dreadnought and Marauder cards, as they already run on about 58V internally for their amplification stages. The phase inversion would need an opamp substitution, or a robust means of dropping the local supply voltage to that device.
Papa is very clever. So is Mark J. I am currently directing some effort to chassis and power supply design, in anticipation of what may come.
Papa is very clever. So is Mark J. I am currently directing some effort to chassis and power supply design, in anticipation of what may come.
I found 60V or more work well with my 50W THF-51S Common Drain Mu Follower amp.
The CCS device depends on whether you have a positive or negative power supply. I chose to ground the drain of the THF-51S for least noise so I used a negative voltage supply and a P channel device, IXTN40P50P, for the CCS.
50W THF-51S Common Drain Mu Follower
IXTN40P50P
The CCS device depends on whether you have a positive or negative power supply. I chose to ground the drain of the THF-51S for least noise so I used a negative voltage supply and a P channel device, IXTN40P50P, for the CCS.
50W THF-51S Common Drain Mu Follower
IXTN40P50P