What sound card do you use, and any sound comparisons between 2SK725 and IRFP240?
Here's my F1J build, thanks Chas for the board group buy. Also about to test a design I did in parallel, related to the F1.
Attachments
Just a brief update. For those who run F1/F1J in unbalanced mode, with one side grounded, consider installing balancing transformer inside. It works great for me. I used this small transformer. Sounds very clean. Although I never pushed it beyond a watt.
https://www.amplifiedparts.com/sites/default/files/associated_files/p-t-lehle-mz-l.pdf
https://www.amplifiedparts.com/sites/default/files/associated_files/p-t-lehle-mz-l.pdf
Attachments
I have not, but I'm interested in the answer. I have an F1J and I'm thinking about building another without the Semis.
I'm managing a GB for the LU1014D from Papa's stash. Papa has donated LU1014D and we've sorted them into matched pairs. Small PCBs for the LU1014D have been created along with the hardware to connect it to the amp PCB.
Parts are shipping this week from vendors and I should be able to distribute items to the group soon. There's still time to sign up. Cost should be low, just a couple of dollars for parts and various shipping to your region.
Thread-
Lovoltech LU1014D Power Jfet Group Buy
LU1014D sign up sheet
I received mine from aliexpress, smd. Had no issue to select four just by using Idss. Managed to attach them to heatsink with just a clamp. I will test them in F1J and report back. I do not participate in any GB.
No worries.
Sounds good. That's the LD1014D, correct? I ordered some from Aliexpress, too. Very inexpensive.
I'd like to hear how they perform. It would be nice to find a substitute for the hard to find and expensive SemiSouths.
If they do work well, please let us know how you integrated them into the F1J.
it looks very promising right now
I was going up with power slowly, so no harm done
at 10 volts power supply, it started to play nice
at 12 volts, 4 volts at drain, sound was loud and clear
at 15 volts supply, 5-6 volts on drain, amazing sound,
but it was drawing 3.5 amps, per channel, so I slowed down
interestingly, when I backed up, and run it at 12 volts
it sounds already amazing, current is manageable, and does not heat up too much
jfets are actually not that hot, its the mosfets
I believe because of very low Rds when fully on, jfet has little resistance and heat is not too much of a problem
I was going up with power slowly, so no harm done
at 10 volts power supply, it started to play nice
at 12 volts, 4 volts at drain, sound was loud and clear
at 15 volts supply, 5-6 volts on drain, amazing sound,
but it was drawing 3.5 amps, per channel, so I slowed down
interestingly, when I backed up, and run it at 12 volts
it sounds already amazing, current is manageable, and does not heat up too much
jfets are actually not that hot, its the mosfets
I believe because of very low Rds when fully on, jfet has little resistance and heat is not too much of a problem
i would prefer parallel jfets
no need for much power, current sounds good
especially in current drive amp
no need for much power, current sounds good
especially in current drive amp
Yup, i have seen your LuDEF, just too many projects. May be later.
I keep my power supply low, so no chance exceeding 20 volts Uds. This little jfet can handle current for sure.
I keep my power supply low, so no chance exceeding 20 volts Uds. This little jfet can handle current for sure.
20V for entire amp
what I meant - keep LU Uds voltage low
ZM is Chicken, I wouldn't go above 5V
what I meant - keep LU Uds voltage low
ZM is Chicken, I wouldn't go above 5V