@lhquam, ZM, XRK .. and other attending gurus:
Now: I hope I do not get too far off topic: but now that you guys are brainstorming on using triode-like behaving LU lego with possibly different FEs or maybe driving a bigger output stage etc:
I have little (next to none) circuit knowledge but there is this circuit which got me intrigued when indra1 floated a sim of it a while back. It uses all Toshiba transistors (1530/201, 2013/313) which I have and would like to put to some use. Now he simmed it with a 2SK79 but he also mentioned a tube (6DJ8) which could be substituted (this would be my last resort but preference is for a vfet-like part or alike pretending SS lego):
Could you guys look at that circuit and provide some comments on how doable some iteration of this might be?? maybe with a LU lego? if not too much to ask.
Thanks a lot!
here is the link to the original post:
https://www.diyaudio.com/forums/pass-labs/314822-greedy-boy-defisit-papas-koans-24.html#post5309442
Now: I hope I do not get too far off topic: but now that you guys are brainstorming on using triode-like behaving LU lego with possibly different FEs or maybe driving a bigger output stage etc:
I have little (next to none) circuit knowledge but there is this circuit which got me intrigued when indra1 floated a sim of it a while back. It uses all Toshiba transistors (1530/201, 2013/313) which I have and would like to put to some use. Now he simmed it with a 2SK79 but he also mentioned a tube (6DJ8) which could be substituted (this would be my last resort but preference is for a vfet-like part or alike pretending SS lego):
Could you guys look at that circuit and provide some comments on how doable some iteration of this might be?? maybe with a LU lego? if not too much to ask.
Thanks a lot!
here is the link to the original post:
https://www.diyaudio.com/forums/pass-labs/314822-greedy-boy-defisit-papas-koans-24.html#post5309442
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I have about 7000 of them. If someone wants to organize a group buy let me know.
Also we are considering a diy f3 kit for the store. Maybe ludef kit as well?
Very exciting indeed! I am definitely interested in any GB and kits if available.
PM sent- let's start working out the details of the group buy. I'll try to connect with Papa in the next day or so and get specifics from him.
Once I have info from both of you, I'll set up a Group Buy posting and start a list of interested parties for Lu1014.
Very exciting indeed! I am definitely interested in any GB and kits if available.
I'm in!
I would be surprised...I would think most commercial outfits would think that there's too many active components just to get a little perfection out of two. It looks like something that only crazed DIYers would do.
Let's do it!
I didn't realize the small size of the TO251 JFET package until carefully studying the LU1014D datasheet and finding the posts about FirstWatt F3 clone builders using copper heat spreaders: JFET's ready for abuse and Mounting LU1014D.
ZM: Some questions about the PCB artwork shown in post #2 and #6:
- Doesn't the PCB fab facility charge extra for the large number of through-holes, and aren't they a bit of overkill?
- Is the hole cutout for the JFET done at the PCB fab house or by you?
- What is the rectangular material between the JFET and the big washer?
- How do you electrically insulate the JFET metal tab from the aluminum heatsink?
-JLCPCB doesn't; no, nothing is overkill if it brings me smile
-fab (second/final batch of pcbs is having slightly bigger/maximised cutout and minimal copper around nearest Via for screw
-just piece of bare pcb material , "frame" leftovers I have from before; not exactly needed - there is some clearance between big washer and pcb, but I felt safer this way;even piece of cloth isolating tape on pcb (under the washer area) will do the job
-on T-Bed - used mica+goop; will advise Keratherm; heck , even will send Keratherm cut for LU in kits
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What is the rectangular material between the JFET and the big washer?:
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How do you electrically insulate the JFET metal tab from the aluminum heatsink?
-just piece of bare pcb material , "frame" leftovers I have from before; not exactly needed - there is some clearance between big washer and pcb, but I felt safer this way;even piece of cloth isolating tape on pcb (under the washer area) will do the job.
Why is electrically insulating material needed? Wouldn't aluminum or copper help?
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How do you electrically insulate the JFET metal tab from the aluminum heatsink?
-on T-Bed - used mica+goop; will advise Keratherm; heck , even will send Keratherm cut for LU in kits
With only 29 mm^2 metal tab area, it seems that best possible thermal conductivity would be advisable.
- see pics - LU is just slightly thicker than pcb itself; without distancer put directly on LU, metal washer would be too close to pcb track and I don't trust in isolation lacquer to withstand too much abuse
- logically, but there is just 1A5 x 2V4 dissipation ; see F3 pics floating around - Pa did it good enough, and didn't loose sleep after
so - Keratherm, just because we can
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I have about 7000 of them. If someone wants to organize a group buy let me know.
Also we are considering a diy f3 kit for the store. Maybe ludef kit as well?
Having F3 and LuDEF kits in the store would be awesome!
ZM:
OK, I think I now understand the problem. Tell me if I am wrong:
The JFET for the right channel is mounted face-up relative to the bottom-side of the PCB, and the JFET for the right channel is mounted face-up relative to the top-side of the PCB. The area of possible short between the washer and a PCB trace is on the bottom-side.
OK, I think I now understand the problem. Tell me if I am wrong:
The JFET for the right channel is mounted face-up relative to the bottom-side of the PCB, and the JFET for the right channel is mounted face-up relative to the top-side of the PCB. The area of possible short between the washer and a PCB trace is on the bottom-side.
exactly
if you look more at renders in post #2, you'll see that in one channel LU is on same side of L bracket as Mosfets ( and yes- due to LU , this pcb can be mounted only if using L bracket), while on the other channel pcb , LU is mounted underside of L bracket , contrary to mosfets (same mounting on both channels)
also visible in post #6 and #8
I wasn't exactly inventive that much, had some influence of original FW solution there, even if Pa arranged LU underside on both channels
if you look more at renders in post #2, you'll see that in one channel LU is on same side of L bracket as Mosfets ( and yes- due to LU , this pcb can be mounted only if using L bracket), while on the other channel pcb , LU is mounted underside of L bracket , contrary to mosfets (same mounting on both channels)
also visible in post #6 and #8
I wasn't exactly inventive that much, had some influence of original FW solution there, even if Pa arranged LU underside on both channels
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buy them, good to have ....... for skin, beauty in general, everything starts with big green
and yes, VFet can be replaced with LU cell