Thank again @itsallinmyhead & @6l6 - I'll go on with the speaker selection and then start also with the F6, at the moment the basic kit set for the F6 is not available... but I'll be notified. 
Let's see how the amp (building) is going on... then a DIY pre-amp could be a good idea.
Again, thanks!
Let's see how the amp (building) is going on... then a DIY pre-amp could be a good idea.Again, thanks!
I will second the recommendation for the Toroidy transformers from Poland. They will wind you custom voltages if you need and the quality and prices are excellent. I suggest getting the high grade options of electrostatic shielding, potting into the polished metal shell and the mounting frame for it and whatever else I may have forgotten about.
I've noticed good high quality products coming out of Poland. In addition to Toroidy, I can recommend Shipibo.Audio for DIY headphone parts and upgrades. Also Lampizator has amused me for years with their postings of DIY explorations that demonstrated their comitmant to quality that ultimately resulted in a HiFi company that has achieved success.
modding F6
Hi TungstenAudio,
I m thinking of modding my F6, Is the FQH44N10 a direct drop-in replacement?
Currently using 6.1V Zener, I probably will have to rebias again after the changes. What kind of bias current should I target for? My heatsink is around 45degC after hours of music on the IRFP240.
Is there anything else I can do for the F6?
Thanks.
Hi TungstenAudio,
I m thinking of modding my F6, Is the FQH44N10 a direct drop-in replacement?
Currently using 6.1V Zener, I probably will have to rebias again after the changes. What kind of bias current should I target for? My heatsink is around 45degC after hours of music on the IRFP240.
Is there anything else I can do for the F6?
Thanks.
Yes, the FQH44N10 is pretty much a drop in replacement for the IRFP 140 or 240. As you expect, it will need an adjustment to the bias and offset. The 6.1V Zener should still be sufficient, though you might consider switching to three green LEDs in series instead. It will help to have a negative tempco bias circuit. The FQH part will also perform well with higher Iq, so you might also try pushing 1.8A through the output stage.
re/ the three green LEDs for temp compensation, which ones would work well re/ temp, noise etc? Could somebody propose a part number (Mouser)?
Thanks a lot! LATB
Hi LATB,
Pico wrote about the temp compensation here, including parts he tested with:
Dumb Biasing Mod, applicable to F6 and other Papa Amps. Possibly My Dumbest Idea Yet
Cheers,
Dennis
Pico wrote about the temp compensation here, including parts he tested with:
Dumb Biasing Mod, applicable to F6 and other Papa Amps. Possibly My Dumbest Idea Yet
Cheers,
Dennis
awesome! 3 x LTL-4231N LTL-4231N Lite-On | Mouser
Thanks for the pointer, I should spend more time on diyaudio to read all these threads...!
Thanks for the pointer, I should spend more time on diyaudio to read all these threads...!
Make some progress today.
It works!
Currently cooking on bench @1.65A, the output is solidly stable near Zero after proper trimmings.
Noticed the temp on the heatsink climb at a faster rate and plateau out quickly too.
Meaning i don't have to wait too long for the amp to get heated up to optimum temp.
Awaiting for the SLB, classis then go full bias!
Thanks NP and TA for sharing your design.
It works!
Currently cooking on bench @1.65A, the output is solidly stable near Zero after proper trimmings.
Noticed the temp on the heatsink climb at a faster rate and plateau out quickly too.
Meaning i don't have to wait too long for the amp to get heated up to optimum temp.
Awaiting for the SLB, classis then go full bias!
Thanks NP and TA for sharing your design.
just kidding, I'm just super jealous 
@Meanie - That is very cool! Thanks for sharing the source.
Also, thanks for the clear pics of the LED implementation. I had read Pico's post thoroughly. Technical piece flew a bit over my head, but I got the gist and began to understand TempCos and whatnot. Seeing it implemented now makes perfect sense from purely an execution standpoint.
Also, thanks for the clear pics of the LED implementation. I had read Pico's post thoroughly. Technical piece flew a bit over my head, but I got the gist and began to understand TempCos and whatnot. Seeing it implemented now makes perfect sense from purely an execution standpoint.
Hi guys. I have a whole set of F6 parts for sale - see my ad in the SWAP meet section. $200 with free shipping for the amplifier sections (almost all the parts you need to stuff the boards including the transformers). Another $50 will get you a stuffed power supply board + (2) IXYS Hexfred bridge rectifiers.
I have too many projects laying around to finish - someone needs to pick this up and run with it. I also have a notebook stuffed with documentation that I will throw in for free.
I have too many projects laying around to finish - someone needs to pick this up and run with it. I also have a notebook stuffed with documentation that I will throw in for free.