Interesting , Why would the F5 with the stiffer power supply and better parts exhibit more 2nd order distortion ?
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My power supply is probably the wimpiest of the lot - I mistakenly ordered 5A 18VCT EI transformers per channel (should have been 10A at least), so only 180VA and with very poor load regulation. I have 80,000uF capacitance per channel, and the amps are built as monoblocks.
Anyway my DC rails are 23V (!) and I operate the amp at full bias. The closest impression I have of the sound of my amp is very similar to amp 1 being discussed, though I don't know if cold is the right word.
I don't have the thermistors any more, I don't know if there's an improvement in the sound quality, but the bias is now much more stable though the amp does take time to warm up.
I've invited a bunch of folks to listen to the amp (with its murdered PCBs after a major troubleshooting session lasting two days). Will post some their impressions later.
Anyway my DC rails are 23V (!) and I operate the amp at full bias. The closest impression I have of the sound of my amp is very similar to amp 1 being discussed, though I don't know if cold is the right word.
I don't have the thermistors any more, I don't know if there's an improvement in the sound quality, but the bias is now much more stable though the amp does take time to warm up.
I've invited a bunch of folks to listen to the amp (with its murdered PCBs after a major troubleshooting session lasting two days). Will post some their impressions later.
Clc ps
Hello Botte,
I'm thinking about winding some coils for a CLC ps for a F5 build. If you are able, please comment on the sound differences you heard between a CRC and CLC PS. Did you wind your own or did you buy them? If you diy, could you give me specifics on your method? Some pics would be nice if you have some on hand. Thanks,
David
Hello Botte,
I'm thinking about winding some coils for a CLC ps for a F5 build. If you are able, please comment on the sound differences you heard between a CRC and CLC PS. Did you wind your own or did you buy them? If you diy, could you give me specifics on your method? Some pics would be nice if you have some on hand. Thanks,
David
No question L in the power supply makes substantial difference in sound for the better compared to CRC. Isolate your P1-R3/P2-R4 (or single resistor) feed to the jfets with the same CLC type arrangement and be prepared for additional benefit.
Botte, what is your operating voltage @1.6A bias with the 22V transformer?
Botte, what is your operating voltage @1.6A bias with the 22V transformer?
I like the F5 sound such as Nelson created him🙂 I do not need further improvement. (maybe my ears are not as good as yours) I read with interest the results of your experiment! My transformer with 17VAC gives out only 21.5 V DC - but sounds good anyway!
My amp run +-32 volts at 1.6 Amps. Here are a few pics.
I originally used this chassis for an aleph 30 copy. I must say that I like the F5 better in my system.
🙂
I originally used this chassis for an aleph 30 copy. I must say that I like the F5 better in my system.
🙂
Feeding Jfets
Hello compressit,
Thanks for your thoughts. I don't understand what you mean: to "isolate your P1-R3/P2-R4 feed..with the same CLC type arrangement." Are you proposing an additional separate CLC network feeding the jfets? If so what values?
Thanks,
David
Hello compressit,
Thanks for your thoughts. I don't understand what you mean: to "isolate your P1-R3/P2-R4 feed..with the same CLC type arrangement." Are you proposing an additional separate CLC network feeding the jfets? If so what values?
Thanks,
David
I figured you'd chime in here soon enough! I would say that I prefer YOUR F5 in your system.
I wonder if the IR fets need a little higher rail voltage to hit their sweet spot over the fairchilds? If so, I'd be amenable to picking up some of the fairchilds and dropping them into my amp (Cheaper than a new trafo). I also plan on stiffening up my PS with some additional capacitance. I don't think I have room for any coils.
Big Block PS
Yes I am, and yes I do. Jensen 4 pole>480uf to ground>2mH aircore. I am not recommending these values or parts, but it's what I had lying around that worked well. The cap to ground didn't measure as doing anything but still remains for now.
My medieval PS will crush your puny CRC 😀
Yes I am, and yes I do. Jensen 4 pole>480uf to ground>2mH aircore. I am not recommending these values or parts, but it's what I had lying around that worked well. The cap to ground didn't measure as doing anything but still remains for now.
My medieval PS will crush your puny CRC 😀
Attachments
Oww, aren't those copper two-side screw terminals pretty.
And the other two dandy looking coils are ?
And the other two dandy looking coils are ?
Every coil has an operating temperature, you'd have to use Ohm's law to calculate the power dissipation (P=IR^2) then determine if there is adequate sinking to dissipate that heat.
*Or you could just use a larger gauge wire... I'd go with 10 or 12 and give the coil some room to breathe.