Panowie,
po pierwsze - proszę czytać uważnie - nie róbcie nadinterpretacji.
Nie napisałem że układ jest de best. Absolutnie nie. Jest to taki letni żarcik, próba zrobienia czegoś prostego. Nazwanie tego pierwszym na świecie lampizatorerm na tranzystorach nawet chyba mało inteligentny człowiek odbierze jako ironię.
Na świecie jest pewnie ze 100 tysięcy tranzystorów, katalog jest grubszy niż yellow pages nowego jorku, więc nie interesuje mnie poszukiwanie który gra lepiej, czy BF czt HD, siemens czy texas. Ani nie zamierzam trenować 20 alternatywnych schematów. Zdumiało mnie tylko że cos tak prostego w ogóle gra, i to bardzo czysto.
Moj prototyp jest na tranzystorze A a nie B, jak mylnie napisałem. Na A przy 1 mA jest bardzo fajnie, wolę to napewno od każdego opampa. W katodzie (ooops w Source) mam blackgaty a jakże.
A dla ciekawych - oto co T.h-o,r/s^ten Loe.s.h (nazwisko celowo zdeformowane) napisał do mnie (on wyjechał z Anglii do Chin i buduje tam swoją fabrykę gdzie planuje odlotowe klocki audio)
Look at LSK389, it is a Dual J-Fet that does not need a "cathode"
(source) bypass and is much lower noise and sounds better. Excellent
matching between the two transistors in one case.
Try LSK389B with 51R source resistor (unbypassed) and a drain resistor
of 2.2KOhm and +18V supply. This gives around 2.5V RMS out.
You can connect a small value capacitor (Silver Mica or Polystyrene,
470pF to 1nF) to create a lowpass around 100KHz (optinal but often
helps).
It may be a good idea to add another J-Fet as follower (another LSK389
for two channels) as Source (Cathode) Follower with a 2K2 Source
(Cathode) resistor.
This gives you under 100 Ohm output Impedance AND more importantly it
pretty much removes the modulation of the powersupply by the signal.
Wima has nice small 4.7uF/63V MKS capacitors that sound surprisingly
good as couplers and also as PSU Capaictor (with a Emitter Follower
based powersupply, 10K from collector to base and 100uF electrolytic
cap to ground, 4.7uF Wima PSU cap for each channel after a 78L18).
Something like this I have used quite a bit in modding CD-Players
without enough space for tubes, just never documented it (obviousness
to anyone skilled in the art and all). Works very well.
A small japanese company uses a similar analog stage to mine, just
more complex and not electrolytic capacitor free:
http://www.icl.co.jp/audio/m3-1.htmThis is for voltage output DAC PCM1716 (also works great on CS4327
which is in my Audio Innovation CD-Player which has this very similar
circuit but my style. In my case I keep the input section around the
2SK170 but use my own Follwer and PSU circuit.
It is quite good, though not as good as the modified Satch with (or
even without) tubes....
This whole thing can also be made balanced, both for Current and
Voltage output DAC. I have made a balanced version for a Pioneer
Legato Link CD-Player (also for one DVD-Player - the DV-505 which
sounds very good with fet analog stage) with good sucess (DAC is
voltage output).
And the J-Fet is also very good to buffer S/P-DIF.
Again, use the 2SK170 or LSK170 with 270R source resistor and 33 Ohm
in series with 0.33uF coupling capacitor from source to S/P-DIF or BNC
jack (values for 5V supply IC digital out, for 3.3V supply chip use
180R source resistor instead). Supply should be 12V.
