.........il transistor ad effetto di campo detto anche Jfet è un componente elettronico che ha un funzionamento completamente assimilabile a quello di una valvola triodo e a detta di molti audiofili anche il suono è molto vicino, percui mi sono detto:"perchè non progettare un buffer a Jfet per lettori CD/DVD"
Il principio è semplicemente quello di un "anode follower triode" riportato al Jfet usando tensioni di anodo ...in questo caso "drain" molto ridotte, infatti un fet lavora bene a partire da 12V!!!!
Il suono??? Non ci sono parole per descrivere il miglioramento su tutti i parametri : soundstage immenso (questo parametro è quello che mi ha maggiormente colpito!), dettagli su tutta la gamma e bassi potenti estesi e dinamici! Un vero piacere di ascolto audiophile!
Exceptional image and sound quality, with wide-ranging format and disc compatibility. Progressive Scanning (PAL/NTSC)
CD upsampling (2x/4x)
108MHz/12-bit video D/A converter
192kHz/24-bit audio D/A converter
DVD-Video, Super VCD, VCD, Audio CD, DVD+RW/+R*, DVDR/- RW* and CD-R/RW*,**,*** playback
MP3, JPEG, DivX and WMA playback (multisession) with navigation display
Picture CD (such as JPEG) playback with display
MP3 fast forward/rewind/repeat/shuffle playback
JPEG/MP3 simultaneous playback with slide show
6-step multiple zoom
Easy operation with GUI (Graphical User Interface)
CD Text display (English)
4 video picture modes
Screen saver
3-step dimmer
Sleep functions
Night mode
Program play
PAL/NTSC conversion
* Only compatible with discs that have been finalized when recording is completed. Some discs may not play due to disc characteristics or recording conditions.
** Only compatible with discs that have been recorded in CD-DA format or Video CD format and Super Video CD format.
*** Some MP3, JPEG, DivX or WMA discs may not play due to disc characteristics or recording conditions.
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BF245 output circuit |
My note:
First time I liked this player "siluette"! It's very slim and pleasant look, but how does this work?
Even before listen it I had to use my screwdriver , take off his upper shield and explore all his secrets!!
What can we find inside this cosy slim player?? Don't expect to find a toroid in the supply session indeed! Like all power supply of those slim player u can find an electronic conversion circuit based on operational IC. They could do well their work giving even a lot of current but they warm a lot sometime and they re a bit less reliable compared to their magnetic friend......anyway this doesn't matter now .....this one is well done with a fair large stabilizer capacitors.
The DAC section is based on a AK4382 japan made which is the jewel of this player (with the highly regarded mediatek chip MT1389FE in the field of video decoding).
Well we can start from the DAC chip stoling the signal from his output pin and developing a new active low pass filter for a very better and audiophile output inside this player!
I thought to use Jfet to simplify all and give the best at sound! ... closest to tube sound as possible!!
After a fairly long setup now it's running soo good giving magic at the music!!!
The recipe:
Swap all critical capacitors with the most performing panasonic or sanyo os-con in the digital section, bypassing most of them with polypropylene caps, grounding the shield of the quartz;
Improve components even in power supply using higher value caps and schottcky diode in rectifier.......
....care all the frame against vibrations with several products to avoid jitter errors of laser pick-up.....
......and at last but not the least important the heart of this audio device : my Jfet buffer!!
It's a kind of tube anode follower...yes guys..jfet is quite close to tube concept and Jfet is the closest in matter of sound!!! ;
The sound:
Now soundstage is huge the music is achieving his 3D dimension now, and in all this space u can much more easily recognize every single instrument like u couldn't do before!U can easily find a space collocation for each of them!
The voices are so natural and more forward and the cymbals sounds so sweet never harsh.....
piano?!!,..the king of instrument sounds like it was in ur room
......and the bass shouldn't be never muddy...they should vibrate from the very deep to the top....speedy and controlled(but this is more a duty for amplifier and speackers......if the source is worthy ;-) )
This is not the only way to tweak one audio device ...I achieved very good results even with fast operational and I didn't tried yet tube inside cd-player cause of lacking room andthe use of high voltage , but I will invent something very soon!
Thanks to Alberto of "Dragun's pub" of Camogli (Ge)!!!!!
He's actually the lucky owner of this fairy sounding device.....
......all the people who would want to hear it ,has to go to his pub , drink a very good beer and just enjoy of a very nice friendly gang and listening outstanding music .......
Grazie Albi!!! ;-)
Now it works in the Brunella house near Asti ...and she's very happy with it!
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