sound quality of different transistors? - Page 4

tomcat · 17th June 2002, 11:09 PM

I agree with you Nelson, neurosis is the right term for a lot of these things, like running things in, some of which is pie in the sky stuff. For example, cables, resistors, etc,... Speakers yes, but passive devices?, mostly I think is some wishfull thinking, allied with instead the ear getting used to the different sound due to whatever changes one had made with extended listening, which incidentally can also (to contradict myself) apply to speakers as well. That is, unless one has an unused reference pair to hand to compare them with. I also agree with your view on topoligy, only I don't think there has been as much work or investigation done into the audible difference between similar devices that basically do the same thing in the same circuit like others have done with tubes... Thats all I was trying to determine when I started this thread...
And now that I have blasphemed and set the cat amongst the pigeons, I better sign off, lest I be smitten by on high...

Let sanity reign supreme and peace be with you...
Cheers,
tomcat

Nelson Pass · 17th June 2002, 11:12 PM

Personally, I retain my balance by reminding myself that
this is the entertainment industry. Whatever entertains
has a right to respect.

tomcat · 17th June 2002, 11:53 PM

Nelson,
Lest you think my comments were directed at you personally, please be reassured they weren't. I was generalising. Otherwise I agree with you... You are right again, it is entertainment, so if it keeps some of us off the steets and occupied, the better.
tomcat

900gripen · 18th June 2002, 02:42 AM

To grege.

Hi Greg,

I note your comments on the AKSA. I haven't seen the current circuit, only an old concept drawing. A suggestion for the DIGI biassing is to replace 2 diodes with transistors connected as diodes
and mount them on the main heatsink. Mount a third diode (1N914/1N4148) on the board with a 200 Ohm multi-turn trimpot
and ajust the quiescent current for 100mA. The two 'diodes' mounted on the heatsink will regulate the biasing when the output devices get hot as Vbe for the two diodes we have made will drop and throttle back the quiescent current. The third diode mounted on the board with the trimpot will hold some biassing so that even when the Vbe drops to minimum on the devices mounted on the heatsink, there will still be some biasing applied to the circuit as not to increase distortion too much! I suggest BD139s for these transistors.

I have tried the Toshiba devices as Tomcat suggested. They are definitely worth the effort of replacing. They put the DIGI-125 ina different league in my opinion.

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17th June 2002, 11:09 PM	#31
tomcat diyAudio Member Join Date: Sep 2001 Location: Sth. Oz	I agree with you Nelson, neurosis is the right term for a lot of these things, like running things in, some of which is pie in the sky stuff. For example, cables, resistors, etc,... Speakers yes, but passive devices?, mostly I think is some wishfull thinking, allied with instead the ear getting used to the different sound due to whatever changes one had made with extended listening, which incidentally can also (to contradict myself) apply to speakers as well. That is, unless one has an unused reference pair to hand to compare them with. I also agree with your view on topoligy, only I don't think there has been as much work or investigation done into the audible difference between similar devices that basically do the same thing in the same circuit like others have done with tubes... Thats all I was trying to determine when I started this thread... And now that I have blasphemed and set the cat amongst the pigeons, I better sign off, lest I be smitten by on high... Let sanity reign supreme and peace be with you... Cheers, tomcat

17th June 2002, 11:12 PM	#32
Nelson Pass The one and only Join Date: Mar 2001	Personally, I retain my balance by reminding myself that this is the entertainment industry. Whatever entertains has a right to respect.

17th June 2002, 11:53 PM	#33
tomcat diyAudio Member Join Date: Sep 2001 Location: Sth. Oz	Nelson, Lest you think my comments were directed at you personally, please be reassured they weren't. I was generalising. Otherwise I agree with you... You are right again, it is entertainment, so if it keeps some of us off the steets and occupied, the better. tomcat

18th June 2002, 02:42 AM	#34
900gripen diyAudio Member Join Date: Jun 2002 Location: Australia	To grege. Hi Greg, I note your comments on the AKSA. I haven't seen the current circuit, only an old concept drawing. A suggestion for the DIGI biassing is to replace 2 diodes with transistors connected as diodes and mount them on the main heatsink. Mount a third diode (1N914/1N4148) on the board with a 200 Ohm multi-turn trimpot and ajust the quiescent current for 100mA. The two 'diodes' mounted on the heatsink will regulate the biasing when the output devices get hot as Vbe for the two diodes we have made will drop and throttle back the quiescent current. The third diode mounted on the board with the trimpot will hold some biassing so that even when the Vbe drops to minimum on the devices mounted on the heatsink, there will still be some biasing applied to the circuit as not to increase distortion too much! I suggest BD139s for these transistors. I have tried the Toshiba devices as Tomcat suggested. They are definitely worth the effort of replacing. They put the DIGI-125 ina different league in my opinion.