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121.127.223.39
hi again guys.....
in my rotel ra971mk2 ( also in ra1060,ra1062 ) , i can see a couple of 1N4003 in series with one end at the +49v rail and the other end at the -49v rail for each channel.
This is rite at the end of the amplifier stage , with the output stage fuse link being rite in middle of the diodes and this tie goes all the way to the power transistors' emitters.( ill upload a pic of the cct if it's still not clear guys )
Now the questions pls-
1)I know the diode is rated for 200v , 1A . In this case is it safe to replace with a schottky or soft recovery with higher or lower voltage rating ?( with higher current rating ).
2) What would be an ideal condidate in this case guys, FREDs or schottky (or the new SiC schottky)
3)Finally if i may ask, what's the purpose of those diodes in the amplifiers' gain stage ?
Pls suggest , this is the last stage that i need to know to begin my surgery.... thanx in advance
Follow Ups:
The best diodes you can use as rectifiers for your PS are the Cree Schottky diodes available from Parts Connection in several flavors : 2, 4, 6 & 10 Amp. Then install snubbers on the output of all your PS bridges with a 0.01 uF stacked film cap in series with a 4/8 ohm CC R across the output of the bridges with the cap on the + output for a + supply & the R connected to Gd. & visa-versa for a - output supply.
Happy Listening !
Have any of you tried using the Fairchild Semi "Stealth" diodes in this application.
Sounds like the combo of fast switching with soft recovery of these stealths would be of benefit vs. the Schottkys.
What do you guys think.
Cheers
you only need snubbers on switching diodes ...schottky's s a mass migration principle and therefore no reverse switching ie a snubber on the schottky's may inhibit their very good performance ....
having swapped more 1nxxxx diodes for schottky's than I'd like to admit to... its clear to me that the gear sounds better if you remove the snubbers often prviously fitted to tame the 1nxxxx diodes clicking .. this of course is only my opinion but I do thinkit sounds better
Why use snubbers with schottky's? Well they don't produce a voltage spike when shutting off but the capacitance of the diode and the inductance of the transformer secondary form a tank circuit which is excited when the diode switches off...
Oh very mature...and incorrect as it happens. Perhaps if you researched the matter you would learn something.
Wired to keep the amp output between the +/- rails, where it should notmally be.
If these diodes ever conduct the amplifier is out of control (so will be your ears!) usually as a combination of overload plus a severe reactive load. There are other fault conditions which could provoke this.
Since they are not power rectifiers or (normally) switching you may conclude that there are other more rewarding components to be tweaked.
thanx clifff ....
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