6L6 posted that he didn't feel fancy rectifiers were necessary for our class A amps, and standard bridges were fine. I don't remember that he thought they degraded the sound. Fancy rectifiers make more difference in AB amps according to Jim. Feel free to experiment and draw your own conclusions. This is DIY after all. 
yes, you are right: page 12, "The same Vishay rectifiers are used here" Nelson wrote....
I remember a very old article from Nelson where he describes that slow bridges are best for class A amps. But later on, he says they are using fast recovery diodes at Pass Labs, to meet some RFI requirements....
So it doesn't really matter, I guess...
There are people who say they hear a difference between rectifier diodes, but as usual I don't hear any ....
Walter
I remember a very old article from Nelson where he describes that slow bridges are best for class A amps. But later on, he says they are using fast recovery diodes at Pass Labs, to meet some RFI requirements....
So it doesn't really matter, I guess...
There are people who say they hear a difference between rectifier diodes, but as usual I don't hear any ....
Walter
What I was getting at is that Nelson has an entire article on PSU, found here -- https://www.passdiy.com/project/articles/power-supplies (yes, the order of the article is messed up a bit)
...and he mentions that slow diodes are better for our class-A PSU.
I've used slow, fast, and very fast diodes and honestly can't tell any difference. Because of that I find that I prefer the 4-pin monolithic diode bridges, as they are very compact, noticeable less expensive than discrete diodes+heatsinks, have little rejected heat and are quite easy to mount.
I would not go out of my way to use high-speed diodes thinking that they are better, but if I have them on hand, I'll gladly use them. The PSUv3 has holes for discrete and heatsinks and if nothing else, they look fantastic. And it is very nice to have one PCB with the entire PSU on it.
The short answer is that there probably isn't a wrong answer.
Where the fast diodes seem to make the most difference isn't in AB amps, but in line-level projects. After a long conversation with Wayne at Burning Amp '11, he explained all the reasons why they are worth using for preamp and phono applications.
No better advice could be given.
...and he mentions that slow diodes are better for our class-A PSU.
I've used slow, fast, and very fast diodes and honestly can't tell any difference. Because of that I find that I prefer the 4-pin monolithic diode bridges, as they are very compact, noticeable less expensive than discrete diodes+heatsinks, have little rejected heat and are quite easy to mount.
I would not go out of my way to use high-speed diodes thinking that they are better, but if I have them on hand, I'll gladly use them. The PSUv3 has holes for discrete and heatsinks and if nothing else, they look fantastic.
And it is very nice to have one PCB with the entire PSU on it. The short answer is that there probably isn't a wrong answer.
Where the fast diodes seem to make the most difference isn't in AB amps, but in line-level projects. After a long conversation with Wayne at Burning Amp '11, he explained all the reasons why they are worth using for preamp and phono applications.
Feel free to experiment and draw your own conclusions. This is DIY after all.
No better advice could be given.
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I wonder how much of that part is driven by sound quality and how much be regulations about how much noise the amps can impart on the line. Not to impugn the products' quality at all, I've just been beaten about the head and shoulders by too many regulations lately.
eeeeee...the head, I can understand. The shoulders...once they're gone, no more head to hold and beat about...
Dear sangram,
I just can't understand the thermistor move. The first version makes much more sense to me, since it acts on the root of the bias mechanism, the jfet drain resistance. The second version, besides your point, confuses me in the sense that even if the thernistor is, as you said, "pinching off" the device Vgs, the voltage generated by the drop on the drain resistor is going to be over the source resistor, increasing the current. Perhaps Mr Pass could enlighten us?
Thanks
Daniel
Any opinions on the ON MUR3020WTG compared to the Vishay MUR3020WTPBF; I ask especially since the price for the ON version is very attractive at $1.69 at Arrow. To my novice eye the data seem similar though the charts look slightly different.
Imo, the key parameter is the Vf and the associated graph. This tells you the cut on point of the diode and its subsequent response and this is relevant to biasing the output stage. Other than that, I don't know that you could tell any difference at all in the parts. On a couple of occasions, I have seen where Nelson uses slight differences in different parts manufacturers parameters to achieve a final goal. A faster/lower Vf means an inherent decrease in bias(maybe not significant) and slower/higher Vf, the opposite.
Finished building my F5T V2 yesterday. Powered on one channel with the bulb tester and no smoke! So for biasing I should shoot for 0.6vdc across the test points on the output boards? I did hook it up to a speaker and only a little sound came out with the full 2v of the source. Thanks! I am preparing the close up pictures for the inevitable issues.