Diodes and Noise

[rp]

Are there axial hexfreds? I ask cause they'd be easier to mount on terminals. I'm up for giving the Fairchild Stealth dual diode a try despite my no hifi parts vow and will add them to a Mouser order. Cheap and I can deal with the TO220 package with a little forethought.

Must they to be heat sunk or no different from axials types? Thanks DR for pointing these out.

I'm not sure if the developing debate is whether diodes can be heard but a CJ MV52 is no amp to sneeze at. This is modern clear transparent warn fast 3D tube stuff. To me the hexfreds vs the stock 1n4007 were night and day across the board - and for the better for once. A year later CJ started putting Hexfreds in their amps. Now whether they bring something in terms of sonics or feel to guitar amps besides lower noise is my question.

God I hope I don't start back sliding and start with the hifi parts in guitar amps again.

[tubeswell]

Like others here, I also have heard audible reduction in 'buzz' using snubber caps on (1N4007) rectifier diodes, and I have tried the rectifier with and without snubber caps and there is a difference.

Mind you the unit I tried this on was a 6G15 clone (built with a FW SS rectifier using 2 diodes on each side of the HT winding), so that would've made the whole set up more prone to picking up extraneous noise (because it is in front of another amp). But the snubber cap definitely reduced the audible buzz.

FWIW this is not a myth or hearsay - it is my own experience

[20to20]

Like others here, I also have heard audible reduction in 'buzz' using snubber caps on (1N4007) rectifier diodes, and I have tried the rectifier with and without snubber caps and there is a difference.

Mind you the unit I tried this on was a 6G15 clone (built with a FW SS rectifier using 2 diodes on each side of the HT winding), so that would've made the whole set up more prone to picking up extraneous noise (because it is in front of another amp). But the snubber cap definitely reduced the audible buzz.

FWIW this is not a myth or hearsay - it is my own experience

You haven't identified the source of the "noise." My point is that there is no audible "noise" from a good rectifier switching off or on. If you want to say a snubber cap can reduce a noise coming from the PS or line, I wouldn't argue that too far. BUT, if the amp came noisy from the factory, I'd call it a crappy amp and send it back, I wouldn't fix it by adding snubbers. If my nice quiet amp from the factory started "buzzing" I wouldn't fix it by adding snubbers. If I built a noisy amp to start with, I wouldn't fix it by adding snubbers, I'd start over or look for mistakes.

[iknowjohnny]

Ok, enough people have noted a buzz even if slight. so i'm gonna take thier word on it and add snubbers just to be safe. heres the question tho....where the %$#@ are you guys getting 1000 volt electro caps, and aren't they huge?! what am i missing here? i doubt i could fit 4 of them in my amp. i'd have to go outside the chassis.

[ChrisM]

You don’t need electrolytic caps. Electro caps probably wouldn’t be good at all.

You want to use ceramics. 1000V (1KV) 10nF (0.01uF) should do the trick.

[iknowjohnny]

ahhh, i see. don't know why i had the idea they ere electros. thanks

[Zippy]

Look on the first page of this thread to see selloutr's implementation...

[iknowjohnny]

Look on the first page of this thread to see selloutr's implementation...

Why the resistors, and are they necassary?

[FYL]

Why the resistors, and are they necassary?

Load balancing. Not required with modern diodes.

[David Root]

rp, I use a small heat sink on the Stealth dual diode, but I only do that because I can't be bothered to take the time to figure out the actual dissipation in my application, it ain't that simple.

I look at it this way: this part is designed for continuous operation at 1200V and 8A on each diode, which means 1200V at 16A for the package. I figure running it at 450V and maybe 300mA or so at maybe 70 deg C ambient is barely tickling it as far as dissipation is concerned. Of course at the rated duty it would need properly designed heatsinking.

[tubeswell]

Like others here, I also have heard audible reduction in 'buzz' using snubber caps on (1N4007) rectifier diodes, and I have tried the rectifier with and without snubber caps and there is a difference.

Mind you the unit I tried this on was a 6G15 clone (built with a FW SS rectifier using 2 diodes on each side of the HT winding), so that would've made the whole set up more prone to picking up extraneous noise (because it is in front of another amp). But the snubber cap definitely reduced the audible buzz.

FWIW this is not a myth or hearsay - it is my own experience

You haven't identified the source of the "noise." My point is that there is no audible "noise" from a good rectifier switching off or on. If you want to say a snubber cap can reduce a noise coming from the PS or line, I wouldn't argue that too far. BUT, if the amp came noisy from the factory, I'd call it a crappy amp and send it back, I wouldn't fix it by adding snubbers. If my nice quiet amp from the factory started "buzzing" I wouldn't fix it by adding snubbers. If I built a noisy amp to start with, I wouldn't fix it by adding snubbers, I'd start over or look for mistakes.

I am fairly certain that the noise that I eliminated was because of the snubbers. It was the only change I made at that time to the amp and it resulted in an audible reduction in the buzz within the noise floor.

It was an amp I built myself from scratch and it had other issues, like many scratch builds do.

Nevertheless the noise reduction (as assessed by myself in that instance) was because of the snubbers - I even took them back out to check that this was true, and the buzz re-appeared, and when I put them back in, the buzz was gone again.

This phenomenon has not only been experienced by myself, but it has also been documented by others far more knowledgeable* than me.

Having said that I am a mere hobbyist, and the observations I have made and that I share in this regard are based purely on my practical experience with my own builds.

* Merlin Blencowe for example

[73GTV]

What about the diode IN5405. Can they be used at all? 3 Amps. I have a bunch of these and I want to use them for something.

http://www.datasheetarchive.com/IN5405-datasheet.html

[20to20]

It was an amp I built myself from scratch and it had other issues, like many scratch builds do.

Nevertheless the noise reduction (as assessed by myself in that instance) was because of the snubbers - I even took them back out to check that this was true, and the buzz re-appeared, and when I put them back in, the buzz was gone again.

Don't stop looking at the design and load. You didn't think you needed snubbers in the beginning, I would assume. The most simple and quiet amps that exist, do so without them. For sure... good luck.

[David Root]

73gtv, sure, but I would still use 3 per side as they're only rated 500V each.They might/might not need snubbers.

That's another nice thing about the Stealths, they do NOT need snubbers, in fact I doubt any hexfred even the early ones needs snubbers.

[ChrisM]

You guys think UF4007 need snubbers?