Diode rectifiers

[joshdfrazier]

I'm beginning to rethink my tube purist ideology and go the diode route. As much as I love having that extra tube in there, the voltage drop, PT strain and decreased bass response just don't seem worth it. Not to mention saving more than a few bucks on parts.

I've never used diodes before. What type should I be using for a 600-700v PT?

[Ang3lus]

you could use the old and popular 1n4007, bypassing it with snubbers.

or, you could use the new UF4007, UF stands for ultra fast

[joshdfrazier]

I was going to experiment with the 4 diode bridge setup, I don't know what a snubber is.

[eddie25]

I was going to experiment with the 4 diode bridge setup, I don't know what a snubber is.

He was talking about the type of diode to use for your bridge.

Some people say there is a switching noise from when the diode turns on and off constantly, so a snubber is a cap across each diode that prevents this. Or, as he suggested, you can use UF4007 instead of regular 1n4007 diodes which are faster and will prevent switching noise as well.

You can also purchase a bridge rectifier that's in a convenient little package, with 4 solder tabs. I use these often when I need space since you can install them directly to the chassis.

[Structo]

I have the UF4007 in my 100w D amp.

Originally I put the snubber caps on them but I later read that they can cause noise on a fast diode, so I clipped them.

Probably bad ears but I can't tell a difference.

[martin manning]

Good reading here: http://www.valvewizard.co.uk/bridge.html

[joshdfrazier]

thanks martin, that is a great read. looks like i will be checking out the uf4007

[telentubes]

Timely topic for me as I just finished making the rectifier board for my new Small Special. I plan on using the .01/1000V ceramic caps as snubbers, parallel to the diodes, but have read that adding 470K resistors , also parallel, will give better performance.
Anybody ever tried the .01uf snubbers/470K resistor/ diode combination?

[Bob Simpson]

turretboards.com has a rectifier mod kit just like that...

Bob

[Phil_S]

To put a fine point on the discussion, tube rectifiers are diodes. Just sayin'... you know...

[Meat&Beer]

^+1 Mr. Phil!

I'm just gonna put this right here, skip to about the 3:10 mark.

http://www.youtube.com/watch?v=wkw1sz3QVOE

I'm awful, I know.

[EtherealWidow]

Edit: Asked why snubbers wouldn't void a rectifier since they passed AC, then googled it. Sorry about that.

http://en.wikipedia.org/wiki/Snubber

[telentubes]

turretboards.com. That's what I built. Cool. Credibility.

[pdf64]

Despite being ubiquitous, 1000V rated diodes in FW / bi-phase tube amp B+ power supplies are often marginal, or used in excess of their voltage rating, especially in conjunction with a standby that removes the load from the B+ winding.
700 x 1.414 = 990V
Pete

[martin manning]

Despite being ubiquitous, 1000V rated diodes in FW / bi-phase tube amp B+ power supplies are often marginal, or used in excess of their voltage rating, especially in conjunction with a standby that removes the load from the B+ winding.
700 x 1.414 = 990V
Pete

Hence 2 or more in series. The caps are probably a good idea to help balance the voltage across each diode, but I'm not convinced that UF4007's will make any difference at 60Hz. Slower silicon diodes might even be quieter.