1N4007 vs. UF4007?

[kleinm]

I was curious if you guys had any experience using UF4007 rectifier diodes in high-gain amplifiers? I've read they can dramatically lower background hum, but I'm also wondering if they'll drop the B+ a little due to the different forward voltage?

I bought a handful to use in my rebuild of the D-type amp I built, and was curious if there is anything I need to beware.

Here are links to Fairchild's datasheets.
http://www.fairchildsemi.com/ds/1N/1N4007.pdf
http://www.fairchildsemi.com/ds/UF/UF4007.pdf

Thanks for the input.

[glasman]

I was curious if you guys had any experience using UF4007 rectifier diodes in high-gain amplifiers? I've read they can dramatically lower background hum, but I'm also wondering if they'll drop the B+ a little due to the different forward voltage?

I bought a handful to use in my rebuild of the D-type amp I built, and was curious if there is anything I need to beware.

Here are links to Fairchild's datasheets.
http://www.fairchildsemi.com/ds/1N/1N4007.pdf
http://www.fairchildsemi.com/ds/UF/UF4007.pdf

Thanks for the input.

I have been using the UF4007 for a few years now. I like them. Not sure if a mere mortal will really hear a diffeence. But it is faster than the 1N4007 and a cost acceptable alternative to a FRED.

Gary

[kleinm]

I have been using the UF4007 for a few years now. I like them. Not sure if a mere mortal will really hear a diffeence. But it is faster than the 1N4007 and a cost acceptable alternative to a FRED.

Gary

Great, thanks for the input Gary! I'll start with them first for my rebuild.

[jaysg]

One of the guys at the old Ampage convinced me to switch over to the UF's for all 1N400n parts. It might have been Rick Ericsson (sp?). He had a notion that the 1N's aren't actually fast enough for the 3x1N4007 strings to output plates that KF liked.

[d2camero]

so...

reverse recovery times:

1N4007 30us
US4007 75ns
Hexfred IR HFA04TB60 60ns


Are there any other reasons to use a more expensive FRED in a guitar amp other than recovery time?

[mhuss]

FRED just sounds cooler.

+1 I've been using the UF series for all my builds.

--mark

[s2]

I've been using them for a while now too. They were roughly the same price as 1Ns when purchased 1,000 at a time, so I figured why not?

My dog won't tell me if she can hear a difference though.

[krash]

I use UF's in everything. And just one per side, so a total of two in an amp.

A little more expensive than a 1N but you only need 1/3 of them per amp.

less parts, less assembly time, less to break...

[roberto]

What about a (EDIT) bridge rectifier (EDIT) with 1N4007s bypassed by 1nF 1kV ceramic caps?

PS
Thanks tele for the correction, I was drawning a wheatstone bridge and made a typo.

The question is the same. Why don't just use the bypassed bridge as usual in many schemes?

[tele_player]

A bridge rectifier is not a wheatstone bridge.

[novosibir]

I was curious if you guys had any experience using UF4007 rectifier diodes in high-gain amplifiers? I've read they can dramatically lower background hum, but I'm also wondering if they'll drop the B+ a little due to the different forward voltage?

The UF's don't drop the B+ voltage and they also don't reduce hum.

What UF's are doing, is reducing the background buzz.

The switching delay of regular diodes is producing all kind of additional frequencies until up into the RF range, from which we may hear the lower frequent artifacts as the well known buzzzzzzzz.

The way this is going is not as on the first sight assumed, that this buzz is riding on the HT voltage rail and fed into the tube's plates, because these artifacts usually a good filtering is suppressing.

It's going, that from the HT rectification these artifacts first are fed back into the PT, where they will be transformed onto the heater's secondary, riding on the heater's supply and then from the preamp filament will be capacitive fed into the preamp cathodes.

I'm using UF's meanwhile a few years in all of my builds, but for the HT supply the UF5408, which is a 3A type, which you can see here in comparasion to one UF4007 (bias supply), which is located next to it:

http://www.larry-amplification.de/galle ... ture&id=94

.. and I'd never go back to the regular diodes. Not only the buzz is disappearing, also the highs of the amp become sweeter, since the buzz artifacts cannot't modulate with the guitar frequencies anymore.

Very important! Don't forget the UF also for the bias supply!

Larry

[El_Martin]

Hi Larry!

Do you use any kind of parallel lo cap (0,1 uF) or rc-combination on your UF rectis?

On my latest built -a Trainwreck- I see those switching peaks even in the output...

Ciao
Martin
PS Merry Christmas to Nuernberg, home of the Christkind

[Normster]

Totally off topic, but every time I see one of Larry's builds I want to hang up my soldering iron and call it quits. Beautiful work!!!

[novosibir]

Do you use any kind of parallel lo cap (0,1 uF) or rc-combination on your UF rectis?

Yes, I have a .1/1100V Polypropylene directly on the diodes from plus to minus and another .047/1100V after Standby just in front of the choke.

On my latest built -a Trainwreck- I see those switching peaks even in the output...

Do you have also an UF in the bias supply? If not, that might be the cause.

If yes, then:
Nothin' is perfect in our real world, also UF's aren't

But when you do have peaks in the output, although UF's everywhere, then they are presumably coming from the B+ to the output plates - and then presumably you might have filter caps with a high ESR (IC's, JJ's, TAD's ?)

Try the Polypropylenes, as suggested above and maybe better go with F&T's or Sprague's as for the filter caps.

Larry

[novosibir]

... every time I see one of Larry's builds I want to hang up my soldering iron and call it quits. Beautiful work!!!

Thanks Norm for your kind words!
When you're saying this, it even counts twice

Larry