Can ultra fast diodes be noisy?

[12AX7]

I used some of those ultra fast diodes to replace the 1N4007's i had as my rectifier after reading about how they can improve tone a bit. I've been chasing a buzz for a month or 2 now and today i was trying to recall any changes i made around the time it started. It occurred to me that was about the time i installed those diodes, so i just had to ask before i go unsoldering them.

[FYL]

I routinely use Gen Semi UF4007s and UF5408s. No noise problems. No buzz.

[LooseChange]

I routinely use 1N4007's. No noise and save lot's of money. 

[12AX7]

I routinely use Gen Semi UF4007s and UF5408s. No noise problems. No buzz.

The UF4007's are what i used. Do you notice any difference in tone? I thought i did but very slight. Seemed like a bit less of that high end harshness. I went back to 1N's for a A/B test then again back to UF just you be sure and i was fairly sure i heard what i heard. But it was slight if not placebo effect.

[kagliostro]

1N4007 are fine

but if you want to use ultra fast diodes

isn't strictly necessary you remove the existing diodes as to substitute it

is sufficient you add one ultra fast diode in series at the exit of the existing rectifier

if ultra fast diodes are used don't use the trick to add a small capacitor in parallel with diodes or in parallel with the transformer secondary to prevent ringing

Kagliostro

[stingray_65]

Can ultra fast diodes be noisy?

Yes, when put in an old coffee can and shook like a maraca they can be noisy  

But I'm a bit of a purist, especially at campfire sing-a-longs, and use rocks instead of solid state components.

I also prefer the edgy clang of limestone and flint-rock compared to the low jangle of granite.

and it's old maxwell house cans or nuthin in my home, none of those fancy red folgers cans that are fit only for collecting screws too good to throw out, but not good enough to sort

LOL sorry it's late, I've worked too many hours and amusing myself at your expense.

But seriously, with even a low (by guitar amp standards) amount of filtering (8uf), the spiking of diodes switching should be drowned out by the ripple of the supply. UFD's IMHO are just overkill in even a hi gain guitar amp.

NOW, that does not mean that when you replaced your diodes or what ever it was you did , did not induce the buzz. Lots of small things could have gone wrong. That is just basic trouble shooting.

I think your in the right church looking at what you changed and the buzz came on, just in the wrong pew thinking its the type of parts you used.

Ray

[DummyLoad]

if you installed a defective diode, damaged one with excessive heat, installed a diode incorrectly, or have a bad connection,  then you would hear "buzz" since you'd be running with a 1/2wave filter. check your work again.

--DL

[12AX7]

Thanks all. I'll throw some 1N's back in today. Now that i've had a few months with the UF's in it my ears will be better equipped to note any difference plus if i DID damage them at all with heat and caused the buzzing i'll be happy to get rid of that.