DIY Audio Projects Forum

I see in all the schematics I have seen so far on the high voltage side of the transformer the rectifier of choice is a full wave rectifier made up of 4 diodes as opposed to a bridge rectifier.
Is there any particular reason for this?

As far as I know, you can find better single diodes rather than rectifiers.

They can be faster (shottky), less noisy and you can use snubber capacitors.


Cheers!

that could be why a head phone amp that i made has a hum in it

Thank you

It will not be a diode bridge causing hum more like lack of filtering or a bad earth somewhere. Generally single diodes can produce a less noisy DC depending on diodes. Each diode or rec. bridge wire should have a 0.01uf poly cap across it (snubbing). This helps reduce any noise further. Lately I have been using rec. bridges over single diodes and just snubbing them.

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Projects: Oatley K272C - headphone amp in a tin can | "VoXDeuX" - Inexpensive two-way speaker | "VoXItBassO" - stereo 12" sub-woofers ]
Website: [ retro-thermionic ]

Four diodes does comprise a "bridge rectifier".

If you see either of these representations in a schema, it is a bridge rectifier (the top is the most common).


Since I am assuming you're referencing the little (or big) 4-pin devices which are in fact an integrated bridge rectifier, the symbol for that is the same, though sometimes a square box or circle showing 4 connections and being labelled as BR# do show up. It should be noted, however, you can not, to my knowledge, obtain fast recovery integrated bridge rectifiers. Therefore, if you want a low noise "bridge", you need to build it from 4 UF400x diodes rather than the 1N400x type.

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The key to a successful build is to keep the smoke IN the circuit.
-Les

Science without religion is lame, religion without science is blind. - Albert Einstien
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LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board
Current project: 6V6 "pseudo Champ" prototype
Still to come (On hold): 6CG7/12AX7 Guitar amp (modified FireFly)

actually the number on them is mb152 they have spade terminals on them and ill increase the filtering to see if that dose the trick.
http://diyaudioprojects.com/Solid/12AU7 ... 17-Headamp

That's the on I have built. I think it turned out pretty well other than the hum that i will fix and as soon as i do get it fixed i will build a stereo tube amp not sure which one i will build(maybe the podwatt or the oddwatt). I have been a hobbyist from about 12 years of age. When my kids were born i didn't do much but now 25 years later something sparked an interest back again.

While the comments are for single diodes to make up a "full wave" rectifier industrial enclosed bridge rectifiers of high quality do exist but are a lot dearer than the normal domestic supply to the public..