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diodes ratings and noise

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Posted on March 16, 2016 at 11:14:05
Someone has asserted that larger rated diodes, rated for higher voltage and or current (of the exact same model diode) can and or do have more noise making them a worse choice for audio if not needed. Is this true and how do you know? Thanks, Tweaker

 

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RE: diodes ratings and noise, posted on November 20, 2016 at 22:41:16
pictureguy
Audiophile

Posts: 22597
Location: SoCal
Joined: October 19, 2008
I'd say it was difficult to compare simply based on ratings.

In-Fab, the start material for each diode will be different. Processing will vary as to implants and photo steps, as well as other steps like etching and so forth. The STEPS will be the same, but measureables will be different between devices making a comparison one for the EARS.

I worked in a fab where ONE of our many products was a FRED in various voltages and such.
Too much is never enough

 

RE: diodes ratings and noise, posted on November 22, 2016 at 09:02:24
jedrider
Audiophile

Posts: 15166
Location: No. California
Joined: December 26, 2003
A lot of audio grade op-amps come in different voltage grades. I always wonder which one to choose when replacing socketed op-amps. I recently bought a batch of 5, so I choose the 40-volt capacity and not the 20-volt one as my operating voltage was mostly +-15 volts, but in one case required 24-volts.

 

RE: diodes ratings and noise, posted on November 22, 2016 at 23:40:48
pictureguy
Audiophile

Posts: 22597
Location: SoCal
Joined: October 19, 2008
When fabricating a SS device, you can make some films thicker or thinner as need arises. When doing so, you MIGHT have to make some other adjustments to the process, though in most cases the steps will be the same with minor changes. A recipe in a machine MIGHT be altered only for time, for example, to yield different film thicknesses for different voltages.

For example, devices which will work in very LOW voltage circuits may have very thin oxide (an insulator) for the GATE. But this is NOT the working voltage of a power device which may be designed to pass 100 volts and perhaps more, like in the case of soem REAL high power stuff.

The above is VASTLY oversimplified but gives you the idea. The takeaway is that a manufacturer will have a process which can be 'tilted' to yield a variety of different devices of the same type. A seperate but RELATED set of process flows will be used (and different start material) for 'N' Channel or 'P' Channel product.
Too much is never enough

 

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