01-12-2016, 08:28 PM
(This post was last modified: 01-12-2016, 08:31 PM by Murphyv310.)
Hi.
Yes adding a diode or diodes will up the PIV but never at 100% unless the diodes are perfect, they need to be de-rated and when I do this I de-rate by 50%.
Having spent many an hour repairing amplifiers I have come across many Marshall and other makes with a string of silicon diodes in the HT supply to up the PIV, never a balancing resistor or cap in sight!
The Metal HT rectifiers (selenium) of days gone were made of many little discs to again up the PIV, some scopes use EHT sticks of many silicon diodes in series for the same reason.
On new build amps I have overkilled on the HT rectification by using 2 IN5408 in series when 1 diode is still in spec but I use balancing resistors and 5kv caps too. My motto is do a job once and do it right!!!
Yes adding a diode or diodes will up the PIV but never at 100% unless the diodes are perfect, they need to be de-rated and when I do this I de-rate by 50%.
Having spent many an hour repairing amplifiers I have come across many Marshall and other makes with a string of silicon diodes in the HT supply to up the PIV, never a balancing resistor or cap in sight!
The Metal HT rectifiers (selenium) of days gone were made of many little discs to again up the PIV, some scopes use EHT sticks of many silicon diodes in series for the same reason.
On new build amps I have overkilled on the HT rectification by using 2 IN5408 in series when 1 diode is still in spec but I use balancing resistors and 5kv caps too. My motto is do a job once and do it right!!!
