Komet B+ Diode

[megawhat]

I've been searching on some info on this. technical description of what this is doing and how it works.

From what I've read, it is in the Torres book and maintains the preamp voltages somewhat.

I don't have access to the book, but can anyone explain what is going on here, and if they have experimented with this...

much appreciated!

[Colossal]

Can you be more specific about which Komet and which diode(s) specifically you are asking about? Rectifier diode? If you are talking about the series of three diodes connecting each power tube plate to ground, they are to protect the output tubes and OT against flyback transients. There are no clipping diodes in the K50, K60 or Constellation if that's what you meant...

[megawhat]

Im talking about the 1N4007 diode in the B+ line of the Komet 60
the one that sits between the points feed the power section and the preamp section.

not the rectifiers and not any other diodes.


second page, at the bottom, between the B+3 and the 10k dropping resistor.

[paulster]

When the power tubes draw loads of current they'll pull down the voltage on the filter caps that are supplying them. At this point the preamp filter caps will be sat at a higher voltage so current will flow the opposite way to normal and they'll try to charge the power amp filter caps to equalise the voltage, dragging their own voltage down along the way.

The diode means that this can't happen and the only thing that will reduce the voltage on the preamp filters is the current drawn by the preamp tubes, so you won't get the same level of power supply compression in the preamp stages.

Hope that 10 second reply makes sense!

[Merlinb]

I think you mean this schem:
http://www.schematicheaven.com/newamps/komet.pdf

It stops the power amp from sucking charge out of the preamp caps during loud passages.

[JamesHealey]

Interesting idea, I think I shall try this on an amp I've just made.

[Andy Le Blanc]

It isolates and decouples, it also reduces power supply instability and motorboating.
Might be a sign of just how unstable the design intention really is.

[megawhat]

Interesting idea, I think I shall try this on an amp I've just made.

If you try it i'd like to hear a report

the 10 seconds reply is fine... now I have that extra bit of detail i understand what is happening.

cheers everyone!