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Dynacord DA16/V

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Racing:
Speaking of "schirmgitter"....
Iīve handled quite a few of these( DA-15īs as well as DA-16īs...18īs and 20īs..(and yes,the following applies to a Jazz or a Hall-Jazz too)) and if thereīs one thing that should be done to even a stock unit it is to calm the voltage for the g2īs down.
Seing where these amps touch down B+ wise,which dials in around the 400 mark,it is a real wise move to install a 5w zener diode vs each screen/g2.
I have used everything from 25V ones to 47V ones and seing the rather limited power digested by the g2īs of EL-84īs...theyīll run happily ever after with any choice of zener.

In my opinion though this NEEDS to be done to make the amp surefire to survive with modern day and era replacement EL-84īs.

Wuffenberg:
Hi racing,
there are already 100 Ohms in the screen grid supply, should be enough already? More is probably only needed if you plan to heavily overdrive the output tubes.

BR
Tom

Germy:
Hier ist noch einer.....

Racing:
@Tom.
No. Not really. If you check a datasheet for EL-84īs we routinely run them way way way pass what is reasonable. Spec calls for 300V maximum for g2.
Modern day n era tubes in turn are NOT what they used to be. Hence why lowering voltage for g2 is a good idea.

Whatīs more a mere fact is that a lower power amp will spend more of its life at wide open throttle,or close to it,then a more powerful amp. What the zeners bring in that case is an amp that at all times lets the anodes/plates take the load and therefore will stand up to going full blast days at end.

What the zeners do primarily,from a practical point of view,is change the g2 nodes reference and thus change the powertubes manner in which it handles transients.
In short the zeners will bring you an entire powerstage that is more "snappy" and willing to comply.

100 Ohms vs g2 in turn isnīt primarily to protect the screens. It is for EMI/RFI protection.

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