Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dragonbat13 on June 20, 2022, 12:39:51 pm

Title: Cascode?
Post by: dragonbat13 on June 20, 2022, 12:39:51 pm

I was reading Merlin's preamp book about the cascode circuit and found it interesting.

Does anybody have any experience using it?

Title: Re: Cascode?
Post by: HotBluePlates on June 20, 2022, 07:50:35 pm

Quote from: dragonbat13 on June 20, 2022, 12:39:51 pm

Does anybody have any experience using it?

I have no experience using a cascode.

I was all excited about it when I first learned of it, many years ago.  I learned it essentially used two triodes to behave like a pentode.

Then others here pointed out that I could simply use a pentode & have a simpler time setting up a gain stage.

They further pointed out that while a cascode (or pentode) has more gain than a single triode, two triodes in cascade (not cascode) deliver more gain than a pentode/cascode.  Even if those two triodes are 12AU7s.

All that pretty much zapped the appeal of a cascode for me, especially once I further found out I would have issues with heater-to-cathode voltage ratings in some tubes when I try using a cascode.