Looking for a simple tube preamp build

[djn]

I did use a toroidal on the off board 20v heater supply for my GM70 and B++ for the 12GN7 driver tubes but that was on a whim. I used a custom air cleaner cover from a Harley to hide it.

I also included a pic of the chassis I made for the compactron amp.

 

[djn]

I saw this on the book. Does it have any validity? And would it work with tube rec?

A simple and cheap part can improve the current, noise and power factor..... , adjusting to ohm main stream current

 

[NickKUK]

Hmm perhaps what you’re looking for is PFC which is switching. Power correcting chokes have been used in the past but I know even less about PC chokes than i do PFC in smps
As far as i know you need the PFC on the primary side.

 

[Bandersnatch]

Hey djn!, if you like the results from adding a series resistance to a cap-input filter, you will LOVE the choke-input filter...
PSUDii is quite good enough to show the benefit you are seeking.

For a diode, examine the big damper diodes. Their only 'cost' is in heater power, but that is just a bigger heater transformer. Two 6CJ3 in || on a full wave will take the load to near 10A...no biggie. Just get a bigger air cleaner cover. S&S?

As to a schematic, examine the Ford Audio Club newsletter from 2020 where my son wrote up the construction of a 6AH4 linestage that delivered ~30 Ohm output Z...

Douglas

 

[djn]

Hi Douglas. I looked back through my emails from Jeff and couldn’t find any Ford newsletters from 2020. Do you have a copy? Dennis.

 

[Bandersnatch]

I do somewhere... should be in the SMAC forum; Jeff has posted them up for a while now.

Douglas

 

[djn]

I’ll look in the SMAC forum.

 

[djn]

I found it in google groups.

 

[Bandersnatch]

errr...that is what I meant. Good thing you are psychic...

It does not take much B+, though a wee bit more would make things easier to allow a larger operating point window to try tuning in.

Douglas

 

[djn]

I’ve been thinking about what to use as a chassis for the preamp and realized I could use bits and pieces of this radar bomb I bought this summer.

 

[Suncalc]

That is very cool. Failure to fully restore that transceiver would be criminal.

 

[Bandersnatch]

That looks a lot like the torpedo hardware I once ran across. Loads and loads of triple-mica 5814's, and 6AR6 power tubes.

Douglas