Gold mine of DI¥ audio tubes schematics from Japan

[Kay Pirinha]

Exactly !
I have to notice a small difference between your schem and the one that I've built, though: The 12AX7's cathode resistors are bypassed capacitively, mine weren't. Hence, it's insufficient bandwith might have had it's cause in the increased output impedance.



Best regards!

 

[Soundhappy]

New on line DIY articles 2005-06 🙂

 

[Lingwendil]

Man, the under-chassis shot on that 6BM8 build is gorgeous!

 

[Soundhappy]

New December articles now on line 2017-18 🙂

 

[Kay Pirinha]

Can anybody please tell me what the pentode does in this circuit?

Best regards!

 

[analog_sa]

It acts as a crude regulator/ripple killer.

 

[Soundhappy]

December update part II 2017-18 Thanks to Old Radio Boy 🙂

 

[JoeAlders]

Kay Pirinha wrote:
"Can anybody please tell me what the pentode does in this circuit?"


To me it looks like a push-pull configuration.

 

[claudio52]

Can anybody please tell me what the pentode does in this circuit?

A mu stage?
http://www.fetaudio.com/wp-content/uploads/2003/09/Mu-Stage.pdf

 

[jazbo8]

It just regulates/filters the B+ voltage for the triode stage.

 

[JoeAlders]

I do not see that as a regulation. Because the signal grid of that pentode, which then must carry some very stable reference voltage, is practically the same as the voltage supplied by that 33uF voltage.

 

[JoeAlders]

Well, I have to admit this last statement is not at all correct looking at this circuit configuration again so consider this as not written... 😱

 

[JoeAlders]

Because I am still fascinated by this circuit configuration,
isn't it something like this:

 

[Zung]

A capacitance multiplier to filter the B+, not a regulator, not crude.

 

[Pyka]

PCL83(P) act as a Pentode mode regulator or an electronic filter.

 

[Soundhappy]

Happy New DIY 2019 update 🙂
articles 2001-2002

 

[adason]

In the 70's ,80's and 90's France have L'Audiophile DiY magazine:

index

index

Best regards

Anybody knows what happened to Audiophile magazine links?

 

[Soundhappy]

@ Adason

Better if You are interested download project documentation quickly.
After we will not know if tomorrow they be still available.
"L'Audiophile" archive is down.
Maybe Wayback Machine can help ?
Internet Archive: Wayback Machine
Greetings 🙂

 

[Soundhappy]

update 2019-2020 🙂

 

[Kay Pirinha]

Well, tons of iron for just two 300b's, I'd say...
Best regards!