Is this Power Section odd or not ??

[kagliostro]

I was doing a search for the schematic of a Stereo Grundig radio that uses a pair of ecl86 tubes, I got it at a Flea Market some time ago (PT and 2 x OT + Tubes donor @ 20€)

it ended to be a Grundig 3299 Stereo

Doing the search I finded one other Stereo Grundig radio schematic that uses 2 x ecl86 tubes, model so302

The schematic seems to be of a Stereo unit with two SE Power Sections BUT .....

But it is a bit odd to me, the cathodes of the pentodes of the ecl86 are both connected to a single cathode plus a single bypass capacitor






 

What is happening there ? I don't remember to have seen such a thing previously, or, better, I've seen it only in an old italian GEM guitar amp, but it was an el84 PP amp but the brand used a pair of SE OT instead of a single PP OT (the friend who restored the amp swapped the two SE OT for a single PP OT)

Have you any idea about this thing ?

THANKS

Franco

 

[PRR]

It is bypassed. It gives DC bias but "little" cross-talk on audio. 

There were push-pull stereo amps with all four power bottles on a single cathode network.

[passaloutre]

It is bypassed. It gives DC bias but "little" cross-talk on audio. 

There were push-pull stereo amps with all four power bottles on a single cathode network.

My stereo (a 60s kit amp) does that. It also uses that cathode current to run the phono preamp filament.

[kagliostro]

Thanks Friends

But if there is Cross Talk, which as far as I know we don't want, what's the reason .... to save the price of a resistor and a capacitor ?


Franco