Mullard 3-3 is not amazing

[jewishjay]

A while back I built this stereo by combining the RIAA phono preamp right out of the RCA tube recieveing manual with the classic Mullard 3-3. The first image is what I built, and it does sound great at half volume or less.

But it has some odd design choices that make it less than ideal. The EF86 runs in almost starvation mode at extreamly low voltage, and is DC coupled to the output stage. I noticed as I turn the volume above 50% the grid of the EL84 goes positive and cuts off.

So I'm thinking of slightly redesigning to a more normal EF86 stage and AC coupled output. The second image is what I'm thinking of building. Any input is welcome, I'm still just "thinking about it."

[PRR]

So what is the bias on the EL84 and what is the Z of the OT?

[HotBluePlates]

A while back I built this stereo ... with the classic Mullard 3-3. ...

But it has some odd design choices that make it less than ideal. ...

Except there are changes around the power supply of the Mullard 3w circuit that changed the plate-load of the EF86 and the screen-connection of the EL84.  As a result, the "classic Mullard 3-3" wasn't built.

Ya gotta include "all the bits" lest the parts left out are the reason for the uninspiring performance (here, that includes some attenuation of the EF86's output).

Mullard Circuits for Audio Amplifiers

[scstill]

I was surprised at how clean and organized the original point wired chassis is on this design
http://www.r-type.org/articles/art-003h.htm

 

[jewishjay]

So what is the bias on the EL84 and what is the Z of the OT?

35ma and 8k....but it also has a 5k tap

[shooter]

nice collection of 20th century reading, saved both, thanks.

[glass54]

+1 Shooter
I was very fortunate to score this booklet in the early 1990's from a man who used to build/maintain cinema sound systems in Sydney
(Australia). He actually lent it to me BUT died shortly after (late 80's), so his wife thought I would benefit as the new owner, because she had no use for it. Fantastic gift 
Regards
Mirek