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nzoomed · 24th May 2021, 11:48 am

I've put this together from different sources.

I basically want a buffered line stage with minimal gain since most digital sources today are able to drive a power amp fine, but may still require a little gain for the phono, I will have an RIAA stage fed into this for the phono input, but may need some gain depending on how much gain I get from the 6922/E88CC that it uses.

I have built on the Baxandall design found here:
https://www.angelfire.com/electronic...mp-Tone-A.html
https://www.angelfire.com/electronic...e-fig-06-1.gif

It uses a 12AU7 as a cathode follower for the input, I've modified it by adding an EF86 in triode mode at the end, which should give a modest gain, but make up for the losses in the tone stack.
The EF86 configuration is essentially based on the Svetlana preamp schematic.

I have also added balance controls and a tone bypass. I'm not 100% sure how this will behave.
Im also interested if there is a way to add NFB to the EF86 to reduce gain and improve linearity like ive read a bit about, I might be able to incorporate a switch into this, or utilize the tone bypass switch to do this, as its possible the volume/gain may increase when bypassed?

24th May 2021, 11:48 am	#1
nzoomed Pentode Join Date: Feb 2016 Location: Tauranga, New Zealand Posts: 132	Advice on this linestage build I've put this together from different sources. I basically want a buffered line stage with minimal gain since most digital sources today are able to drive a power amp fine, but may still require a little gain for the phono, I will have an RIAA stage fed into this for the phono input, but may need some gain depending on how much gain I get from the 6922/E88CC that it uses. I have built on the Baxandall design found here: https://www.angelfire.com/electronic...mp-Tone-A.html https://www.angelfire.com/electronic...e-fig-06-1.gif It uses a 12AU7 as a cathode follower for the input, I've modified it by adding an EF86 in triode mode at the end, which should give a modest gain, but make up for the losses in the tone stack. The EF86 configuration is essentially based on the Svetlana preamp schematic. I have also added balance controls and a tone bypass. I'm not 100% sure how this will behave. Im also interested if there is a way to add NFB to the EF86 to reduce gain and improve linearity like ive read a bit about, I might be able to incorporate a switch into this, or utilize the tone bypass switch to do this, as its possible the volume/gain may increase when bypassed? Attached Thumbnails