New Tube-buffered LM1875 based on MiniRef

[erikovsky]

Hi all,

I designed a new Tube-buffered LM1875, which is based on MiniRef by linxguru.

Attach schematic and PCB layout.

Any suggestions?

 

[erikovsky]

Power supply section.

20-0-20 VAC in, +-25VDC/+-15VDC/+6.3VDC.
(It's 7806 actually used.)

 

[linuxguru]

Cool - I missed this for 3+ years. I'd probably go with 6688/E180F at low rails (say +/- 12V) for the input cathode follower, but YMMV.

I'm a little confused by the 47 uF bipolar cap in the inverting (feedback) network of the Howland - it would effectively block DC and low frequencies during the operation of the current pump, and change the AC response character.

What is its purpose, and how does it sound?